README.md

@@ -1,5 +1,5 @@
 # Micro
-![Coverage](https://img.shields.io/badge/Coverage-43.9%25-yellow)
+![Coverage](https://img.shields.io/badge/Coverage-44.6%25-yellow)
 [![License](https://img.shields.io/:license-apache-blue.svg)](https://opensource.org/licenses/Apache-2.0)
 [![Doc](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/go.unistack.org/micro/v3?tab=overview)
 [![Status](https://git.unistack.org/unistack-org/micro/actions/workflows/job_tests.yml/badge.svg?branch=v3)](https://git.unistack.org/unistack-org/micro/actions?query=workflow%3Abuild+branch%3Av3+event%3Apush)

broker/broker.go

@@ -6,8 +6,8 @@ import (
 	"errors"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
 )
 
 // DefaultBroker default memory broker
@@ -18,10 +18,6 @@ var (
 	ErrNotConnected = errors.New("broker not connected")
 	// ErrDisconnected returns when broker disconnected
 	ErrDisconnected = errors.New("broker disconnected")
-	// ErrInvalidMessage returns when invalid Message passed
-	ErrInvalidMessage = errors.New("invalid message")
-	// ErrInvalidHandler returns when subscriber passed to Subscribe
-	ErrInvalidHandler = errors.New("invalid handler")
 	// DefaultGracefulTimeout
 	DefaultGracefulTimeout = 5 * time.Second
 )
@@ -40,12 +36,14 @@ type Broker interface {
 	Connect(ctx context.Context) error
 	// Disconnect disconnect from broker
 	Disconnect(ctx context.Context) error
-	// NewMessage create new broker message to publish.
-	NewMessage(ctx context.Context, hdr metadata.Metadata, body interface{}, opts ...PublishOption) (Message, error)
 	// Publish message to broker topic
-	Publish(ctx context.Context, topic string, messages ...Message) error
+	Publish(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error
 	// Subscribe subscribes to topic message via handler
-	Subscribe(ctx context.Context, topic string, handler interface{}, opts ...SubscribeOption) (Subscriber, error)
+	Subscribe(ctx context.Context, topic string, h Handler, opts ...SubscribeOption) (Subscriber, error)
+	// BatchPublish messages to broker with multiple topics
+	BatchPublish(ctx context.Context, msgs []*Message, opts ...PublishOption) error
+	// BatchSubscribe subscribes to topic messages via handler
+	BatchSubscribe(ctx context.Context, topic string, h BatchHandler, opts ...SubscribeOption) (Subscriber, error)
 	// String type of broker
 	String() string
 	// Live returns broker liveness
@@ -57,27 +55,72 @@ type Broker interface {
 }
 
 type (
-	FuncPublish   func(ctx context.Context, topic string, messages ...Message) error
+	FuncPublish        func(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error
 	HookPublish        func(next FuncPublish) FuncPublish
-	FuncSubscribe func(ctx context.Context, topic string, handler interface{}, opts ...SubscribeOption) (Subscriber, error)
+	FuncBatchPublish   func(ctx context.Context, msgs []*Message, opts ...PublishOption) error
+	HookBatchPublish   func(next FuncBatchPublish) FuncBatchPublish
+	FuncSubscribe      func(ctx context.Context, topic string, h Handler, opts ...SubscribeOption) (Subscriber, error)
 	HookSubscribe      func(next FuncSubscribe) FuncSubscribe
+	FuncBatchSubscribe func(ctx context.Context, topic string, h BatchHandler, opts ...SubscribeOption) (Subscriber, error)
+	HookBatchSubscribe func(next FuncBatchSubscribe) FuncBatchSubscribe
 )
 
-// Message is given to a subscription handler for processing
+// Handler is used to process messages via a subscription of a topic.
-type Message interface {
+type Handler func(Event) error
-	// Context for the message.
+
+// Events contains multiple events
+type Events []Event
+
+// Ack try to ack all events and return
+func (evs Events) Ack() error {
+	var err error
+	for _, ev := range evs {
+		if err = ev.Ack(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// SetError sets error on event
+func (evs Events) SetError(err error) {
+	for _, ev := range evs {
+		ev.SetError(err)
+	}
+}
+
+// BatchHandler is used to process messages in batches via a subscription of a topic.
+type BatchHandler func(Events) error
+
+// Event is given to a subscription handler for processing
+type Event interface {
+	// Context return context.Context for event
 	Context() context.Context
-	// Topic returns message destination topic.
+	// Topic returns event topic
 	Topic() string
-	// Header returns message headers.
+	// Message returns broker message
-	Header() metadata.Metadata
+	Message() *Message
-	// Body returns broker message []byte slice
+	// Ack acknowledge message
-	Body() []byte
-	// Unmarshal try to decode message body to dst.
-	// This is helper method that uses codec.Unmarshal.
-	Unmarshal(dst interface{}, opts ...codec.Option) error
-	// Ack acknowledge message if supported.
 	Ack() error
+	// Error returns message error (like decoding errors or some other)
+	Error() error
+	// SetError set event processing error
+	SetError(err error)
+}
+
+// Message is used to transfer data
+type Message struct {
+	// Header contains message metadata
+	Header metadata.Metadata
+	// Body contains message body
+	Body codec.RawMessage
+}
+
+// NewMessage create broker message with topic filled
+func NewMessage(topic string) *Message {
+	m := &Message{Header: metadata.New(2)}
+	m.Header.Set(metadata.HeaderTopic, topic)
+	return m
 }
 
 // Subscriber is a convenience return type for the Subscribe method

broker/context.go

@@ -51,3 +51,13 @@ func SetOption(k, v interface{}) Option {
 		o.Context = context.WithValue(o.Context, k, v)
 	}
 }
+
+// SetPublishOption returns a function to setup a context with given value
+func SetPublishOption(k, v interface{}) PublishOption {
+	return func(o *PublishOptions) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, k, v)
+	}
+}

broker/context_test.go

@@ -49,6 +49,17 @@ func TestSetSubscribeOption(t *testing.T) {
 	}
 }
 
+func TestSetPublishOption(t *testing.T) {
+	type key struct{}
+	o := SetPublishOption(key{}, "test")
+	opts := &PublishOptions{}
+	o(opts)
+
+	if v, ok := opts.Context.Value(key{}).(string); !ok || v == "" {
+		t.Fatal("SetPublishOption not works")
+	}
+}
+
 func TestSetOption(t *testing.T) {
 	type key struct{}
 	o := SetOption(key{}, "test")

broker/memory/memory.go

@@ -2,104 +2,66 @@ package broker
 
 import (
 	"context"
-	"strings"
 	"sync"
 
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/options"
+	maddr "go.unistack.org/micro/v3/util/addr"
-	maddr "go.unistack.org/micro/v4/util/addr"
+	"go.unistack.org/micro/v3/util/id"
-	"go.unistack.org/micro/v4/util/id"
+	mnet "go.unistack.org/micro/v3/util/net"
-	mnet "go.unistack.org/micro/v4/util/net"
+	"go.unistack.org/micro/v3/util/rand"
-	"go.unistack.org/micro/v4/util/rand"
 )
 
-type Broker struct {
+type memoryBroker struct {
 	funcPublish        broker.FuncPublish
+	funcBatchPublish   broker.FuncBatchPublish
 	funcSubscribe      broker.FuncSubscribe
-	subscribers   map[string][]*Subscriber
+	funcBatchSubscribe broker.FuncBatchSubscribe
+	subscribers        map[string][]*memorySubscriber
 	addr               string
 	opts               broker.Options
 	sync.RWMutex
 	connected bool
 }
 
-type memoryMessage struct {
+type memoryEvent struct {
-	c     codec.Codec
+	err     error
+	message interface{}
 	topic   string
-	ctx   context.Context
+	opts    broker.Options
-	body  []byte
-	hdr   metadata.Metadata
-	opts  broker.PublishOptions
 }
 
-func (m *memoryMessage) Ack() error {
+type memorySubscriber struct {
-	return nil
-}
-
-func (m *memoryMessage) Body() []byte {
-	return m.body
-}
-
-func (m *memoryMessage) Header() metadata.Metadata {
-	return m.hdr
-}
-
-func (m *memoryMessage) Context() context.Context {
-	return m.ctx
-}
-
-func (m *memoryMessage) Topic() string {
-	return ""
-}
-
-func (m *memoryMessage) Unmarshal(dst interface{}, opts ...codec.Option) error {
-	return m.c.Unmarshal(m.body, dst)
-}
-
-type Subscriber struct {
 	ctx          context.Context
 	exit         chan bool
-	handler interface{}
+	handler      broker.Handler
+	batchhandler broker.BatchHandler
 	id           string
 	topic        string
 	opts         broker.SubscribeOptions
 }
 
-func (b *Broker) newCodec(ct string) (codec.Codec, error) {
+func (m *memoryBroker) Options() broker.Options {
-	if idx := strings.IndexRune(ct, ';'); idx >= 0 {
+	return m.opts
-		ct = ct[:idx]
-	}
-	b.RLock()
-	c, ok := b.opts.Codecs[ct]
-	b.RUnlock()
-	if ok {
-		return c, nil
-	}
-	return nil, codec.ErrUnknownContentType
 }
 
-func (b *Broker) Options() broker.Options {
+func (m *memoryBroker) Address() string {
-	return b.opts
+	return m.addr
 }
 
-func (b *Broker) Address() string {
+func (m *memoryBroker) Connect(ctx context.Context) error {
-	return b.addr
-}
-
-func (b *Broker) Connect(ctx context.Context) error {
 	select {
 	case <-ctx.Done():
 		return ctx.Err()
 	default:
 	}
 
-	b.Lock()
+	m.Lock()
-	defer b.Unlock()
+	defer m.Unlock()
 
-	if b.connected {
+	if m.connected {
 		return nil
 	}
 
@@ -113,128 +75,156 @@ func (b *Broker) Connect(ctx context.Context) error {
 	// set addr with port
 	addr = mnet.HostPort(addr, 10000+i)
 
-	b.addr = addr
+	m.addr = addr
-	b.connected = true
+	m.connected = true
 
 	return nil
 }
 
-func (b *Broker) Disconnect(ctx context.Context) error {
+func (m *memoryBroker) Disconnect(ctx context.Context) error {
 	select {
 	case <-ctx.Done():
 		return ctx.Err()
 	default:
 	}
 
-	b.Lock()
+	m.Lock()
-	defer b.Unlock()
+	defer m.Unlock()
 
-	if !b.connected {
+	if !m.connected {
 		return nil
 	}
 
-	b.connected = false
+	m.connected = false
 	return nil
 }
 
-func (b *Broker) Init(opts ...broker.Option) error {
+func (m *memoryBroker) Init(opts ...broker.Option) error {
 	for _, o := range opts {
-		o(&b.opts)
+		o(&m.opts)
 	}
 
-	b.funcPublish = b.fnPublish
+	m.funcPublish = m.fnPublish
-	b.funcSubscribe = b.fnSubscribe
+	m.funcBatchPublish = m.fnBatchPublish
+	m.funcSubscribe = m.fnSubscribe
+	m.funcBatchSubscribe = m.fnBatchSubscribe
 
-	b.opts.Hooks.EachPrev(func(hook options.Hook) {
+	m.opts.Hooks.EachPrev(func(hook options.Hook) {
 		switch h := hook.(type) {
 		case broker.HookPublish:
-			b.funcPublish = h(b.funcPublish)
+			m.funcPublish = h(m.funcPublish)
+		case broker.HookBatchPublish:
+			m.funcBatchPublish = h(m.funcBatchPublish)
 		case broker.HookSubscribe:
-			b.funcSubscribe = h(b.funcSubscribe)
+			m.funcSubscribe = h(m.funcSubscribe)
+		case broker.HookBatchSubscribe:
+			m.funcBatchSubscribe = h(m.funcBatchSubscribe)
 		}
 	})
 
 	return nil
 }
 
-func (b *Broker) NewMessage(ctx context.Context, hdr metadata.Metadata, body interface{}, opts ...broker.PublishOption) (broker.Message, error) {
+func (m *memoryBroker) Publish(ctx context.Context, topic string, msg *broker.Message, opts ...broker.PublishOption) error {
-	options := broker.NewPublishOptions(opts...)
+	return m.funcPublish(ctx, topic, msg, opts...)
-	m := &memoryMessage{ctx: ctx, hdr: hdr, opts: options}
-	c, err := b.newCodec(m.opts.ContentType)
-	if err == nil {
-		m.body, err = c.Marshal(body)
-	}
-	if err != nil {
-		return nil, err
-	}
-
-	return m, nil
 }
 
-func (b *Broker) Publish(ctx context.Context, topic string, messages ...broker.Message) error {
+func (m *memoryBroker) fnPublish(ctx context.Context, topic string, msg *broker.Message, opts ...broker.PublishOption) error {
-	return b.funcPublish(ctx, topic, messages...)
+	msg.Header.Set(metadata.HeaderTopic, topic)
+	return m.publish(ctx, []*broker.Message{msg}, opts...)
 }
 
-func (b *Broker) fnPublish(ctx context.Context, topic string, messages ...broker.Message) error {
+func (m *memoryBroker) BatchPublish(ctx context.Context, msgs []*broker.Message, opts ...broker.PublishOption) error {
-	return b.publish(ctx, topic, messages...)
+	return m.funcBatchPublish(ctx, msgs, opts...)
 }
 
-func (b *Broker) publish(ctx context.Context, topic string, messages ...broker.Message) error {
+func (m *memoryBroker) fnBatchPublish(ctx context.Context, msgs []*broker.Message, opts ...broker.PublishOption) error {
-	b.RLock()
+	return m.publish(ctx, msgs, opts...)
-	if !b.connected {
+}
-		b.RUnlock()
+
+func (m *memoryBroker) publish(ctx context.Context, msgs []*broker.Message, opts ...broker.PublishOption) error {
+	m.RLock()
+	if !m.connected {
+		m.RUnlock()
 		return broker.ErrNotConnected
 	}
-	b.RUnlock()
+	m.RUnlock()
+
+	var err error
 
 	select {
 	case <-ctx.Done():
 		return ctx.Err()
 	default:
+		options := broker.NewPublishOptions(opts...)
+
+		msgTopicMap := make(map[string]broker.Events)
+		for _, v := range msgs {
+			p := &memoryEvent{opts: m.opts}
+
+			if m.opts.Codec == nil || options.BodyOnly {
+				p.topic, _ = v.Header.Get(metadata.HeaderTopic)
+				p.message = v.Body
+			} else {
+				p.topic, _ = v.Header.Get(metadata.HeaderTopic)
+				p.message, err = m.opts.Codec.Marshal(v)
+				if err != nil {
+					return err
+				}
+			}
+			msgTopicMap[p.topic] = append(msgTopicMap[p.topic], p)
 		}
 
-	b.RLock()
+		beh := m.opts.BatchErrorHandler
-	subs, ok := b.subscribers[topic]
+		eh := m.opts.ErrorHandler
-	b.RUnlock()
+
+		for t, ms := range msgTopicMap {
+			m.RLock()
+			subs, ok := m.subscribers[t]
+			m.RUnlock()
 			if !ok {
-		return nil
+				continue
 			}
 
-	var err error
-
 			for _, sub := range subs {
-		switch s := sub.handler.(type) {
+				if sub.opts.BatchErrorHandler != nil {
-		default:
+					beh = sub.opts.BatchErrorHandler
-			if b.opts.Logger.V(logger.ErrorLevel) {
-				b.opts.Logger.Error(ctx, "broker  handler error", broker.ErrInvalidHandler)
 				}
-		case func(broker.Message) error:
+				if sub.opts.ErrorHandler != nil {
-			for _, message := range messages {
+					eh = sub.opts.ErrorHandler
-				msg, ok := message.(*memoryMessage)
+				}
-				if !ok {
+
-					if b.opts.Logger.V(logger.ErrorLevel) {
+				switch {
-						b.opts.Logger.Error(ctx, "broker handler error", broker.ErrInvalidMessage)
+				// batch processing
+				case sub.batchhandler != nil:
+					if err = sub.batchhandler(ms); err != nil {
+						ms.SetError(err)
+						if beh != nil {
+							_ = beh(ms)
+						} else if m.opts.Logger.V(logger.ErrorLevel) {
+							m.opts.Logger.Error(m.opts.Context, err.Error())
+						}
+					} else if sub.opts.AutoAck {
+						if err = ms.Ack(); err != nil {
+							m.opts.Logger.Error(m.opts.Context, "broker ack error", err)
 						}
 					}
-				msg.topic = topic
+					// single processing
-				if err = s(msg); err == nil && sub.opts.AutoAck {
+				case sub.handler != nil:
-					err = msg.Ack()
+					for _, p := range ms {
+						if err = sub.handler(p); err != nil {
+							p.SetError(err)
+							if eh != nil {
+								_ = eh(p)
+							} else if m.opts.Logger.V(logger.ErrorLevel) {
+								m.opts.Logger.Error(m.opts.Context, "broker handler error", err)
 							}
-				if err != nil {
+						} else if sub.opts.AutoAck {
-					if b.opts.Logger.V(logger.ErrorLevel) {
+							if err = p.Ack(); err != nil {
-						b.opts.Logger.Error(ctx, "broker handler error", err)
+								m.opts.Logger.Error(m.opts.Context, "broker ack error", err)
 							}
 						}
 					}
-		case func([]broker.Message) error:
-			if err = s(messages); err == nil && sub.opts.AutoAck {
-				for _, message := range messages {
-					err = message.Ack()
-					if err != nil {
-						if b.opts.Logger.V(logger.ErrorLevel) {
-							b.opts.Logger.Error(ctx, "broker handler error", err)
-						}
-					}
 				}
 			}
 		}
@@ -243,21 +233,17 @@ func (b *Broker) publish(ctx context.Context, topic string, messages ...broker.M
 	return nil
 }
 
-func (b *Broker) Subscribe(ctx context.Context, topic string, handler interface{}, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+func (m *memoryBroker) BatchSubscribe(ctx context.Context, topic string, handler broker.BatchHandler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
-	return b.funcSubscribe(ctx, topic, handler, opts...)
+	return m.funcBatchSubscribe(ctx, topic, handler, opts...)
 }
 
-func (b *Broker) fnSubscribe(ctx context.Context, topic string, handler interface{}, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+func (m *memoryBroker) fnBatchSubscribe(ctx context.Context, topic string, handler broker.BatchHandler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
-	if err := broker.IsValidHandler(handler); err != nil {
+	m.RLock()
-		return nil, err
+	if !m.connected {
-	}
+		m.RUnlock()
-
-	b.RLock()
-	if !b.connected {
-		b.RUnlock()
 		return nil, broker.ErrNotConnected
 	}
-	b.RUnlock()
+	m.RUnlock()
 
 	sid, err := id.New()
 	if err != nil {
@@ -266,7 +252,56 @@ func (b *Broker) fnSubscribe(ctx context.Context, topic string, handler interfac
 
 	options := broker.NewSubscribeOptions(opts...)
 
-	sub := &Subscriber{
+	sub := &memorySubscriber{
+		exit:         make(chan bool, 1),
+		id:           sid,
+		topic:        topic,
+		batchhandler: handler,
+		opts:         options,
+		ctx:          ctx,
+	}
+
+	m.Lock()
+	m.subscribers[topic] = append(m.subscribers[topic], sub)
+	m.Unlock()
+
+	go func() {
+		<-sub.exit
+		m.Lock()
+		newSubscribers := make([]*memorySubscriber, 0, len(m.subscribers)-1)
+		for _, sb := range m.subscribers[topic] {
+			if sb.id == sub.id {
+				continue
+			}
+			newSubscribers = append(newSubscribers, sb)
+		}
+		m.subscribers[topic] = newSubscribers
+		m.Unlock()
+	}()
+
+	return sub, nil
+}
+
+func (m *memoryBroker) Subscribe(ctx context.Context, topic string, handler broker.Handler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+	return m.funcSubscribe(ctx, topic, handler, opts...)
+}
+
+func (m *memoryBroker) fnSubscribe(ctx context.Context, topic string, handler broker.Handler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+	m.RLock()
+	if !m.connected {
+		m.RUnlock()
+		return nil, broker.ErrNotConnected
+	}
+	m.RUnlock()
+
+	sid, err := id.New()
+	if err != nil {
+		return nil, err
+	}
+
+	options := broker.NewSubscribeOptions(opts...)
+
+	sub := &memorySubscriber{
 		exit:    make(chan bool, 1),
 		id:      sid,
 		topic:   topic,
@@ -275,64 +310,102 @@ func (b *Broker) fnSubscribe(ctx context.Context, topic string, handler interfac
 		ctx:     ctx,
 	}
 
-	b.Lock()
+	m.Lock()
-	b.subscribers[topic] = append(b.subscribers[topic], sub)
+	m.subscribers[topic] = append(m.subscribers[topic], sub)
-	b.Unlock()
+	m.Unlock()
 
 	go func() {
 		<-sub.exit
-		b.Lock()
+		m.Lock()
-		newSubscribers := make([]*Subscriber, 0, len(b.subscribers)-1)
+		newSubscribers := make([]*memorySubscriber, 0, len(m.subscribers)-1)
-		for _, sb := range b.subscribers[topic] {
+		for _, sb := range m.subscribers[topic] {
 			if sb.id == sub.id {
 				continue
 			}
 			newSubscribers = append(newSubscribers, sb)
 		}
-		b.subscribers[topic] = newSubscribers
+		m.subscribers[topic] = newSubscribers
-		b.Unlock()
+		m.Unlock()
 	}()
 
 	return sub, nil
 }
 
-func (b *Broker) String() string {
+func (m *memoryBroker) String() string {
 	return "memory"
 }
 
-func (b *Broker) Name() string {
+func (m *memoryBroker) Name() string {
-	return b.opts.Name
+	return m.opts.Name
 }
 
-func (b *Broker) Live() bool {
+func (m *memoryBroker) Live() bool {
 	return true
 }
 
-func (b *Broker) Ready() bool {
+func (m *memoryBroker) Ready() bool {
 	return true
 }
 
-func (b *Broker) Health() bool {
+func (m *memoryBroker) Health() bool {
 	return true
 }
 
-func (m *Subscriber) Options() broker.SubscribeOptions {
+func (m *memoryEvent) Topic() string {
-	return m.opts
-}
-
-func (m *Subscriber) Topic() string {
 	return m.topic
 }
 
-func (m *Subscriber) Unsubscribe(ctx context.Context) error {
+func (m *memoryEvent) Message() *broker.Message {
+	switch v := m.message.(type) {
+	case *broker.Message:
+		return v
+	case []byte:
+		msg := &broker.Message{}
+		if err := m.opts.Codec.Unmarshal(v, msg); err != nil {
+			if m.opts.Logger.V(logger.ErrorLevel) {
+				m.opts.Logger.Error(m.opts.Context, "[memory]: failed to unmarshal: %v", err)
+			}
+			return nil
+		}
+		return msg
+	}
+
+	return nil
+}
+
+func (m *memoryEvent) Ack() error {
+	return nil
+}
+
+func (m *memoryEvent) Error() error {
+	return m.err
+}
+
+func (m *memoryEvent) SetError(err error) {
+	m.err = err
+}
+
+func (m *memoryEvent) Context() context.Context {
+	return m.opts.Context
+}
+
+func (m *memorySubscriber) Options() broker.SubscribeOptions {
+	return m.opts
+}
+
+func (m *memorySubscriber) Topic() string {
+	return m.topic
+}
+
+func (m *memorySubscriber) Unsubscribe(ctx context.Context) error {
 	m.exit <- true
 	return nil
 }
 
 // NewBroker return new memory broker
 func NewBroker(opts ...broker.Option) broker.Broker {
-	return &Broker{
+	return &memoryBroker{
 		opts:        broker.NewOptions(opts...),
-		subscribers: make(map[string][]*Subscriber),
+		subscribers: make(map[string][]*memorySubscriber),
 	}
 }

broker/memory/memory_test.go

@@ -5,23 +5,12 @@ import (
 	"fmt"
 	"testing"
 
-	"go.uber.org/atomic"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/codec"
-	"go.unistack.org/micro/v4/metadata"
 )
 
-type hldr struct {
+func TestMemoryBatchBroker(t *testing.T) {
-	c atomic.Int64
+	b := NewBroker()
-}
-
-func (h *hldr) Handler(m broker.Message) error {
-	h.c.Add(1)
-	return nil
-}
-
-func TestMemoryBroker(t *testing.T) {
-	b := NewBroker(broker.Codec("application/octet-stream", codec.NewCodec()))
 	ctx := context.Background()
 
 	if err := b.Init(); err != nil {
@@ -33,31 +22,32 @@ func TestMemoryBroker(t *testing.T) {
 	}
 
 	topic := "test"
-	count := int64(10)
+	count := 10
 
-	h := &hldr{}
+	fn := func(evts broker.Events) error {
+		return evts.Ack()
+	}
 
-	sub, err := b.Subscribe(ctx, topic, h.Handler)
+	sub, err := b.BatchSubscribe(ctx, topic, fn)
 	if err != nil {
 		t.Fatalf("Unexpected error subscribing %v", err)
 	}
 
-	for i := int64(0); i < count; i++ {
+	msgs := make([]*broker.Message, 0, count)
-		message, err := b.NewMessage(ctx,
+	for i := 0; i < count; i++ {
-			metadata.Pairs(
+		message := &broker.Message{
-				"foo", "bar",
+			Header: map[string]string{
-				"id", fmt.Sprintf("%d", i),
+				metadata.HeaderTopic: topic,
-			),
+				"foo":                "bar",
-			[]byte(`"hello world"`),
+				"id":                 fmt.Sprintf("%d", i),
-			broker.PublishContentType("application/octet-stream"),
+			},
-		)
+			Body: []byte(`"hello world"`),
-		if err != nil {
+		}
-			t.Fatal(err)
+		msgs = append(msgs, message)
 	}
 
-		if err := b.Publish(ctx, topic, message); err != nil {
+	if err := b.BatchPublish(ctx, msgs); err != nil {
-			t.Fatalf("Unexpected error publishing %d err: %v", i, err)
+		t.Fatalf("Unexpected error publishing %v", err)
-		}
 	}
 
 	if err := sub.Unsubscribe(ctx); err != nil {
@@ -67,8 +57,58 @@ func TestMemoryBroker(t *testing.T) {
 	if err := b.Disconnect(ctx); err != nil {
 		t.Fatalf("Unexpected connect error %v", err)
 	}
+}
 
-	if h.c.Load() != count {
+func TestMemoryBroker(t *testing.T) {
-		t.Fatal("invalid messages count received")
+	b := NewBroker()
+	ctx := context.Background()
+
+	if err := b.Init(); err != nil {
+		t.Fatalf("Unexpected init error %v", err)
+	}
+
+	if err := b.Connect(ctx); err != nil {
+		t.Fatalf("Unexpected connect error %v", err)
+	}
+
+	topic := "test"
+	count := 10
+
+	fn := func(_ broker.Event) error {
+		return nil
+	}
+
+	sub, err := b.Subscribe(ctx, topic, fn)
+	if err != nil {
+		t.Fatalf("Unexpected error subscribing %v", err)
+	}
+
+	msgs := make([]*broker.Message, 0, count)
+	for i := 0; i < count; i++ {
+		message := &broker.Message{
+			Header: map[string]string{
+				metadata.HeaderTopic: topic,
+				"foo":                "bar",
+				"id":                 fmt.Sprintf("%d", i),
+			},
+			Body: []byte(`"hello world"`),
+		}
+		msgs = append(msgs, message)
+
+		if err := b.Publish(ctx, topic, message); err != nil {
+			t.Fatalf("Unexpected error publishing %d err: %v", i, err)
+		}
+	}
+
+	if err := b.BatchPublish(ctx, msgs); err != nil {
+		t.Fatalf("Unexpected error publishing %v", err)
+	}
+
+	if err := sub.Unsubscribe(ctx); err != nil {
+		t.Fatalf("Unexpected error unsubscribing from %s: %v", topic, err)
+	}
+
+	if err := b.Disconnect(ctx); err != nil {
+		t.Fatalf("Unexpected connect error %v", err)
 	}
 }

broker/noop.go

@@ -3,37 +3,24 @@ package broker
 import (
 	"context"
 	"strings"
-	"sync"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/metadata"
-	"go.unistack.org/micro/v4/options"
 )
 
 type NoopBroker struct {
 	funcPublish        FuncPublish
+	funcBatchPublish   FuncBatchPublish
 	funcSubscribe      FuncSubscribe
+	funcBatchSubscribe FuncBatchSubscribe
 	opts               Options
-	sync.RWMutex
-}
-
-func (b *NoopBroker) newCodec(ct string) (codec.Codec, error) {
-	if idx := strings.IndexRune(ct, ';'); idx >= 0 {
-		ct = ct[:idx]
-	}
-	b.RLock()
-	c, ok := b.opts.Codecs[ct]
-	b.RUnlock()
-	if ok {
-		return c, nil
-	}
-	return nil, codec.ErrUnknownContentType
 }
 
 func NewBroker(opts ...Option) *NoopBroker {
 	b := &NoopBroker{opts: NewOptions(opts...)}
 	b.funcPublish = b.fnPublish
+	b.funcBatchPublish = b.fnBatchPublish
 	b.funcSubscribe = b.fnSubscribe
+	b.funcBatchSubscribe = b.fnBatchSubscribe
 
 	return b
 }
@@ -68,14 +55,20 @@ func (b *NoopBroker) Init(opts ...Option) error {
 	}
 
 	b.funcPublish = b.fnPublish
+	b.funcBatchPublish = b.fnBatchPublish
 	b.funcSubscribe = b.fnSubscribe
+	b.funcBatchSubscribe = b.fnBatchSubscribe
 
 	b.opts.Hooks.EachPrev(func(hook options.Hook) {
 		switch h := hook.(type) {
 		case HookPublish:
 			b.funcPublish = h(b.funcPublish)
+		case HookBatchPublish:
+			b.funcBatchPublish = h(b.funcBatchPublish)
 		case HookSubscribe:
 			b.funcSubscribe = h(b.funcSubscribe)
+		case HookBatchSubscribe:
+			b.funcBatchSubscribe = h(b.funcBatchSubscribe)
 		}
 	})
 
@@ -94,72 +87,43 @@ func (b *NoopBroker) Address() string {
 	return strings.Join(b.opts.Addrs, ",")
 }
 
-type noopMessage struct {
+func (b *NoopBroker) fnBatchPublish(_ context.Context, _ []*Message, _ ...PublishOption) error {
-	c    codec.Codec
-	ctx  context.Context
-	body []byte
-	hdr  metadata.Metadata
-	opts PublishOptions
-}
-
-func (m *noopMessage) Ack() error {
 	return nil
 }
 
-func (m *noopMessage) Body() []byte {
+func (b *NoopBroker) BatchPublish(ctx context.Context, msgs []*Message, opts ...PublishOption) error {
-	return m.body
+	return b.funcBatchPublish(ctx, msgs, opts...)
 }
 
-func (m *noopMessage) Header() metadata.Metadata {
+func (b *NoopBroker) fnPublish(_ context.Context, _ string, _ *Message, _ ...PublishOption) error {
-	return m.hdr
-}
-
-func (m *noopMessage) Context() context.Context {
-	return m.ctx
-}
-
-func (m *noopMessage) Topic() string {
-	return ""
-}
-
-func (m *noopMessage) Unmarshal(dst interface{}, opts ...codec.Option) error {
-	return m.c.Unmarshal(m.body, dst)
-}
-
-func (b *NoopBroker) NewMessage(ctx context.Context, hdr metadata.Metadata, body interface{}, opts ...PublishOption) (Message, error) {
-	options := NewPublishOptions(opts...)
-	m := &noopMessage{ctx: ctx, hdr: hdr, opts: options}
-	c, err := b.newCodec(m.opts.ContentType)
-	if err == nil {
-		m.body, err = c.Marshal(body)
-	}
-	if err != nil {
-		return nil, err
-	}
-
-	return m, nil
-}
-
-func (b *NoopBroker) fnPublish(_ context.Context, _ string, _ ...Message) error {
 	return nil
 }
 
-func (b *NoopBroker) Publish(ctx context.Context, topic string, msg ...Message) error {
+func (b *NoopBroker) Publish(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error {
-	return b.funcPublish(ctx, topic, msg...)
+	return b.funcPublish(ctx, topic, msg, opts...)
 }
 
 type NoopSubscriber struct {
 	ctx          context.Context
 	topic        string
-	handler interface{}
+	handler      Handler
+	batchHandler BatchHandler
 	opts         SubscribeOptions
 }
 
-func (b *NoopBroker) fnSubscribe(ctx context.Context, topic string, handler interface{}, opts ...SubscribeOption) (Subscriber, error) {
+func (b *NoopBroker) fnBatchSubscribe(ctx context.Context, topic string, handler BatchHandler, opts ...SubscribeOption) (Subscriber, error) {
+	return &NoopSubscriber{ctx: ctx, topic: topic, opts: NewSubscribeOptions(opts...), batchHandler: handler}, nil
+}
+
+func (b *NoopBroker) BatchSubscribe(ctx context.Context, topic string, handler BatchHandler, opts ...SubscribeOption) (Subscriber, error) {
+	return b.funcBatchSubscribe(ctx, topic, handler, opts...)
+}
+
+func (b *NoopBroker) fnSubscribe(ctx context.Context, topic string, handler Handler, opts ...SubscribeOption) (Subscriber, error) {
 	return &NoopSubscriber{ctx: ctx, topic: topic, opts: NewSubscribeOptions(opts...), handler: handler}, nil
 }
 
-func (b *NoopBroker) Subscribe(ctx context.Context, topic string, handler interface{}, opts ...SubscribeOption) (Subscriber, error) {
+func (b *NoopBroker) Subscribe(ctx context.Context, topic string, handler Handler, opts ...SubscribeOption) (Subscriber, error) {
 	return b.funcSubscribe(ctx, topic, handler, opts...)
 }
 

broker/noop_test.go

@@ -10,9 +10,9 @@ type testHook struct {
 }
 
 func (t *testHook) Publish1(fn FuncPublish) FuncPublish {
-	return func(ctx context.Context, topic string, messages ...Message) error {
+	return func(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error {
 		t.f = true
-		return fn(ctx, topic, messages...)
+		return fn(ctx, topic, msg, opts...)
 	}
 }
 

broker/options.go

@@ -5,13 +5,13 @@ import (
 	"crypto/tls"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/sync"
+	"go.unistack.org/micro/v3/sync"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Options struct
@@ -23,8 +23,8 @@ type Options struct {
 	Tracer tracer.Tracer
 	// Register can be used for clustering
 	Register register.Register
-	// Codecs holds the codecs for marshal/unmarshal based on content-type
+	// Codec holds the codec for marshal/unmarshal
-	Codecs map[string]codec.Codec
+	Codec codec.Codec
 	// Logger used for logging
 	Logger logger.Logger
 	// Meter used for metrics
@@ -37,6 +37,11 @@ type Options struct {
 	// TLSConfig holds tls.TLSConfig options
 	TLSConfig *tls.Config
 
+	// ErrorHandler used when broker can't unmarshal incoming message
+	ErrorHandler Handler
+	// BatchErrorHandler used when broker can't unmashal incoming messages
+	BatchErrorHandler BatchHandler
+
 	// Addrs holds the broker address
 	Addrs []string
 	// Hooks can be run before broker Publish/BatchPublish and
@@ -54,11 +59,10 @@ func NewOptions(opts ...Option) Options {
 		Logger:          logger.DefaultLogger,
 		Context:         context.Background(),
 		Meter:           meter.DefaultMeter,
-		Codecs:          make(map[string]codec.Codec),
+		Codec:           codec.DefaultCodec,
 		Tracer:          tracer.DefaultTracer,
 		GracefulTimeout: DefaultGracefulTimeout,
 	}
-
 	for _, o := range opts {
 		o(&options)
 	}
@@ -74,16 +78,17 @@ func Context(ctx context.Context) Option {
 
 // PublishOptions struct
 type PublishOptions struct {
-	// ContentType for message body
+	// Context holds external options
-	ContentType string
+	Context context.Context
-	// BodyOnly flag says the message contains raw body bytes and don't need
+	// BodyOnly flag says the message contains raw body bytes
-	// codec Marshal method
 	BodyOnly bool
 }
 
 // NewPublishOptions creates PublishOptions struct
 func NewPublishOptions(opts ...PublishOption) PublishOptions {
-	options := PublishOptions{}
+	options := PublishOptions{
+		Context: context.Background(),
+	}
 	for _, o := range opts {
 		o(&options)
 	}
@@ -94,6 +99,10 @@ func NewPublishOptions(opts ...PublishOption) PublishOptions {
 type SubscribeOptions struct {
 	// Context holds external options
 	Context context.Context
+	// ErrorHandler used when broker can't unmarshal incoming message
+	ErrorHandler Handler
+	// BatchErrorHandler used when broker can't unmashal incoming messages
+	BatchErrorHandler BatchHandler
 	// Group holds consumer group
 	Group string
 	// AutoAck flag specifies auto ack of incoming message when no error happens
@@ -112,13 +121,6 @@ type Option func(*Options)
 // PublishOption func
 type PublishOption func(*PublishOptions)
 
-// PublishContentType sets message content-type that used to Marshal
-func PublishContentType(ct string) PublishOption {
-	return func(o *PublishOptions) {
-		o.ContentType = ct
-	}
-}
-
 // PublishBodyOnly publish only body of the message
 func PublishBodyOnly(b bool) PublishOption {
 	return func(o *PublishOptions) {
@@ -126,6 +128,13 @@ func PublishBodyOnly(b bool) PublishOption {
 	}
 }
 
+// PublishContext sets the context
+func PublishContext(ctx context.Context) PublishOption {
+	return func(o *PublishOptions) {
+		o.Context = ctx
+	}
+}
+
 // Addrs sets the host addresses to be used by the broker
 func Addrs(addrs ...string) Option {
 	return func(o *Options) {
@@ -133,10 +142,51 @@ func Addrs(addrs ...string) Option {
 	}
 }
 
-// Codec sets the codec used for encoding/decoding messages
+// Codec sets the codec used for encoding/decoding used where
-func Codec(ct string, c codec.Codec) Option {
+// a broker does not support headers
+func Codec(c codec.Codec) Option {
 	return func(o *Options) {
-		o.Codecs[ct] = c
+		o.Codec = c
+	}
+}
+
+// ErrorHandler will catch all broker errors that cant be handled
+// in normal way, for example Codec errors
+func ErrorHandler(h Handler) Option {
+	return func(o *Options) {
+		o.ErrorHandler = h
+	}
+}
+
+// BatchErrorHandler will catch all broker errors that cant be handled
+// in normal way, for example Codec errors
+func BatchErrorHandler(h BatchHandler) Option {
+	return func(o *Options) {
+		o.BatchErrorHandler = h
+	}
+}
+
+// SubscribeErrorHandler will catch all broker errors that cant be handled
+// in normal way, for example Codec errors
+func SubscribeErrorHandler(h Handler) SubscribeOption {
+	return func(o *SubscribeOptions) {
+		o.ErrorHandler = h
+	}
+}
+
+// SubscribeBatchErrorHandler will catch all broker errors that cant be handled
+// in normal way, for example Codec errors
+func SubscribeBatchErrorHandler(h BatchHandler) SubscribeOption {
+	return func(o *SubscribeOptions) {
+		o.BatchErrorHandler = h
+	}
+}
+
+// Queue sets the subscribers queue
+// Deprecated
+func Queue(name string) SubscribeOption {
+	return func(o *SubscribeOptions) {
+		o.Group = name
 	}
 }
 
@@ -203,6 +253,14 @@ func SubscribeContext(ctx context.Context) SubscribeOption {
 	}
 }
 
+// DisableAutoAck disables auto ack
+// Deprecated
+func DisableAutoAck() SubscribeOption {
+	return func(o *SubscribeOptions) {
+		o.AutoAck = false
+	}
+}
+
 // SubscribeAutoAck contol auto acking of messages
 // after they have been handled.
 func SubscribeAutoAck(b bool) SubscribeOption {

client/backoff.go

@@ -5,7 +5,7 @@ import (
 	"math"
 	"time"
 
-	"go.unistack.org/micro/v4/util/backoff"
+	"go.unistack.org/micro/v3/util/backoff"
 )
 
 // BackoffFunc is the backoff call func

client/client.go

@@ -5,8 +5,8 @@ import (
 	"context"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
 )
 
 var (
@@ -29,14 +29,18 @@ var (
 )
 
 // Client is the interface used to make requests to services.
+// It supports Request/Response via Transport and Publishing via the Broker.
 // It also supports bidirectional streaming of requests.
 type Client interface {
 	Name() string
 	Init(opts ...Option) error
 	Options() Options
+	NewMessage(topic string, msg interface{}, opts ...MessageOption) Message
 	NewRequest(service string, endpoint string, req interface{}, opts ...RequestOption) Request
 	Call(ctx context.Context, req Request, rsp interface{}, opts ...CallOption) error
 	Stream(ctx context.Context, req Request, opts ...CallOption) (Stream, error)
+	Publish(ctx context.Context, msg Message, opts ...PublishOption) error
+	BatchPublish(ctx context.Context, msg []Message, opts ...PublishOption) error
 	String() string
 }
 
@@ -45,8 +49,20 @@ type (
 	HookCall         func(next FuncCall) FuncCall
 	FuncStream       func(ctx context.Context, req Request, opts ...CallOption) (Stream, error)
 	HookStream       func(next FuncStream) FuncStream
+	FuncPublish      func(ctx context.Context, msg Message, opts ...PublishOption) error
+	HookPublish      func(next FuncPublish) FuncPublish
+	FuncBatchPublish func(ctx context.Context, msg []Message, opts ...PublishOption) error
+	HookBatchPublish func(next FuncBatchPublish) FuncBatchPublish
 )
 
+// Message is the interface for publishing asynchronously
+type Message interface {
+	Topic() string
+	Payload() interface{}
+	ContentType() string
+	Metadata() metadata.Metadata
+}
+
 // Request is the interface for a synchronous request used by Call or Stream
 type Request interface {
 	// The service to call
@@ -105,5 +121,11 @@ type Option func(*Options)
 // CallOption used by Call or Stream
 type CallOption func(*CallOptions)
 
+// PublishOption used by Publish
+type PublishOption func(*PublishOptions)
+
+// MessageOption used by NewMessage
+type MessageOption func(*MessageOptions)
+
 // RequestOption used by NewRequest
 type RequestOption func(*RequestOptions)

client/context.go

@@ -32,6 +32,16 @@ func NewContext(ctx context.Context, c Client) context.Context {
 	return context.WithValue(ctx, clientKey{}, c)
 }
 
+// SetPublishOption returns a function to setup a context with given value
+func SetPublishOption(k, v interface{}) PublishOption {
+	return func(o *PublishOptions) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, k, v)
+	}
+}
+
 // SetCallOption returns a function to setup a context with given value
 func SetCallOption(k, v interface{}) CallOption {
 	return func(o *CallOptions) {

client/context_test.go

@@ -39,6 +39,17 @@ func TestNewNilContext(t *testing.T) {
 	}
 }
 
+func TestSetPublishOption(t *testing.T) {
+	type key struct{}
+	o := SetPublishOption(key{}, "test")
+	opts := &PublishOptions{}
+	o(opts)
+
+	if v, ok := opts.Context.Value(key{}).(string); !ok || v == "" {
+		t.Fatal("SetPublishOption not works")
+	}
+}
+
 func TestSetCallOption(t *testing.T) {
 	type key struct{}
 	o := SetCallOption(key{}, "test")

client/lookup.go

@@ -4,8 +4,8 @@ import (
 	"context"
 	"sort"
 
-	"go.unistack.org/micro/v4/errors"
+	"go.unistack.org/micro/v3/errors"
-	"go.unistack.org/micro/v4/router"
+	"go.unistack.org/micro/v3/router"
 )
 
 // LookupFunc is used to lookup routes for a service

client/noop.go

@@ -3,16 +3,18 @@ package client
 import (
 	"context"
 	"fmt"
+	"os"
 	"strconv"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/errors"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/errors"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/selector"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/semconv"
+	"go.unistack.org/micro/v3/selector"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/semconv"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // DefaultCodecs will be used to encode/decode data
@@ -21,11 +23,19 @@ var DefaultCodecs = map[string]codec.Codec{
 }
 
 type noopClient struct {
+	funcPublish      FuncPublish
+	funcBatchPublish FuncBatchPublish
 	funcCall         FuncCall
 	funcStream       FuncStream
 	opts             Options
 }
 
+type noopMessage struct {
+	topic   string
+	payload interface{}
+	opts    MessageOptions
+}
+
 type noopRequest struct {
 	body        interface{}
 	codec       codec.Codec
@@ -42,6 +52,8 @@ func NewClient(opts ...Option) Client {
 
 	n.funcCall = n.fnCall
 	n.funcStream = n.fnStream
+	n.funcPublish = n.fnPublish
+	n.funcBatchPublish = n.fnBatchPublish
 
 	return n
 }
@@ -146,6 +158,32 @@ func (n *noopStream) CloseSend() error {
 	return n.err
 }
 
+func (n *noopMessage) Topic() string {
+	return n.topic
+}
+
+func (n *noopMessage) Payload() interface{} {
+	return n.payload
+}
+
+func (n *noopMessage) ContentType() string {
+	return n.opts.ContentType
+}
+
+func (n *noopMessage) Metadata() metadata.Metadata {
+	return n.opts.Metadata
+}
+
+func (n *noopClient) newCodec(contentType string) (codec.Codec, error) {
+	if cf, ok := n.opts.Codecs[contentType]; ok {
+		return cf, nil
+	}
+	if cf, ok := DefaultCodecs[contentType]; ok {
+		return cf, nil
+	}
+	return nil, codec.ErrUnknownContentType
+}
+
 func (n *noopClient) Init(opts ...Option) error {
 	for _, o := range opts {
 		o(&n.opts)
@@ -153,6 +191,8 @@ func (n *noopClient) Init(opts ...Option) error {
 
 	n.funcCall = n.fnCall
 	n.funcStream = n.fnStream
+	n.funcPublish = n.fnPublish
+	n.funcBatchPublish = n.fnBatchPublish
 
 	n.opts.Hooks.EachPrev(func(hook options.Hook) {
 		switch h := hook.(type) {
@@ -160,6 +200,10 @@ func (n *noopClient) Init(opts ...Option) error {
 			n.funcCall = h(n.funcCall)
 		case HookStream:
 			n.funcStream = h(n.funcStream)
+		case HookPublish:
+			n.funcPublish = h(n.funcPublish)
+		case HookBatchPublish:
+			n.funcBatchPublish = h(n.funcBatchPublish)
 		}
 	})
 
@@ -332,6 +376,11 @@ func (n *noopClient) NewRequest(service, endpoint string, _ interface{}, _ ...Re
 	return &noopRequest{service: service, endpoint: endpoint}
 }
 
+func (n *noopClient) NewMessage(topic string, msg interface{}, opts ...MessageOption) Message {
+	options := NewMessageOptions(append([]MessageOption{MessageContentType(n.opts.ContentType)}, opts...)...)
+	return &noopMessage{topic: topic, payload: msg, opts: options}
+}
+
 func (n *noopClient) Stream(ctx context.Context, req Request, opts ...CallOption) (Stream, error) {
 	ts := time.Now()
 	n.opts.Meter.Counter(semconv.ClientRequestInflight, "endpoint", req.Endpoint()).Inc()
@@ -500,3 +549,90 @@ func (n *noopClient) fnStream(ctx context.Context, req Request, opts ...CallOpti
 func (n *noopClient) stream(ctx context.Context, _ string, _ Request, _ CallOptions) (Stream, error) {
 	return &noopStream{ctx: ctx}, nil
 }
+
+func (n *noopClient) BatchPublish(ctx context.Context, ps []Message, opts ...PublishOption) error {
+	return n.funcBatchPublish(ctx, ps, opts...)
+}
+
+func (n *noopClient) fnBatchPublish(ctx context.Context, ps []Message, opts ...PublishOption) error {
+	return n.publish(ctx, ps, opts...)
+}
+
+func (n *noopClient) Publish(ctx context.Context, p Message, opts ...PublishOption) error {
+	return n.funcPublish(ctx, p, opts...)
+}
+
+func (n *noopClient) fnPublish(ctx context.Context, p Message, opts ...PublishOption) error {
+	return n.publish(ctx, []Message{p}, opts...)
+}
+
+func (n *noopClient) publish(ctx context.Context, ps []Message, opts ...PublishOption) error {
+	options := NewPublishOptions(opts...)
+
+	msgs := make([]*broker.Message, 0, len(ps))
+
+	// get proxy
+	exchange := ""
+	if v, ok := os.LookupEnv("MICRO_PROXY"); ok {
+		exchange = v
+	}
+	// get the exchange
+	if len(options.Exchange) > 0 {
+		exchange = options.Exchange
+	}
+
+	omd, ok := metadata.FromOutgoingContext(ctx)
+	if !ok {
+		omd = metadata.New(0)
+	}
+
+	for _, p := range ps {
+		md := metadata.Copy(omd)
+		topic := p.Topic()
+		if len(exchange) > 0 {
+			topic = exchange
+		}
+		md[metadata.HeaderTopic] = topic
+		iter := p.Metadata().Iterator()
+		var k, v string
+		for iter.Next(&k, &v) {
+			md.Set(k, v)
+		}
+
+		md[metadata.HeaderContentType] = p.ContentType()
+
+		var body []byte
+
+		// passed in raw data
+		if d, ok := p.Payload().(*codec.Frame); ok {
+			body = d.Data
+		} else {
+			// use codec for payload
+			cf, err := n.newCodec(p.ContentType())
+			if err != nil {
+				return errors.InternalServerError("go.micro.client", "%s", err)
+			}
+
+			// set the body
+			b, err := cf.Marshal(p.Payload())
+			if err != nil {
+				return errors.InternalServerError("go.micro.client", "%s", err)
+			}
+			body = b
+		}
+
+		msgs = append(msgs, &broker.Message{Header: md, Body: body})
+	}
+
+	if len(msgs) == 1 {
+		return n.opts.Broker.Publish(ctx, msgs[0].Header[metadata.HeaderTopic], msgs[0],
+			broker.PublishContext(options.Context),
+			broker.PublishBodyOnly(options.BodyOnly),
+		)
+	}
+
+	return n.opts.Broker.BatchPublish(ctx, msgs,
+		broker.PublishContext(options.Context),
+		broker.PublishBodyOnly(options.BodyOnly),
+	)
+}

client/noop_test.go

@@ -0,0 +1,35 @@
+package client
+
+import (
+	"context"
+	"testing"
+)
+
+type testHook struct {
+	f bool
+}
+
+func (t *testHook) Publish(fn FuncPublish) FuncPublish {
+	return func(ctx context.Context, msg Message, opts ...PublishOption) error {
+		t.f = true
+		return fn(ctx, msg, opts...)
+	}
+}
+
+func TestNoopHook(t *testing.T) {
+	h := &testHook{}
+
+	c := NewClient(Hooks(HookPublish(h.Publish)))
+
+	if err := c.Init(); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := c.Publish(context.TODO(), c.NewMessage("", nil, MessageContentType("application/octet-stream"))); err != nil {
+		t.Fatal(err)
+	}
+
+	if !h.f {
+		t.Fatal("hook not works")
+	}
+}

client/options.go

@@ -6,17 +6,17 @@ import (
 	"net"
 	"time"
 
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/router"
+	"go.unistack.org/micro/v3/router"
-	"go.unistack.org/micro/v4/selector"
+	"go.unistack.org/micro/v3/selector"
-	"go.unistack.org/micro/v4/selector/random"
+	"go.unistack.org/micro/v3/selector/random"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Options holds client options
@@ -137,6 +137,43 @@ func Context(ctx context.Context) Option {
 	}
 }
 
+// NewPublishOptions create new PublishOptions struct from option
+func NewPublishOptions(opts ...PublishOption) PublishOptions {
+	options := PublishOptions{}
+	for _, o := range opts {
+		o(&options)
+	}
+	return options
+}
+
+// PublishOptions holds publish options
+type PublishOptions struct {
+	// Context used for external options
+	Context context.Context
+	// Exchange topic exchange name
+	Exchange string
+	// BodyOnly will publish only message body
+	BodyOnly bool
+}
+
+// NewMessageOptions creates message options struct
+func NewMessageOptions(opts ...MessageOption) MessageOptions {
+	options := MessageOptions{Metadata: metadata.New(1)}
+	for _, o := range opts {
+		o(&options)
+	}
+	return options
+}
+
+// MessageOptions holds client message options
+type MessageOptions struct {
+	// Metadata additional metadata
+	Metadata metadata.Metadata
+	// ContentType specify content-type of message
+	// deprecated
+	ContentType string
+}
+
 // NewRequestOptions creates new RequestOptions struct
 func NewRequestOptions(opts ...RequestOption) RequestOptions {
 	options := RequestOptions{}
@@ -337,6 +374,43 @@ func DialTimeout(d time.Duration) Option {
 	}
 }
 
+// WithExchange sets the exchange to route a message through
+// Deprecated
+func WithExchange(e string) PublishOption {
+	return func(o *PublishOptions) {
+		o.Exchange = e
+	}
+}
+
+// PublishExchange sets the exchange to route a message through
+func PublishExchange(e string) PublishOption {
+	return func(o *PublishOptions) {
+		o.Exchange = e
+	}
+}
+
+// WithBodyOnly publish only message body
+// DERECATED
+func WithBodyOnly(b bool) PublishOption {
+	return func(o *PublishOptions) {
+		o.BodyOnly = b
+	}
+}
+
+// PublishBodyOnly publish only message body
+func PublishBodyOnly(b bool) PublishOption {
+	return func(o *PublishOptions) {
+		o.BodyOnly = b
+	}
+}
+
+// PublishContext sets the context in publish options
+func PublishContext(ctx context.Context) PublishOption {
+	return func(o *PublishOptions) {
+		o.Context = ctx
+	}
+}
+
 // WithContextDialer pass ContextDialer to client call
 func WithContextDialer(fn func(context.Context, string) (net.Conn, error)) CallOption {
 	return func(o *CallOptions) {
@@ -448,6 +522,30 @@ func WithSelectOptions(sops ...selector.SelectOption) CallOption {
 	}
 }
 
+// WithMessageContentType sets the message content type
+// Deprecated
+func WithMessageContentType(ct string) MessageOption {
+	return func(o *MessageOptions) {
+		o.Metadata.Set(metadata.HeaderContentType, ct)
+		o.ContentType = ct
+	}
+}
+
+// MessageContentType sets the message content type
+func MessageContentType(ct string) MessageOption {
+	return func(o *MessageOptions) {
+		o.Metadata.Set(metadata.HeaderContentType, ct)
+		o.ContentType = ct
+	}
+}
+
+// MessageMetadata sets the message metadata
+func MessageMetadata(k, v string) MessageOption {
+	return func(o *MessageOptions) {
+		o.Metadata.Set(k, v)
+	}
+}
+
 // StreamingRequest specifies that request is streaming
 func StreamingRequest(b bool) RequestOption {
 	return func(o *RequestOptions) {

client/retry.go

@@ -3,7 +3,7 @@ package client
 import (
 	"context"
 
-	"go.unistack.org/micro/v4/errors"
+	"go.unistack.org/micro/v3/errors"
 )
 
 // RetryFunc that returning either false or a non-nil error will result in the call not being retried

client/retry_test.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"testing"
 
-	"go.unistack.org/micro/v4/errors"
+	"go.unistack.org/micro/v3/errors"
 )
 
 func TestRetryAlways(t *testing.T) {

client/test_request.go

@@ -1,7 +1,7 @@
 package client
 
 import (
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
 )
 
 type testRequest struct {

cluster/cluster.go

@@ -3,7 +3,7 @@ package cluster
 import (
 	"context"
 
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
 )
 
 // Message sent to member in cluster

codec/frame.proto

@@ -17,7 +17,7 @@ syntax = "proto3";
 package micro.codec;
 
 option cc_enable_arenas = true;
-option go_package = "go.unistack.org/micro/v4/codec;codec";
+option go_package = "go.unistack.org/micro/v3/codec;codec";
 option java_multiple_files = true;
 option java_outer_classname = "MicroCodec";
 option java_package = "micro.codec";

codec/noop.go

@@ -3,7 +3,7 @@ package codec
 import (
 	"encoding/json"
 
-	codecpb "go.unistack.org/micro-proto/v4/codec"
+	codecpb "go.unistack.org/micro-proto/v3/codec"
 )
 
 type noopCodec struct {

codec/options.go

@@ -3,9 +3,9 @@ package codec
 import (
 	"context"
 
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Option func

config/default.go

@@ -9,10 +9,10 @@ import (
 
 	"dario.cat/mergo"
 	"github.com/google/uuid"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/options"
-	mid "go.unistack.org/micro/v4/util/id"
+	mid "go.unistack.org/micro/v3/util/id"
-	rutil "go.unistack.org/micro/v4/util/reflect"
+	rutil "go.unistack.org/micro/v3/util/reflect"
-	mtime "go.unistack.org/micro/v4/util/time"
+	mtime "go.unistack.org/micro/v3/util/time"
 )
 
 type defaultConfig struct {
@@ -210,7 +210,7 @@ func fillValue(value reflect.Value, val string) error {
 				return err
 			}
 			value.Set(reflect.ValueOf(v))
-		case value.Type().String() == "time.Duration" && value.Type().PkgPath() == "go.unistack.org/micro/v4/util/time":
+		case value.Type().String() == "time.Duration" && value.Type().PkgPath() == "go.unistack.org/micro/v3/util/time":
 			v, err := mtime.ParseDuration(val)
 			if err != nil {
 				return err

config/default_test.go

@@ -7,8 +7,8 @@ import (
 	"testing"
 	"time"
 
-	"go.unistack.org/micro/v4/config"
+	"go.unistack.org/micro/v3/config"
-	mtime "go.unistack.org/micro/v4/util/time"
+	mtime "go.unistack.org/micro/v3/util/time"
 )
 
 type cfg struct {

config/options.go

@@ -4,11 +4,11 @@ import (
 	"context"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Options hold the config options

errors/errors.proto

@@ -17,7 +17,7 @@ syntax = "proto3";
 package micro.errors;
 
 option cc_enable_arenas = true;
-option go_package = "go.unistack.org/micro/v4/errors;errors";
+option go_package = "go.unistack.org/micro/v3/errors;errors";
 option java_multiple_files = true;
 option java_outer_classname = "MicroErrors";
 option java_package = "micro.errors";

event.go

@@ -0,0 +1,27 @@
+package micro
+
+import (
+	"context"
+
+	"go.unistack.org/micro/v3/client"
+)
+
+// Event is used to publish messages to a topic
+type Event interface {
+	// Publish publishes a message to the event topic
+	Publish(ctx context.Context, msg interface{}, opts ...client.PublishOption) error
+}
+
+type event struct {
+	c     client.Client
+	topic string
+}
+
+// NewEvent creates a new event publisher
+func NewEvent(topic string, c client.Client) Event {
+	return &event{c, topic}
+}
+
+func (e *event) Publish(ctx context.Context, msg interface{}, opts ...client.PublishOption) error {
+	return e.c.Publish(ctx, e.c.NewMessage(e.topic, msg), opts...)
+}

flow/default.go

@@ -6,12 +6,12 @@ import (
 	"sync"
 
 	"github.com/silas/dag"
-	"go.unistack.org/micro/v4/client"
+	"go.unistack.org/micro/v3/client"
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/store"
+	"go.unistack.org/micro/v3/store"
-	"go.unistack.org/micro/v4/util/id"
+	"go.unistack.org/micro/v3/util/id"
 )
 
 type microFlow struct {

flow/flow.go

@@ -7,7 +7,7 @@ import (
 	"sync"
 	"sync/atomic"
 
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
 )
 
 var (

flow/options.go

@@ -4,11 +4,11 @@ import (
 	"context"
 	"time"
 
-	"go.unistack.org/micro/v4/client"
+	"go.unistack.org/micro/v3/client"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/store"
+	"go.unistack.org/micro/v3/store"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Option func

fsm/fsm_test.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"testing"
 
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
 )
 
 func TestFSMStart(t *testing.T) {

go.mod

@@ -1,34 +1,43 @@
-module go.unistack.org/micro/v4
+module go.unistack.org/micro/v3
 
 go 1.22.0
 
 require (
 	dario.cat/mergo v1.0.1
 	github.com/DATA-DOG/go-sqlmock v1.5.2
-	github.com/KimMachineGun/automemlimit v0.7.0
+	github.com/KimMachineGun/automemlimit v0.6.1
 	github.com/ash3in/uuidv8 v1.2.0
 	github.com/google/uuid v1.6.0
 	github.com/matoous/go-nanoid v1.5.1
 	github.com/patrickmn/go-cache v2.1.0+incompatible
 	github.com/silas/dag v0.0.0-20220518035006-a7e85ada93c5
-	go.uber.org/atomic v1.11.0
 	go.uber.org/automaxprocs v1.6.0
-	go.unistack.org/micro-proto/v4 v4.1.0
+	go.unistack.org/micro-proto/v3 v3.4.1
 	golang.org/x/sync v0.10.0
-	google.golang.org/grpc v1.69.4
+	google.golang.org/grpc v1.69.2
-	google.golang.org/protobuf v1.36.3
+	google.golang.org/protobuf v1.36.1
 	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
+	github.com/cilium/ebpf v0.16.0 // indirect
+	github.com/containerd/cgroups/v3 v3.0.4 // indirect
+	github.com/containerd/log v0.1.0 // indirect
+	github.com/coreos/go-systemd/v22 v22.5.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
-	github.com/kr/pretty v0.3.1 // indirect
+	github.com/docker/go-units v0.5.0 // indirect
+	github.com/godbus/dbus/v5 v5.1.0 // indirect
+	github.com/moby/sys/userns v0.1.0 // indirect
+	github.com/opencontainers/runtime-spec v1.2.0 // indirect
 	github.com/pbnjay/memory v0.0.0-20210728143218-7b4eea64cf58 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/rogpeppe/go-internal v1.13.1 // indirect
+	github.com/sirupsen/logrus v1.9.3 // indirect
 	github.com/stretchr/testify v1.10.0 // indirect
-	golang.org/x/net v0.34.0 // indirect
+	go.uber.org/goleak v1.3.0 // indirect
-	golang.org/x/sys v0.29.0 // indirect
+	golang.org/x/exp v0.0.0-20241210194714-1829a127f884 // indirect
+	golang.org/x/net v0.33.0 // indirect
+	golang.org/x/sys v0.28.0 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20241216192217-9240e9c98484 // indirect
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
 )

go.sum

@@ -2,19 +2,39 @@ dario.cat/mergo v1.0.1 h1:Ra4+bf83h2ztPIQYNP99R6m+Y7KfnARDfID+a+vLl4s=
 dario.cat/mergo v1.0.1/go.mod h1:uNxQE+84aUszobStD9th8a29P2fMDhsBdgRYvZOxGmk=
 github.com/DATA-DOG/go-sqlmock v1.5.2 h1:OcvFkGmslmlZibjAjaHm3L//6LiuBgolP7OputlJIzU=
 github.com/DATA-DOG/go-sqlmock v1.5.2/go.mod h1:88MAG/4G7SMwSE3CeA0ZKzrT5CiOU3OJ+JlNzwDqpNU=
-github.com/KimMachineGun/automemlimit v0.7.0 h1:7G06p/dMSf7G8E6oq+f2uOPuVncFyIlDI/pBWK49u88=
+github.com/KimMachineGun/automemlimit v0.6.1 h1:ILa9j1onAAMadBsyyUJv5cack8Y1WT26yLj/V+ulKp8=
-github.com/KimMachineGun/automemlimit v0.7.0/go.mod h1:QZxpHaGOQoYvFhv/r4u3U0JTC2ZcOwbSr11UZF46UBM=
+github.com/KimMachineGun/automemlimit v0.6.1/go.mod h1:T7xYht7B8r6AG/AqFcUdc7fzd2bIdBKmepfP2S1svPY=
 github.com/ash3in/uuidv8 v1.2.0 h1:2oogGdtCPwaVtyvPPGin4TfZLtOGE5F+W++E880G6SI=
 github.com/ash3in/uuidv8 v1.2.0/go.mod h1:BnU0wJBxnzdEKmVg4xckBkD+VZuecTFTUP3M0dWgyY4=
-github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/cilium/ebpf v0.16.0 h1:+BiEnHL6Z7lXnlGUsXQPPAE7+kenAd4ES8MQ5min0Ok=
+github.com/cilium/ebpf v0.16.0/go.mod h1:L7u2Blt2jMM/vLAVgjxluxtBKlz3/GWjB0dMOEngfwE=
+github.com/containerd/cgroups/v3 v3.0.4 h1:2fs7l3P0Qxb1nKWuJNFiwhp2CqiKzho71DQkDrHJIo4=
+github.com/containerd/cgroups/v3 v3.0.4/go.mod h1:SA5DLYnXO8pTGYiAHXz94qvLQTKfVM5GEVisn4jpins=
+github.com/containerd/log v0.1.0 h1:TCJt7ioM2cr/tfR8GPbGf9/VRAX8D2B4PjzCpfX540I=
+github.com/containerd/log v0.1.0/go.mod h1:VRRf09a7mHDIRezVKTRCrOq78v577GXq3bSa3EhrzVo=
+github.com/coreos/go-systemd/v22 v22.5.0 h1:RrqgGjYQKalulkV8NGVIfkXQf6YYmOyiJKk8iXXhfZs=
+github.com/coreos/go-systemd/v22 v22.5.0/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/docker/go-units v0.5.0 h1:69rxXcBk27SvSaaxTtLh/8llcHD8vYHT7WSdRZ/jvr4=
+github.com/docker/go-units v0.5.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk=
+github.com/go-quicktest/qt v1.101.0 h1:O1K29Txy5P2OK0dGo59b7b0LR6wKfIhttaAhHUyn7eI=
+github.com/go-quicktest/qt v1.101.0/go.mod h1:14Bz/f7NwaXPtdYEgzsx46kqSxVwTbzVZsDC26tQJow=
+github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+github.com/godbus/dbus/v5 v5.1.0 h1:4KLkAxT3aOY8Li4FRJe/KvhoNFFxo0m6fNuFUO8QJUk=
+github.com/godbus/dbus/v5 v5.1.0/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
 github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/josharian/native v1.1.0 h1:uuaP0hAbW7Y4l0ZRQ6C9zfb7Mg1mbFKry/xzDAfmtLA=
+github.com/josharian/native v1.1.0/go.mod h1:7X/raswPFr05uY3HiLlYeyQntB6OO7E/d2Cu7qoaN2w=
+github.com/jsimonetti/rtnetlink/v2 v2.0.1 h1:xda7qaHDSVOsADNouv7ukSuicKZO7GgVUCXxpaIEIlM=
+github.com/jsimonetti/rtnetlink/v2 v2.0.1/go.mod h1:7MoNYNbb3UaDHtF8udiJo/RH6VsTKP1pqKLUTVCvToE=
 github.com/kisielk/sqlstruct v0.0.0-20201105191214-5f3e10d3ab46/go.mod h1:yyMNCyc/Ib3bDTKd379tNMpB/7/H5TjM2Y9QJ5THLbE=
 github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
@@ -25,44 +45,59 @@ github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/matoous/go-nanoid v1.5.1 h1:aCjdvTyO9LLnTIi0fgdXhOPPvOHjpXN6Ik9DaNjIct4=
 github.com/matoous/go-nanoid v1.5.1/go.mod h1:zyD2a71IubI24efhpvkJz+ZwfwagzgSO6UNiFsZKN7U=
+github.com/mdlayher/netlink v1.7.2 h1:/UtM3ofJap7Vl4QWCPDGXY8d3GIY2UGSDbK+QWmY8/g=
+github.com/mdlayher/netlink v1.7.2/go.mod h1:xraEF7uJbxLhc5fpHL4cPe221LI2bdttWlU+ZGLfQSw=
+github.com/mdlayher/socket v0.4.1 h1:eM9y2/jlbs1M615oshPQOHZzj6R6wMT7bX5NPiQvn2U=
+github.com/mdlayher/socket v0.4.1/go.mod h1:cAqeGjoufqdxWkD7DkpyS+wcefOtmu5OQ8KuoJGIReA=
+github.com/moby/sys/userns v0.1.0 h1:tVLXkFOxVu9A64/yh59slHVv9ahO9UIev4JZusOLG/g=
+github.com/moby/sys/userns v0.1.0/go.mod h1:IHUYgu/kao6N8YZlp9Cf444ySSvCmDlmzUcYfDHOl28=
+github.com/opencontainers/runtime-spec v1.2.0 h1:z97+pHb3uELt/yiAWD691HNHQIF07bE7dzrbT927iTk=
+github.com/opencontainers/runtime-spec v1.2.0/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
 github.com/patrickmn/go-cache v2.1.0+incompatible h1:HRMgzkcYKYpi3C8ajMPV8OFXaaRUnok+kx1WdO15EQc=
 github.com/patrickmn/go-cache v2.1.0+incompatible/go.mod h1:3Qf8kWWT7OJRJbdiICTKqZju1ZixQ/KpMGzzAfe6+WQ=
 github.com/pbnjay/memory v0.0.0-20210728143218-7b4eea64cf58 h1:onHthvaw9LFnH4t2DcNVpwGmV9E1BkGknEliJkfwQj0=
 github.com/pbnjay/memory v0.0.0-20210728143218-7b4eea64cf58/go.mod h1:DXv8WO4yhMYhSNPKjeNKa5WY9YCIEBRbNzFFPJbWO6Y=
-github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRIccs7FGNTlIRMkT8wgtp5eCXdBlqhYGL6U=
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prashantv/gostub v1.1.0 h1:BTyx3RfQjRHnUWaGF9oQos79AlQ5k8WNktv7VGvVH4g=
 github.com/prashantv/gostub v1.1.0/go.mod h1:A5zLQHz7ieHGG7is6LLXLz7I8+3LZzsrV0P1IAHhP5U=
-github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
 github.com/rogpeppe/go-internal v1.13.1 h1:KvO1DLK/DRN07sQ1LQKScxyZJuNnedQ5/wKSR38lUII=
 github.com/rogpeppe/go-internal v1.13.1/go.mod h1:uMEvuHeurkdAXX61udpOXGD/AzZDWNMNyH2VO9fmH0o=
 github.com/silas/dag v0.0.0-20220518035006-a7e85ada93c5 h1:G/FZtUu7a6NTWl3KUHMV9jkLAh/Rvtf03NWMHaEDl+E=
 github.com/silas/dag v0.0.0-20220518035006-a7e85ada93c5/go.mod h1:7RTUFBdIRC9nZ7/3RyRNH1bdqIShrDejd1YbLwgPS+I=
+github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
+github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
-go.uber.org/atomic v1.11.0 h1:ZvwS0R+56ePWxUNi+Atn9dWONBPp/AUETXlHW0DxSjE=
-go.uber.org/atomic v1.11.0/go.mod h1:LUxbIzbOniOlMKjJjyPfpl4v+PKK2cNJn91OQbhoJI0=
 go.uber.org/automaxprocs v1.6.0 h1:O3y2/QNTOdbF+e/dpXNNW7Rx2hZ4sTIPyybbxyNqTUs=
 go.uber.org/automaxprocs v1.6.0/go.mod h1:ifeIMSnPZuznNm6jmdzmU3/bfk01Fe2fotchwEFJ8r8=
-go.unistack.org/micro-proto/v4 v4.1.0 h1:qPwL2n/oqh9RE3RTTDgt28XK3QzV597VugQPaw9lKUk=
+go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
-go.unistack.org/micro-proto/v4 v4.1.0/go.mod h1:ArmK7o+uFvxSY3dbJhKBBX4Pm1rhWdLEFf3LxBrMtec=
+go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
-golang.org/x/net v0.34.0 h1:Mb7Mrk043xzHgnRM88suvJFwzVrRfHEHJEl5/71CKw0=
+go.unistack.org/micro-proto/v3 v3.4.1 h1:UTjLSRz2YZuaHk9iSlVqqsA50JQNAEK2ZFboGqtEa9Q=
-golang.org/x/net v0.34.0/go.mod h1:di0qlW3YNM5oh6GqDGQr92MyTozJPmybPK4Ev/Gm31k=
+go.unistack.org/micro-proto/v3 v3.4.1/go.mod h1:okx/cnOhzuCX0ggl/vToatbCupi0O44diiiLLsZ93Zo=
+golang.org/x/exp v0.0.0-20241210194714-1829a127f884 h1:Y/Mj/94zIQQGHVSv1tTtQBDaQaJe62U9bkDZKKyhPCU=
+golang.org/x/exp v0.0.0-20241210194714-1829a127f884/go.mod h1:qj5a5QZpwLU2NLQudwIN5koi3beDhSAlJwa67PuM98c=
+golang.org/x/net v0.33.0 h1:74SYHlV8BIgHIFC/LrYkOGIwL19eTYXQ5wc6TBuO36I=
+golang.org/x/net v0.33.0/go.mod h1:HXLR5J+9DxmrqMwG9qjGCxZ+zKXxBru04zlTvWlWuN4=
 golang.org/x/sync v0.10.0 h1:3NQrjDixjgGwUOCaF8w2+VYHv0Ve/vGYSbdkTa98gmQ=
 golang.org/x/sync v0.10.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
-golang.org/x/sys v0.29.0 h1:TPYlXGxvx1MGTn2GiZDhnjPA9wZzZeGKHHmKhHYvgaU=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.29.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.28.0 h1:Fksou7UEQUWlKvIdsqzJmUmCX3cZuD2+P3XyyzwMhlA=
+golang.org/x/sys v0.28.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/text v0.21.0 h1:zyQAAkrwaneQ066sspRyJaG9VNi/YJ1NfzcGB3hZ/qo=
 golang.org/x/text v0.21.0/go.mod h1:4IBbMaMmOPCJ8SecivzSH54+73PCFmPWxNTLm+vZkEQ=
 google.golang.org/genproto/googleapis/rpc v0.0.0-20241216192217-9240e9c98484 h1:Z7FRVJPSMaHQxD0uXU8WdgFh8PseLM8Q8NzhnpMrBhQ=
 google.golang.org/genproto/googleapis/rpc v0.0.0-20241216192217-9240e9c98484/go.mod h1:lcTa1sDdWEIHMWlITnIczmw5w60CF9ffkb8Z+DVmmjA=
-google.golang.org/grpc v1.69.4 h1:MF5TftSMkd8GLw/m0KM6V8CMOCY6NZ1NQDPGFgbTt4A=
+google.golang.org/grpc v1.69.2 h1:U3S9QEtbXC0bYNvRtcoklF3xGtLViumSYxWykJS+7AU=
-google.golang.org/grpc v1.69.4/go.mod h1:vyjdE6jLBI76dgpDojsFGNaHlxdjXN9ghpnd2o7JGZ4=
+google.golang.org/grpc v1.69.2/go.mod h1:vyjdE6jLBI76dgpDojsFGNaHlxdjXN9ghpnd2o7JGZ4=
-google.golang.org/protobuf v1.36.3 h1:82DV7MYdb8anAVi3qge1wSnMDrnKK7ebr+I0hHRN1BU=
+google.golang.org/protobuf v1.36.1 h1:yBPeRvTftaleIgM3PZ/WBIZ7XM/eEYAaEyCwvyjq/gk=
-google.golang.org/protobuf v1.36.3/go.mod h1:9fA7Ob0pmnwhb644+1+CVWFRbNajQ6iRojtC/QF5bRE=
+google.golang.org/protobuf v1.36.1/go.mod h1:9fA7Ob0pmnwhb644+1+CVWFRbNajQ6iRojtC/QF5bRE=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

logger/options.go

@@ -8,7 +8,7 @@ import (
 	"slices"
 	"time"
 
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
 )
 
 // Option func signature

logger/slog/slog.go

@@ -13,9 +13,9 @@ import (
 	"sync/atomic"
 	"time"
 
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/semconv"
+	"go.unistack.org/micro/v3/semconv"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 const (

logger/slog/slog_test.go

@@ -12,9 +12,9 @@ import (
 	"time"
 
 	"github.com/google/uuid"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/util/buffer"
+	"go.unistack.org/micro/v3/util/buffer"
 )
 
 // always first to have proper check
@@ -412,10 +412,9 @@ func Test_WithContextAttrFunc(t *testing.T) {
 			}
 			attrs := make([]interface{}, 0, 10)
 			for k, v := range md {
-				key := strings.ToLower(k)
+				switch k {
-				switch key {
+				case "X-Request-Id", "Phone", "External-Id", "Source-Service", "X-App-Install-Id", "Client-Id", "Client-Ip":
-				case "x-request-id", "phone", "external-Id", "source-service", "x-app-install-id", "client-id", "client-ip":
+					attrs = append(attrs, strings.ToLower(k), v)
-					attrs = append(attrs, key, v[0])
 				}
 			}
 			return attrs

logger/unwrap/unwrap.go

@@ -8,7 +8,7 @@ import (
 	"strconv"
 	"strings"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
 )
 
 const sf = "0-+# "

logger/unwrap/unwrap_test.go

@@ -5,7 +5,7 @@ import (
 	"strings"
 	"testing"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
 )
 
 func TestUnwrap(t *testing.T) {

metadata/context.go

@@ -0,0 +1,179 @@
+// Package metadata is a way of defining message headers
+package metadata
+
+import (
+	"context"
+)
+
+type (
+	mdIncomingKey struct{}
+	mdOutgoingKey struct{}
+	mdKey         struct{}
+)
+
+// FromIncomingContext returns metadata from incoming ctx
+// returned metadata shoud not be modified or race condition happens
+func FromIncomingContext(ctx context.Context) (Metadata, bool) {
+	if ctx == nil {
+		return nil, false
+	}
+	md, ok := ctx.Value(mdIncomingKey{}).(*rawMetadata)
+	if !ok || md.md == nil {
+		return nil, false
+	}
+	return md.md, ok
+}
+
+// MustIncomingContext returns metadata from incoming ctx
+// returned metadata shoud not be modified or race condition happens.
+// If metadata not exists panics.
+func MustIncomingContext(ctx context.Context) Metadata {
+	md, ok := FromIncomingContext(ctx)
+	if !ok {
+		panic("missing metadata")
+	}
+	return md
+}
+
+// FromOutgoingContext returns metadata from outgoing ctx
+// returned metadata shoud not be modified or race condition happens
+func FromOutgoingContext(ctx context.Context) (Metadata, bool) {
+	if ctx == nil {
+		return nil, false
+	}
+	md, ok := ctx.Value(mdOutgoingKey{}).(*rawMetadata)
+	if !ok || md.md == nil {
+		return nil, false
+	}
+	return md.md, ok
+}
+
+// MustOutgoingContext returns metadata from outgoing ctx
+// returned metadata shoud not be modified or race condition happens.
+// If metadata not exists panics.
+func MustOutgoingContext(ctx context.Context) Metadata {
+	md, ok := FromOutgoingContext(ctx)
+	if !ok {
+		panic("missing metadata")
+	}
+	return md
+}
+
+// FromContext returns metadata from the given context
+// returned metadata shoud not be modified or race condition happens
+func FromContext(ctx context.Context) (Metadata, bool) {
+	if ctx == nil {
+		return nil, false
+	}
+	md, ok := ctx.Value(mdKey{}).(*rawMetadata)
+	if !ok || md.md == nil {
+		return nil, false
+	}
+	return md.md, ok
+}
+
+// MustContext returns metadata from the given context
+// returned metadata shoud not be modified or race condition happens
+func MustContext(ctx context.Context) Metadata {
+	md, ok := FromContext(ctx)
+	if !ok {
+		panic("missing metadata")
+	}
+	return md
+}
+
+// NewContext creates a new context with the given metadata
+func NewContext(ctx context.Context, md Metadata) context.Context {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	return context.WithValue(ctx, mdKey{}, &rawMetadata{md})
+}
+
+// SetOutgoingContext modify outgoing context with given metadata
+func SetOutgoingContext(ctx context.Context, md Metadata) bool {
+	if ctx == nil {
+		return false
+	}
+	if omd, ok := ctx.Value(mdOutgoingKey{}).(*rawMetadata); ok {
+		omd.md = md
+		return true
+	}
+	return false
+}
+
+// SetIncomingContext modify incoming context with given metadata
+func SetIncomingContext(ctx context.Context, md Metadata) bool {
+	if ctx == nil {
+		return false
+	}
+	if omd, ok := ctx.Value(mdIncomingKey{}).(*rawMetadata); ok {
+		omd.md = md
+		return true
+	}
+	return false
+}
+
+// NewIncomingContext creates a new context with incoming metadata attached
+func NewIncomingContext(ctx context.Context, md Metadata) context.Context {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	return context.WithValue(ctx, mdIncomingKey{}, &rawMetadata{md})
+}
+
+// NewOutgoingContext creates a new context with outcoming metadata attached
+func NewOutgoingContext(ctx context.Context, md Metadata) context.Context {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	return context.WithValue(ctx, mdOutgoingKey{}, &rawMetadata{md})
+}
+
+// AppendOutgoingContext apends new md to context
+func AppendOutgoingContext(ctx context.Context, kv ...string) context.Context {
+	md, ok := Pairs(kv...)
+	if !ok {
+		return ctx
+	}
+	omd, ok := FromOutgoingContext(ctx)
+	if !ok {
+		return NewOutgoingContext(ctx, md)
+	}
+	for k, v := range md {
+		omd.Set(k, v)
+	}
+	return ctx
+}
+
+// AppendIncomingContext apends new md to context
+func AppendIncomingContext(ctx context.Context, kv ...string) context.Context {
+	md, ok := Pairs(kv...)
+	if !ok {
+		return ctx
+	}
+	omd, ok := FromIncomingContext(ctx)
+	if !ok {
+		return NewIncomingContext(ctx, md)
+	}
+	for k, v := range md {
+		omd.Set(k, v)
+	}
+	return ctx
+}
+
+// AppendContext apends new md to context
+func AppendContext(ctx context.Context, kv ...string) context.Context {
+	md, ok := Pairs(kv...)
+	if !ok {
+		return ctx
+	}
+	omd, ok := FromContext(ctx)
+	if !ok {
+		return NewContext(ctx, md)
+	}
+	for k, v := range md {
+		omd.Set(k, v)
+	}
+	return ctx
+}

metadata/context_test.go

@@ -0,0 +1,140 @@
+package metadata
+
+import (
+	"context"
+	"testing"
+)
+
+func TestFromNilContext(t *testing.T) {
+	// nolint: staticcheck
+	c, ok := FromContext(nil)
+	if ok || c != nil {
+		t.Fatal("FromContext not works")
+	}
+}
+
+func TestNewNilContext(t *testing.T) {
+	// nolint: staticcheck
+	ctx := NewContext(nil, New(0))
+
+	c, ok := FromContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("NewContext not works")
+	}
+}
+
+func TestFromContext(t *testing.T) {
+	ctx := context.WithValue(context.TODO(), mdKey{}, &rawMetadata{New(0)})
+
+	c, ok := FromContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("FromContext not works")
+	}
+}
+
+func TestNewContext(t *testing.T) {
+	ctx := NewContext(context.TODO(), New(0))
+
+	c, ok := FromContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("NewContext not works")
+	}
+}
+
+func TestFromIncomingContext(t *testing.T) {
+	ctx := context.WithValue(context.TODO(), mdIncomingKey{}, &rawMetadata{New(0)})
+
+	c, ok := FromIncomingContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("FromIncomingContext not works")
+	}
+}
+
+func TestFromOutgoingContext(t *testing.T) {
+	ctx := context.WithValue(context.TODO(), mdOutgoingKey{}, &rawMetadata{New(0)})
+
+	c, ok := FromOutgoingContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("FromOutgoingContext not works")
+	}
+}
+
+func TestSetIncomingContext(t *testing.T) {
+	md := New(1)
+	md.Set("key", "val")
+	ctx := context.WithValue(context.TODO(), mdIncomingKey{}, &rawMetadata{})
+	if !SetIncomingContext(ctx, md) {
+		t.Fatal("SetIncomingContext not works")
+	}
+	md, ok := FromIncomingContext(ctx)
+	if md == nil || !ok {
+		t.Fatal("SetIncomingContext not works")
+	} else if v, ok := md.Get("key"); !ok || v != "val" {
+		t.Fatal("SetIncomingContext not works")
+	}
+}
+
+func TestSetOutgoingContext(t *testing.T) {
+	md := New(1)
+	md.Set("key", "val")
+	ctx := context.WithValue(context.TODO(), mdOutgoingKey{}, &rawMetadata{})
+	if !SetOutgoingContext(ctx, md) {
+		t.Fatal("SetOutgoingContext not works")
+	}
+	md, ok := FromOutgoingContext(ctx)
+	if md == nil || !ok {
+		t.Fatal("SetOutgoingContext not works")
+	} else if v, ok := md.Get("key"); !ok || v != "val" {
+		t.Fatal("SetOutgoingContext not works")
+	}
+}
+
+func TestNewIncomingContext(t *testing.T) {
+	md := New(1)
+	md.Set("key", "val")
+	ctx := NewIncomingContext(context.TODO(), md)
+
+	c, ok := FromIncomingContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("NewIncomingContext not works")
+	}
+}
+
+func TestNewOutgoingContext(t *testing.T) {
+	md := New(1)
+	md.Set("key", "val")
+	ctx := NewOutgoingContext(context.TODO(), md)
+
+	c, ok := FromOutgoingContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("NewOutgoingContext not works")
+	}
+}
+
+func TestAppendIncomingContext(t *testing.T) {
+	md := New(1)
+	md.Set("key1", "val1")
+	ctx := AppendIncomingContext(context.TODO(), "key2", "val2")
+
+	nmd, ok := FromIncomingContext(ctx)
+	if nmd == nil || !ok {
+		t.Fatal("AppendIncomingContext not works")
+	}
+	if v, ok := nmd.Get("key2"); !ok || v != "val2" {
+		t.Fatal("AppendIncomingContext not works")
+	}
+}
+
+func TestAppendOutgoingContext(t *testing.T) {
+	md := New(1)
+	md.Set("key1", "val1")
+	ctx := AppendOutgoingContext(context.TODO(), "key2", "val2")
+
+	nmd, ok := FromOutgoingContext(ctx)
+	if nmd == nil || !ok {
+		t.Fatal("AppendOutgoingContext not works")
+	}
+	if v, ok := nmd.Get("key2"); !ok || v != "val2" {
+		t.Fatal("AppendOutgoingContext not works")
+	}
+}

metadata/headers.go

@@ -1,19 +0,0 @@
-// Package metadata is a way of defining message headers
-package metadata
-
-var (
-	// HeaderTopic is the header name that contains topic name
-	HeaderTopic = "Micro-Topic"
-	// HeaderContentType specifies content type of message
-	HeaderContentType = "Content-Type"
-	// HeaderEndpoint specifies endpoint in service
-	HeaderEndpoint = "Micro-Endpoint"
-	// HeaderService specifies service
-	HeaderService = "Micro-Service"
-	// HeaderTimeout specifies timeout of operation
-	HeaderTimeout = "Micro-Timeout"
-	// HeaderAuthorization specifies Authorization header
-	HeaderAuthorization = "Authorization"
-	// HeaderXRequestID specifies request id
-	HeaderXRequestID = "X-Request-Id"
-)

metadata/metadata.go

@@ -1,462 +1,41 @@
+// Package metadata is a way of defining message headers
 package metadata
 
 import (
-	"context"
-	"fmt"
 	"net/textproto"
 	"sort"
 	"strings"
 )
 
-// defaultMetadataSize used when need to init new Metadata
+var (
-var defaultMetadataSize = 2
+	// HeaderTopic is the header name that contains topic name
-
+	HeaderTopic = "Micro-Topic"
-// Metadata is a mapping from metadata keys to values. Users should use the following
+	// HeaderContentType specifies content type of message
-// two convenience functions New and Pairs to generate Metadata.
+	HeaderContentType = "Content-Type"
-type Metadata map[string][]string
+	// HeaderEndpoint specifies endpoint in service
-
+	HeaderEndpoint = "Micro-Endpoint"
-// New creates an zero Metadata.
+	// HeaderService specifies service
-func New(l int) Metadata {
+	HeaderService = "Micro-Service"
-	if l == 0 {
+	// HeaderTimeout specifies timeout of operation
-		l = defaultMetadataSize
+	HeaderTimeout = "Micro-Timeout"
-	}
+	// HeaderAuthorization specifies Authorization header
-	md := make(Metadata, l)
+	HeaderAuthorization = "Authorization"
-	return md
+	// HeaderXRequestID specifies request id
-}
+	HeaderXRequestID = "X-Request-Id"
-
-// NewWithMetadata creates an Metadata from a given key-value map.
-func NewWithMetadata(m map[string]string) Metadata {
-	md := make(Metadata, len(m))
-	for key, val := range m {
-		md[key] = append(md[key], val)
-	}
-	return md
-}
-
-// Pairs returns an Metadata formed by the mapping of key, value ...
-// Pairs panics if len(kv) is odd.
-func Pairs(kv ...string) Metadata {
-	if len(kv)%2 == 1 {
-		panic(fmt.Sprintf("metadata: Pairs got the odd number of input pairs for metadata: %d", len(kv)))
-	}
-	md := make(Metadata, len(kv)/2)
-	for i := 0; i < len(kv); i += 2 {
-		md[kv[i]] = append(md[kv[i]], kv[i+1])
-	}
-	return md
-}
-
-// Len returns the number of items in Metadata.
-func (md Metadata) Len() int {
-	return len(md)
-}
-
-// Copy returns a copy of Metadata.
-func Copy(src Metadata) Metadata {
-	out := make(Metadata, len(src))
-	for k, v := range src {
-		out[k] = copyOf(v)
-	}
-	return out
-}
-
-// Copy returns a copy of Metadata.
-func (md Metadata) Copy() Metadata {
-	out := make(Metadata, len(md))
-	for k, v := range md {
-		out[k] = copyOf(v)
-	}
-	return out
-}
-
-// AsHTTP1 returns a copy of Metadata
-// with CanonicalMIMEHeaderKey.
-func (md Metadata) AsHTTP1() map[string][]string {
-	out := make(map[string][]string, len(md))
-	for k, v := range md {
-		out[textproto.CanonicalMIMEHeaderKey(k)] = copyOf(v)
-	}
-	return out
-}
-
-// AsHTTP1 returns a copy of Metadata
-// with strings.ToLower.
-func (md Metadata) AsHTTP2() map[string][]string {
-	out := make(map[string][]string, len(md))
-	for k, v := range md {
-		out[strings.ToLower(k)] = copyOf(v)
-	}
-	return out
-}
-
-// CopyTo copies Metadata to out.
-func (md Metadata) CopyTo(out Metadata) {
-	for k, v := range md {
-		out[k] = copyOf(v)
-	}
-}
-
-// Get obtains the values for a given key.
-func (md Metadata) MustGet(k string) []string {
-	v, ok := md.Get(k)
-	if !ok {
-		panic("missing metadata key")
-	}
-	return v
-}
-
-// Get obtains the values for a given key.
-func (md Metadata) Get(k string) ([]string, bool) {
-	v, ok := md[k]
-	if !ok {
-		v, ok = md[strings.ToLower(k)]
-	}
-	if !ok {
-		v, ok = md[textproto.CanonicalMIMEHeaderKey(k)]
-	}
-	return v, ok
-}
-
-// MustGetJoined obtains the values for a given key
-// with joined values with "," symbol
-func (md Metadata) MustGetJoined(k string) string {
-	v, ok := md.GetJoined(k)
-	if !ok {
-		panic("missing metadata key")
-	}
-	return v
-}
-
-// GetJoined obtains the values for a given key
-// with joined values with "," symbol
-func (md Metadata) GetJoined(k string) (string, bool) {
-	v, ok := md.Get(k)
-	if !ok {
-		return "", ok
-	}
-	return strings.Join(v, ","), true
-}
-
-// Set sets the value of a given key with a slice of values.
-func (md Metadata) Add(key string, vals ...string) {
-	if len(vals) == 0 {
-		return
-	}
-	md[key] = vals
-}
-
-// Set sets the value of a given key with a slice of values.
-func (md Metadata) Set(kvs ...string) {
-	if len(kvs)%2 == 1 {
-		panic(fmt.Sprintf("metadata: Set got an odd number of input pairs for metadata: %d", len(kvs)))
-	}
-
-	for i := 0; i < len(kvs); i += 2 {
-		md[kvs[i]] = append(md[kvs[i]], kvs[i+1])
-	}
-}
-
-// Append adds the values to key k, not overwriting what was already stored at
-// that key.
-func (md Metadata) Append(key string, vals ...string) {
-	if len(vals) == 0 {
-		return
-	}
-	md[key] = append(md[key], vals...)
-}
-
-// Del removes the values for a given keys k.
-func (md Metadata) Del(k ...string) {
-	for i := range k {
-		delete(md, k[i])
-		delete(md, strings.ToLower(k[i]))
-		delete(md, textproto.CanonicalMIMEHeaderKey(k[i]))
-	}
-}
-
-// Join joins any number of Metadatas into a single Metadata.
-//
-// The order of values for each key is determined by the order in which the Metadatas
-// containing those values are presented to Join.
-func Join(mds ...Metadata) Metadata {
-	out := Metadata{}
-	for _, Metadata := range mds {
-		for k, v := range Metadata {
-			out[k] = append(out[k], v...)
-		}
-	}
-	return out
-}
-
-type (
-	metadataIncomingKey struct{}
-	metadataOutgoingKey struct{}
-	metadataCurrentKey  struct{}
 )
 
-// NewContext creates a new context with Metadata attached. Metadata must
+// Metadata is our way of representing request headers internally.
-// not be modified after calling this function.
+// They're used at the RPC level and translate back and forth
-func NewContext(ctx context.Context, md Metadata) context.Context {
+// from Transport headers.
-	return context.WithValue(ctx, metadataCurrentKey{}, rawMetadata{md: md})
+type Metadata map[string]string
-}
-
-// NewIncomingContext creates a new context with incoming Metadata attached. Metadata must
-// not be modified after calling this function.
-func NewIncomingContext(ctx context.Context, md Metadata) context.Context {
-	return context.WithValue(ctx, metadataIncomingKey{}, rawMetadata{md: md})
-}
-
-// NewOutgoingContext creates a new context with outgoing Metadata attached. If used
-// in conjunction with AppendOutgoingContext, NewOutgoingContext will
-// overwrite any previously-appended metadata. Metadata must not be modified after
-// calling this function.
-func NewOutgoingContext(ctx context.Context, md Metadata) context.Context {
-	return context.WithValue(ctx, metadataOutgoingKey{}, rawMetadata{md: md})
-}
-
-// AppendContext returns a new context with the provided kv merged
-// with any existing metadata in the context. Please refer to the documentation
-// of Pairs for a description of kv.
-func AppendContext(ctx context.Context, kv ...string) context.Context {
-	if len(kv)%2 == 1 {
-		panic(fmt.Sprintf("metadata: AppendContext got an odd number of input pairs for metadata: %d", len(kv)))
-	}
-	md, _ := ctx.Value(metadataCurrentKey{}).(rawMetadata)
-	added := make([][]string, len(md.added)+1)
-	copy(added, md.added)
-	kvCopy := make([]string, 0, len(kv))
-	for i := 0; i < len(kv); i += 2 {
-		kvCopy = append(kvCopy, strings.ToLower(kv[i]), kv[i+1])
-	}
-	added[len(added)-1] = kvCopy
-	return context.WithValue(ctx, metadataCurrentKey{}, rawMetadata{md: md.md, added: added})
-}
-
-// AppendIncomingContext returns a new context with the provided kv merged
-// with any existing metadata in the context. Please refer to the documentation
-// of Pairs for a description of kv.
-func AppendIncomingContext(ctx context.Context, kv ...string) context.Context {
-	if len(kv)%2 == 1 {
-		panic(fmt.Sprintf("metadata: AppendIncomingContext got an odd number of input pairs for metadata: %d", len(kv)))
-	}
-	md, _ := ctx.Value(metadataIncomingKey{}).(rawMetadata)
-	added := make([][]string, len(md.added)+1)
-	copy(added, md.added)
-	kvCopy := make([]string, 0, len(kv))
-	for i := 0; i < len(kv); i += 2 {
-		kvCopy = append(kvCopy, strings.ToLower(kv[i]), kv[i+1])
-	}
-	added[len(added)-1] = kvCopy
-	return context.WithValue(ctx, metadataIncomingKey{}, rawMetadata{md: md.md, added: added})
-}
-
-// AppendOutgoingContext returns a new context with the provided kv merged
-// with any existing metadata in the context. Please refer to the documentation
-// of Pairs for a description of kv.
-func AppendOutgoingContext(ctx context.Context, kv ...string) context.Context {
-	if len(kv)%2 == 1 {
-		panic(fmt.Sprintf("metadata: AppendOutgoingContext got an odd number of input pairs for metadata: %d", len(kv)))
-	}
-	md, _ := ctx.Value(metadataOutgoingKey{}).(rawMetadata)
-	added := make([][]string, len(md.added)+1)
-	copy(added, md.added)
-	kvCopy := make([]string, 0, len(kv))
-	for i := 0; i < len(kv); i += 2 {
-		kvCopy = append(kvCopy, strings.ToLower(kv[i]), kv[i+1])
-	}
-	added[len(added)-1] = kvCopy
-	return context.WithValue(ctx, metadataOutgoingKey{}, rawMetadata{md: md.md, added: added})
-}
-
-// FromContext returns the metadata in ctx if it exists.
-func FromContext(ctx context.Context) (Metadata, bool) {
-	raw, ok := ctx.Value(metadataCurrentKey{}).(rawMetadata)
-	if !ok {
-		return nil, false
-	}
-	metadataSize := len(raw.md)
-	for i := range raw.added {
-		metadataSize += len(raw.added[i]) / 2
-	}
-
-	out := make(Metadata, metadataSize)
-	for k, v := range raw.md {
-		out[k] = copyOf(v)
-	}
-	for _, added := range raw.added {
-		if len(added)%2 == 1 {
-			panic(fmt.Sprintf("metadata: FromContext got an odd number of input pairs for metadata: %d", len(added)))
-		}
-
-		for i := 0; i < len(added); i += 2 {
-			out[added[i]] = append(out[added[i]], added[i+1])
-		}
-	}
-	return out, true
-}
-
-// MustContext returns the metadata in ctx.
-func MustContext(ctx context.Context) Metadata {
-	md, ok := FromContext(ctx)
-	if !ok {
-		panic("missing metadata")
-	}
-	return md
-}
-
-// FromIncomingContext returns the incoming metadata in ctx if it exists.
-func FromIncomingContext(ctx context.Context) (Metadata, bool) {
-	raw, ok := ctx.Value(metadataIncomingKey{}).(rawMetadata)
-	if !ok {
-		return nil, false
-	}
-	metadataSize := len(raw.md)
-	for i := range raw.added {
-		metadataSize += len(raw.added[i]) / 2
-	}
-
-	out := make(Metadata, metadataSize)
-	for k, v := range raw.md {
-		out[k] = copyOf(v)
-	}
-	for _, added := range raw.added {
-		if len(added)%2 == 1 {
-			panic(fmt.Sprintf("metadata: FromIncomingContext got an odd number of input pairs for metadata: %d", len(added)))
-		}
-
-		for i := 0; i < len(added); i += 2 {
-			out[added[i]] = append(out[added[i]], added[i+1])
-		}
-	}
-	return out, true
-}
-
-// MustIncomingContext returns the incoming metadata in ctx.
-func MustIncomingContext(ctx context.Context) Metadata {
-	md, ok := FromIncomingContext(ctx)
-	if !ok {
-		panic("missing metadata")
-	}
-	return md
-}
-
-// ValueFromIncomingContext returns the metadata value corresponding to the metadata
-// key from the incoming metadata if it exists. Keys are matched in a case insensitive
-// manner.
-func ValueFromIncomingContext(ctx context.Context, key string) []string {
-	raw, ok := ctx.Value(metadataIncomingKey{}).(rawMetadata)
-	if !ok {
-		return nil
-	}
-
-	if v, ok := raw.md[key]; ok {
-		return copyOf(v)
-	}
-	for k, v := range raw.md {
-		// Case insensitive comparison: Metadata is a map, and there's no guarantee
-		// that the Metadata attached to the context is created using our helper
-		// functions.
-		if strings.EqualFold(k, key) {
-			return copyOf(v)
-		}
-	}
-	return nil
-}
-
-// ValueFromCurrentContext returns the metadata value corresponding to the metadata
-// key from the incoming metadata if it exists. Keys are matched in a case insensitive
-// manner.
-func ValueFromCurrentContext(ctx context.Context, key string) []string {
-	md, ok := ctx.Value(metadataCurrentKey{}).(rawMetadata)
-	if !ok {
-		return nil
-	}
-
-	if v, ok := md.md[key]; ok {
-		return copyOf(v)
-	}
-	for k, v := range md.md {
-		// Case insensitive comparison: Metadata is a map, and there's no guarantee
-		// that the Metadata attached to the context is created using our helper
-		// functions.
-		if strings.EqualFold(k, key) {
-			return copyOf(v)
-		}
-	}
-	return nil
-}
-
-// MustOutgoingContext returns the outgoing metadata in ctx.
-func MustOutgoingContext(ctx context.Context) Metadata {
-	md, ok := FromOutgoingContext(ctx)
-	if !ok {
-		panic("missing metadata")
-	}
-	return md
-}
-
-// ValueFromOutgoingContext returns the metadata value corresponding to the metadata
-// key from the incoming metadata if it exists. Keys are matched in a case insensitive
-// manner.
-func ValueFromOutgoingContext(ctx context.Context, key string) []string {
-	md, ok := ctx.Value(metadataOutgoingKey{}).(rawMetadata)
-	if !ok {
-		return nil
-	}
-
-	if v, ok := md.md[key]; ok {
-		return copyOf(v)
-	}
-	for k, v := range md.md {
-		// Case insensitive comparison: Metadata is a map, and there's no guarantee
-		// that the Metadata attached to the context is created using our helper
-		// functions.
-		if strings.EqualFold(k, key) {
-			return copyOf(v)
-		}
-	}
-	return nil
-}
-
-func copyOf(v []string) []string {
-	vals := make([]string, len(v))
-	copy(vals, v)
-	return vals
-}
-
-// FromOutgoingContext returns the outgoing metadata in ctx if it exists.
-func FromOutgoingContext(ctx context.Context) (Metadata, bool) {
-	raw, ok := ctx.Value(metadataOutgoingKey{}).(rawMetadata)
-	if !ok {
-		return nil, false
-	}
-
-	metadataSize := len(raw.md)
-	for i := range raw.added {
-		metadataSize += len(raw.added[i]) / 2
-	}
-
-	out := make(Metadata, metadataSize)
-	for k, v := range raw.md {
-		out[k] = copyOf(v)
-	}
-	for _, added := range raw.added {
-		if len(added)%2 == 1 {
-			panic(fmt.Sprintf("metadata: FromOutgoingContext got an odd number of input pairs for metadata: %d", len(added)))
-		}
-
-		for i := 0; i < len(added); i += 2 {
-			out[added[i]] = append(out[added[i]], added[i+1])
-		}
-	}
-	return out, ok
-}
 
 type rawMetadata struct {
 	md Metadata
-	added [][]string
 }
 
+// defaultMetadataSize used when need to init new Metadata
+var defaultMetadataSize = 2
+
 // Iterator used to iterate over metadata with order
 type Iterator struct {
 	md   Metadata
@@ -466,18 +45,14 @@ type Iterator struct {
 }
 
 // Next advance iterator to next element
-func (iter *Iterator) Next(k *string, v *[]string) bool {
+func (iter *Iterator) Next(k, v *string) bool {
 	if iter.cur+1 > iter.cnt {
 		return false
 	}
 
-	if k != nil && v != nil {
 	*k = iter.keys[iter.cur]
-		vv := iter.md[*k]
+	*v = iter.md[*k]
-		*v = make([]string, len(vv))
-		copy(*v, vv)
 	iter.cur++
-	}
 	return true
 }
 
@@ -491,3 +66,102 @@ func (md Metadata) Iterator() *Iterator {
 	sort.Strings(iter.keys)
 	return iter
 }
+
+func (md Metadata) MustGet(key string) string {
+	val, ok := md.Get(key)
+	if !ok {
+		panic("missing metadata key")
+	}
+	return val
+}
+
+// Get returns value from metadata by key
+func (md Metadata) Get(key string) (string, bool) {
+	// fast path
+	val, ok := md[key]
+	if !ok {
+		// slow path
+		val, ok = md[textproto.CanonicalMIMEHeaderKey(key)]
+		if !ok {
+			val, ok = md[strings.ToLower(key)]
+		}
+	}
+	return val, ok
+}
+
+// Set is used to store value in metadata
+func (md Metadata) Set(kv ...string) {
+	if len(kv)%2 == 1 {
+		kv = kv[:len(kv)-1]
+	}
+	for idx := 0; idx < len(kv); idx += 2 {
+		md[textproto.CanonicalMIMEHeaderKey(kv[idx])] = kv[idx+1]
+	}
+}
+
+// Del is used to remove value from metadata
+func (md Metadata) Del(keys ...string) {
+	for _, key := range keys {
+		// fast path
+		delete(md, key)
+		// slow path
+		delete(md, textproto.CanonicalMIMEHeaderKey(key))
+		// very slow path
+		delete(md, strings.ToLower(key))
+	}
+}
+
+// Copy makes a copy of the metadata
+func (md Metadata) CopyTo(dst Metadata) {
+	for k, v := range md {
+		dst[k] = v
+	}
+}
+
+// Copy makes a copy of the metadata
+func Copy(md Metadata, exclude ...string) Metadata {
+	nmd := New(len(md))
+	for k, v := range md {
+		nmd[k] = v
+	}
+	nmd.Del(exclude...)
+	return nmd
+}
+
+// New return new sized metadata
+func New(size int) Metadata {
+	if size == 0 {
+		size = defaultMetadataSize
+	}
+	return make(Metadata, size)
+}
+
+// Merge merges metadata to existing metadata, overwriting if specified
+func Merge(omd Metadata, mmd Metadata, overwrite bool) Metadata {
+	var ok bool
+	nmd := Copy(omd)
+	for key, val := range mmd {
+		_, ok = nmd[key]
+		switch {
+		case ok && !overwrite:
+			continue
+		case val != "":
+			nmd[key] = val
+		case ok && val == "":
+			nmd.Del(key)
+		}
+	}
+	return nmd
+}
+
+// Pairs from which metadata created
+func Pairs(kv ...string) (Metadata, bool) {
+	if len(kv)%2 == 1 {
+		return nil, false
+	}
+	md := New(len(kv) / 2)
+	for idx := 0; idx < len(kv); idx += 2 {
+		md[kv[idx]] = kv[idx+1]
+	}
+	return md, true
+}

metadata/metadata_test.go

@@ -5,21 +5,10 @@ import (
 	"testing"
 )
 
-/*
-func TestAppendOutgoingContextModify(t *testing.T) {
-	md := Pairs("key1", "val1")
-	ctx := NewOutgoingContext(context.TODO(), md)
-	nctx := AppendOutgoingContext(ctx, "key1", "val3", "key2", "val2")
-	_ = nctx
-	omd := MustOutgoingContext(nctx)
-	fmt.Printf("%#+v\n", omd)
-}
-*/
-
 func TestLowercase(t *testing.T) {
 	md := New(1)
-	md["x-request-id"] = []string{"12345"}
+	md["x-request-id"] = "12345"
-	v, ok := md.GetJoined("X-Request-Id")
+	v, ok := md.Get("X-Request-Id")
 	if !ok || v == "" {
 		t.Fatalf("metadata invalid %#+v", md)
 	}
@@ -49,12 +38,15 @@ func TestMultipleUsage(t *testing.T) {
 
 func TestMetadataSetMultiple(t *testing.T) {
 	md := New(4)
-	md.Set("key1", "val1", "key2", "val2")
+	md.Set("key1", "val1", "key2", "val2", "key3")
 
-	if v, ok := md.GetJoined("key1"); !ok || v != "val1" {
+	if v, ok := md.Get("key1"); !ok || v != "val1" {
 		t.Fatalf("invalid kv %#+v", md)
 	}
-	if v, ok := md.GetJoined("key2"); !ok || v != "val2" {
+	if v, ok := md.Get("key2"); !ok || v != "val2" {
+		t.Fatalf("invalid kv %#+v", md)
+	}
+	if _, ok := md.Get("key3"); ok {
 		t.Fatalf("invalid kv %#+v", md)
 	}
 }
@@ -72,12 +64,22 @@ func TestAppend(t *testing.T) {
 }
 
 func TestPairs(t *testing.T) {
-	md := Pairs("key1", "val1", "key2", "val2")
+	md, ok := Pairs("key1", "val1", "key2", "val2")
-	if _, ok := md.Get("key1"); !ok {
+	if !ok {
+		t.Fatal("odd number of kv")
+	}
+	if _, ok = md.Get("key1"); !ok {
 		t.Fatal("key1 not found")
 	}
 }
 
+func testCtx(ctx context.Context) {
+	md := New(2)
+	md.Set("Key1", "Val1_new")
+	md.Set("Key3", "Val3")
+	SetOutgoingContext(ctx, md)
+}
+
 func TestPassing(t *testing.T) {
 	ctx := context.TODO()
 	md1 := New(2)
@@ -85,62 +87,69 @@ func TestPassing(t *testing.T) {
 	md1.Set("Key2", "Val2")
 
 	ctx = NewIncomingContext(ctx, md1)
-
+	testCtx(ctx)
 	_, ok := FromOutgoingContext(ctx)
 	if ok {
 		t.Fatalf("create outgoing context")
 	}
 
-	ctx = NewOutgoingContext(ctx, md1)
+	ctx = NewOutgoingContext(ctx, New(1))
-
+	testCtx(ctx)
 	md, ok := FromOutgoingContext(ctx)
 	if !ok {
 		t.Fatalf("missing metadata from outgoing context")
 	}
-	if v, ok := md.Get("Key1"); !ok || v[0] != "Val1" {
+	if v, ok := md.Get("Key1"); !ok || v != "Val1_new" {
 		t.Fatalf("invalid metadata value %#+v", md)
 	}
 }
 
-func TestIterator(t *testing.T) {
+func TestMerge(t *testing.T) {
-	md := Pairs(
+	omd := Metadata{
-		"1Last", "last",
+		"key1": "val1",
-		"2First", "first",
+	}
-		"3Second", "second",
+	mmd := Metadata{
-	)
+		"key2": "val2",
+	}
+
+	nmd := Merge(omd, mmd, true)
+	if len(nmd) != 2 {
+		t.Fatalf("merge failed: %v", nmd)
+	}
+}
+
+func TestIterator(_ *testing.T) {
+	md := Metadata{
+		"1Last":   "last",
+		"2First":  "first",
+		"3Second": "second",
+	}
 
 	iter := md.Iterator()
-	var k string
+	var k, v string
-	var v []string
-	chk := New(3)
-	for iter.Next(&k, &v) {
-		chk[k] = v
-	}
 
-	for k, v := range chk {
+	for iter.Next(&k, &v) {
-		if cv, ok := md[k]; !ok || len(cv) != len(v) || cv[0] != v[0] {
+		// fmt.Printf("k: %s, v: %s\n", k, v)
-			t.Fatalf("XXXX %#+v %#+v", chk, md)
-		}
 	}
 }
 
 func TestMedataCanonicalKey(t *testing.T) {
 	md := New(1)
 	md.Set("x-request-id", "12345")
-	v, ok := md.GetJoined("x-request-id")
+	v, ok := md.Get("x-request-id")
 	if !ok {
 		t.Fatalf("failed to get x-request-id")
 	} else if v != "12345" {
 		t.Fatalf("invalid metadata value: %s != %s", "12345", v)
 	}
 
-	v, ok = md.GetJoined("X-Request-Id")
+	v, ok = md.Get("X-Request-Id")
 	if !ok {
 		t.Fatalf("failed to get x-request-id")
 	} else if v != "12345" {
 		t.Fatalf("invalid metadata value: %s != %s", "12345", v)
 	}
-	v, ok = md.GetJoined("X-Request-ID")
+	v, ok = md.Get("X-Request-ID")
 	if !ok {
 		t.Fatalf("failed to get x-request-id")
 	} else if v != "12345" {
@@ -153,7 +162,7 @@ func TestMetadataSet(t *testing.T) {
 
 	md.Set("Key", "val")
 
-	val, ok := md.GetJoined("Key")
+	val, ok := md.Get("Key")
 	if !ok {
 		t.Fatal("key Key not found")
 	}
@@ -164,8 +173,8 @@ func TestMetadataSet(t *testing.T) {
 
 func TestMetadataDelete(t *testing.T) {
 	md := Metadata{
-		"Foo": []string{"bar"},
+		"Foo": "bar",
-		"Baz": []string{"empty"},
+		"Baz": "empty",
 	}
 
 	md.Del("Baz")
@@ -175,16 +184,25 @@ func TestMetadataDelete(t *testing.T) {
 	}
 }
 
+func TestNilContext(t *testing.T) {
+	var ctx context.Context
+
+	_, ok := FromContext(ctx)
+	if ok {
+		t.Fatal("nil context")
+	}
+}
+
 func TestMetadataCopy(t *testing.T) {
 	md := Metadata{
-		"Foo": []string{"bar"},
+		"Foo": "bar",
-		"Bar": []string{"baz"},
+		"Bar": "baz",
 	}
 
 	cp := Copy(md)
 
 	for k, v := range md {
-		if cv := cp[k]; cv[0] != v[0] {
+		if cv := cp[k]; cv != v {
 			t.Fatalf("Got %s:%s for %s:%s", k, cv, k, v)
 		}
 	}
@@ -192,7 +210,7 @@ func TestMetadataCopy(t *testing.T) {
 
 func TestMetadataContext(t *testing.T) {
 	md := Metadata{
-		"Foo": []string{"bar"},
+		"Foo": "bar",
 	}
 
 	ctx := NewContext(context.TODO(), md)
@@ -202,7 +220,7 @@ func TestMetadataContext(t *testing.T) {
 		t.Errorf("Unexpected error retrieving metadata, got %t", ok)
 	}
 
-	if emd["Foo"][0] != md["Foo"][0] {
+	if emd["Foo"] != md["Foo"] {
 		t.Errorf("Expected key: %s val: %s, got key: %s val: %s", "Foo", md["Foo"], "Foo", emd["Foo"])
 	}
 
@@ -211,88 +229,13 @@ func TestMetadataContext(t *testing.T) {
 	}
 }
 
-func TestFromContext(t *testing.T) {
+func TestCopy(t *testing.T) {
-	ctx := context.WithValue(context.TODO(), metadataCurrentKey{}, rawMetadata{md: New(0)})
+	md := New(2)
-
+	md.Set("key1", "val1", "key2", "val2")
-	c, ok := FromContext(ctx)
+	nmd := Copy(md, "key2")
-	if c == nil || !ok {
+	if len(nmd) != 1 {
-		t.Fatal("FromContext not works")
+		t.Fatal("Copy exclude not works")
-	}
+	} else if nmd["Key1"] != "val1" {
-}
+		t.Fatal("Copy exclude not works")
-
-func TestNewContext(t *testing.T) {
-	ctx := NewContext(context.TODO(), New(0))
-
-	c, ok := FromContext(ctx)
-	if c == nil || !ok {
-		t.Fatal("NewContext not works")
-	}
-}
-
-func TestFromIncomingContext(t *testing.T) {
-	ctx := context.WithValue(context.TODO(), metadataIncomingKey{}, rawMetadata{md: New(0)})
-
-	c, ok := FromIncomingContext(ctx)
-	if c == nil || !ok {
-		t.Fatal("FromIncomingContext not works")
-	}
-}
-
-func TestFromOutgoingContext(t *testing.T) {
-	ctx := context.WithValue(context.TODO(), metadataOutgoingKey{}, rawMetadata{md: New(0)})
-
-	c, ok := FromOutgoingContext(ctx)
-	if c == nil || !ok {
-		t.Fatal("FromOutgoingContext not works")
-	}
-}
-
-func TestNewIncomingContext(t *testing.T) {
-	md := New(1)
-	md.Set("key", "val")
-	ctx := NewIncomingContext(context.TODO(), md)
-
-	c, ok := FromIncomingContext(ctx)
-	if c == nil || !ok {
-		t.Fatal("NewIncomingContext not works")
-	}
-}
-
-func TestNewOutgoingContext(t *testing.T) {
-	md := New(1)
-	md.Set("key", "val")
-	ctx := NewOutgoingContext(context.TODO(), md)
-
-	c, ok := FromOutgoingContext(ctx)
-	if c == nil || !ok {
-		t.Fatal("NewOutgoingContext not works")
-	}
-}
-
-func TestAppendIncomingContext(t *testing.T) {
-	md := New(1)
-	md.Set("key1", "val1")
-	ctx := AppendIncomingContext(context.TODO(), "key2", "val2")
-
-	nmd, ok := FromIncomingContext(ctx)
-	if nmd == nil || !ok {
-		t.Fatal("AppendIncomingContext not works")
-	}
-	if v, ok := nmd.GetJoined("key2"); !ok || v != "val2" {
-		t.Fatal("AppendIncomingContext not works")
-	}
-}
-
-func TestAppendOutgoingContext(t *testing.T) {
-	md := New(1)
-	md.Set("key1", "val1")
-	ctx := AppendOutgoingContext(context.TODO(), "key2", "val2")
-
-	nmd, ok := FromOutgoingContext(ctx)
-	if nmd == nil || !ok {
-		t.Fatal("AppendOutgoingContext not works")
-	}
-	if v, ok := nmd.GetJoined("key2"); !ok || v != "val2" {
-		t.Fatal("AppendOutgoingContext not works")
 	}
 }

micro.go

@@ -3,21 +3,21 @@ package micro
 import (
 	"reflect"
 
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/client"
+	"go.unistack.org/micro/v3/client"
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/flow"
+	"go.unistack.org/micro/v3/flow"
-	"go.unistack.org/micro/v4/fsm"
+	"go.unistack.org/micro/v3/fsm"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/resolver"
+	"go.unistack.org/micro/v3/resolver"
-	"go.unistack.org/micro/v4/router"
+	"go.unistack.org/micro/v3/router"
-	"go.unistack.org/micro/v4/selector"
+	"go.unistack.org/micro/v3/selector"
-	"go.unistack.org/micro/v4/server"
+	"go.unistack.org/micro/v3/server"
-	"go.unistack.org/micro/v4/store"
+	"go.unistack.org/micro/v3/store"
-	"go.unistack.org/micro/v4/sync"
+	"go.unistack.org/micro/v3/sync"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 func As(b any, target any) bool {

micro_test.go

@@ -6,9 +6,8 @@ import (
 	"reflect"
 	"testing"
 
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/fsm"
+	"go.unistack.org/micro/v3/fsm"
-	"go.unistack.org/micro/v4/metadata"
 )
 
 func TestAs(t *testing.T) {
@@ -62,8 +61,6 @@ func TestAs(t *testing.T) {
 	}
 }
 
-var _ broker.Broker = (*bro)(nil)
-
 type bro struct {
 	name string
 }
@@ -90,18 +87,23 @@ func (p *bro) Connect(_ context.Context) error { return nil }
 // Disconnect disconnect from broker
 func (p *bro) Disconnect(_ context.Context) error { return nil }
 
-// NewMessage creates new message
-func (p *bro) NewMessage(_ context.Context, _ metadata.Metadata, _ interface{}, _ ...broker.PublishOption) (broker.Message, error) {
-	return nil, nil
-}
-
 // Publish message, msg can be single broker.Message or []broker.Message
-func (p *bro) Publish(_ context.Context, _ string, _ ...broker.Message) error {
+func (p *bro) Publish(_ context.Context, _ string, _ *broker.Message, _ ...broker.PublishOption) error {
 	return nil
 }
 
+// BatchPublish messages to broker with multiple topics
+func (p *bro) BatchPublish(_ context.Context, _ []*broker.Message, _ ...broker.PublishOption) error {
+	return nil
+}
+
+// BatchSubscribe subscribes to topic messages via handler
+func (p *bro) BatchSubscribe(_ context.Context, _ string, _ broker.BatchHandler, _ ...broker.SubscribeOption) (broker.Subscriber, error) {
+	return nil, nil
+}
+
 // Subscribe subscribes to topic message via handler
-func (p *bro) Subscribe(_ context.Context, _ string, _ interface{}, _ ...broker.SubscribeOption) (broker.Subscriber, error) {
+func (p *bro) Subscribe(_ context.Context, _ string, _ broker.Handler, _ ...broker.SubscribeOption) (broker.Subscriber, error) {
 	return nil, nil
 }
 

network/network.go

@@ -0,0 +1,55 @@
+// Package network is for creating internetworks
+package network
+
+import (
+	"go.unistack.org/micro/v3/client"
+	"go.unistack.org/micro/v3/server"
+)
+
+// Error is network node errors
+type Error interface {
+	// Count is current count of errors
+	Count() int
+	// Msg is last error message
+	Msg() string
+}
+
+// Status is node status
+type Status interface {
+	// Error reports error status
+	Error() Error
+}
+
+// Node is network node
+type Node interface {
+	// Id is node id
+	Id() string
+	// Address is node bind address
+	Address() string
+	// Peers returns node peers
+	Peers() []Node
+	// Network is the network node is in
+	Network() Network
+	// Status returns node status
+	Status() Status
+}
+
+// Network is micro network
+type Network interface {
+	// Node is network node
+	Node
+	// Initialise options
+	Init(...Option) error
+	// Options returns the network options
+	Options() Options
+	// Name of the network
+	Name() string
+	// Connect starts the resolver and tunnel server
+	Connect() error
+	// Close stops the tunnel and resolving
+	Close() error
+	// Client is micro client
+	Client() client.Client
+	// Server is micro server
+	Server() server.Server
+}

network/options.go

@@ -0,0 +1,135 @@
+package network
+
+import (
+	"go.unistack.org/micro/v3/logger"
+	"go.unistack.org/micro/v3/meter"
+	"go.unistack.org/micro/v3/network/tunnel"
+	"go.unistack.org/micro/v3/proxy"
+	"go.unistack.org/micro/v3/router"
+	"go.unistack.org/micro/v3/tracer"
+	"go.unistack.org/micro/v3/util/id"
+)
+
+// Option func
+type Option func(*Options)
+
+// Options configure network
+type Options struct {
+	// Router used for routing
+	Router router.Router
+	// Proxy holds the proxy
+	Proxy proxy.Proxy
+	// Logger used for logging
+	Logger logger.Logger
+	// Meter used for metrics
+	Meter meter.Meter
+	// Tracer used for tracing
+	Tracer tracer.Tracer
+	// Tunnel used for transfer data
+	Tunnel tunnel.Tunnel
+	// ID of the node
+	ID string
+	// Name of the network
+	Name string
+	// Address to bind to
+	Address string
+	// Advertise sets the address to advertise
+	Advertise string
+	// Nodes is a list of nodes to connect to
+	Nodes []string
+}
+
+// ID sets the id of the network node
+func ID(id string) Option {
+	return func(o *Options) {
+		o.ID = id
+	}
+}
+
+// Name sets the network name
+func Name(n string) Option {
+	return func(o *Options) {
+		o.Name = n
+	}
+}
+
+// Address sets the network address
+func Address(a string) Option {
+	return func(o *Options) {
+		o.Address = a
+	}
+}
+
+// Advertise sets the address to advertise
+func Advertise(a string) Option {
+	return func(o *Options) {
+		o.Advertise = a
+	}
+}
+
+// Nodes is a list of nodes to connect to
+func Nodes(n ...string) Option {
+	return func(o *Options) {
+		o.Nodes = n
+	}
+}
+
+// Tunnel sets the network tunnel
+func Tunnel(t tunnel.Tunnel) Option {
+	return func(o *Options) {
+		o.Tunnel = t
+	}
+}
+
+// Router sets the network router
+func Router(r router.Router) Option {
+	return func(o *Options) {
+		o.Router = r
+	}
+}
+
+// Proxy sets the network proxy
+func Proxy(p proxy.Proxy) Option {
+	return func(o *Options) {
+		o.Proxy = p
+	}
+}
+
+// Logger sets the network logger
+func Logger(l logger.Logger) Option {
+	return func(o *Options) {
+		o.Logger = l
+	}
+}
+
+// Meter sets the meter
+func Meter(m meter.Meter) Option {
+	return func(o *Options) {
+		o.Meter = m
+	}
+}
+
+// Tracer to be used for tracing
+func Tracer(t tracer.Tracer) Option {
+	return func(o *Options) {
+		o.Tracer = t
+	}
+}
+
+// NewOptions returns network default options
+func NewOptions(opts ...Option) Options {
+	options := Options{
+		ID:      id.MustNew(),
+		Name:    "go.micro",
+		Address: ":0",
+		Logger:  logger.DefaultLogger,
+		Meter:   meter.DefaultMeter,
+		Tracer:  tracer.DefaultTracer,
+	}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return options
+}

network/transport/context.go

@@ -0,0 +1,34 @@
+package transport
+
+import (
+	"context"
+)
+
+type transportKey struct{}
+
+// FromContext get transport from context
+func FromContext(ctx context.Context) (Transport, bool) {
+	if ctx == nil {
+		return nil, false
+	}
+	c, ok := ctx.Value(transportKey{}).(Transport)
+	return c, ok
+}
+
+// NewContext put transport in context
+func NewContext(ctx context.Context, c Transport) context.Context {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	return context.WithValue(ctx, transportKey{}, c)
+}
+
+// SetOption returns a function to setup a context with given value
+func SetOption(k, v interface{}) Option {
+	return func(o *Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, k, v)
+	}
+}

network/transport/memory.go

@@ -0,0 +1,258 @@
+package transport
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net"
+	"sync"
+	"time"
+
+	maddr "go.unistack.org/micro/v3/util/addr"
+	mnet "go.unistack.org/micro/v3/util/net"
+	"go.unistack.org/micro/v3/util/rand"
+)
+
+type memorySocket struct {
+	ctx     context.Context
+	recv    chan *Message
+	exit    chan bool
+	lexit   chan bool
+	send    chan *Message
+	local   string
+	remote  string
+	timeout time.Duration
+	sync.RWMutex
+}
+
+type memoryClient struct {
+	*memorySocket
+	opts DialOptions
+}
+
+type memoryListener struct {
+	lopts ListenOptions
+	ctx   context.Context
+	exit  chan bool
+	conn  chan *memorySocket
+	addr  string
+	topts Options
+	sync.RWMutex
+}
+
+type memoryTransport struct {
+	listeners map[string]*memoryListener
+	opts      Options
+	sync.RWMutex
+}
+
+func (ms *memorySocket) Recv(m *Message) error {
+	ms.RLock()
+	defer ms.RUnlock()
+
+	ctx := ms.ctx
+	if ms.timeout > 0 {
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ms.ctx, ms.timeout)
+		defer cancel()
+	}
+
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-ms.exit:
+		return errors.New("connection closed")
+	case <-ms.lexit:
+		return errors.New("server connection closed")
+	case cm := <-ms.recv:
+		*m = *cm
+	}
+	return nil
+}
+
+func (ms *memorySocket) Local() string {
+	return ms.local
+}
+
+func (ms *memorySocket) Remote() string {
+	return ms.remote
+}
+
+func (ms *memorySocket) Send(m *Message) error {
+	ms.RLock()
+	defer ms.RUnlock()
+
+	ctx := ms.ctx
+	if ms.timeout > 0 {
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ms.ctx, ms.timeout)
+		defer cancel()
+	}
+
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-ms.exit:
+		return errors.New("connection closed")
+	case <-ms.lexit:
+		return errors.New("server connection closed")
+	case ms.send <- m:
+	}
+	return nil
+}
+
+func (ms *memorySocket) Close() error {
+	ms.Lock()
+	defer ms.Unlock()
+	select {
+	case <-ms.exit:
+		return nil
+	default:
+		close(ms.exit)
+	}
+	return nil
+}
+
+func (m *memoryListener) Addr() string {
+	return m.addr
+}
+
+func (m *memoryListener) Close() error {
+	m.Lock()
+	defer m.Unlock()
+	select {
+	case <-m.exit:
+		return nil
+	default:
+		close(m.exit)
+	}
+	return nil
+}
+
+func (m *memoryListener) Accept(fn func(Socket)) error {
+	for {
+		select {
+		case <-m.exit:
+			return nil
+		case c := <-m.conn:
+			go fn(&memorySocket{
+				lexit:   c.lexit,
+				exit:    c.exit,
+				send:    c.recv,
+				recv:    c.send,
+				local:   c.Remote(),
+				remote:  c.Local(),
+				timeout: m.topts.Timeout,
+				ctx:     m.topts.Context,
+			})
+		}
+	}
+}
+
+func (m *memoryTransport) Dial(ctx context.Context, addr string, opts ...DialOption) (Client, error) {
+	m.RLock()
+	defer m.RUnlock()
+
+	listener, ok := m.listeners[addr]
+	if !ok {
+		return nil, errors.New("could not dial " + addr)
+	}
+
+	options := NewDialOptions(opts...)
+
+	client := &memoryClient{
+		&memorySocket{
+			send:    make(chan *Message),
+			recv:    make(chan *Message),
+			exit:    make(chan bool),
+			lexit:   listener.exit,
+			local:   addr,
+			remote:  addr,
+			timeout: m.opts.Timeout,
+			ctx:     m.opts.Context,
+		},
+		options,
+	}
+
+	// pseudo connect
+	select {
+	case <-listener.exit:
+		return nil, errors.New("connection error")
+	case listener.conn <- client.memorySocket:
+	}
+
+	return client, nil
+}
+
+func (m *memoryTransport) Listen(ctx context.Context, addr string, opts ...ListenOption) (Listener, error) {
+	m.Lock()
+	defer m.Unlock()
+
+	options := NewListenOptions(opts...)
+
+	host, port, err := net.SplitHostPort(addr)
+	if err != nil {
+		return nil, err
+	}
+
+	addr, err = maddr.Extract(host)
+	if err != nil {
+		return nil, err
+	}
+
+	// if zero port then randomly assign one
+	if len(port) > 0 && port == "0" {
+		var rng rand.Rand
+		i := rng.Intn(20000)
+		port = fmt.Sprintf("%d", 10000+i)
+	}
+
+	// set addr with port
+	addr = mnet.HostPort(addr, port)
+
+	if _, ok := m.listeners[addr]; ok {
+		return nil, errors.New("already listening on " + addr)
+	}
+
+	listener := &memoryListener{
+		lopts: options,
+		topts: m.opts,
+		addr:  addr,
+		conn:  make(chan *memorySocket),
+		exit:  make(chan bool),
+		ctx:   m.opts.Context,
+	}
+
+	m.listeners[addr] = listener
+
+	return listener, nil
+}
+
+func (m *memoryTransport) Init(opts ...Option) error {
+	for _, o := range opts {
+		o(&m.opts)
+	}
+	return nil
+}
+
+func (m *memoryTransport) Options() Options {
+	return m.opts
+}
+
+func (m *memoryTransport) String() string {
+	return "memory"
+}
+
+func (m *memoryTransport) Name() string {
+	return m.opts.Name
+}
+
+// NewTransport returns new memory transport with options
+func NewTransport(opts ...Option) Transport {
+	options := NewOptions(opts...)
+
+	return &memoryTransport{
+		opts:      options,
+		listeners: make(map[string]*memoryListener),
+	}
+}

network/transport/memory_test.go

@@ -0,0 +1,100 @@
+package transport
+
+import (
+	"context"
+	"os"
+	"testing"
+)
+
+func TestMemoryTransport(t *testing.T) {
+	tr := NewTransport()
+	ctx := context.Background()
+	// bind / listen
+	l, err := tr.Listen(ctx, "127.0.0.1:8080")
+	if err != nil {
+		t.Fatalf("Unexpected error listening %v", err)
+	}
+	defer l.Close()
+
+	cherr := make(chan error, 1)
+	// accept
+	go func() {
+		if nerr := l.Accept(func(sock Socket) {
+			for {
+				var m Message
+				if rerr := sock.Recv(&m); rerr != nil {
+					cherr <- rerr
+					return
+				}
+				if len(os.Getenv("INTEGRATION_TESTS")) == 0 {
+					t.Logf("Server Received %s", string(m.Body))
+				}
+				if cerr := sock.Send(&Message{
+					Body: []byte(`pong`),
+				}); cerr != nil {
+					cherr <- cerr
+					return
+				}
+			}
+		}); nerr != nil {
+			cherr <- err
+		}
+	}()
+
+	// dial
+	c, err := tr.Dial(ctx, "127.0.0.1:8080")
+	if err != nil {
+		t.Fatalf("Unexpected error dialing %v", err)
+	}
+	defer c.Close()
+
+	select {
+	case err := <-cherr:
+		t.Fatal(err)
+	default:
+		// send <=> receive
+		for i := 0; i < 3; i++ {
+			if err := c.Send(&Message{
+				Body: []byte(`ping`),
+			}); err != nil {
+				return
+			}
+			var m Message
+			if err := c.Recv(&m); err != nil {
+				return
+			}
+			if len(os.Getenv("INTEGRATION_TESTS")) == 0 {
+				t.Logf("Client Received %s", string(m.Body))
+			}
+		}
+	}
+}
+
+func TestListener(t *testing.T) {
+	tr := NewTransport()
+	ctx := context.Background()
+	// bind / listen on random port
+	l, err := tr.Listen(ctx, ":0")
+	if err != nil {
+		t.Fatalf("Unexpected error listening %v", err)
+	}
+	defer l.Close()
+
+	// try again
+	l2, err := tr.Listen(ctx, ":0")
+	if err != nil {
+		t.Fatalf("Unexpected error listening %v", err)
+	}
+	defer l2.Close()
+
+	// now make sure it still fails
+	l3, err := tr.Listen(ctx, ":8080")
+	if err != nil {
+		t.Fatalf("Unexpected error listening %v", err)
+	}
+	defer l3.Close()
+
+	if _, err := tr.Listen(ctx, ":8080"); err == nil {
+		t.Fatal("Expected error binding to :8080 got nil")
+	}
+}

network/transport/options.go

@@ -0,0 +1,175 @@
+package transport
+
+import (
+	"context"
+	"crypto/tls"
+	"time"
+
+	"go.unistack.org/micro/v3/codec"
+	"go.unistack.org/micro/v3/logger"
+	"go.unistack.org/micro/v3/meter"
+	"go.unistack.org/micro/v3/tracer"
+)
+
+// Options struct holds the transport options
+type Options struct {
+	// Meter used for metrics
+	Meter meter.Meter
+	// Tracer used for tracing
+	Tracer tracer.Tracer
+	// Codec used for marshal/unmarshal messages
+	Codec codec.Codec
+	// Logger used for logging
+	Logger logger.Logger
+	// Context holds external options
+	Context context.Context
+	// TLSConfig holds tls.TLSConfig options
+	TLSConfig *tls.Config
+	// Name holds the transport name
+	Name string
+	// Addrs holds the transport addrs
+	Addrs []string
+	// Timeout holds the timeout
+	Timeout time.Duration
+}
+
+// NewOptions returns new options
+func NewOptions(opts ...Option) Options {
+	options := Options{
+		Logger:  logger.DefaultLogger,
+		Meter:   meter.DefaultMeter,
+		Tracer:  tracer.DefaultTracer,
+		Context: context.Background(),
+	}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return options
+}
+
+// DialOptions struct
+type DialOptions struct {
+	// Context holds the external options
+	Context context.Context
+	// Timeout holds the timeout
+	Timeout time.Duration
+	// Stream flag
+	Stream bool
+}
+
+// NewDialOptions returns new DialOptions
+func NewDialOptions(opts ...DialOption) DialOptions {
+	options := DialOptions{
+		Timeout: DefaultDialTimeout,
+		Context: context.Background(),
+	}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return options
+}
+
+// ListenOptions struct
+type ListenOptions struct {
+	// TODO: add tls options when listening
+	// Currently set in global options
+	// Context holds the external options
+	Context context.Context
+	// TLSConfig holds the *tls.Config options
+	TLSConfig *tls.Config
+}
+
+// NewListenOptions returns new ListenOptions
+func NewListenOptions(opts ...ListenOption) ListenOptions {
+	options := ListenOptions{
+		Context: context.Background(),
+	}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return options
+}
+
+// Addrs to use for transport
+func Addrs(addrs ...string) Option {
+	return func(o *Options) {
+		o.Addrs = addrs
+	}
+}
+
+// Logger sets the logger
+func Logger(l logger.Logger) Option {
+	return func(o *Options) {
+		o.Logger = l
+	}
+}
+
+// Meter sets the meter
+func Meter(m meter.Meter) Option {
+	return func(o *Options) {
+		o.Meter = m
+	}
+}
+
+// Context sets the context
+func Context(ctx context.Context) Option {
+	return func(o *Options) {
+		o.Context = ctx
+	}
+}
+
+// Codec sets the codec used for encoding where the transport
+// does not support message headers
+func Codec(c codec.Codec) Option {
+	return func(o *Options) {
+		o.Codec = c
+	}
+}
+
+// Timeout sets the timeout for Send/Recv execution
+func Timeout(t time.Duration) Option {
+	return func(o *Options) {
+		o.Timeout = t
+	}
+}
+
+// TLSConfig to be used for the transport.
+func TLSConfig(t *tls.Config) Option {
+	return func(o *Options) {
+		o.TLSConfig = t
+	}
+}
+
+// WithStream indicates whether this is a streaming connection
+func WithStream() DialOption {
+	return func(o *DialOptions) {
+		o.Stream = true
+	}
+}
+
+// WithTimeout used when dialling the remote side
+func WithTimeout(d time.Duration) DialOption {
+	return func(o *DialOptions) {
+		o.Timeout = d
+	}
+}
+
+// Tracer to be used for tracing
+func Tracer(t tracer.Tracer) Option {
+	return func(o *Options) {
+		o.Tracer = t
+	}
+}
+
+// Name sets the name
+func Name(n string) Option {
+	return func(o *Options) {
+		o.Name = n
+	}
+}

network/transport/transport.go

@@ -0,0 +1,63 @@
+// Package transport is an interface for synchronous connection based communication
+package transport
+
+import (
+	"context"
+	"time"
+
+	"go.unistack.org/micro/v3/metadata"
+)
+
+var (
+	// DefaultTransport is the global default transport
+	DefaultTransport = NewTransport()
+	// DefaultDialTimeout the default dial timeout
+	DefaultDialTimeout = time.Second * 5
+)
+
+// Transport is an interface which is used for communication between
+// services. It uses connection based socket send/recv semantics and
+// has various implementations; http, grpc, quic.
+type Transport interface {
+	Init(...Option) error
+	Options() Options
+	Dial(ctx context.Context, addr string, opts ...DialOption) (Client, error)
+	Listen(ctx context.Context, addr string, opts ...ListenOption) (Listener, error)
+	String() string
+}
+
+// Message is used to transfer data
+type Message struct {
+	Header metadata.Metadata
+	Body   []byte
+}
+
+// Socket bastraction interface
+type Socket interface {
+	Recv(*Message) error
+	Send(*Message) error
+	Close() error
+	Local() string
+	Remote() string
+}
+
+// Client is the socket owner
+type Client interface {
+	Socket
+}
+
+// Listener is the interface for stream oriented messaging
+type Listener interface {
+	Addr() string
+	Close() error
+	Accept(func(Socket)) error
+}
+
+// Option is the option signature
+type Option func(*Options)
+
+// DialOption is the option signature
+type DialOption func(*DialOptions)
+
+// ListenOption is the option signature
+type ListenOption func(*ListenOptions)

network/tunnel/broker/broker.go

@@ -0,0 +1,372 @@
+// Package broker is a tunnel broker
+package broker
+
+import (
+	"context"
+	"fmt"
+
+	"go.unistack.org/micro/v3/broker"
+	"go.unistack.org/micro/v3/logger"
+	"go.unistack.org/micro/v3/metadata"
+	"go.unistack.org/micro/v3/network/transport"
+	"go.unistack.org/micro/v3/network/tunnel"
+)
+
+type tunBroker struct {
+	tunnel tunnel.Tunnel
+	opts   broker.Options
+}
+
+type tunSubscriber struct {
+	listener tunnel.Listener
+	handler  broker.Handler
+	closed   chan bool
+	topic    string
+	opts     broker.SubscribeOptions
+}
+
+type tunBatchSubscriber struct {
+	listener tunnel.Listener
+	handler  broker.BatchHandler
+	closed   chan bool
+	topic    string
+	opts     broker.SubscribeOptions
+}
+
+type tunEvent struct {
+	err     error
+	message *broker.Message
+	topic   string
+}
+
+// used to access tunnel from options context
+type (
+	tunnelKey  struct{}
+	tunnelAddr struct{}
+)
+
+func (t *tunBroker) Live() bool {
+	return true
+}
+
+func (t *tunBroker) Ready() bool {
+	return true
+}
+
+func (t *tunBroker) Health() bool {
+	return true
+}
+
+func (t *tunBroker) Init(opts ...broker.Option) error {
+	for _, o := range opts {
+		o(&t.opts)
+	}
+	return nil
+}
+
+func (t *tunBroker) Name() string {
+	return t.opts.Name
+}
+
+func (t *tunBroker) Options() broker.Options {
+	return t.opts
+}
+
+func (t *tunBroker) Address() string {
+	return t.tunnel.Address()
+}
+
+func (t *tunBroker) Connect(ctx context.Context) error {
+	return t.tunnel.Connect(ctx)
+}
+
+func (t *tunBroker) Disconnect(ctx context.Context) error {
+	return t.tunnel.Close(ctx)
+}
+
+func (t *tunBroker) BatchPublish(ctx context.Context, msgs []*broker.Message, _ ...broker.PublishOption) error {
+	// TODO: this is probably inefficient, we might want to just maintain an open connection
+	// it may be easier to add broadcast to the tunnel
+	topicMap := make(map[string]tunnel.Session)
+
+	var err error
+	for _, msg := range msgs {
+		topic, _ := msg.Header.Get(metadata.HeaderTopic)
+		c, ok := topicMap[topic]
+		if !ok {
+			c, err = t.tunnel.Dial(ctx, topic, tunnel.DialMode(tunnel.Multicast))
+			if err != nil {
+				return err
+			}
+			defer c.Close()
+			topicMap[topic] = c
+		}
+
+		if err = c.Send(&transport.Message{
+			Header: msg.Header,
+			Body:   msg.Body,
+		}); err != nil {
+			//	msg.SetError(err)
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (t *tunBroker) Publish(ctx context.Context, topic string, m *broker.Message, _ ...broker.PublishOption) error {
+	// TODO: this is probably inefficient, we might want to just maintain an open connection
+	// it may be easier to add broadcast to the tunnel
+	c, err := t.tunnel.Dial(ctx, topic, tunnel.DialMode(tunnel.Multicast))
+	if err != nil {
+		return err
+	}
+	defer c.Close()
+
+	return c.Send(&transport.Message{
+		Header: m.Header,
+		Body:   m.Body,
+	})
+}
+
+func (t *tunBroker) BatchSubscribe(ctx context.Context, topic string, h broker.BatchHandler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+	l, err := t.tunnel.Listen(ctx, topic, tunnel.ListenMode(tunnel.Multicast))
+	if err != nil {
+		return nil, err
+	}
+
+	tunSub := &tunBatchSubscriber{
+		topic:    topic,
+		handler:  h,
+		opts:     broker.NewSubscribeOptions(opts...),
+		closed:   make(chan bool),
+		listener: l,
+	}
+
+	// start processing
+	go tunSub.run()
+
+	return tunSub, nil
+}
+
+func (t *tunBroker) Subscribe(ctx context.Context, topic string, h broker.Handler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+	l, err := t.tunnel.Listen(ctx, topic, tunnel.ListenMode(tunnel.Multicast))
+	if err != nil {
+		return nil, err
+	}
+
+	tunSub := &tunSubscriber{
+		topic:    topic,
+		handler:  h,
+		opts:     broker.NewSubscribeOptions(opts...),
+		closed:   make(chan bool),
+		listener: l,
+	}
+
+	// start processing
+	go tunSub.run()
+
+	return tunSub, nil
+}
+
+func (t *tunBroker) String() string {
+	return "tunnel"
+}
+
+func (t *tunBatchSubscriber) run() {
+	for {
+		// accept a new connection
+		c, err := t.listener.Accept()
+		if err != nil {
+			select {
+			case <-t.closed:
+				return
+			default:
+				continue
+			}
+		}
+
+		// receive message
+		m := new(transport.Message)
+		if err := c.Recv(m); err != nil {
+			if logger.DefaultLogger.V(logger.ErrorLevel) {
+				logger.DefaultLogger.Error(t.opts.Context, err.Error(), err)
+			}
+			if err = c.Close(); err != nil {
+				if logger.DefaultLogger.V(logger.ErrorLevel) {
+					logger.DefaultLogger.Error(t.opts.Context, err.Error(), err)
+				}
+			}
+			continue
+		}
+
+		// close the connection
+		c.Close()
+
+		evts := broker.Events{&tunEvent{
+			topic: t.topic,
+			message: &broker.Message{
+				Header: m.Header,
+				Body:   m.Body,
+			},
+		}}
+		// handle the message
+		go func() {
+			_ = t.handler(evts)
+		}()
+
+	}
+}
+
+func (t *tunSubscriber) run() {
+	for {
+		// accept a new connection
+		c, err := t.listener.Accept()
+		if err != nil {
+			select {
+			case <-t.closed:
+				return
+			default:
+				continue
+			}
+		}
+
+		// receive message
+		m := new(transport.Message)
+		if err := c.Recv(m); err != nil {
+			if logger.DefaultLogger.V(logger.ErrorLevel) {
+				logger.DefaultLogger.Error(t.opts.Context, err.Error(), err)
+			}
+			if err = c.Close(); err != nil {
+				if logger.DefaultLogger.V(logger.ErrorLevel) {
+					logger.DefaultLogger.Error(t.opts.Context, err.Error(), err)
+				}
+			}
+			continue
+		}
+
+		// close the connection
+		c.Close()
+
+		// handle the message
+		go func() {
+			_ = t.handler(&tunEvent{
+				topic: t.topic,
+				message: &broker.Message{
+					Header: m.Header,
+					Body:   m.Body,
+				},
+			})
+		}()
+	}
+}
+
+func (t *tunBatchSubscriber) Options() broker.SubscribeOptions {
+	return t.opts
+}
+
+func (t *tunBatchSubscriber) Topic() string {
+	return t.topic
+}
+
+func (t *tunBatchSubscriber) Unsubscribe(ctx context.Context) error {
+	select {
+	case <-t.closed:
+		return nil
+	default:
+		close(t.closed)
+		return t.listener.Close()
+	}
+}
+
+func (t *tunSubscriber) Options() broker.SubscribeOptions {
+	return t.opts
+}
+
+func (t *tunSubscriber) Topic() string {
+	return t.topic
+}
+
+func (t *tunSubscriber) Unsubscribe(ctx context.Context) error {
+	select {
+	case <-t.closed:
+		return nil
+	default:
+		close(t.closed)
+		return t.listener.Close()
+	}
+}
+
+func (t *tunEvent) Topic() string {
+	return t.topic
+}
+
+func (t *tunEvent) Message() *broker.Message {
+	return t.message
+}
+
+func (t *tunEvent) Ack() error {
+	return nil
+}
+
+func (t *tunEvent) Error() error {
+	return t.err
+}
+
+func (t *tunEvent) SetError(err error) {
+	t.err = err
+}
+
+func (t *tunEvent) Context() context.Context {
+	return context.TODO()
+}
+
+// NewBroker returns new tunnel broker
+func NewBroker(opts ...broker.Option) (broker.Broker, error) {
+	options := broker.NewOptions(opts...)
+
+	t, ok := options.Context.Value(tunnelKey{}).(tunnel.Tunnel)
+	if !ok {
+		return nil, fmt.Errorf("tunnel not set")
+	}
+
+	a, ok := options.Context.Value(tunnelAddr{}).(string)
+	if ok {
+		// initialise address
+		if err := t.Init(tunnel.Address(a)); err != nil {
+			return nil, err
+		}
+	}
+
+	if len(options.Addrs) > 0 {
+		// initialise nodes
+		if err := t.Init(tunnel.Nodes(options.Addrs...)); err != nil {
+			return nil, err
+		}
+	}
+
+	return &tunBroker{
+		opts:   options,
+		tunnel: t,
+	}, nil
+}
+
+// WithAddress sets the tunnel address
+func WithAddress(a string) broker.Option {
+	return func(o *broker.Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, tunnelAddr{}, a)
+	}
+}
+
+// WithTunnel sets the internal tunnel
+func WithTunnel(t tunnel.Tunnel) broker.Option {
+	return func(o *broker.Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, tunnelKey{}, t)
+	}
+}

network/tunnel/options.go

@@ -0,0 +1,192 @@
+package tunnel
+
+import (
+	"time"
+
+	"go.unistack.org/micro/v3/logger"
+	"go.unistack.org/micro/v3/meter"
+	"go.unistack.org/micro/v3/network/transport"
+	"go.unistack.org/micro/v3/tracer"
+	"go.unistack.org/micro/v3/util/id"
+)
+
+var (
+	// DefaultAddress is default tunnel bind address
+	DefaultAddress = ":0"
+	// DefaultToken the shared default token
+	DefaultToken = "go.micro.tunnel"
+)
+
+// Option func signature
+type Option func(*Options)
+
+// Options provides network configuration options
+type Options struct {
+	// Logger used for logging
+	Logger logger.Logger
+	// Meter used for metrics
+	Meter meter.Meter
+	// Tracer used for tracing
+	Tracer tracer.Tracer
+	// Transport used for communication
+	Transport transport.Transport
+	// Token the shared auth token
+	Token string
+	// Name holds the tunnel name
+	Name string
+	// ID holds the tunnel id
+	ID string
+	// Address holds the tunnel address
+	Address string
+	// Nodes holds the tunnel nodes
+	Nodes []string
+}
+
+// DialOption func
+type DialOption func(*DialOptions)
+
+// DialOptions provides dial options
+type DialOptions struct {
+	// Link specifies the link to use
+	Link string
+	// specify mode of the session
+	Mode Mode
+	// Wait for connection to be accepted
+	Wait bool
+	// the dial timeout
+	Timeout time.Duration
+}
+
+// ListenOption func
+type ListenOption func(*ListenOptions)
+
+// ListenOptions provides listen options
+type ListenOptions struct {
+	// Mode specify mode of the session
+	Mode Mode
+	// Timeout the read timeout
+	Timeout time.Duration
+}
+
+// ID sets the tunnel id
+func ID(id string) Option {
+	return func(o *Options) {
+		o.ID = id
+	}
+}
+
+// Logger sets the logger
+func Logger(l logger.Logger) Option {
+	return func(o *Options) {
+		o.Logger = l
+	}
+}
+
+// Meter sets the meter
+func Meter(m meter.Meter) Option {
+	return func(o *Options) {
+		o.Meter = m
+	}
+}
+
+// Address sets the tunnel address
+func Address(a string) Option {
+	return func(o *Options) {
+		o.Address = a
+	}
+}
+
+// Nodes specify remote network nodes
+func Nodes(n ...string) Option {
+	return func(o *Options) {
+		o.Nodes = n
+	}
+}
+
+// Token sets the shared token for auth
+func Token(t string) Option {
+	return func(o *Options) {
+		o.Token = t
+	}
+}
+
+// Transport listens for incoming connections
+func Transport(t transport.Transport) Option {
+	return func(o *Options) {
+		o.Transport = t
+	}
+}
+
+// ListenMode option
+func ListenMode(m Mode) ListenOption {
+	return func(o *ListenOptions) {
+		o.Mode = m
+	}
+}
+
+// ListenTimeout for reads and writes on the listener session
+func ListenTimeout(t time.Duration) ListenOption {
+	return func(o *ListenOptions) {
+		o.Timeout = t
+	}
+}
+
+// DialMode multicast sets the multicast option to send only to those mapped
+func DialMode(m Mode) DialOption {
+	return func(o *DialOptions) {
+		o.Mode = m
+	}
+}
+
+// DialTimeout sets the dial timeout of the connection
+func DialTimeout(t time.Duration) DialOption {
+	return func(o *DialOptions) {
+		o.Timeout = t
+	}
+}
+
+// DialLink specifies the link to pin this connection to.
+// This is not applicable if the multicast option is set.
+func DialLink(id string) DialOption {
+	return func(o *DialOptions) {
+		o.Link = id
+	}
+}
+
+// DialWait specifies whether to wait for the connection
+// to be accepted before returning the session
+func DialWait(b bool) DialOption {
+	return func(o *DialOptions) {
+		o.Wait = b
+	}
+}
+
+// NewOptions returns router default options with filled values
+func NewOptions(opts ...Option) Options {
+	options := Options{
+		ID:      id.MustNew(),
+		Address: DefaultAddress,
+		Token:   DefaultToken,
+		Logger:  logger.DefaultLogger,
+		Meter:   meter.DefaultMeter,
+		Tracer:  tracer.DefaultTracer,
+	}
+	for _, o := range opts {
+		o(&options)
+	}
+	return options
+}
+
+// Tracer to be used for tracing
+func Tracer(t tracer.Tracer) Option {
+	return func(o *Options) {
+		o.Tracer = t
+	}
+}
+
+// Name sets the name
+func Name(n string) Option {
+	return func(o *Options) {
+		o.Name = n
+	}
+}

network/tunnel/transport/listener.go

@@ -0,0 +1,30 @@
+package transport
+
+import (
+	"go.unistack.org/micro/v3/network/transport"
+	"go.unistack.org/micro/v3/network/tunnel"
+)
+
+type tunListener struct {
+	l tunnel.Listener
+}
+
+func (t *tunListener) Addr() string {
+	return t.l.Channel()
+}
+
+func (t *tunListener) Close() error {
+	return t.l.Close()
+}
+
+func (t *tunListener) Accept(fn func(socket transport.Socket)) error {
+	for {
+		// accept connection
+		c, err := t.l.Accept()
+		if err != nil {
+			return err
+		}
+		// execute the function
+		go fn(c)
+	}
+}

network/tunnel/transport/transport.go

@@ -0,0 +1,113 @@
+// Package transport provides a tunnel transport
+package transport
+
+import (
+	"context"
+	"fmt"
+
+	"go.unistack.org/micro/v3/network/transport"
+	"go.unistack.org/micro/v3/network/tunnel"
+)
+
+type tunTransport struct {
+	tunnel  tunnel.Tunnel
+	options transport.Options
+}
+
+type tunnelKey struct{}
+
+type transportKey struct{}
+
+func (t *tunTransport) Init(opts ...transport.Option) error {
+	for _, o := range opts {
+		o(&t.options)
+	}
+
+	// close the existing tunnel
+	if t.tunnel != nil {
+		t.tunnel.Close(context.TODO())
+	}
+
+	// get the tunnel
+	tun, ok := t.options.Context.Value(tunnelKey{}).(tunnel.Tunnel)
+	if !ok {
+		return fmt.Errorf("tunnel not set")
+	}
+
+	// get the transport
+	tr, ok := t.options.Context.Value(transportKey{}).(transport.Transport)
+	if ok {
+		_ = tun.Init(tunnel.Transport(tr))
+	}
+
+	// set the tunnel
+	t.tunnel = tun
+
+	return nil
+}
+
+func (t *tunTransport) Dial(ctx context.Context, addr string, opts ...transport.DialOption) (transport.Client, error) {
+	if err := t.tunnel.Connect(ctx); err != nil {
+		return nil, err
+	}
+
+	c, err := t.tunnel.Dial(ctx, addr)
+	if err != nil {
+		return nil, err
+	}
+
+	return c, nil
+}
+
+func (t *tunTransport) Listen(ctx context.Context, addr string, opts ...transport.ListenOption) (transport.Listener, error) {
+	if err := t.tunnel.Connect(ctx); err != nil {
+		return nil, err
+	}
+
+	l, err := t.tunnel.Listen(ctx, addr)
+	if err != nil {
+		return nil, err
+	}
+
+	return &tunListener{l}, nil
+}
+
+func (t *tunTransport) Options() transport.Options {
+	return t.options
+}
+
+func (t *tunTransport) String() string {
+	return "tunnel"
+}
+
+// NewTransport honours the initialiser used in
+func NewTransport(opts ...transport.Option) transport.Transport {
+	t := &tunTransport{
+		options: transport.Options{},
+	}
+
+	// initialise
+	// t.Init(opts...)
+
+	return t
+}
+
+// WithTunnel sets the internal tunnel
+func WithTunnel(t tunnel.Tunnel) transport.Option {
+	return func(o *transport.Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, tunnelKey{}, t)
+	}
+}
+
+// WithTransport sets the internal transport
+func WithTransport(t transport.Transport) transport.Option {
+	return func(o *transport.Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, transportKey{}, t)
+	}
+}

network/tunnel/tunnel.go

@@ -0,0 +1,106 @@
+// Package tunnel provides gre network tunnelling
+package tunnel
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"go.unistack.org/micro/v3/network/transport"
+)
+
+// DefaultTunnel contains default tunnel implementation
+var DefaultTunnel Tunnel
+
+const (
+	// Unicast send over one link
+	Unicast Mode = iota
+	// Multicast send to all channel listeners
+	Multicast
+	// Broadcast send to all links
+	Broadcast
+)
+
+var (
+	// DefaultDialTimeout is the dial timeout if none is specified
+	DefaultDialTimeout = time.Second * 5
+	// ErrDialTimeout is returned by a call to Dial where the timeout occurs
+	ErrDialTimeout = errors.New("dial timeout")
+	// ErrDiscoverChan is returned when we failed to receive the "announce" back from a discovery
+	ErrDiscoverChan = errors.New("failed to discover channel")
+	// ErrLinkNotFound is returned when a link is specified at dial time and does not exist
+	ErrLinkNotFound = errors.New("link not found")
+	// ErrLinkDisconnected is returned when a link we attempt to send to is disconnected
+	ErrLinkDisconnected = errors.New("link not connected")
+	// ErrLinkLoopback is returned when attempting to send an outbound message over loopback link
+	ErrLinkLoopback = errors.New("link is loopback")
+	// ErrLinkRemote is returned when attempting to send a loopback message over remote link
+	ErrLinkRemote = errors.New("link is remote")
+	// ErrReadTimeout is a timeout on session.Recv
+	ErrReadTimeout = errors.New("read timeout")
+	// ErrDecryptingData is for when theres a nonce error
+	ErrDecryptingData = errors.New("error decrypting data")
+)
+
+// Mode of the session
+type Mode uint8
+
+// Tunnel creates a gre tunnel on top of the micro/transport.
+// It establishes multiple streams using the Micro-Tunnel-Channel header
+// and Micro-Tunnel-Session header. The tunnel id is a hash of
+// the address being requested.
+type Tunnel interface {
+	// Init initializes tunnel with options
+	Init(opts ...Option) error
+	// Address returns the address the tunnel is listening on
+	Address() string
+	// Connect connects the tunnel
+	Connect(ctx context.Context) error
+	// Close closes the tunnel
+	Close(ctx context.Context) error
+	// Links returns all the links the tunnel is connected to
+	Links() []Link
+	// Dial allows a client to connect to a channel
+	Dial(ctx context.Context, channel string, opts ...DialOption) (Session, error)
+	// Listen allows to accept connections on a channel
+	Listen(ctx context.Context, channel string, opts ...ListenOption) (Listener, error)
+	// String returns the name of the tunnel implementation
+	String() string
+}
+
+// Link represents internal links to the tunnel
+type Link interface {
+	// Id returns the link unique Id
+	Id() string
+	// Delay is the current load on the link (lower is better)
+	Delay() int64
+	// Length returns the roundtrip time as nanoseconds (lower is better)
+	Length() int64
+	// Current transfer rate as bits per second (lower is better)
+	Rate() float64
+	// Is this a loopback link
+	Loopback() bool
+	// State of the link: connected/closed/error
+	State() string
+	// honours transport socket
+	transport.Socket
+}
+
+// Listener provides similar constructs to the transport.Listener
+type Listener interface {
+	Accept() (Session, error)
+	Channel() string
+	Close() error
+}
+
+// Session is a unique session created when dialling or accepting connections on the tunnel
+type Session interface {
+	// The unique session id
+	Id() string
+	// The channel name
+	Channel() string
+	// The link the session is on
+	Link() string
+	// a transport socket
+	transport.Socket
+}

options.go

@@ -5,17 +5,17 @@ import (
 	"fmt"
 	"time"
 
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/client"
+	"go.unistack.org/micro/v3/client"
-	"go.unistack.org/micro/v4/config"
+	"go.unistack.org/micro/v3/config"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/router"
+	"go.unistack.org/micro/v3/router"
-	"go.unistack.org/micro/v4/server"
+	"go.unistack.org/micro/v3/server"
-	"go.unistack.org/micro/v4/store"
+	"go.unistack.org/micro/v3/store"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Options for micro service

options/options.go

@@ -1,222 +0,0 @@
-package options
-
-import (
-	"reflect"
-	"strings"
-	"time"
-
-	"github.com/spf13/cast"
-	mreflect "go.unistack.org/micro/v3/util/reflect"
-)
-
-// Options interface must be used by all options
-type Validator interface {
-	// Validate returns nil, if all options are correct,
-	// otherwise returns an error explaining the mistake
-	Validate() error
-}
-
-// Option func signature
-type Option func(interface{}) error
-
-// Apply assign options to struct src
-func Apply(src interface{}, opts ...Option) error {
-	for _, opt := range opts {
-		if err := opt(src); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-// SetValueByPath set src struct field to val dst via path
-func SetValueByPath(src interface{}, dst interface{}, path string) error {
-	var err error
-
-	switch v := dst.(type) {
-	case []interface{}:
-		if len(v) == 1 {
-			dst = v[0]
-		}
-	}
-
-	var sv reflect.Value
-	switch t := src.(type) {
-	case reflect.Value:
-		sv = t
-	default:
-		sv = reflect.ValueOf(src)
-	}
-
-	parts := strings.Split(path, ".")
-
-	for _, p := range parts {
-
-		if sv.Kind() == reflect.Ptr {
-			sv = sv.Elem()
-		}
-		if sv.Kind() != reflect.Struct {
-			return mreflect.ErrInvalidStruct
-		}
-
-		typ := sv.Type()
-		for idx := 0; idx < typ.NumField(); idx++ {
-			fld := typ.Field(idx)
-			val := sv.Field(idx)
-
-			/*
-				if len(fld.PkgPath) != 0 {
-					continue
-				}
-			*/
-
-			if fld.Anonymous {
-				if len(parts) == 1 && val.Kind() == reflect.Struct {
-					if err = SetValueByPath(val, dst, p); err != nil {
-						return err
-					}
-				}
-			}
-
-			if fld.Name != p && !strings.EqualFold(strings.ToLower(fld.Name), strings.ToLower(p)) {
-				continue
-			}
-
-			switch val.Interface().(type) {
-			case []time.Duration:
-				dst, err = cast.ToDurationSliceE(dst)
-				if err != nil {
-					return err
-				}
-				reflect.Copy(val, reflect.ValueOf(dst))
-				return nil
-			case time.Duration:
-				dst, err = cast.ToDurationE(dst)
-				if err != nil {
-					return err
-				}
-				val.Set(reflect.ValueOf(dst))
-				return nil
-			case time.Time:
-				dst, err = cast.ToTimeE(dst)
-				if err != nil {
-					return err
-				}
-				val.Set(reflect.ValueOf(dst))
-				return nil
-			}
-
-			switch val.Kind() {
-			case reflect.Map:
-				if val.IsZero() {
-					val.Set(reflect.MakeMap(val.Type()))
-				}
-
-				return setMap(val.Interface(), dst)
-			case reflect.Array, reflect.Slice:
-				switch val.Type().Elem().Kind() {
-				case reflect.Bool:
-					dst, err = cast.ToBoolSliceE(dst)
-				case reflect.String:
-					dst, err = cast.ToStringSliceE(dst)
-				case reflect.Float32:
-					dst, err = toFloat32SliceE(dst)
-				case reflect.Float64:
-					dst, err = toFloat64SliceE(dst)
-				case reflect.Int8:
-					dst, err = toInt8SliceE(dst)
-				case reflect.Int:
-					dst, err = cast.ToIntSliceE(dst)
-				case reflect.Int16:
-					dst, err = toInt16SliceE(dst)
-				case reflect.Int32:
-					dst, err = toInt32SliceE(dst)
-				case reflect.Int64:
-					dst, err = toInt64SliceE(dst)
-				case reflect.Uint8:
-					dst, err = toUint8SliceE(dst)
-				case reflect.Uint:
-					dst, err = toUintSliceE(dst)
-				case reflect.Uint16:
-					dst, err = toUint16SliceE(dst)
-				case reflect.Uint32:
-					dst, err = toUint32SliceE(dst)
-				case reflect.Uint64:
-					dst, err = toUint64SliceE(dst)
-				}
-				if err != nil {
-					return err
-				}
-				if val.Kind() == reflect.Slice {
-					val.Set(reflect.ValueOf(dst))
-				} else {
-					reflect.Copy(val, reflect.ValueOf(dst))
-				}
-				return nil
-			case reflect.Float32:
-				dst, err = toFloat32SliceE(dst)
-			case reflect.Float64:
-				dst, err = toFloat64SliceE(dst)
-			case reflect.Bool:
-				dst, err = cast.ToBoolE(dst)
-			case reflect.String:
-				dst, err = cast.ToStringE(dst)
-			case reflect.Int8:
-				dst, err = cast.ToInt8E(dst)
-			case reflect.Int:
-				dst, err = cast.ToIntE(dst)
-			case reflect.Int16:
-				dst, err = cast.ToInt16E(dst)
-			case reflect.Int32:
-				dst, err = cast.ToInt32E(dst)
-			case reflect.Int64:
-				dst, err = cast.ToInt64E(dst)
-			case reflect.Uint8:
-				dst, err = cast.ToUint8E(dst)
-			case reflect.Uint:
-				dst, err = cast.ToUintE(dst)
-			case reflect.Uint16:
-				dst, err = cast.ToUint16E(dst)
-			case reflect.Uint32:
-				dst, err = cast.ToUint32E(dst)
-			case reflect.Uint64:
-				dst, err = cast.ToUint64E(dst)
-			default:
-			}
-			if err != nil {
-				return err
-			}
-			val.Set(reflect.ValueOf(dst))
-		}
-	}
-
-	return nil
-}
-
-// NewOption create new option with name
-func NewOption(name string) func(...interface{}) Option {
-	return func(dst ...interface{}) Option {
-		return func(src interface{}) error {
-			return SetValueByPath(src, dst, name)
-		}
-	}
-}
-
-var (
-	Address   = NewOption("Address")
-	Name      = NewOption("Name")
-	Broker    = NewOption("Broker")
-	Logger    = NewOption("Logger")
-	Meter     = NewOption("Meter")
-	Tracer    = NewOption("Tracer")
-	Store     = NewOption("Store")
-	Register  = NewOption("Register")
-	Router    = NewOption("Router")
-	Codec     = NewOption("Codec")
-	Codecs    = NewOption("Codecs")
-	Client    = NewOption("Client")
-	Context   = NewOption("Context")
-	TLSConfig = NewOption("TLSConfig")
-	Metadata  = NewOption("Metadata")
-	Timeout   = NewOption("Timeout")
-)

options/options_test.go

@@ -1,181 +0,0 @@
-package options_test
-
-import (
-	"crypto/tls"
-	"sync"
-	"testing"
-
-	"go.unistack.org/micro/v4/options"
-)
-
-type codec interface {
-	Marshal(v interface{}, opts ...options.Option) ([]byte, error)
-	Unmarshal(b []byte, v interface{}, opts ...options.Option) error
-	String() string
-}
-
-func TestCodecs(t *testing.T) {
-	type s struct {
-		Codecs map[string]codec
-	}
-
-	wg := &sync.WaitGroup{}
-	tc := &tls.Config{InsecureSkipVerify: true}
-	opts := []options.Option{
-		options.NewOption("Codecs")(wg),
-		options.NewOption("TLSConfig")(tc),
-	}
-
-	src := &s{}
-
-	if err := options.Apply(src, opts...); err != nil {
-		t.Fatal(err)
-	}
-}
-
-func TestSpecial(t *testing.T) {
-	type s struct {
-		Wait      *sync.WaitGroup
-		TLSConfig *tls.Config
-	}
-
-	wg := &sync.WaitGroup{}
-	tc := &tls.Config{InsecureSkipVerify: true}
-	opts := []options.Option{
-		options.NewOption("Wait")(wg),
-		options.NewOption("TLSConfig")(tc),
-	}
-
-	src := &s{}
-
-	if err := options.Apply(src, opts...); err != nil {
-		t.Fatal(err)
-	}
-
-	if src.Wait == nil {
-		t.Fatalf("failed to set Wait %#+v", src)
-	}
-
-	if src.TLSConfig == nil {
-		t.Fatalf("failed to set TLSConfig %#+v", src)
-	}
-
-	if src.TLSConfig.InsecureSkipVerify != true {
-		t.Fatalf("failed to set TLSConfig %#+v", src)
-	}
-}
-
-func TestNested(t *testing.T) {
-	type server struct {
-		Address []string
-	}
-	type ownserver struct {
-		server
-		OwnField string
-	}
-
-	opts := []options.Option{
-		options.Address("host:port"),
-		options.NewOption("OwnField")("fieldval"),
-	}
-
-	src := &ownserver{}
-
-	if err := options.Apply(src, opts...); err != nil {
-		t.Fatal(err)
-	}
-
-	if src.Address[0] != "host:port" {
-		t.Fatalf("failed to set Address %#+v", src)
-	}
-
-	if src.OwnField != "fieldval" {
-		t.Fatalf("failed to set OwnField %#+v", src)
-	}
-}
-
-func TestAddress(t *testing.T) {
-	type s struct {
-		Address []string
-	}
-
-	opts := []options.Option{options.Address("host:port")}
-
-	src := &s{}
-
-	if err := options.Apply(src, opts...); err != nil {
-		t.Fatal(err)
-	}
-
-	if src.Address[0] != "host:port" {
-		t.Fatalf("failed to set Address %#+v", src)
-	}
-}
-
-func TestNewOption(t *testing.T) {
-	type s struct {
-		Address []string
-	}
-
-	opts := []options.Option{options.NewOption("Address")("host1:port1", "host2:port2")}
-
-	src := &s{}
-
-	if err := options.Apply(src, opts...); err != nil {
-		t.Fatal(err)
-	}
-
-	if src.Address[0] != "host1:port1" {
-		t.Fatalf("failed to set Address %#+v", src)
-	}
-	if src.Address[1] != "host2:port2" {
-		t.Fatalf("failed to set Address %#+v", src)
-	}
-}
-
-func TestArray(t *testing.T) {
-	type s struct {
-		Address [1]string
-	}
-
-	opts := []options.Option{options.NewOption("Address")("host:port", "host1:port1")}
-
-	src := &s{}
-
-	if err := options.Apply(src, opts...); err != nil {
-		t.Fatal(err)
-	}
-
-	if src.Address[0] != "host:port" {
-		t.Fatalf("failed to set Address %#+v", src)
-	}
-}
-
-func TestMap(t *testing.T) {
-	type s struct {
-		Metadata map[string]string
-	}
-
-	opts := []options.Option{
-		options.NewOption("Metadata")("key1", "val1"),
-		options.NewOption("Metadata")(map[string]string{"key2": "val2"}),
-	}
-
-	src := &s{}
-
-	if err := options.Apply(src, opts...); err != nil {
-		t.Fatal(err)
-	}
-
-	if len(src.Metadata) != 2 {
-		t.Fatalf("failed to set Metadata %#+v", src)
-	}
-
-	if src.Metadata["key1"] != "val1" {
-		t.Fatalf("failed to set Metadata %#+v", src)
-	}
-
-	if src.Metadata["key2"] != "val2" {
-		t.Fatalf("failed to set Metadata %#+v", src)
-	}
-}

options/util.go

@@ -1,577 +0,0 @@
-package options
-
-import (
-	"fmt"
-	"reflect"
-
-	"github.com/spf13/cast"
-)
-
-func toInt8SliceE(i interface{}) ([]int8, error) {
-	if i == nil {
-		return []int8{}, fmt.Errorf("unable to cast %#v of type %T to []int8", i, i)
-	}
-
-	switch v := i.(type) {
-	case []int8:
-		return v, nil
-	}
-
-	kind := reflect.TypeOf(i).Kind()
-	switch kind {
-	case reflect.Slice, reflect.Array:
-		s := reflect.ValueOf(i)
-		a := make([]int8, s.Len())
-		for j := 0; j < s.Len(); j++ {
-			val, err := cast.ToInt8E(s.Index(j).Interface())
-			if err != nil {
-				return []int8{}, fmt.Errorf("unable to cast %#v of type %T to []int8", i, i)
-			}
-			a[j] = val
-		}
-		return a, nil
-	default:
-		return []int8{}, fmt.Errorf("unable to cast %#v of type %T to []int8", i, i)
-	}
-}
-
-func toInt16SliceE(i interface{}) ([]int16, error) {
-	if i == nil {
-		return []int16{}, fmt.Errorf("unable to cast %#v of type %T to []int16", i, i)
-	}
-
-	switch v := i.(type) {
-	case []int16:
-		return v, nil
-	}
-
-	kind := reflect.TypeOf(i).Kind()
-	switch kind {
-	case reflect.Slice, reflect.Array:
-		s := reflect.ValueOf(i)
-		a := make([]int16, s.Len())
-		for j := 0; j < s.Len(); j++ {
-			val, err := cast.ToInt16E(s.Index(j).Interface())
-			if err != nil {
-				return []int16{}, fmt.Errorf("unable to cast %#v of type %T to []int16", i, i)
-			}
-			a[j] = val
-		}
-		return a, nil
-	default:
-		return []int16{}, fmt.Errorf("unable to cast %#v of type %T to []int16", i, i)
-	}
-}
-
-func toInt32SliceE(i interface{}) ([]int32, error) {
-	if i == nil {
-		return []int32{}, fmt.Errorf("unable to cast %#v of type %T to []int32", i, i)
-	}
-
-	switch v := i.(type) {
-	case []int32:
-		return v, nil
-	}
-
-	kind := reflect.TypeOf(i).Kind()
-	switch kind {
-	case reflect.Slice, reflect.Array:
-		s := reflect.ValueOf(i)
-		a := make([]int32, s.Len())
-		for j := 0; j < s.Len(); j++ {
-			val, err := cast.ToInt32E(s.Index(j).Interface())
-			if err != nil {
-				return []int32{}, fmt.Errorf("unable to cast %#v of type %T to []int32", i, i)
-			}
-			a[j] = val
-		}
-		return a, nil
-	default:
-		return []int32{}, fmt.Errorf("unable to cast %#v of type %T to []int32", i, i)
-	}
-}
-
-func toInt64SliceE(i interface{}) ([]int64, error) {
-	if i == nil {
-		return []int64{}, fmt.Errorf("unable to cast %#v of type %T to []int64", i, i)
-	}
-
-	switch v := i.(type) {
-	case []int64:
-		return v, nil
-	}
-
-	kind := reflect.TypeOf(i).Kind()
-	switch kind {
-	case reflect.Slice, reflect.Array:
-		s := reflect.ValueOf(i)
-		a := make([]int64, s.Len())
-		for j := 0; j < s.Len(); j++ {
-			val, err := cast.ToInt64E(s.Index(j).Interface())
-			if err != nil {
-				return []int64{}, fmt.Errorf("unable to cast %#v of type %T to []int64", i, i)
-			}
-			a[j] = val
-		}
-		return a, nil
-	default:
-		return []int64{}, fmt.Errorf("unable to cast %#v of type %T to []int64", i, i)
-	}
-}
-
-func toUintSliceE(i interface{}) ([]uint, error) {
-	if i == nil {
-		return []uint{}, fmt.Errorf("unable to cast %#v of type %T to []uint", i, i)
-	}
-
-	switch v := i.(type) {
-	case []uint:
-		return v, nil
-	}
-
-	kind := reflect.TypeOf(i).Kind()
-	switch kind {
-	case reflect.Slice, reflect.Array:
-		s := reflect.ValueOf(i)
-		a := make([]uint, s.Len())
-		for j := 0; j < s.Len(); j++ {
-			val, err := cast.ToUintE(s.Index(j).Interface())
-			if err != nil {
-				return []uint{}, fmt.Errorf("unable to cast %#v of type %T to []uint", i, i)
-			}
-			a[j] = val
-		}
-		return a, nil
-	default:
-		return []uint{}, fmt.Errorf("unable to cast %#v of type %T to []uint", i, i)
-	}
-}
-
-func toUint8SliceE(i interface{}) ([]uint8, error) {
-	if i == nil {
-		return []uint8{}, fmt.Errorf("unable to cast %#v of type %T to []uint8", i, i)
-	}
-
-	switch v := i.(type) {
-	case []uint8:
-		return v, nil
-	}
-
-	kind := reflect.TypeOf(i).Kind()
-	switch kind {
-	case reflect.Slice, reflect.Array:
-		s := reflect.ValueOf(i)
-		a := make([]uint8, s.Len())
-		for j := 0; j < s.Len(); j++ {
-			val, err := cast.ToUint8E(s.Index(j).Interface())
-			if err != nil {
-				return []uint8{}, fmt.Errorf("unable to cast %#v of type %T to []uint8", i, i)
-			}
-			a[j] = val
-		}
-		return a, nil
-	default:
-		return []uint8{}, fmt.Errorf("unable to cast %#v of type %T to []uint8", i, i)
-	}
-}
-
-func toUint16SliceE(i interface{}) ([]uint16, error) {
-	if i == nil {
-		return []uint16{}, fmt.Errorf("unable to cast %#v of type %T to []uint16", i, i)
-	}
-
-	switch v := i.(type) {
-	case []uint16:
-		return v, nil
-	}
-
-	kind := reflect.TypeOf(i).Kind()
-	switch kind {
-	case reflect.Slice, reflect.Array:
-		s := reflect.ValueOf(i)
-		a := make([]uint16, s.Len())
-		for j := 0; j < s.Len(); j++ {
-			val, err := cast.ToUint16E(s.Index(j).Interface())
-			if err != nil {
-				return []uint16{}, fmt.Errorf("unable to cast %#v of type %T to []uint16", i, i)
-			}
-			a[j] = val
-		}
-		return a, nil
-	default:
-		return []uint16{}, fmt.Errorf("unable to cast %#v of type %T to []uint16", i, i)
-	}
-}
-
-func toUint32SliceE(i interface{}) ([]uint32, error) {
-	if i == nil {
-		return []uint32{}, fmt.Errorf("unable to cast %#v of type %T to []uint32", i, i)
-	}
-
-	switch v := i.(type) {
-	case []uint32:
-		return v, nil
-	}
-
-	kind := reflect.TypeOf(i).Kind()
-	switch kind {
-	case reflect.Slice, reflect.Array:
-		s := reflect.ValueOf(i)
-		a := make([]uint32, s.Len())
-		for j := 0; j < s.Len(); j++ {
-			val, err := cast.ToUint32E(s.Index(j).Interface())
-			if err != nil {
-				return []uint32{}, fmt.Errorf("unable to cast %#v of type %T to []uint32", i, i)
-			}
-			a[j] = val
-		}
-		return a, nil
-	default:
-		return []uint32{}, fmt.Errorf("unable to cast %#v of type %T to []uint32", i, i)
-	}
-}
-
-func toUint64SliceE(i interface{}) ([]uint64, error) {
-	if i == nil {
-		return []uint64{}, fmt.Errorf("unable to cast %#v of type %T to []uint64", i, i)
-	}
-
-	switch v := i.(type) {
-	case []uint64:
-		return v, nil
-	}
-
-	kind := reflect.TypeOf(i).Kind()
-	switch kind {
-	case reflect.Slice, reflect.Array:
-		s := reflect.ValueOf(i)
-		a := make([]uint64, s.Len())
-		for j := 0; j < s.Len(); j++ {
-			val, err := cast.ToUint64E(s.Index(j).Interface())
-			if err != nil {
-				return []uint64{}, fmt.Errorf("unable to cast %#v of type %T to []uint64", i, i)
-			}
-			a[j] = val
-		}
-		return a, nil
-	default:
-		return []uint64{}, fmt.Errorf("unable to cast %#v of type %T to []uint64", i, i)
-	}
-}
-
-func toFloat32SliceE(i interface{}) ([]float32, error) {
-	if i == nil {
-		return []float32{}, fmt.Errorf("unable to cast %#v of type %T to []float32", i, i)
-	}
-
-	switch v := i.(type) {
-	case []float32:
-		return v, nil
-	}
-
-	kind := reflect.TypeOf(i).Kind()
-	switch kind {
-	case reflect.Slice, reflect.Array:
-		s := reflect.ValueOf(i)
-		a := make([]float32, s.Len())
-		for j := 0; j < s.Len(); j++ {
-			val, err := cast.ToFloat32E(s.Index(j).Interface())
-			if err != nil {
-				return []float32{}, fmt.Errorf("unable to cast %#v of type %T to []float32", i, i)
-			}
-			a[j] = val
-		}
-		return a, nil
-	default:
-		return []float32{}, fmt.Errorf("unable to cast %#v of type %T to []float32", i, i)
-	}
-}
-
-func toFloat64SliceE(i interface{}) ([]float64, error) {
-	if i == nil {
-		return []float64{}, fmt.Errorf("unable to cast %#v of type %T to []float64", i, i)
-	}
-
-	switch v := i.(type) {
-	case []float64:
-		return v, nil
-	}
-
-	kind := reflect.TypeOf(i).Kind()
-	switch kind {
-	case reflect.Slice, reflect.Array:
-		s := reflect.ValueOf(i)
-		a := make([]float64, s.Len())
-		for j := 0; j < s.Len(); j++ {
-			val, err := cast.ToFloat64E(s.Index(j).Interface())
-			if err != nil {
-				return []float64{}, fmt.Errorf("unable to cast %#v of type %T to []float64", i, i)
-			}
-			a[j] = val
-		}
-		return a, nil
-	default:
-		return []float64{}, fmt.Errorf("unable to cast %#v of type %T to []float32", i, i)
-	}
-}
-
-func setMap(src interface{}, dst interface{}) error {
-	var err error
-
-	if src == nil {
-		return fmt.Errorf("unable to cast %#v of type %T", src, src)
-	}
-	if dst == nil {
-		return fmt.Errorf("unable to cast %#v of type %T", dst, dst)
-	}
-
-	val := reflect.ValueOf(src)
-
-	keyKind := val.Type().Key().Kind()
-	valKind := val.Type().Elem().Kind()
-
-	switch v := dst.(type) {
-	case []interface{}:
-		if len(v) == 1 {
-			dstVal := reflect.ValueOf(v[0])
-			if dstVal.Kind() != reflect.Map {
-				return nil
-			}
-			mapIter := dstVal.MapRange()
-			for mapIter.Next() {
-				var (
-					keyVal interface{}
-					valVal interface{}
-				)
-				switch keyKind {
-				case reflect.Bool:
-					keyVal, err = cast.ToBoolE(mapIter.Key())
-				case reflect.String:
-					keyVal, err = cast.ToStringE(mapIter.Key())
-				case reflect.Float32:
-					keyVal, err = cast.ToFloat32E(mapIter.Key())
-				case reflect.Float64:
-					keyVal, err = cast.ToFloat64E(mapIter.Key())
-				case reflect.Int8:
-					keyVal, err = cast.ToInt8E(mapIter.Key())
-				case reflect.Int:
-					keyVal, err = cast.ToIntE(mapIter.Key())
-				case reflect.Int16:
-					keyVal, err = cast.ToInt16E(mapIter.Key())
-				case reflect.Int32:
-					keyVal, err = cast.ToInt32E(mapIter.Key())
-				case reflect.Int64:
-					keyVal, err = cast.ToInt64E(mapIter.Key())
-				case reflect.Uint8:
-					keyVal, err = cast.ToUint8E(mapIter.Key())
-				case reflect.Uint:
-					keyVal, err = cast.ToUintE(mapIter.Key())
-				case reflect.Uint16:
-					keyVal, err = cast.ToUint16E(mapIter.Key())
-				case reflect.Uint32:
-					keyVal, err = cast.ToUint32E(mapIter.Key())
-				case reflect.Uint64:
-					keyVal, err = cast.ToUint64E(mapIter.Key())
-				}
-				if err != nil {
-					return err
-				}
-				switch valKind {
-				case reflect.Bool:
-					valVal, err = cast.ToBoolE(mapIter.Value())
-				case reflect.String:
-					valVal, err = cast.ToStringE(mapIter.Value())
-				case reflect.Float32:
-					valVal, err = cast.ToFloat32E(mapIter.Value())
-				case reflect.Float64:
-					valVal, err = cast.ToFloat64E(mapIter.Value())
-				case reflect.Int8:
-					valVal, err = cast.ToInt8E(mapIter.Value())
-				case reflect.Int:
-					valVal, err = cast.ToIntE(mapIter.Value())
-				case reflect.Int16:
-					valVal, err = cast.ToInt16E(mapIter.Value())
-				case reflect.Int32:
-					valVal, err = cast.ToInt32E(mapIter.Value())
-				case reflect.Int64:
-					valVal, err = cast.ToInt64E(mapIter.Value())
-				case reflect.Uint8:
-					valVal, err = cast.ToUint8E(mapIter.Value())
-				case reflect.Uint:
-					valVal, err = cast.ToUintE(mapIter.Value())
-				case reflect.Uint16:
-					valVal, err = cast.ToUint16E(mapIter.Value())
-				case reflect.Uint32:
-					valVal, err = cast.ToUint32E(mapIter.Value())
-				case reflect.Uint64:
-					valVal, err = cast.ToUint64E(mapIter.Value())
-				}
-				if err != nil {
-					return err
-				}
-
-				val.SetMapIndex(reflect.ValueOf(keyVal), reflect.ValueOf(valVal))
-			}
-			return nil
-		}
-		if l := len(v) % 2; l == 1 {
-			v = v[:len(v)-1]
-		}
-		var (
-			keyVal interface{}
-			valVal interface{}
-		)
-		for i := 0; i < len(v); i += 2 {
-			switch keyKind {
-			case reflect.Bool:
-				keyVal, err = cast.ToBoolE(v[i])
-			case reflect.String:
-				keyVal, err = cast.ToStringE(v[i])
-			case reflect.Float32:
-				keyVal, err = cast.ToFloat32E(v[i])
-			case reflect.Float64:
-				keyVal, err = cast.ToFloat64E(v[i])
-			case reflect.Int8:
-				keyVal, err = cast.ToInt8E(v[i])
-			case reflect.Int:
-				keyVal, err = cast.ToIntE(v[i])
-			case reflect.Int16:
-				keyVal, err = cast.ToInt16E(v[i])
-			case reflect.Int32:
-				keyVal, err = cast.ToInt32E(v[i])
-			case reflect.Int64:
-				keyVal, err = cast.ToInt64E(v[i])
-			case reflect.Uint8:
-				keyVal, err = cast.ToUint8E(v[i])
-			case reflect.Uint:
-				keyVal, err = cast.ToUintE(v[i])
-			case reflect.Uint16:
-				keyVal, err = cast.ToUint16E(v[i])
-			case reflect.Uint32:
-				keyVal, err = cast.ToUint32E(v[i])
-			case reflect.Uint64:
-				keyVal, err = cast.ToUint64E(v[i])
-			}
-			if err != nil {
-				return err
-			}
-			switch valKind {
-			case reflect.Bool:
-				valVal, err = cast.ToBoolE(v[i+1])
-			case reflect.String:
-				valVal, err = cast.ToStringE(v[i+1])
-			case reflect.Float32:
-				valVal, err = cast.ToFloat32E(v[i+1])
-			case reflect.Float64:
-				valVal, err = cast.ToFloat64E(v[i+1])
-			case reflect.Int8:
-				valVal, err = cast.ToInt8E(v[i+1])
-			case reflect.Int:
-				valVal, err = cast.ToIntE(v[i+1])
-			case reflect.Int16:
-				valVal, err = cast.ToInt16E(v[i+1])
-			case reflect.Int32:
-				valVal, err = cast.ToInt32E(v[i+1])
-			case reflect.Int64:
-				valVal, err = cast.ToInt64E(v[i+1])
-			case reflect.Uint8:
-				valVal, err = cast.ToUint8E(v[i+1])
-			case reflect.Uint:
-				valVal, err = cast.ToUintE(v[i+1])
-			case reflect.Uint16:
-				valVal, err = cast.ToUint16E(v[i+1])
-			case reflect.Uint32:
-				valVal, err = cast.ToUint32E(v[i+1])
-			case reflect.Uint64:
-				valVal, err = cast.ToUint64E(v[i+1])
-			}
-			if err != nil {
-				return err
-			}
-
-			val.SetMapIndex(reflect.ValueOf(keyVal), reflect.ValueOf(valVal))
-		}
-	default:
-		dstVal := reflect.ValueOf(dst)
-		if dstVal.Kind() != reflect.Map {
-			return nil
-		}
-		mapIter := dstVal.MapRange()
-		for mapIter.Next() {
-			var (
-				keyVal interface{}
-				valVal interface{}
-			)
-			switch keyKind {
-			case reflect.Bool:
-				keyVal, err = cast.ToBoolE(mapIter.Key())
-			case reflect.String:
-				keyVal, err = cast.ToStringE(mapIter.Key())
-			case reflect.Float32:
-				keyVal, err = cast.ToFloat32E(mapIter.Key())
-			case reflect.Float64:
-				keyVal, err = cast.ToFloat64E(mapIter.Key())
-			case reflect.Int8:
-				keyVal, err = cast.ToInt8E(mapIter.Key())
-			case reflect.Int:
-				keyVal, err = cast.ToIntE(mapIter.Key())
-			case reflect.Int16:
-				keyVal, err = cast.ToInt16E(mapIter.Key())
-			case reflect.Int32:
-				keyVal, err = cast.ToInt32E(mapIter.Key())
-			case reflect.Int64:
-				keyVal, err = cast.ToInt64E(mapIter.Key())
-			case reflect.Uint8:
-				keyVal, err = cast.ToUint8E(mapIter.Key())
-			case reflect.Uint:
-				keyVal, err = cast.ToUintE(mapIter.Key())
-			case reflect.Uint16:
-				keyVal, err = cast.ToUint16E(mapIter.Key())
-			case reflect.Uint32:
-				keyVal, err = cast.ToUint32E(mapIter.Key())
-			case reflect.Uint64:
-				keyVal, err = cast.ToUint64E(mapIter.Key())
-			}
-			if err != nil {
-				return err
-			}
-			switch valKind {
-			case reflect.Bool:
-				valVal, err = cast.ToBoolE(mapIter.Value())
-			case reflect.String:
-				valVal, err = cast.ToStringE(mapIter.Value())
-			case reflect.Float32:
-				valVal, err = cast.ToFloat32E(mapIter.Value())
-			case reflect.Float64:
-				valVal, err = cast.ToFloat64E(mapIter.Value())
-			case reflect.Int8:
-				valVal, err = cast.ToInt8E(mapIter.Value())
-			case reflect.Int:
-				valVal, err = cast.ToIntE(mapIter.Value())
-			case reflect.Int16:
-				valVal, err = cast.ToInt16E(mapIter.Value())
-			case reflect.Int32:
-				valVal, err = cast.ToInt32E(mapIter.Value())
-			case reflect.Int64:
-				valVal, err = cast.ToInt64E(mapIter.Value())
-			case reflect.Uint8:
-				valVal, err = cast.ToUint8E(mapIter.Value())
-			case reflect.Uint:
-				valVal, err = cast.ToUintE(mapIter.Value())
-			case reflect.Uint16:
-				valVal, err = cast.ToUint16E(mapIter.Value())
-			case reflect.Uint32:
-				valVal, err = cast.ToUint32E(mapIter.Value())
-			case reflect.Uint64:
-				valVal, err = cast.ToUint64E(mapIter.Value())
-			}
-			if err != nil {
-				return err
-			}
-
-			val.SetMapIndex(reflect.ValueOf(keyVal), reflect.ValueOf(valVal))
-		}
-		return nil
-	}
-	return nil
-}

profiler/http/http.go

@@ -7,7 +7,7 @@ import (
 	"net/http/pprof"
 	"sync"
 
-	profile "go.unistack.org/micro/v4/profiler"
+	profile "go.unistack.org/micro/v3/profiler"
 )
 
 type httpProfile struct {

profiler/pprof/pprof.go

@@ -9,7 +9,7 @@ import (
 	"sync"
 	"time"
 
-	profile "go.unistack.org/micro/v4/profiler"
+	profile "go.unistack.org/micro/v3/profiler"
 )
 
 type profiler struct {

proxy/options.go

@@ -0,0 +1,98 @@
+// Package proxy is a transparent proxy built on the micro/server
+package proxy
+
+import (
+	"go.unistack.org/micro/v3/client"
+	"go.unistack.org/micro/v3/logger"
+	"go.unistack.org/micro/v3/meter"
+	"go.unistack.org/micro/v3/router"
+	"go.unistack.org/micro/v3/tracer"
+)
+
+// Options for proxy
+type Options struct {
+	// Tracer used for tracing
+	Tracer tracer.Tracer
+	// Client for communication
+	Client client.Client
+	// Router for routing
+	Router router.Router
+	// Logger used for logging
+	Logger logger.Logger
+	// Meter used for metrics
+	Meter meter.Meter
+	// Links holds the communication links
+	Links map[string]client.Client
+	// Endpoint holds the destination address
+	Endpoint string
+}
+
+// Option func signature
+type Option func(o *Options)
+
+// NewOptions returns new options struct that filled by opts
+func NewOptions(opts ...Option) Options {
+	options := Options{
+		Logger: logger.DefaultLogger,
+		Meter:  meter.DefaultMeter,
+		Tracer: tracer.DefaultTracer,
+	}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return options
+}
+
+// WithEndpoint sets a proxy endpoint
+func WithEndpoint(e string) Option {
+	return func(o *Options) {
+		o.Endpoint = e
+	}
+}
+
+// WithClient sets the client
+func WithClient(c client.Client) Option {
+	return func(o *Options) {
+		o.Client = c
+	}
+}
+
+// WithRouter specifies the router to use
+func WithRouter(r router.Router) Option {
+	return func(o *Options) {
+		o.Router = r
+	}
+}
+
+// WithLogger specifies the logger to use
+func WithLogger(l logger.Logger) Option {
+	return func(o *Options) {
+		o.Logger = l
+	}
+}
+
+// WithMeter specifies the meter to use
+func WithMeter(m meter.Meter) Option {
+	return func(o *Options) {
+		o.Meter = m
+	}
+}
+
+// WithLink sets a link for outbound requests
+func WithLink(name string, c client.Client) Option {
+	return func(o *Options) {
+		if o.Links == nil {
+			o.Links = make(map[string]client.Client)
+		}
+		o.Links[name] = c
+	}
+}
+
+// Tracer to be used for tracing
+func Tracer(t tracer.Tracer) Option {
+	return func(o *Options) {
+		o.Tracer = t
+	}
+}

proxy/proxy.go

@@ -0,0 +1,21 @@
+// Package proxy is a transparent proxy built on the micro/server
+package proxy
+
+import (
+	"context"
+
+	"go.unistack.org/micro/v3/server"
+)
+
+// DefaultEndpoint holds default proxy address
+var DefaultEndpoint = "localhost:9090"
+
+// Proxy can be used as a proxy server for micro services
+type Proxy interface {
+	// ProcessMessage handles inbound messages
+	ProcessMessage(context.Context, server.Message) error
+	// ServeRequest handles inbound requests
+	ServeRequest(context.Context, server.Request, server.Response) error
+	// Name of the proxy protocol
+	String() string
+}

register/memory/memory.go

@@ -6,10 +6,9 @@ import (
 	"sync"
 	"time"
 
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/util/id"
-	"go.unistack.org/micro/v4/util/id"
 )
 
 var (
@@ -26,6 +25,7 @@ type node struct {
 type record struct {
 	Name     string
 	Version  string
+	Metadata map[string]string
 	Nodes    map[string]*node
 }
 
@@ -160,14 +160,19 @@ func (m *memory) Register(_ context.Context, s *register.Service, opts ...regist
 			continue
 		}
 
-		md := metadata.Copy(n.Metadata)
+		metadata := make(map[string]string, len(n.Metadata))
+
+		// make copy of metadata
+		for k, v := range n.Metadata {
+			metadata[k] = v
+		}
 
 		// add the node
 		srvs[s.Name][s.Version].Nodes[n.ID] = &node{
 			Node: &register.Node{
 				ID:       n.ID,
 				Address:  n.Address,
-				Metadata: md,
+				Metadata: metadata,
 			},
 			TTL:      options.TTL,
 			LastSeen: time.Now(),
@@ -447,15 +452,23 @@ func serviceToRecord(s *register.Service, ttl time.Duration) *record {
 }
 
 func recordToService(r *record, namespace string) *register.Service {
+	metadata := make(map[string]string, len(r.Metadata))
+	for k, v := range r.Metadata {
+		metadata[k] = v
+	}
+
 	nodes := make([]*register.Node, len(r.Nodes))
 	i := 0
 	for _, n := range r.Nodes {
-		nmd := metadata.Copy(n.Metadata)
+		md := make(map[string]string, len(n.Metadata))
+		for k, v := range n.Metadata {
+			md[k] = v
+		}
 
 		nodes[i] = &register.Node{
 			ID:       n.ID,
 			Address:  n.Address,
-			Metadata: nmd,
+			Metadata: md,
 		}
 		i++
 	}

register/memory/memory_test.go

@@ -7,7 +7,7 @@ import (
 	"testing"
 	"time"
 
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
 )
 
 var testData = map[string][]*register.Service{

register/options.go

@@ -5,10 +5,10 @@ import (
 	"crypto/tls"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Options holds options for register

register/register.go

@@ -5,7 +5,7 @@ import (
 	"context"
 	"errors"
 
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
 )
 
 const (

resolver/dns/dns.go

@@ -7,7 +7,7 @@ import (
 	"sync"
 	"time"
 
-	"go.unistack.org/micro/v4/resolver"
+	"go.unistack.org/micro/v3/resolver"
 )
 
 // Resolver is a DNS network resolve

resolver/dnssrv/dnssrv.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"net"
 
-	"go.unistack.org/micro/v4/resolver"
+	"go.unistack.org/micro/v3/resolver"
 )
 
 // Resolver is a DNS network resolve

resolver/http/http.go

@@ -8,7 +8,7 @@ import (
 	"net/http"
 	"net/url"
 
-	"go.unistack.org/micro/v4/resolver"
+	"go.unistack.org/micro/v3/resolver"
 )
 
 // nolint: golint,revive

resolver/noop/noop.go

@@ -2,7 +2,7 @@
 package noop
 
 import (
-	"go.unistack.org/micro/v4/resolver"
+	"go.unistack.org/micro/v3/resolver"
 )
 
 // Resolver contains noop resolver

resolver/registry/registry.go

@@ -4,8 +4,8 @@ package register
 import (
 	"context"
 
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/resolver"
+	"go.unistack.org/micro/v3/resolver"
 )
 
 // Resolver is a register network resolver

resolver/static/static.go

@@ -2,7 +2,7 @@
 package static
 
 import (
-	"go.unistack.org/micro/v4/resolver"
+	"go.unistack.org/micro/v3/resolver"
 )
 
 // Resolver returns a static list of nodes. In the event the node list

router/options.go

@@ -3,9 +3,9 @@ package router
 import (
 	"context"
 
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/util/id"
+	"go.unistack.org/micro/v3/util/id"
 )
 
 // Options are router options

router/route.go

@@ -3,7 +3,7 @@ package router
 import (
 	"hash/fnv"
 
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
 )
 
 var (

selector/random/random.go

@@ -1,8 +1,8 @@
 package random
 
 import (
-	"go.unistack.org/micro/v4/selector"
+	"go.unistack.org/micro/v3/selector"
-	"go.unistack.org/micro/v4/util/rand"
+	"go.unistack.org/micro/v3/util/rand"
 )
 
 type random struct{}

selector/random/random_test.go

@@ -3,7 +3,7 @@ package random
 import (
 	"testing"
 
-	"go.unistack.org/micro/v4/selector"
+	"go.unistack.org/micro/v3/selector"
 )
 
 func TestRandom(t *testing.T) {

selector/roundrobin/roundrobin.go

@@ -1,8 +1,8 @@
 package roundrobin
 
 import (
-	"go.unistack.org/micro/v4/selector"
+	"go.unistack.org/micro/v3/selector"
-	"go.unistack.org/micro/v4/util/rand"
+	"go.unistack.org/micro/v3/util/rand"
 )
 
 // NewSelector returns an initialised round robin selector

selector/roundrobin/roundrobin_test.go

@@ -3,7 +3,7 @@ package roundrobin
 import (
 	"testing"
 
-	"go.unistack.org/micro/v4/selector"
+	"go.unistack.org/micro/v3/selector"
 )
 
 func TestRoundRobin(t *testing.T) {

server/errors.go

@@ -1,6 +1,6 @@
 package server
 
-import "go.unistack.org/micro/v4/errors"
+import "go.unistack.org/micro/v3/errors"
 
 type Error struct {
 	id string

server/errors_test.go

@@ -3,7 +3,7 @@ package server
 import (
 	"testing"
 
-	"go.unistack.org/micro/v4/errors"
+	"go.unistack.org/micro/v3/errors"
 )
 
 func TestError(t *testing.T) {

server/noop.go

@@ -1,17 +1,24 @@
 package server
 
 import (
+	"context"
 	"fmt"
 	"reflect"
+	"runtime/debug"
+	"strings"
 	"sync"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/errors"
-	maddr "go.unistack.org/micro/v4/util/addr"
+	"go.unistack.org/micro/v3/logger"
-	mnet "go.unistack.org/micro/v4/util/net"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/util/rand"
+	"go.unistack.org/micro/v3/options"
+	"go.unistack.org/micro/v3/register"
+	maddr "go.unistack.org/micro/v3/util/addr"
+	mnet "go.unistack.org/micro/v3/util/net"
+	"go.unistack.org/micro/v3/util/rand"
 )
 
 // DefaultCodecs will be used to encode/decode
@@ -19,6 +26,10 @@ var DefaultCodecs = map[string]codec.Codec{
 	"application/octet-stream": codec.NewCodec(),
 }
 
+const (
+	defaultContentType = "application/json"
+)
+
 type rpcHandler struct {
 	opts    HandlerOptions
 	handler interface{}
@@ -55,6 +66,7 @@ type noopServer struct {
 	wg          *sync.WaitGroup
 	rsvc        *register.Service
 	handlers    map[string]Handler
+	subscribers map[*subscriber][]broker.Subscriber
 	exit        chan chan error
 	opts        Options
 	sync.RWMutex
@@ -68,12 +80,25 @@ func NewServer(opts ...Option) Server {
 	if n.handlers == nil {
 		n.handlers = make(map[string]Handler)
 	}
+	if n.subscribers == nil {
+		n.subscribers = make(map[*subscriber][]broker.Subscriber)
+	}
 	if n.exit == nil {
 		n.exit = make(chan chan error)
 	}
 	return n
 }
 
+func (n *noopServer) newCodec(contentType string) (codec.Codec, error) {
+	if cf, ok := n.opts.Codecs[contentType]; ok {
+		return cf, nil
+	}
+	if cf, ok := DefaultCodecs[contentType]; ok {
+		return cf, nil
+	}
+	return nil, codec.ErrUnknownContentType
+}
+
 func (n *noopServer) Live() bool {
 	return true
 }
@@ -95,10 +120,65 @@ func (n *noopServer) Name() string {
 	return n.opts.Name
 }
 
+func (n *noopServer) Subscribe(sb Subscriber) error {
+	sub, ok := sb.(*subscriber)
+	if !ok {
+		return fmt.Errorf("invalid subscriber: expected *subscriber")
+	} else if len(sub.handlers) == 0 {
+		return fmt.Errorf("invalid subscriber: no handler functions")
+	}
+
+	if err := ValidateSubscriber(sb); err != nil {
+		return err
+	}
+
+	n.Lock()
+	if _, ok = n.subscribers[sub]; ok {
+		n.Unlock()
+		return fmt.Errorf("subscriber %v already exists", sub)
+	}
+
+	n.subscribers[sub] = nil
+	n.Unlock()
+	return nil
+}
+
+type rpcMessage struct {
+	payload     interface{}
+	codec       codec.Codec
+	header      metadata.Metadata
+	topic       string
+	contentType string
+}
+
+func (r *rpcMessage) ContentType() string {
+	return r.contentType
+}
+
+func (r *rpcMessage) Topic() string {
+	return r.topic
+}
+
+func (r *rpcMessage) Body() interface{} {
+	return r.payload
+}
+
+func (r *rpcMessage) Header() metadata.Metadata {
+	return r.header
+}
+
+func (r *rpcMessage) Codec() codec.Codec {
+	return r.codec
+}
+
 func (n *noopServer) NewHandler(h interface{}, opts ...HandlerOption) Handler {
 	return newRPCHandler(h, opts...)
 }
 
+func (n *noopServer) NewSubscriber(topic string, sb interface{}, opts ...SubscriberOption) Subscriber {
+	return newSubscriber(topic, sb, opts...)
+}
+
 func (n *noopServer) Init(opts ...Option) error {
 	for _, o := range opts {
 		o(&n.opts)
@@ -107,6 +187,9 @@ func (n *noopServer) Init(opts ...Option) error {
 	if n.handlers == nil {
 		n.handlers = make(map[string]Handler, 1)
 	}
+	if n.subscribers == nil {
+		n.subscribers = make(map[*subscriber][]broker.Subscriber, 1)
+	}
 
 	if n.exit == nil {
 		n.exit = make(chan chan error)
@@ -205,6 +288,33 @@ func (n *noopServer) Deregister() error {
 
 	n.registered = false
 
+	cx := config.Context
+
+	wg := sync.WaitGroup{}
+	for sb, subs := range n.subscribers {
+		for idx := range subs {
+			if sb.Options().Context != nil {
+				cx = sb.Options().Context
+			}
+
+			ncx := cx
+			wg.Add(1)
+			go func(s broker.Subscriber) {
+				defer wg.Done()
+				if config.Logger.V(logger.InfoLevel) {
+					config.Logger.Info(n.opts.Context, "unsubscribing from topic: "+s.Topic())
+				}
+				if err := s.Unsubscribe(ncx); err != nil {
+					if config.Logger.V(logger.ErrorLevel) {
+						config.Logger.Error(n.opts.Context, "unsubscribing from topic: "+s.Topic(), err)
+					}
+				}
+			}(subs[idx])
+		}
+		n.subscribers[sb] = nil
+	}
+	wg.Wait()
+
 	n.Unlock()
 	return nil
 }
@@ -241,6 +351,21 @@ func (n *noopServer) Start() error {
 	}
 	n.Unlock()
 
+	// only connect if we're subscribed
+	if len(n.subscribers) > 0 {
+		// connect to the broker
+		if err := config.Broker.Connect(config.Context); err != nil {
+			if config.Logger.V(logger.ErrorLevel) {
+				config.Logger.Error(n.opts.Context, fmt.Sprintf("broker [%s] connect error", config.Broker.String()), err)
+			}
+			return err
+		}
+
+		if config.Logger.V(logger.InfoLevel) {
+			config.Logger.Info(n.opts.Context, fmt.Sprintf("broker [%s] Connected to %s", config.Broker.String(), config.Broker.Address()))
+		}
+	}
+
 	// use RegisterCheck func before register
 	// nolint: nestif
 	if err := config.RegisterCheck(config.Context); err != nil {
@@ -256,6 +381,10 @@ func (n *noopServer) Start() error {
 		}
 	}
 
+	if err := n.subscribe(); err != nil {
+		return err
+	}
+
 	go func() {
 		t := new(time.Ticker)
 
@@ -339,6 +468,42 @@ func (n *noopServer) Start() error {
 	return nil
 }
 
+func (n *noopServer) subscribe() error {
+	config := n.Options()
+
+	subCtx := config.Context
+
+	for sb := range n.subscribers {
+
+		if cx := sb.Options().Context; cx != nil {
+			subCtx = cx
+		}
+
+		opts := []broker.SubscribeOption{
+			broker.SubscribeContext(subCtx),
+			broker.SubscribeAutoAck(sb.Options().AutoAck),
+			broker.SubscribeBodyOnly(sb.Options().BodyOnly),
+		}
+
+		if queue := sb.Options().Queue; len(queue) > 0 {
+			opts = append(opts, broker.SubscribeGroup(queue))
+		}
+
+		if config.Logger.V(logger.InfoLevel) {
+			config.Logger.Info(n.opts.Context, "subscribing to topic: "+sb.Topic())
+		}
+
+		sub, err := config.Broker.Subscribe(subCtx, sb.Topic(), n.createSubHandler(sb, config), opts...)
+		if err != nil {
+			return err
+		}
+
+		n.subscribers[sb] = []broker.Subscriber{sub}
+	}
+
+	return nil
+}
+
 func (n *noopServer) Stop() error {
 	n.RLock()
 	if !n.started {
@@ -358,3 +523,195 @@ func (n *noopServer) Stop() error {
 
 	return err
 }
+
+func newSubscriber(topic string, sub interface{}, opts ...SubscriberOption) Subscriber {
+	var handlers []*handler
+
+	options := NewSubscriberOptions(opts...)
+
+	if typ := reflect.TypeOf(sub); typ.Kind() == reflect.Func {
+		h := &handler{
+			method: reflect.ValueOf(sub),
+		}
+
+		switch typ.NumIn() {
+		case 1:
+			h.reqType = typ.In(0)
+		case 2:
+			h.ctxType = typ.In(0)
+			h.reqType = typ.In(1)
+		}
+
+		handlers = append(handlers, h)
+	} else {
+		for m := 0; m < typ.NumMethod(); m++ {
+			method := typ.Method(m)
+			h := &handler{
+				method: method.Func,
+			}
+
+			switch method.Type.NumIn() {
+			case 2:
+				h.reqType = method.Type.In(1)
+			case 3:
+				h.ctxType = method.Type.In(1)
+				h.reqType = method.Type.In(2)
+			}
+
+			handlers = append(handlers, h)
+		}
+	}
+
+	return &subscriber{
+		rcvr:       reflect.ValueOf(sub),
+		typ:        reflect.TypeOf(sub),
+		topic:      topic,
+		subscriber: sub,
+		handlers:   handlers,
+		opts:       options,
+	}
+}
+
+//nolint:gocyclo
+func (n *noopServer) createSubHandler(sb *subscriber, opts Options) broker.Handler {
+	return func(p broker.Event) (err error) {
+		defer func() {
+			if r := recover(); r != nil {
+				n.RLock()
+				config := n.opts
+				n.RUnlock()
+				if config.Logger.V(logger.ErrorLevel) {
+					config.Logger.Error(n.opts.Context, "panic recovered: ", r)
+					config.Logger.Error(n.opts.Context, string(debug.Stack()))
+				}
+				err = errors.InternalServerError(n.opts.Name+".subscriber", "panic recovered: %v", r)
+			}
+		}()
+
+		msg := p.Message()
+		// if we don't have headers, create empty map
+		if msg.Header == nil {
+			msg.Header = metadata.New(2)
+		}
+
+		ct := msg.Header["Content-Type"]
+		if len(ct) == 0 {
+			msg.Header.Set(metadata.HeaderContentType, defaultContentType)
+			ct = defaultContentType
+		}
+		cf, err := n.newCodec(ct)
+		if err != nil {
+			return err
+		}
+
+		hdr := metadata.New(len(msg.Header))
+		for k, v := range msg.Header {
+			hdr.Set(k, v)
+		}
+
+		ctx := metadata.NewIncomingContext(sb.opts.Context, hdr)
+
+		results := make(chan error, len(sb.handlers))
+
+		for i := 0; i < len(sb.handlers); i++ {
+			handler := sb.handlers[i]
+
+			var isVal bool
+			var req reflect.Value
+
+			if handler.reqType.Kind() == reflect.Ptr {
+				req = reflect.New(handler.reqType.Elem())
+			} else {
+				req = reflect.New(handler.reqType)
+				isVal = true
+			}
+			if isVal {
+				req = req.Elem()
+			}
+
+			if err = cf.Unmarshal(msg.Body, req.Interface()); err != nil {
+				return err
+			}
+
+			fn := func(ctx context.Context, msg Message) error {
+				var vals []reflect.Value
+				if sb.typ.Kind() != reflect.Func {
+					vals = append(vals, sb.rcvr)
+				}
+				if handler.ctxType != nil {
+					vals = append(vals, reflect.ValueOf(ctx))
+				}
+
+				vals = append(vals, reflect.ValueOf(msg.Body()))
+
+				returnValues := handler.method.Call(vals)
+				if rerr := returnValues[0].Interface(); rerr != nil {
+					return rerr.(error)
+				}
+				return nil
+			}
+
+			opts.Hooks.EachPrev(func(hook options.Hook) {
+				if h, ok := hook.(HookSubHandler); ok {
+					fn = h(fn)
+				}
+			})
+
+			if n.wg != nil {
+				n.wg.Add(1)
+			}
+			go func() {
+				if n.wg != nil {
+					defer n.wg.Done()
+				}
+				cerr := fn(ctx, &rpcMessage{
+					topic:       sb.topic,
+					contentType: ct,
+					payload:     req.Interface(),
+					header:      msg.Header,
+				})
+				results <- cerr
+			}()
+		}
+		var errors []string
+		for i := 0; i < len(sb.handlers); i++ {
+			if rerr := <-results; rerr != nil {
+				errors = append(errors, rerr.Error())
+			}
+		}
+		if len(errors) > 0 {
+			err = fmt.Errorf("subscriber error: %s", strings.Join(errors, "\n"))
+		}
+		return err
+	}
+}
+
+func (s *subscriber) Topic() string {
+	return s.topic
+}
+
+func (s *subscriber) Subscriber() interface{} {
+	return s.subscriber
+}
+
+func (s *subscriber) Options() SubscriberOptions {
+	return s.opts
+}
+
+type subscriber struct {
+	topic string
+
+	typ        reflect.Type
+	subscriber interface{}
+
+	handlers []*handler
+
+	rcvr reflect.Value
+	opts SubscriberOptions
+}
+
+type handler struct {
+	reqType reflect.Type
+	ctxType reflect.Type
+	method  reflect.Value
+}

server/noop_test.go

@@ -0,0 +1,124 @@
+package server_test
+
+import (
+	"context"
+	"fmt"
+	"testing"
+
+	"go.unistack.org/micro/v3/broker"
+	"go.unistack.org/micro/v3/client"
+	"go.unistack.org/micro/v3/codec"
+	"go.unistack.org/micro/v3/logger"
+	"go.unistack.org/micro/v3/options"
+	"go.unistack.org/micro/v3/server"
+)
+
+type TestHandler struct {
+	t *testing.T
+}
+
+type TestMessage struct {
+	Name string
+}
+
+func (h *TestHandler) SingleSubHandler(ctx context.Context, msg *codec.Frame) error {
+	// fmt.Printf("msg %s\n", msg.Data)
+	return nil
+}
+
+func TestNoopSub(t *testing.T) {
+	ctx := context.Background()
+
+	b := broker.NewBroker()
+
+	if err := b.Init(); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := b.Connect(ctx); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := logger.DefaultLogger.Init(logger.WithLevel(logger.ErrorLevel)); err != nil {
+		t.Fatal(err)
+	}
+	s := server.NewServer(
+		server.Broker(b),
+		server.Codec("application/octet-stream", codec.NewCodec()),
+	)
+	if err := s.Init(); err != nil {
+		t.Fatal(err)
+	}
+
+	c := client.NewClient(
+		client.Broker(b),
+		client.Codec("application/octet-stream", codec.NewCodec()),
+		client.ContentType("application/octet-stream"),
+	)
+	if err := c.Init(); err != nil {
+		t.Fatal(err)
+	}
+	h := &TestHandler{t: t}
+
+	if err := s.Subscribe(s.NewSubscriber("single_topic", h.SingleSubHandler,
+		server.SubscriberQueue("queue"),
+	)); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := s.Start(); err != nil {
+		t.Fatal(err)
+	}
+
+	msgs := make([]client.Message, 0, 8)
+	for i := 0; i < 8; i++ {
+		msgs = append(msgs, c.NewMessage("batch_topic", &codec.Frame{Data: []byte(fmt.Sprintf(`{"name": "test_name %d"}`, i))}))
+	}
+
+	if err := c.BatchPublish(ctx, msgs); err != nil {
+		t.Fatal(err)
+	}
+
+	defer func() {
+		if err := s.Stop(); err != nil {
+			t.Fatal(err)
+		}
+	}()
+}
+
+func TestHooks_Wrap(t *testing.T) {
+	n := 5
+	fn1 := func(next server.FuncSubHandler) server.FuncSubHandler {
+		return func(ctx context.Context, msg server.Message) (err error) {
+			n *= 2
+			return next(ctx, msg)
+		}
+	}
+	fn2 := func(next server.FuncSubHandler) server.FuncSubHandler {
+		return func(ctx context.Context, msg server.Message) (err error) {
+			n -= 10
+			return next(ctx, msg)
+		}
+	}
+
+	hs := &options.Hooks{}
+	hs.Append(server.HookSubHandler(fn1), server.HookSubHandler(fn2))
+
+	var fn = func(ctx context.Context, msg server.Message) error {
+		return nil
+	}
+
+	hs.EachPrev(func(hook options.Hook) {
+		if h, ok := hook.(server.HookSubHandler); ok {
+			fn = h(fn)
+		}
+	})
+
+	if err := fn(nil, nil); err != nil {
+		t.Fatal(err)
+	}
+
+	if n != 0 {
+		t.Fatalf("uncorrected hooks call")
+	}
+}

server/options.go

@@ -7,16 +7,16 @@ import (
 	"sync"
 	"time"
 
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	msync "go.unistack.org/micro/v4/sync"
+	msync "go.unistack.org/micro/v3/sync"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
-	"go.unistack.org/micro/v4/util/id"
+	"go.unistack.org/micro/v3/util/id"
 )
 
 // Option func

server/registry.go

@@ -4,10 +4,10 @@ import (
 	"net"
 	"time"
 
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/util/addr"
+	"go.unistack.org/micro/v3/util/addr"
-	"go.unistack.org/micro/v4/util/backoff"
+	"go.unistack.org/micro/v3/util/backoff"
 )
 
 var (
@@ -77,6 +77,10 @@ func NewRegisterService(s Server) (*register.Service, error) {
 	}
 	node.Metadata = metadata.Copy(opts.Metadata)
 
+	node.Metadata["server"] = s.String()
+	node.Metadata["broker"] = opts.Broker.String()
+	node.Metadata["register"] = opts.Register.String()
+
 	return &register.Service{
 		Name:    opts.Name,
 		Version: opts.Version,

server/server.go

@@ -3,11 +3,10 @@ package server
 
 import (
 	"context"
-	"errors"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
 )
 
 // DefaultServer default server
@@ -52,6 +51,10 @@ type Server interface {
 	Handle(h Handler) error
 	// Create a new handler
 	NewHandler(h interface{}, opts ...HandlerOption) Handler
+	// Create a new subscriber
+	NewSubscriber(topic string, h interface{}, opts ...SubscriberOption) Subscriber
+	// Register a subscriber
+	Subscribe(s Subscriber) error
 	// Start the server
 	Start() error
 	// Stop the server
@@ -67,10 +70,36 @@ type Server interface {
 }
 
 type (
+	FuncSubHandler func(ctx context.Context, ms Message) error
+	HookSubHandler func(next FuncSubHandler) FuncSubHandler
 	FuncHandler    func(ctx context.Context, req Request, rsp interface{}) error
 	HookHandler    func(next FuncHandler) FuncHandler
 )
 
+/*
+// Router handle serving messages
+type Router interface {
+	// ProcessMessage processes a message
+	ProcessMessage(ctx context.Context, msg Message) error
+	// ServeRequest processes a request to completion
+	ServeRequest(ctx context.Context, req Request, rsp Response) error
+}
+*/
+
+// Message is an async message interface
+type Message interface {
+	// Topic of the message
+	Topic() string
+	// The decoded payload value
+	Body() interface{}
+	// The content type of the payload
+	ContentType() string
+	// The raw headers of the message
+	Header() metadata.Metadata
+	// Codec used to decode the message
+	Codec() codec.Codec
+}
+
 // Request is a synchronous request interface
 type Request interface {
 	// Service name requested
@@ -143,20 +172,11 @@ type Handler interface {
 	Options() HandlerOptions
 }
 
-type serverHeaderKey struct{}
+// Subscriber interface represents a subscription to a given topic using
-
+// a specific subscriber function or object with endpoints. It mirrors
-func ResponseMetadata(ctx context.Context, md *metadata.Metadata) context.Context {
+// the handler in its behaviour.
-	return context.WithValue(ctx, serverHeaderKey{}, md)
+type Subscriber interface {
-}
+	Topic() string
-
+	Subscriber() interface{}
-func SetResponseMetadata(ctx context.Context, md metadata.Metadata) error {
+	Options() SubscriberOptions
-	if md.Len() == 0 {
-		return nil
-	}
-	h, ok := ctx.Value(serverHeaderKey{}).(*metadata.Metadata)
-	if !ok || h == nil {
-		return errors.New("missing metadata")
-	}
-	md.CopyTo(*h)
-	return nil
 }

server/subscriber.go

@@ -1,4 +1,4 @@
-package broker
+package server
 
 import (
 	"fmt"
@@ -8,8 +8,7 @@ import (
 )
 
 const (
-	messageSig  = "func(broker.Message) error"
+	subSig = "func(context.Context, interface{}) error"
-	messagesSig = "func([]broker.Message) error"
 )
 
 // Precompute the reflect type for error. Can't use error directly
@@ -32,31 +31,31 @@ func isExportedOrBuiltinType(t reflect.Type) bool {
 	return isExported(t.Name()) || t.PkgPath() == ""
 }
 
-// IsValidHandler func signature
+// ValidateSubscriber func signature
-func IsValidHandler(sub interface{}) error {
+func ValidateSubscriber(sub Subscriber) error {
-	typ := reflect.TypeOf(sub)
+	typ := reflect.TypeOf(sub.Subscriber())
 	var argType reflect.Type
 	switch typ.Kind() {
 	case reflect.Func:
 		name := "Func"
 		switch typ.NumIn() {
-		case 1:
+		case 2:
-			argType = typ.In(0)
+			argType = typ.In(1)
 		default:
-			return fmt.Errorf("subscriber %v takes wrong number of args: %v required signature %s", name, typ.NumIn(), messageSig)
+			return fmt.Errorf("subscriber %v takes wrong number of args: %v required signature %s", name, typ.NumIn(), subSig)
 		}
 		if !isExportedOrBuiltinType(argType) {
 			return fmt.Errorf("subscriber %v argument type not exported: %v", name, argType)
 		}
 		if typ.NumOut() != 1 {
 			return fmt.Errorf("subscriber %v has wrong number of return values: %v require signature %s",
-				name, typ.NumOut(), messageSig)
+				name, typ.NumOut(), subSig)
 		}
 		if returnType := typ.Out(0); returnType != typeOfError {
 			return fmt.Errorf("subscriber %v returns %v not error", name, returnType.String())
 		}
 	default:
-		hdlr := reflect.ValueOf(sub)
+		hdlr := reflect.ValueOf(sub.Subscriber())
 		name := reflect.Indirect(hdlr).Type().Name()
 
 		for m := 0; m < typ.NumMethod(); m++ {
@@ -66,7 +65,7 @@ func IsValidHandler(sub interface{}) error {
 				argType = method.Type.In(2)
 			default:
 				return fmt.Errorf("subscriber %v.%v takes wrong number of args: %v required signature %s",
-					name, method.Name, method.Type.NumIn(), messageSig)
+					name, method.Name, method.Type.NumIn(), subSig)
 			}
 
 			if !isExportedOrBuiltinType(argType) {
@@ -75,7 +74,7 @@ func IsValidHandler(sub interface{}) error {
 			if method.Type.NumOut() != 1 {
 				return fmt.Errorf(
 					"subscriber %v.%v has wrong number of return values: %v require signature %s",
-					name, method.Name, method.Type.NumOut(), messageSig)
+					name, method.Name, method.Type.NumOut(), subSig)
 			}
 			if returnType := method.Type.Out(0); returnType != typeOfError {
 				return fmt.Errorf("subscriber %v.%v returns %v not error", name, method.Name, returnType.String())

server/wrapper.go

@@ -9,9 +9,17 @@ import (
 // request and response types.
 type HandlerFunc func(ctx context.Context, req Request, rsp interface{}) error
 
+// SubscriberFunc represents a single method of a subscriber. It's used primarily
+// for the wrappers. What's handed to the actual method is the concrete
+// publication message.
+type SubscriberFunc func(ctx context.Context, msg Message) error
+
 // HandlerWrapper wraps the HandlerFunc and returns the equivalent
 type HandlerWrapper func(HandlerFunc) HandlerFunc
 
+// SubscriberWrapper wraps the SubscriberFunc and returns the equivalent
+type SubscriberWrapper func(SubscriberFunc) SubscriberFunc
+
 // StreamWrapper wraps a Stream interface and returns the equivalent.
 // Because streams exist for the lifetime of a method invocation this
 // is a convenient way to wrap a Stream as its in use for trace, monitoring,

service.go

@@ -9,17 +9,17 @@ import (
 
 	"github.com/KimMachineGun/automemlimit/memlimit"
 	"go.uber.org/automaxprocs/maxprocs"
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/client"
+	"go.unistack.org/micro/v3/client"
-	"go.unistack.org/micro/v4/config"
+	"go.unistack.org/micro/v3/config"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/router"
+	"go.unistack.org/micro/v3/router"
-	"go.unistack.org/micro/v4/server"
+	"go.unistack.org/micro/v3/server"
-	"go.unistack.org/micro/v4/store"
+	"go.unistack.org/micro/v3/store"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
-	utildns "go.unistack.org/micro/v4/util/dns"
+	utildns "go.unistack.org/micro/v3/util/dns"
 )
 
 func init() {
@@ -95,6 +95,11 @@ func RegisterHandler(s server.Server, h interface{}, opts ...server.HandlerOptio
 	return s.Handle(s.NewHandler(h, opts...))
 }
 
+// RegisterSubscriber is syntactic sugar for registering a subscriber
+func RegisterSubscriber(topic string, s server.Server, h interface{}, opts ...server.SubscriberOption) error {
+	return s.Subscribe(s.NewSubscriber(topic, h, opts...))
+}
+
 type service struct {
 	done chan struct{}
 	opts Options

service_test.go

@@ -1,19 +1,20 @@
 package micro
 
 import (
+	"context"
 	"reflect"
 	"testing"
 
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/client"
+	"go.unistack.org/micro/v3/client"
-	"go.unistack.org/micro/v4/config"
+	"go.unistack.org/micro/v3/config"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/router"
+	"go.unistack.org/micro/v3/router"
-	"go.unistack.org/micro/v4/server"
+	"go.unistack.org/micro/v3/server"
-	"go.unistack.org/micro/v4/store"
+	"go.unistack.org/micro/v3/store"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 func TestClient(t *testing.T) {
@@ -79,6 +80,41 @@ func TestRegisterHandler(t *testing.T) {
 	}
 }
 
+func TestRegisterSubscriber(t *testing.T) {
+	type args struct {
+		topic string
+		s     server.Server
+		h     interface{}
+		opts  []server.SubscriberOption
+	}
+	h := func(_ context.Context, _ interface{}) error {
+		return nil
+	}
+	tests := []struct {
+		name    string
+		args    args
+		wantErr bool
+	}{
+		{
+			name: "RegisterSubscriber",
+			args: args{
+				topic: "test",
+				s:     server.DefaultServer,
+				h:     h,
+				opts:  nil,
+			},
+			wantErr: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if err := RegisterSubscriber(tt.args.topic, tt.args.s, tt.args.h, tt.args.opts...); (err != nil) != tt.wantErr {
+				t.Errorf("RegisterSubscriber() error = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}
+
 func TestNewService(t *testing.T) {
 	type args struct {
 		opts []Option

store/memory/memory.go

@@ -8,8 +8,8 @@ import (
 	"time"
 
 	cache "github.com/patrickmn/go-cache"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/store"
+	"go.unistack.org/micro/v3/store"
 )
 
 // NewStore returns a memory store

store/memory/memory_test.go

@@ -5,7 +5,7 @@ import (
 	"testing"
 	"time"
 
-	"go.unistack.org/micro/v4/store"
+	"go.unistack.org/micro/v3/store"
 )
 
 type testHook struct {

store/noop.go

@@ -5,8 +5,8 @@ import (
 	"sync"
 	"sync/atomic"
 
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/util/id"
+	"go.unistack.org/micro/v3/util/id"
 )
 
 var _ Store = (*noopStore)(nil)

store/options.go

@@ -5,12 +5,12 @@ import (
 	"crypto/tls"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Options contains configuration for the Store

sync/options.go

@@ -3,9 +3,9 @@ package sync
 import (
 	"time"
 
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Options holds the sync options

tracer/memory/memory.go

@@ -4,8 +4,8 @@ import (
 	"context"
 	"time"
 
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
-	"go.unistack.org/micro/v4/util/id"
+	"go.unistack.org/micro/v3/util/id"
 )
 
 var _ tracer.Tracer = (*Tracer)(nil)