cleanup interfaces for v4

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

broker/broker.go

@@ -10,13 +10,15 @@ import (
 )
 
 // DefaultBroker default memory broker
-var DefaultBroker = NewBroker()
+var DefaultBroker Broker // =  NewBroker()
 
 var (
 	// ErrNotConnected returns when broker used but not connected yet
 	ErrNotConnected = errors.New("broker not connected")
 	// ErrDisconnected returns when broker disconnected
 	ErrDisconnected = errors.New("broker disconnected")
+	// ErrInvalidMessage returns when message has nvalid format
+	ErrInvalidMessage = errors.New("broker message has invalid format")
 )
 
 // Broker is an interface used for asynchronous messaging.
@@ -33,61 +35,33 @@ type Broker interface {
 	Connect(ctx context.Context) error
 	// Disconnect disconnect from broker
 	Disconnect(ctx context.Context) error
+	// NewMessage creates new broker message
+	NewMessage(endpoint string, req interface{}, opts ...MessageOption) Message
 	// Publish message to broker topic
-	Publish(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error
+	Publish(ctx context.Context, msg interface{}, opts ...PublishOption) error
 	// Subscribe subscribes to topic message via handler
-	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)
+	Subscribe(ctx context.Context, topic string, handler interface{}, opts ...SubscribeOption) (Subscriber, error)
 	// String type of broker
 	String() string
 }
 
-// Handler is used to process messages via a subscription of a topic.
-type Handler func(Event) error
-
-// 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 {
+// Message is given to a subscription handler for processing
+type Message interface {
+	// Context for the message
+	Context() context.Context
 	// Topic returns event topic
 	Topic() string
-	// Message returns broker message
-	Message() *Message
+	// Body returns broker message
+	Body() interface{}
 	// Ack acknowledge message
 	Ack() error
 	// Error returns message error (like decoding errors or some other)
+	// In this case Body contains raw []byte from broker
 	Error() error
-	// SetError set event processing error
-	SetError(err error)
 }
 
-// Message is used to transfer data
-type Message struct {
+// RawMessage is used to transfer data
+type RawMessage struct {
 	// Header contains message metadata
 	Header metadata.Metadata
 	// Body contains message body
@@ -95,8 +69,8 @@ type Message struct {
 }
 
 // NewMessage create broker message with topic filled
-func NewMessage(topic string) *Message {
-	m := &Message{Header: metadata.New(2)}
+func NewRawMessage(topic string) *RawMessage {
+	m := &RawMessage{Header: metadata.New(2)}
 	m.Header.Set(metadata.HeaderTopic, topic)
 	return m
 }