Add pluggable codec support

client/options.go

@@ -7,9 +7,11 @@ import (
 )
 
 type options struct {
-	broker    broker.Broker
-	registry  registry.Registry
-	transport transport.Transport
+	contentType string
+	codecs      map[string]CodecFunc
+	broker      broker.Broker
+	registry    registry.Registry
+	transport   transport.Transport
 }
 
 func Broker(b broker.Broker) Option {
@@ -18,6 +20,18 @@ func Broker(b broker.Broker) Option {
 	}
 }
 
+func Codec(contentType string, cf CodecFunc) Option {
+	return func(o *options) {
+		o.codecs[contentType] = cf
+	}
+}
+
+func ContentType(ct string) Option {
+	return func(o *options) {
+		o.contentType = ct
+	}
+}
+
 func Registry(r registry.Registry) Option {
 	return func(o *options) {
 		o.registry = r