Add configurable codecs for broker/transport

broker/broker.go

@@ -31,12 +31,22 @@ type Publication interface {
 	Ack() error
 }
 
+// Subscriber is a convenience return type for the Subscribe method
 type Subscriber interface {
 	Options() SubscribeOptions
 	Topic() string
 	Unsubscribe() error
 }
 
+// Codec is used for encoding where the broker doesn't natively support
+// headers in the message type. In this case the entire message is
+// encoded as the payload
+type Codec interface {
+	Marshal(interface{}) ([]byte, error)
+	Unmarshal([]byte, interface{}) error
+	String() string
+}
+
 var (
 	DefaultBroker Broker = newHttpBroker()
 )

broker/codec.go

@@ -0,0 +1,19 @@
+package broker
+
+import (
+	"encoding/json"
+)
+
+type jsonCodec struct{}
+
+func (j jsonCodec) Marshal(v interface{}) ([]byte, error) {
+	return json.Marshal(v)
+}
+
+func (j jsonCodec) Unmarshal(d []byte, v interface{}) error {
+	return json.Unmarshal(d, v)
+}
+
+func (j jsonCodec) String() string {
+	return "json"
+}

broker/codec/json/json.go

@@ -0,0 +1,25 @@
+package json
+
+import (
+	"encoding/json"
+
+	"github.com/micro/go-micro/broker"
+)
+
+type jsonCodec struct{}
+
+func (j jsonCodec) Marshal(v interface{}) ([]byte, error) {
+	return json.Marshal(v)
+}
+
+func (j jsonCodec) Unmarshal(d []byte, v interface{}) error {
+	return json.Unmarshal(d, v)
+}
+
+func (j jsonCodec) String() string {
+	return "json"
+}
+
+func NewCodec() broker.Codec {
+	return jsonCodec{}
+}

broker/codec/noop/noop.go

@@ -0,0 +1,34 @@
+package noop
+
+import (
+	"errors"
+
+	"github.com/micro/go-micro/broker"
+)
+
+type noopCodec struct{}
+
+func (n noopCodec) Marshal(v interface{}) ([]byte, error) {
+	msg, ok := v.(*broker.Message)
+	if !ok {
+		return nil, errors.New("invalid message")
+	}
+	return msg.Body, nil
+}
+
+func (n noopCodec) Unmarshal(d []byte, v interface{}) error {
+	msg, ok := v.(*broker.Message)
+	if !ok {
+		return errors.New("invalid message")
+	}
+	msg.Body = d
+	return nil
+}
+
+func (n noopCodec) String() string {
+	return "noop"
+}
+
+func NewCodec() broker.Codec {
+	return noopCodec{}
+}

broker/http_broker.go

@@ -3,7 +3,6 @@ package broker
 import (
 	"bytes"
 	"crypto/tls"
-	"encoding/json"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -96,6 +95,7 @@ func newTransport(config *tls.Config) *http.Transport {
 
 func newHttpBroker(opts ...Option) Broker {
 	options := Options{
+		Codec:   jsonCodec{},
 		Context: context.TODO(),
 	}
 
@@ -269,7 +269,7 @@ func (h *httpBroker) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	}
 
 	var m *Message
-	if err = json.Unmarshal(b, &m); err != nil {
+	if err = h.opts.Codec.Unmarshal(b, &m); err != nil {
 		errr := errors.InternalServerError("go.micro.broker", fmt.Sprintf("Error parsing request body: %v", err))
 		w.WriteHeader(500)
 		w.Write([]byte(errr.Error()))
@@ -352,7 +352,7 @@ func (h *httpBroker) Publish(topic string, msg *Message, opts ...PublishOption)
 
 	m.Header[":topic"] = topic
 
-	b, err := json.Marshal(m)
+	b, err := h.opts.Codec.Marshal(m)
 	if err != nil {
 		return err
 	}

broker/options.go

@@ -10,6 +10,7 @@ import (
 type Options struct {
 	Addrs     []string
 	Secure    bool
+	Codec     Codec
 	TLSConfig *tls.Config
 
 	// Other options for implementations of the interface
@@ -96,6 +97,14 @@ func Secure(b bool) Option {
 	}
 }
 
+// Codec sets the codec used for encoding/decoding used where
+// a broker does not support headers
+func SetCodec(c Codec) Option {
+	return func(o *Options) {
+		o.Codec = c
+	}
+}
+
 // Specify TLS Config
 func TLSConfig(t *tls.Config) Option {
 	return func(o *Options) {