Updated codec interface and code. Painful stuff

codec/codec.go

@@ -1,12 +1,47 @@
 package codec
 
-// Codec used to encode and decode request/responses
+import (
+	"io"
+)
+
+const (
+	Error MessageType = iota
+	Request
+	Response
+	Publication
+)
+
+type MessageType int
+
+// Takes in a connection/buffer and returns a new Codec
+type NewCodec func(io.ReadWriteCloser) Codec
+
+// Codec encodes/decodes various types of
+// messages used within go-micro
 type Codec interface {
-	// Marshal returns the wire format of v.
-	Marshal(v interface{}) ([]byte, error)
-	// Unmarshal parses the wire format into v.
-	Unmarshal(data []byte, v interface{}) error
-	// String returns the name of the Codec implementation. The returned
-	// string will be used as part of content type in transmission.
+	Encoder
+	Decoder
+	Close() error
 	String() string
 }
+
+type Encoder interface {
+	Write(*Message, interface{}) error
+}
+
+type Decoder interface {
+	ReadHeader(*Message, MessageType) error
+	ReadBody(interface{}) error
+}
+
+// Message represents detailed information about
+// the communication, likely followed by the body.
+// In the case of an error, body may be nil.
+type Message struct {
+	Id      uint64
+	Type    MessageType
+	Target  string
+	Method  string
+	Error   string
+	Headers map[string]string
+}