Further consolidate the libraries

server/grpc/README.md

@@ -0,0 +1,30 @@
+# GRPC Server
+
+The grpc server is a [micro.Server](https://godoc.org/github.com/micro/go-micro/server#Server) compatible server.
+
+## Overview
+
+The server makes use of the [google.golang.org/grpc](google.golang.org/grpc) framework for the underlying server 
+but continues to use micro handler signatures and protoc-gen-micro generated code.
+
+## Usage
+
+Specify the server to your micro service
+
+```go
+import (
+        "github.com/micro/go-micro"
+        "github.com/micro/go-plugins/server/grpc"
+)
+
+func main() {
+        service := micro.NewService(
+                // This needs to be first as it replaces the underlying server
+                // which causes any configuration set before it
+                // to be discarded
+                micro.Server(grpc.NewServer()),
+                micro.Name("greeter"),
+        )
+}
+```
+**NOTE**: Setting the gRPC server and/or client causes the underlying the server/client to be replaced which causes any previous configuration set on that server/client to be discarded. It is therefore recommended to set gRPC server/client before any other configuration

server/grpc/buffer.go

@@ -0,0 +1,14 @@
+package grpc
+
+import (
+	"bytes"
+)
+
+type buffer struct {
+	*bytes.Buffer
+}
+
+func (b *buffer) Close() error {
+	b.Buffer.Reset()
+	return nil
+}

server/grpc/codec.go

@@ -0,0 +1,82 @@
+package grpc
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/micro/go-micro/codec"
+	"github.com/micro/go-micro/codec/jsonrpc"
+	"github.com/micro/go-micro/codec/protorpc"
+	"google.golang.org/grpc/encoding"
+)
+
+type jsonCodec struct{}
+type bytesCodec struct{}
+type protoCodec struct{}
+
+var (
+	defaultGRPCCodecs = map[string]encoding.Codec{
+		"application/json":         jsonCodec{},
+		"application/proto":        protoCodec{},
+		"application/protobuf":     protoCodec{},
+		"application/octet-stream": protoCodec{},
+		"application/grpc":         protoCodec{},
+		"application/grpc+json":    jsonCodec{},
+		"application/grpc+proto":   protoCodec{},
+		"application/grpc+bytes":   bytesCodec{},
+	}
+
+	defaultRPCCodecs = map[string]codec.NewCodec{
+		"application/json":         jsonrpc.NewCodec,
+		"application/json-rpc":     jsonrpc.NewCodec,
+		"application/protobuf":     protorpc.NewCodec,
+		"application/proto-rpc":    protorpc.NewCodec,
+		"application/octet-stream": protorpc.NewCodec,
+	}
+)
+
+func (protoCodec) Marshal(v interface{}) ([]byte, error) {
+	return proto.Marshal(v.(proto.Message))
+}
+
+func (protoCodec) Unmarshal(data []byte, v interface{}) error {
+	return proto.Unmarshal(data, v.(proto.Message))
+}
+
+func (protoCodec) Name() string {
+	return "proto"
+}
+
+func (jsonCodec) Marshal(v interface{}) ([]byte, error) {
+	return json.Marshal(v)
+}
+
+func (jsonCodec) Unmarshal(data []byte, v interface{}) error {
+	return json.Unmarshal(data, v)
+}
+
+func (jsonCodec) Name() string {
+	return "json"
+}
+
+func (bytesCodec) Marshal(v interface{}) ([]byte, error) {
+	b, ok := v.(*[]byte)
+	if !ok {
+		return nil, fmt.Errorf("failed to marshal: %v is not type of *[]byte", v)
+	}
+	return *b, nil
+}
+
+func (bytesCodec) Unmarshal(data []byte, v interface{}) error {
+	b, ok := v.(*[]byte)
+	if !ok {
+		return fmt.Errorf("failed to unmarshal: %v is not type of *[]byte", v)
+	}
+	*b = data
+	return nil
+}
+
+func (bytesCodec) Name() string {
+	return "bytes"
+}

server/grpc/debug.go

@@ -0,0 +1,15 @@
+package grpc
+
+import (
+	"github.com/micro/go-micro/server"
+	"github.com/micro/go-micro/server/debug"
+)
+
+// We use this to wrap any debug handlers so we preserve the signature Debug.{Method}
+type Debug struct {
+	debug.DebugHandler
+}
+
+func registerDebugHandler(s server.Server) {
+	s.Handle(s.NewHandler(&Debug{s.Options().DebugHandler}, server.InternalHandler(true)))
+}

server/grpc/error.go

@@ -0,0 +1,42 @@
+package grpc
+
+import (
+	"net/http"
+
+	"github.com/micro/go-micro/errors"
+	"google.golang.org/grpc/codes"
+)
+
+func microError(err *errors.Error) codes.Code {
+	switch err {
+	case nil:
+		return codes.OK
+	}
+
+	switch err.Code {
+	case http.StatusOK:
+		return codes.OK
+	case http.StatusBadRequest:
+		return codes.InvalidArgument
+	case http.StatusRequestTimeout:
+		return codes.DeadlineExceeded
+	case http.StatusNotFound:
+		return codes.NotFound
+	case http.StatusConflict:
+		return codes.AlreadyExists
+	case http.StatusForbidden:
+		return codes.PermissionDenied
+	case http.StatusUnauthorized:
+		return codes.Unauthenticated
+	case http.StatusPreconditionFailed:
+		return codes.FailedPrecondition
+	case http.StatusNotImplemented:
+		return codes.Unimplemented
+	case http.StatusInternalServerError:
+		return codes.Internal
+	case http.StatusServiceUnavailable:
+		return codes.Unavailable
+	}
+
+	return codes.Unknown
+}

server/grpc/extractor.go

@@ -0,0 +1,120 @@
+package grpc
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+
+	"github.com/micro/go-micro/registry"
+)
+
+func extractValue(v reflect.Type, d int) *registry.Value {
+	if d == 3 {
+		return nil
+	}
+	if v == nil {
+		return nil
+	}
+
+	if v.Kind() == reflect.Ptr {
+		v = v.Elem()
+	}
+
+	arg := &registry.Value{
+		Name: v.Name(),
+		Type: v.Name(),
+	}
+
+	switch v.Kind() {
+	case reflect.Struct:
+		for i := 0; i < v.NumField(); i++ {
+			f := v.Field(i)
+			val := extractValue(f.Type, d+1)
+			if val == nil {
+				continue
+			}
+
+			// if we can find a json tag use it
+			if tags := f.Tag.Get("json"); len(tags) > 0 {
+				parts := strings.Split(tags, ",")
+				if parts[0] == "-" || parts[0] == "omitempty" {
+					continue
+				}
+				val.Name = parts[0]
+			}
+
+			// if there's no name default it
+			if len(val.Name) == 0 {
+				val.Name = v.Field(i).Name
+			}
+
+			arg.Values = append(arg.Values, val)
+		}
+	case reflect.Slice:
+		p := v.Elem()
+		if p.Kind() == reflect.Ptr {
+			p = p.Elem()
+		}
+		arg.Type = "[]" + p.Name()
+		val := extractValue(v.Elem(), d+1)
+		if val != nil {
+			arg.Values = append(arg.Values, val)
+		}
+	}
+
+	return arg
+}
+
+func extractEndpoint(method reflect.Method) *registry.Endpoint {
+	if method.PkgPath != "" {
+		return nil
+	}
+
+	var rspType, reqType reflect.Type
+	var stream bool
+	mt := method.Type
+
+	switch mt.NumIn() {
+	case 3:
+		reqType = mt.In(1)
+		rspType = mt.In(2)
+	case 4:
+		reqType = mt.In(2)
+		rspType = mt.In(3)
+	default:
+		return nil
+	}
+
+	// are we dealing with a stream?
+	switch rspType.Kind() {
+	case reflect.Func, reflect.Interface:
+		stream = true
+	}
+
+	request := extractValue(reqType, 0)
+	response := extractValue(rspType, 0)
+
+	return &registry.Endpoint{
+		Name:     method.Name,
+		Request:  request,
+		Response: response,
+		Metadata: map[string]string{
+			"stream": fmt.Sprintf("%v", stream),
+		},
+	}
+}
+
+func extractSubValue(typ reflect.Type) *registry.Value {
+	var reqType reflect.Type
+	switch typ.NumIn() {
+	case 1:
+		reqType = typ.In(0)
+	case 2:
+		reqType = typ.In(1)
+	case 3:
+		reqType = typ.In(2)
+	default:
+		return nil
+	}
+	return extractValue(reqType, 0)
+}

server/grpc/extractor_test.go

@@ -0,0 +1,65 @@
+package grpc
+
+import (
+	"context"
+	"reflect"
+	"testing"
+
+	"github.com/micro/go-micro/registry"
+)
+
+type testHandler struct{}
+
+type testRequest struct{}
+
+type testResponse struct{}
+
+func (t *testHandler) Test(ctx context.Context, req *testRequest, rsp *testResponse) error {
+	return nil
+}
+
+func TestExtractEndpoint(t *testing.T) {
+	handler := &testHandler{}
+	typ := reflect.TypeOf(handler)
+
+	var endpoints []*registry.Endpoint
+
+	for m := 0; m < typ.NumMethod(); m++ {
+		if e := extractEndpoint(typ.Method(m)); e != nil {
+			endpoints = append(endpoints, e)
+		}
+	}
+
+	if i := len(endpoints); i != 1 {
+		t.Errorf("Expected 1 endpoint, have %d", i)
+	}
+
+	if endpoints[0].Name != "Test" {
+		t.Errorf("Expected handler Test, got %s", endpoints[0].Name)
+	}
+
+	if endpoints[0].Request == nil {
+		t.Error("Expected non nil request")
+	}
+
+	if endpoints[0].Response == nil {
+		t.Error("Expected non nil request")
+	}
+
+	if endpoints[0].Request.Name != "testRequest" {
+		t.Errorf("Expected testRequest got %s", endpoints[0].Request.Name)
+	}
+
+	if endpoints[0].Response.Name != "testResponse" {
+		t.Errorf("Expected testResponse got %s", endpoints[0].Response.Name)
+	}
+
+	if endpoints[0].Request.Type != "testRequest" {
+		t.Errorf("Expected testRequest type got %s", endpoints[0].Request.Type)
+	}
+
+	if endpoints[0].Response.Type != "testResponse" {
+		t.Errorf("Expected testResponse type got %s", endpoints[0].Response.Type)
+	}
+
+}

server/grpc/grpc.go

@@ -0,0 +1,731 @@
+// Package grpc provides a grpc server
+package grpc
+
+import (
+	"context"
+	"crypto/tls"
+	"fmt"
+	"net"
+	"reflect"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/micro/go-micro/broker"
+	"github.com/micro/go-micro/cmd"
+	"github.com/micro/go-micro/codec"
+	"github.com/micro/go-micro/errors"
+	meta "github.com/micro/go-micro/metadata"
+	"github.com/micro/go-micro/registry"
+	"github.com/micro/go-micro/server"
+	"github.com/micro/go-micro/util/addr"
+	mgrpc "github.com/micro/go-micro/util/grpc"
+	"github.com/micro/go-micro/util/log"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/encoding"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/status"
+)
+
+var (
+	// DefaultMaxMsgSize define maximum message size that server can send
+	// or receive.  Default value is 4MB.
+	DefaultMaxMsgSize = 1024 * 1024 * 4
+)
+
+const (
+	defaultContentType = "application/grpc"
+)
+
+type grpcServer struct {
+	rpc  *rServer
+	srv  *grpc.Server
+	exit chan chan error
+	wg   *sync.WaitGroup
+
+	sync.RWMutex
+	opts        server.Options
+	handlers    map[string]server.Handler
+	subscribers map[*subscriber][]broker.Subscriber
+	// used for first registration
+	registered bool
+}
+
+func init() {
+	encoding.RegisterCodec(jsonCodec{})
+	encoding.RegisterCodec(bytesCodec{})
+
+	cmd.DefaultServers["grpc"] = NewServer
+}
+
+func newGRPCServer(opts ...server.Option) server.Server {
+	options := newOptions(opts...)
+
+	// create a grpc server
+	srv := &grpcServer{
+		opts: options,
+		rpc: &rServer{
+			serviceMap: make(map[string]*service),
+		},
+		handlers:    make(map[string]server.Handler),
+		subscribers: make(map[*subscriber][]broker.Subscriber),
+		exit:        make(chan chan error),
+		wg:          wait(options.Context),
+	}
+
+	// configure the grpc server
+	srv.configure()
+
+	return srv
+}
+
+func (g *grpcServer) configure(opts ...server.Option) {
+	// Don't reprocess where there's no config
+	if len(opts) == 0 && g.srv != nil {
+		return
+	}
+
+	for _, o := range opts {
+		o(&g.opts)
+	}
+
+	maxMsgSize := g.getMaxMsgSize()
+
+	gopts := []grpc.ServerOption{
+		grpc.MaxRecvMsgSize(maxMsgSize),
+		grpc.MaxSendMsgSize(maxMsgSize),
+		grpc.UnknownServiceHandler(g.handler),
+	}
+
+	if creds := g.getCredentials(); creds != nil {
+		gopts = append(gopts, grpc.Creds(creds))
+	}
+
+	if opts := g.getGrpcOptions(); opts != nil {
+		gopts = append(gopts, opts...)
+	}
+
+	g.srv = grpc.NewServer(gopts...)
+}
+
+func (g *grpcServer) getMaxMsgSize() int {
+	if g.opts.Context == nil {
+		return DefaultMaxMsgSize
+	}
+	s, ok := g.opts.Context.Value(maxMsgSizeKey{}).(int)
+	if !ok {
+		return DefaultMaxMsgSize
+	}
+	return s
+}
+
+func (g *grpcServer) getCredentials() credentials.TransportCredentials {
+	if g.opts.Context != nil {
+		if v := g.opts.Context.Value(tlsAuth{}); v != nil {
+			tls := v.(*tls.Config)
+			return credentials.NewTLS(tls)
+		}
+	}
+	return nil
+}
+
+func (g *grpcServer) getGrpcOptions() []grpc.ServerOption {
+	if g.opts.Context == nil {
+		return nil
+	}
+
+	v := g.opts.Context.Value(grpcOptions{})
+
+	if v == nil {
+		return nil
+	}
+
+	opts, ok := v.([]grpc.ServerOption)
+
+	if !ok {
+		return nil
+	}
+
+	return opts
+}
+
+func (g *grpcServer) handler(srv interface{}, stream grpc.ServerStream) error {
+	if g.wg != nil {
+		g.wg.Add(1)
+		defer g.wg.Done()
+	}
+
+	fullMethod, ok := grpc.MethodFromServerStream(stream)
+	if !ok {
+		return grpc.Errorf(codes.Internal, "method does not exist in context")
+	}
+
+	serviceName, methodName, err := mgrpc.ServiceMethod(fullMethod)
+	if err != nil {
+		return status.New(codes.InvalidArgument, err.Error()).Err()
+	}
+
+	g.rpc.mu.Lock()
+	service := g.rpc.serviceMap[serviceName]
+	g.rpc.mu.Unlock()
+
+	if service == nil {
+		return status.New(codes.Unimplemented, fmt.Sprintf("unknown service %v", service)).Err()
+	}
+
+	mtype := service.method[methodName]
+	if mtype == nil {
+		return status.New(codes.Unimplemented, fmt.Sprintf("unknown service %v", service)).Err()
+	}
+
+	// get grpc metadata
+	gmd, ok := metadata.FromIncomingContext(stream.Context())
+	if !ok {
+		gmd = metadata.MD{}
+	}
+
+	// copy the metadata to go-micro.metadata
+	md := meta.Metadata{}
+	for k, v := range gmd {
+		md[k] = strings.Join(v, ", ")
+	}
+
+	// timeout for server deadline
+	to := md["timeout"]
+
+	// get content type
+	ct := defaultContentType
+	if ctype, ok := md["x-content-type"]; ok {
+		ct = ctype
+	}
+
+	delete(md, "x-content-type")
+	delete(md, "timeout")
+
+	// create new context
+	ctx := meta.NewContext(stream.Context(), md)
+
+	// set the timeout if we have it
+	if len(to) > 0 {
+		if n, err := strconv.ParseUint(to, 10, 64); err == nil {
+			ctx, _ = context.WithTimeout(ctx, time.Duration(n))
+		}
+	}
+
+	// process unary
+	if !mtype.stream {
+		return g.processRequest(stream, service, mtype, ct, ctx)
+	}
+
+	// process stream
+	return g.processStream(stream, service, mtype, ct, ctx)
+}
+
+func (g *grpcServer) processRequest(stream grpc.ServerStream, service *service, mtype *methodType, ct string, ctx context.Context) error {
+	for {
+		var argv, replyv reflect.Value
+
+		// Decode the argument value.
+		argIsValue := false // if true, need to indirect before calling.
+		if mtype.ArgType.Kind() == reflect.Ptr {
+			argv = reflect.New(mtype.ArgType.Elem())
+		} else {
+			argv = reflect.New(mtype.ArgType)
+			argIsValue = true
+		}
+
+		// Unmarshal request
+		if err := stream.RecvMsg(argv.Interface()); err != nil {
+			return err
+		}
+
+		if argIsValue {
+			argv = argv.Elem()
+		}
+
+		// reply value
+		replyv = reflect.New(mtype.ReplyType.Elem())
+
+		function := mtype.method.Func
+		var returnValues []reflect.Value
+
+		cc, err := g.newGRPCCodec(ct)
+		if err != nil {
+			return errors.InternalServerError("go.micro.server", err.Error())
+		}
+		b, err := cc.Marshal(argv.Interface())
+		if err != nil {
+			return err
+		}
+
+		// create a client.Request
+		r := &rpcRequest{
+			service:     g.opts.Name,
+			contentType: ct,
+			method:      fmt.Sprintf("%s.%s", service.name, mtype.method.Name),
+			body:        b,
+			payload:     argv.Interface(),
+		}
+
+		// define the handler func
+		fn := func(ctx context.Context, req server.Request, rsp interface{}) error {
+			returnValues = function.Call([]reflect.Value{service.rcvr, mtype.prepareContext(ctx), reflect.ValueOf(argv.Interface()), reflect.ValueOf(rsp)})
+
+			// The return value for the method is an error.
+			if err := returnValues[0].Interface(); err != nil {
+				return err.(error)
+			}
+
+			return nil
+		}
+
+		// wrap the handler func
+		for i := len(g.opts.HdlrWrappers); i > 0; i-- {
+			fn = g.opts.HdlrWrappers[i-1](fn)
+		}
+
+		statusCode := codes.OK
+		statusDesc := ""
+
+		// execute the handler
+		if appErr := fn(ctx, r, replyv.Interface()); appErr != nil {
+			if err, ok := appErr.(*rpcError); ok {
+				statusCode = err.code
+				statusDesc = err.desc
+			} else if err, ok := appErr.(*errors.Error); ok {
+				statusCode = microError(err)
+				statusDesc = appErr.Error()
+			} else {
+				statusCode = convertCode(appErr)
+				statusDesc = appErr.Error()
+			}
+			return status.New(statusCode, statusDesc).Err()
+		}
+		if err := stream.SendMsg(replyv.Interface()); err != nil {
+			return err
+		}
+		return status.New(statusCode, statusDesc).Err()
+	}
+}
+
+func (g *grpcServer) processStream(stream grpc.ServerStream, service *service, mtype *methodType, ct string, ctx context.Context) error {
+	opts := g.opts
+
+	r := &rpcRequest{
+		service:     opts.Name,
+		contentType: ct,
+		method:      fmt.Sprintf("%s.%s", service.name, mtype.method.Name),
+		stream:      true,
+	}
+
+	ss := &rpcStream{
+		request: r,
+		s:       stream,
+	}
+
+	function := mtype.method.Func
+	var returnValues []reflect.Value
+
+	// Invoke the method, providing a new value for the reply.
+	fn := func(ctx context.Context, req server.Request, stream interface{}) error {
+		returnValues = function.Call([]reflect.Value{service.rcvr, mtype.prepareContext(ctx), reflect.ValueOf(stream)})
+		if err := returnValues[0].Interface(); err != nil {
+			return err.(error)
+		}
+
+		return nil
+	}
+
+	for i := len(opts.HdlrWrappers); i > 0; i-- {
+		fn = opts.HdlrWrappers[i-1](fn)
+	}
+
+	statusCode := codes.OK
+	statusDesc := ""
+
+	appErr := fn(ctx, r, ss)
+	if appErr != nil {
+		if err, ok := appErr.(*rpcError); ok {
+			statusCode = err.code
+			statusDesc = err.desc
+		} else if err, ok := appErr.(*errors.Error); ok {
+			statusCode = microError(err)
+			statusDesc = appErr.Error()
+		} else {
+			statusCode = convertCode(appErr)
+			statusDesc = appErr.Error()
+		}
+	}
+
+	return status.New(statusCode, statusDesc).Err()
+}
+
+func (g *grpcServer) newGRPCCodec(contentType string) (encoding.Codec, error) {
+	codecs := make(map[string]encoding.Codec)
+	if g.opts.Context != nil {
+		if v := g.opts.Context.Value(codecsKey{}); v != nil {
+			codecs = v.(map[string]encoding.Codec)
+		}
+	}
+	if c, ok := codecs[contentType]; ok {
+		return c, nil
+	}
+	if c, ok := defaultGRPCCodecs[contentType]; ok {
+		return c, nil
+	}
+	return nil, fmt.Errorf("Unsupported Content-Type: %s", contentType)
+}
+
+func (g *grpcServer) newCodec(contentType string) (codec.NewCodec, error) {
+	if cf, ok := g.opts.Codecs[contentType]; ok {
+		return cf, nil
+	}
+	if cf, ok := defaultRPCCodecs[contentType]; ok {
+		return cf, nil
+	}
+	return nil, fmt.Errorf("Unsupported Content-Type: %s", contentType)
+}
+
+func (g *grpcServer) Options() server.Options {
+	opts := g.opts
+	return opts
+}
+
+func (g *grpcServer) Init(opts ...server.Option) error {
+	g.configure(opts...)
+	return nil
+}
+
+func (g *grpcServer) NewHandler(h interface{}, opts ...server.HandlerOption) server.Handler {
+	return newRpcHandler(h, opts...)
+}
+
+func (g *grpcServer) Handle(h server.Handler) error {
+	if err := g.rpc.register(h.Handler()); err != nil {
+		return err
+	}
+
+	g.handlers[h.Name()] = h
+	return nil
+}
+
+func (g *grpcServer) NewSubscriber(topic string, sb interface{}, opts ...server.SubscriberOption) server.Subscriber {
+	return newSubscriber(topic, sb, opts...)
+}
+
+func (g *grpcServer) Subscribe(sb server.Subscriber) error {
+	sub, ok := sb.(*subscriber)
+	if !ok {
+		return fmt.Errorf("invalid subscriber: expected *subscriber")
+	}
+	if len(sub.handlers) == 0 {
+		return fmt.Errorf("invalid subscriber: no handler functions")
+	}
+
+	if err := validateSubscriber(sb); err != nil {
+		return err
+	}
+
+	g.Lock()
+
+	_, ok = g.subscribers[sub]
+	if ok {
+		return fmt.Errorf("subscriber %v already exists", sub)
+	}
+	g.subscribers[sub] = nil
+	g.Unlock()
+	return nil
+}
+
+func (g *grpcServer) Register() error {
+	// parse address for host, port
+	config := g.opts
+	var advt, host string
+	var port int
+
+	// check the advertise address first
+	// if it exists then use it, otherwise
+	// use the address
+	if len(config.Advertise) > 0 {
+		advt = config.Advertise
+	} else {
+		advt = config.Address
+	}
+
+	parts := strings.Split(advt, ":")
+	if len(parts) > 1 {
+		host = strings.Join(parts[:len(parts)-1], ":")
+		port, _ = strconv.Atoi(parts[len(parts)-1])
+	} else {
+		host = parts[0]
+	}
+
+	addr, err := addr.Extract(host)
+	if err != nil {
+		return err
+	}
+
+	// register service
+	node := &registry.Node{
+		Id:       config.Name + "-" + config.Id,
+		Address:  addr,
+		Port:     port,
+		Metadata: config.Metadata,
+	}
+
+	node.Metadata["broker"] = config.Broker.String()
+	node.Metadata["registry"] = config.Registry.String()
+	node.Metadata["server"] = g.String()
+	node.Metadata["transport"] = g.String()
+	// node.Metadata["transport"] = config.Transport.String()
+
+	g.RLock()
+	// Maps are ordered randomly, sort the keys for consistency
+	var handlerList []string
+	for n, e := range g.handlers {
+		// Only advertise non internal handlers
+		if !e.Options().Internal {
+			handlerList = append(handlerList, n)
+		}
+	}
+	sort.Strings(handlerList)
+
+	var subscriberList []*subscriber
+	for e := range g.subscribers {
+		// Only advertise non internal subscribers
+		if !e.Options().Internal {
+			subscriberList = append(subscriberList, e)
+		}
+	}
+	sort.Slice(subscriberList, func(i, j int) bool {
+		return subscriberList[i].topic > subscriberList[j].topic
+	})
+
+	var endpoints []*registry.Endpoint
+	for _, n := range handlerList {
+		endpoints = append(endpoints, g.handlers[n].Endpoints()...)
+	}
+	for _, e := range subscriberList {
+		endpoints = append(endpoints, e.Endpoints()...)
+	}
+	g.RUnlock()
+
+	service := &registry.Service{
+		Name:      config.Name,
+		Version:   config.Version,
+		Nodes:     []*registry.Node{node},
+		Endpoints: endpoints,
+	}
+
+	g.Lock()
+	registered := g.registered
+	g.Unlock()
+
+	if !registered {
+		log.Logf("Registering node: %s", node.Id)
+	}
+
+	// create registry options
+	rOpts := []registry.RegisterOption{registry.RegisterTTL(config.RegisterTTL)}
+
+	if err := config.Registry.Register(service, rOpts...); err != nil {
+		return err
+	}
+
+	// already registered? don't need to register subscribers
+	if registered {
+		return nil
+	}
+
+	g.Lock()
+	defer g.Unlock()
+
+	g.registered = true
+
+	for sb, _ := range g.subscribers {
+		handler := g.createSubHandler(sb, g.opts)
+		var opts []broker.SubscribeOption
+		if queue := sb.Options().Queue; len(queue) > 0 {
+			opts = append(opts, broker.Queue(queue))
+		}
+
+		if !sb.Options().AutoAck {
+			opts = append(opts, broker.DisableAutoAck())
+		}
+
+		sub, err := config.Broker.Subscribe(sb.Topic(), handler, opts...)
+		if err != nil {
+			return err
+		}
+		g.subscribers[sb] = []broker.Subscriber{sub}
+	}
+
+	return nil
+}
+
+func (g *grpcServer) Deregister() error {
+	config := g.opts
+	var advt, host string
+	var port int
+
+	// check the advertise address first
+	// if it exists then use it, otherwise
+	// use the address
+	if len(config.Advertise) > 0 {
+		advt = config.Advertise
+	} else {
+		advt = config.Address
+	}
+
+	parts := strings.Split(advt, ":")
+	if len(parts) > 1 {
+		host = strings.Join(parts[:len(parts)-1], ":")
+		port, _ = strconv.Atoi(parts[len(parts)-1])
+	} else {
+		host = parts[0]
+	}
+
+	addr, err := addr.Extract(host)
+	if err != nil {
+		return err
+	}
+
+	node := &registry.Node{
+		Id:      config.Name + "-" + config.Id,
+		Address: addr,
+		Port:    port,
+	}
+
+	service := &registry.Service{
+		Name:    config.Name,
+		Version: config.Version,
+		Nodes:   []*registry.Node{node},
+	}
+
+	log.Logf("Deregistering node: %s", node.Id)
+	if err := config.Registry.Deregister(service); err != nil {
+		return err
+	}
+
+	g.Lock()
+
+	if !g.registered {
+		g.Unlock()
+		return nil
+	}
+
+	g.registered = false
+
+	for sb, subs := range g.subscribers {
+		for _, sub := range subs {
+			log.Logf("Unsubscribing from topic: %s", sub.Topic())
+			sub.Unsubscribe()
+		}
+		g.subscribers[sb] = nil
+	}
+
+	g.Unlock()
+	return nil
+}
+
+func (g *grpcServer) Start() error {
+	registerDebugHandler(g)
+	config := g.opts
+
+	// micro: config.Transport.Listen(config.Address)
+	ts, err := net.Listen("tcp", config.Address)
+	if err != nil {
+		return err
+	}
+
+	log.Logf("Server [grpc] Listening on %s", ts.Addr().String())
+	g.Lock()
+	g.opts.Address = ts.Addr().String()
+	g.Unlock()
+
+	// connect to the broker
+	if err := config.Broker.Connect(); err != nil {
+		return err
+	}
+
+	log.Logf("Broker [%s] Listening on %s", config.Broker.String(), config.Broker.Address())
+
+	// announce self to the world
+	if err := g.Register(); err != nil {
+		log.Log("Server register error: ", err)
+	}
+
+	// micro: go ts.Accept(s.accept)
+	go func() {
+		if err := g.srv.Serve(ts); err != nil {
+			log.Log("gRPC Server start error: ", err)
+		}
+	}()
+
+	go func() {
+		t := new(time.Ticker)
+
+		// only process if it exists
+		if g.opts.RegisterInterval > time.Duration(0) {
+			// new ticker
+			t = time.NewTicker(g.opts.RegisterInterval)
+		}
+
+		// return error chan
+		var ch chan error
+
+	Loop:
+		for {
+			select {
+			// register self on interval
+			case <-t.C:
+				if err := g.Register(); err != nil {
+					log.Log("Server register error: ", err)
+				}
+			// wait for exit
+			case ch = <-g.exit:
+				break Loop
+			}
+		}
+
+		// deregister self
+		if err := g.Deregister(); err != nil {
+			log.Log("Server deregister error: ", err)
+		}
+
+		// wait for waitgroup
+		if g.wg != nil {
+			g.wg.Wait()
+		}
+
+		// stop the grpc server
+		g.srv.GracefulStop()
+
+		// close transport
+		ch <- nil
+
+		// disconnect broker
+		config.Broker.Disconnect()
+	}()
+
+	return nil
+}
+
+func (g *grpcServer) Stop() error {
+	ch := make(chan error)
+	g.exit <- ch
+	return <-ch
+}
+
+func (g *grpcServer) String() string {
+	return "grpc"
+}
+
+func NewServer(opts ...server.Option) server.Server {
+	return newGRPCServer(opts...)
+}

server/grpc/grpc_test.go

@@ -0,0 +1,66 @@
+package grpc
+
+import (
+	"context"
+	"testing"
+
+	"github.com/micro/go-micro/registry/memory"
+	"github.com/micro/go-micro/server"
+	"google.golang.org/grpc"
+
+	pb "github.com/micro/examples/greeter/srv/proto/hello"
+)
+
+// server is used to implement helloworld.GreeterServer.
+type sayServer struct{}
+
+// SayHello implements helloworld.GreeterServer
+func (s *sayServer) Hello(ctx context.Context, req *pb.Request, rsp *pb.Response) error {
+	rsp.Msg = "Hello " + req.Name
+	return nil
+}
+
+func TestGRPCServer(t *testing.T) {
+	r := memory.NewRegistry()
+	s := NewServer(
+		server.Name("foo"),
+		server.Registry(r),
+	)
+
+	pb.RegisterSayHandler(s, &sayServer{})
+
+	if err := s.Start(); err != nil {
+		t.Fatalf("failed to start: %v", err)
+	}
+
+	// check registration
+	services, err := r.GetService("foo")
+	if err != nil || len(services) == 0 {
+		t.Fatalf("failed to get service: %v # %d", err, len(services))
+	}
+
+	defer func() {
+		if err := s.Stop(); err != nil {
+			t.Fatalf("failed to stop: %v", err)
+		}
+	}()
+
+	cc, err := grpc.Dial(s.Options().Address, grpc.WithInsecure())
+	if err != nil {
+		t.Fatalf("failed to dial server: %v", err)
+	}
+
+	testMethods := []string{"/helloworld.Say/Hello", "/greeter.helloworld.Say/Hello"}
+
+	for _, method := range testMethods {
+		rsp := pb.Response{}
+
+		if err := cc.Invoke(context.Background(), method, &pb.Request{Name: "John"}, &rsp); err != nil {
+			t.Fatalf("error calling server: %v", err)
+		}
+
+		if rsp.Msg != "Hello John" {
+			t.Fatalf("Got unexpected response %v", rsp.Msg)
+		}
+	}
+}

server/grpc/handler.go

@@ -0,0 +1,66 @@
+package grpc
+
+import (
+	"reflect"
+
+	"github.com/micro/go-micro/registry"
+	"github.com/micro/go-micro/server"
+)
+
+type rpcHandler struct {
+	name      string
+	handler   interface{}
+	endpoints []*registry.Endpoint
+	opts      server.HandlerOptions
+}
+
+func newRpcHandler(handler interface{}, opts ...server.HandlerOption) server.Handler {
+	options := server.HandlerOptions{
+		Metadata: make(map[string]map[string]string),
+	}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	typ := reflect.TypeOf(handler)
+	hdlr := reflect.ValueOf(handler)
+	name := reflect.Indirect(hdlr).Type().Name()
+
+	var endpoints []*registry.Endpoint
+
+	for m := 0; m < typ.NumMethod(); m++ {
+		if e := extractEndpoint(typ.Method(m)); e != nil {
+			e.Name = name + "." + e.Name
+
+			for k, v := range options.Metadata[e.Name] {
+				e.Metadata[k] = v
+			}
+
+			endpoints = append(endpoints, e)
+		}
+	}
+
+	return &rpcHandler{
+		name:      name,
+		handler:   handler,
+		endpoints: endpoints,
+		opts:      options,
+	}
+}
+
+func (r *rpcHandler) Name() string {
+	return r.name
+}
+
+func (r *rpcHandler) Handler() interface{} {
+	return r.handler
+}
+
+func (r *rpcHandler) Endpoints() []*registry.Endpoint {
+	return r.endpoints
+}
+
+func (r *rpcHandler) Options() server.HandlerOptions {
+	return r.opts
+}

server/grpc/options.go

@@ -0,0 +1,113 @@
+package grpc
+
+import (
+	"context"
+	"crypto/tls"
+
+	"github.com/micro/go-micro/broker"
+	"github.com/micro/go-micro/codec"
+	"github.com/micro/go-micro/registry"
+	"github.com/micro/go-micro/server"
+	"github.com/micro/go-micro/server/debug"
+	"github.com/micro/go-micro/transport"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/encoding"
+)
+
+type codecsKey struct{}
+type tlsAuth struct{}
+type maxMsgSizeKey struct{}
+type grpcOptions struct{}
+
+// gRPC Codec to be used to encode/decode requests for a given content type
+func Codec(contentType string, c encoding.Codec) server.Option {
+	return func(o *server.Options) {
+		codecs := make(map[string]encoding.Codec)
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		if v := o.Context.Value(codecsKey{}); v != nil {
+			codecs = v.(map[string]encoding.Codec)
+		}
+		codecs[contentType] = c
+		o.Context = context.WithValue(o.Context, codecsKey{}, codecs)
+	}
+}
+
+// AuthTLS should be used to setup a secure authentication using TLS
+func AuthTLS(t *tls.Config) server.Option {
+	return func(o *server.Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, tlsAuth{}, t)
+	}
+}
+
+// Options to be used to configure gRPC options
+func Options(opts ...grpc.ServerOption) server.Option {
+	return func(o *server.Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, grpcOptions{}, opts)
+	}
+}
+
+//
+// MaxMsgSize set the maximum message in bytes the server can receive and
+// send.  Default maximum message size is 4 MB.
+//
+func MaxMsgSize(s int) server.Option {
+	return func(o *server.Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, maxMsgSizeKey{}, s)
+	}
+}
+
+func newOptions(opt ...server.Option) server.Options {
+	opts := server.Options{
+		Codecs:   make(map[string]codec.NewCodec),
+		Metadata: map[string]string{},
+	}
+
+	for _, o := range opt {
+		o(&opts)
+	}
+
+	if opts.Broker == nil {
+		opts.Broker = broker.DefaultBroker
+	}
+
+	if opts.Registry == nil {
+		opts.Registry = registry.DefaultRegistry
+	}
+
+	if opts.Transport == nil {
+		opts.Transport = transport.DefaultTransport
+	}
+
+	if opts.DebugHandler == nil {
+		opts.DebugHandler = debug.DefaultDebugHandler
+	}
+
+	if len(opts.Address) == 0 {
+		opts.Address = server.DefaultAddress
+	}
+
+	if len(opts.Name) == 0 {
+		opts.Name = server.DefaultName
+	}
+
+	if len(opts.Id) == 0 {
+		opts.Id = server.DefaultId
+	}
+
+	if len(opts.Version) == 0 {
+		opts.Version = server.DefaultVersion
+	}
+
+	return opts
+}

server/grpc/request.go

@@ -0,0 +1,70 @@
+package grpc
+
+import (
+	"github.com/micro/go-micro/codec"
+)
+
+type rpcRequest struct {
+	service     string
+	method      string
+	contentType string
+	codec       codec.Codec
+	header      map[string]string
+	body        []byte
+	stream      bool
+	payload     interface{}
+}
+
+type rpcMessage struct {
+	topic       string
+	contentType string
+	payload     interface{}
+}
+
+func (r *rpcRequest) ContentType() string {
+	return r.contentType
+}
+
+func (r *rpcRequest) Service() string {
+	return r.service
+}
+
+func (r *rpcRequest) Method() string {
+	return r.method
+}
+
+func (r *rpcRequest) Endpoint() string {
+	return r.method
+}
+
+func (r *rpcRequest) Codec() codec.Reader {
+	return r.codec
+}
+
+func (r *rpcRequest) Header() map[string]string {
+	return r.header
+}
+
+func (r *rpcRequest) Read() ([]byte, error) {
+	return r.body, nil
+}
+
+func (r *rpcRequest) Stream() bool {
+	return r.stream
+}
+
+func (r *rpcRequest) Body() interface{} {
+	return r.payload
+}
+
+func (r *rpcMessage) ContentType() string {
+	return r.contentType
+}
+
+func (r *rpcMessage) Topic() string {
+	return r.topic
+}
+
+func (r *rpcMessage) Payload() interface{} {
+	return r.payload
+}

server/grpc/server.go

@@ -0,0 +1,180 @@
+package grpc
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+//
+// Meh, we need to get rid of this shit
+
+import (
+	"context"
+	"errors"
+	"reflect"
+	"sync"
+	"unicode"
+	"unicode/utf8"
+
+	"github.com/micro/go-micro/server"
+	"github.com/micro/go-micro/util/log"
+)
+
+var (
+	// Precompute the reflect type for error. Can't use error directly
+	// because Typeof takes an empty interface value. This is annoying.
+	typeOfError = reflect.TypeOf((*error)(nil)).Elem()
+)
+
+type methodType struct {
+	method      reflect.Method
+	ArgType     reflect.Type
+	ReplyType   reflect.Type
+	ContextType reflect.Type
+	stream      bool
+}
+
+type service struct {
+	name   string                 // name of service
+	rcvr   reflect.Value          // receiver of methods for the service
+	typ    reflect.Type           // type of the receiver
+	method map[string]*methodType // registered methods
+}
+
+// server represents an RPC Server.
+type rServer struct {
+	mu         sync.Mutex // protects the serviceMap
+	serviceMap map[string]*service
+}
+
+// Is this an exported - upper case - name?
+func isExported(name string) bool {
+	rune, _ := utf8.DecodeRuneInString(name)
+	return unicode.IsUpper(rune)
+}
+
+// Is this type exported or a builtin?
+func isExportedOrBuiltinType(t reflect.Type) bool {
+	for t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+	// PkgPath will be non-empty even for an exported type,
+	// so we need to check the type name as well.
+	return isExported(t.Name()) || t.PkgPath() == ""
+}
+
+// prepareEndpoint() returns a methodType for the provided method or nil
+// in case if the method was unsuitable.
+func prepareEndpoint(method reflect.Method) *methodType {
+	mtype := method.Type
+	mname := method.Name
+	var replyType, argType, contextType reflect.Type
+	var stream bool
+
+	// Endpoint() must be exported.
+	if method.PkgPath != "" {
+		return nil
+	}
+
+	switch mtype.NumIn() {
+	case 3:
+		// assuming streaming
+		argType = mtype.In(2)
+		contextType = mtype.In(1)
+		stream = true
+	case 4:
+		// method that takes a context
+		argType = mtype.In(2)
+		replyType = mtype.In(3)
+		contextType = mtype.In(1)
+	default:
+		log.Log("method", mname, "of", mtype, "has wrong number of ins:", mtype.NumIn())
+		return nil
+	}
+
+	if stream {
+		// check stream type
+		streamType := reflect.TypeOf((*server.Stream)(nil)).Elem()
+		if !argType.Implements(streamType) {
+			log.Log(mname, "argument does not implement Streamer interface:", argType)
+			return nil
+		}
+	} else {
+		// if not stream check the replyType
+
+		// First arg need not be a pointer.
+		if !isExportedOrBuiltinType(argType) {
+			log.Log(mname, "argument type not exported:", argType)
+			return nil
+		}
+
+		if replyType.Kind() != reflect.Ptr {
+			log.Log("method", mname, "reply type not a pointer:", replyType)
+			return nil
+		}
+
+		// Reply type must be exported.
+		if !isExportedOrBuiltinType(replyType) {
+			log.Log("method", mname, "reply type not exported:", replyType)
+			return nil
+		}
+	}
+
+	// Endpoint() needs one out.
+	if mtype.NumOut() != 1 {
+		log.Log("method", mname, "has wrong number of outs:", mtype.NumOut())
+		return nil
+	}
+	// The return type of the method must be error.
+	if returnType := mtype.Out(0); returnType != typeOfError {
+		log.Log("method", mname, "returns", returnType.String(), "not error")
+		return nil
+	}
+	return &methodType{method: method, ArgType: argType, ReplyType: replyType, ContextType: contextType, stream: stream}
+}
+
+func (server *rServer) register(rcvr interface{}) error {
+	server.mu.Lock()
+	defer server.mu.Unlock()
+	if server.serviceMap == nil {
+		server.serviceMap = make(map[string]*service)
+	}
+	s := new(service)
+	s.typ = reflect.TypeOf(rcvr)
+	s.rcvr = reflect.ValueOf(rcvr)
+	sname := reflect.Indirect(s.rcvr).Type().Name()
+	if sname == "" {
+		log.Fatal("rpc: no service name for type", s.typ.String())
+	}
+	if !isExported(sname) {
+		s := "rpc Register: type " + sname + " is not exported"
+		log.Log(s)
+		return errors.New(s)
+	}
+	if _, present := server.serviceMap[sname]; present {
+		return errors.New("rpc: service already defined: " + sname)
+	}
+	s.name = sname
+	s.method = make(map[string]*methodType)
+
+	// Install the methods
+	for m := 0; m < s.typ.NumMethod(); m++ {
+		method := s.typ.Method(m)
+		if mt := prepareEndpoint(method); mt != nil {
+			s.method[method.Name] = mt
+		}
+	}
+
+	if len(s.method) == 0 {
+		s := "rpc Register: type " + sname + " has no exported methods of suitable type"
+		log.Log(s)
+		return errors.New(s)
+	}
+	server.serviceMap[s.name] = s
+	return nil
+}
+
+func (m *methodType) prepareContext(ctx context.Context) reflect.Value {
+	if contextv := reflect.ValueOf(ctx); contextv.IsValid() {
+		return contextv
+	}
+	return reflect.Zero(m.ContextType)
+}

server/grpc/stream.go

@@ -0,0 +1,38 @@
+package grpc
+
+import (
+	"context"
+
+	"github.com/micro/go-micro/server"
+	"google.golang.org/grpc"
+)
+
+// rpcStream implements a server side Stream.
+type rpcStream struct {
+	s       grpc.ServerStream
+	request server.Request
+}
+
+func (r *rpcStream) Close() error {
+	return nil
+}
+
+func (r *rpcStream) Error() error {
+	return nil
+}
+
+func (r *rpcStream) Request() server.Request {
+	return r.request
+}
+
+func (r *rpcStream) Context() context.Context {
+	return r.s.Context()
+}
+
+func (r *rpcStream) Send(m interface{}) error {
+	return r.s.SendMsg(m)
+}
+
+func (r *rpcStream) Recv(m interface{}) error {
+	return r.s.RecvMsg(m)
+}

server/grpc/subscriber.go

@@ -0,0 +1,262 @@
+package grpc
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"reflect"
+
+	"github.com/micro/go-micro/broker"
+	"github.com/micro/go-micro/codec"
+	"github.com/micro/go-micro/metadata"
+	"github.com/micro/go-micro/registry"
+	"github.com/micro/go-micro/server"
+)
+
+const (
+	subSig = "func(context.Context, interface{}) error"
+)
+
+type handler struct {
+	method  reflect.Value
+	reqType reflect.Type
+	ctxType reflect.Type
+}
+
+type subscriber struct {
+	topic      string
+	rcvr       reflect.Value
+	typ        reflect.Type
+	subscriber interface{}
+	handlers   []*handler
+	endpoints  []*registry.Endpoint
+	opts       server.SubscriberOptions
+}
+
+func newSubscriber(topic string, sub interface{}, opts ...server.SubscriberOption) server.Subscriber {
+
+	options := server.SubscriberOptions{
+		AutoAck: true,
+	}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	var endpoints []*registry.Endpoint
+	var handlers []*handler
+
+	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)
+
+		endpoints = append(endpoints, &registry.Endpoint{
+			Name:    "Func",
+			Request: extractSubValue(typ),
+			Metadata: map[string]string{
+				"topic":      topic,
+				"subscriber": "true",
+			},
+		})
+	} else {
+		hdlr := reflect.ValueOf(sub)
+		name := reflect.Indirect(hdlr).Type().Name()
+
+		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)
+
+			endpoints = append(endpoints, &registry.Endpoint{
+				Name:    name + "." + method.Name,
+				Request: extractSubValue(method.Type),
+				Metadata: map[string]string{
+					"topic":      topic,
+					"subscriber": "true",
+				},
+			})
+		}
+	}
+
+	return &subscriber{
+		rcvr:       reflect.ValueOf(sub),
+		typ:        reflect.TypeOf(sub),
+		topic:      topic,
+		subscriber: sub,
+		handlers:   handlers,
+		endpoints:  endpoints,
+		opts:       options,
+	}
+}
+
+func validateSubscriber(sub server.Subscriber) error {
+	typ := reflect.TypeOf(sub.Subscriber())
+	var argType reflect.Type
+
+	if typ.Kind() == reflect.Func {
+		name := "Func"
+		switch typ.NumIn() {
+		case 2:
+			argType = typ.In(1)
+		default:
+			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 outs: %v require signature %s",
+				name, typ.NumOut(), subSig)
+		}
+		if returnType := typ.Out(0); returnType != typeOfError {
+			return fmt.Errorf("subscriber %v returns %v not error", name, returnType.String())
+		}
+	} else {
+		hdlr := reflect.ValueOf(sub.Subscriber())
+		name := reflect.Indirect(hdlr).Type().Name()
+
+		for m := 0; m < typ.NumMethod(); m++ {
+			method := typ.Method(m)
+
+			switch method.Type.NumIn() {
+			case 3:
+				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(), subSig)
+			}
+
+			if !isExportedOrBuiltinType(argType) {
+				return fmt.Errorf("%v argument type not exported: %v", name, argType)
+			}
+			if method.Type.NumOut() != 1 {
+				return fmt.Errorf(
+					"subscriber %v.%v has wrong number of outs: %v require signature %s",
+					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())
+			}
+		}
+	}
+
+	return nil
+}
+
+func (g *grpcServer) createSubHandler(sb *subscriber, opts server.Options) broker.Handler {
+	return func(p broker.Publication) error {
+		msg := p.Message()
+		ct := msg.Header["Content-Type"]
+		cf, err := g.newCodec(ct)
+		if err != nil {
+			return err
+		}
+
+		hdr := make(map[string]string)
+		for k, v := range msg.Header {
+			hdr[k] = v
+		}
+		delete(hdr, "Content-Type")
+		ctx := metadata.NewContext(context.Background(), hdr)
+
+		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()
+			}
+
+			b := &buffer{bytes.NewBuffer(msg.Body)}
+			co := cf(b)
+			defer co.Close()
+
+			if err := co.ReadHeader(&codec.Message{}, codec.Publication); err != nil {
+				return err
+			}
+
+			if err := co.ReadBody(req.Interface()); err != nil {
+				return err
+			}
+
+			fn := func(ctx context.Context, msg server.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.Payload()))
+
+				returnValues := handler.method.Call(vals)
+				if err := returnValues[0].Interface(); err != nil {
+					return err.(error)
+				}
+				return nil
+			}
+
+			for i := len(opts.SubWrappers); i > 0; i-- {
+				fn = opts.SubWrappers[i-1](fn)
+			}
+
+			g.wg.Add(1)
+			go func() {
+				defer g.wg.Done()
+				fn(ctx, &rpcMessage{
+					topic:       sb.topic,
+					contentType: ct,
+					payload:     req.Interface(),
+				})
+			}()
+		}
+		return nil
+	}
+}
+
+func (s *subscriber) Topic() string {
+	return s.topic
+}
+
+func (s *subscriber) Subscriber() interface{} {
+	return s.subscriber
+}
+
+func (s *subscriber) Endpoints() []*registry.Endpoint {
+	return s.endpoints
+}
+
+func (s *subscriber) Options() server.SubscriberOptions {
+	return s.opts
+}

server/grpc/util.go

@@ -0,0 +1,60 @@
+package grpc
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os"
+	"sync"
+
+	"google.golang.org/grpc/codes"
+)
+
+// rpcError defines the status from an RPC.
+type rpcError struct {
+	code codes.Code
+	desc string
+}
+
+func (e *rpcError) Error() string {
+	return fmt.Sprintf("rpc error: code = %d desc = %s", e.code, e.desc)
+}
+
+// convertCode converts a standard Go error into its canonical code. Note that
+// this is only used to translate the error returned by the server applications.
+func convertCode(err error) codes.Code {
+	switch err {
+	case nil:
+		return codes.OK
+	case io.EOF:
+		return codes.OutOfRange
+	case io.ErrClosedPipe, io.ErrNoProgress, io.ErrShortBuffer, io.ErrShortWrite, io.ErrUnexpectedEOF:
+		return codes.FailedPrecondition
+	case os.ErrInvalid:
+		return codes.InvalidArgument
+	case context.Canceled:
+		return codes.Canceled
+	case context.DeadlineExceeded:
+		return codes.DeadlineExceeded
+	}
+	switch {
+	case os.IsExist(err):
+		return codes.AlreadyExists
+	case os.IsNotExist(err):
+		return codes.NotFound
+	case os.IsPermission(err):
+		return codes.PermissionDenied
+	}
+	return codes.Unknown
+}
+
+func wait(ctx context.Context) *sync.WaitGroup {
+	if ctx == nil {
+		return nil
+	}
+	wg, ok := ctx.Value("wait").(*sync.WaitGroup)
+	if !ok {
+		return nil
+	}
+	return wg
+}