Split encoding logic

Add encoding package to define encoding interface.
Update spdy package msgpack encoding to using new interface.

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

Author: dmcgowan

encoding/types.go

@@ -0,0 +1,78 @@
+package encoding
+
+import (
+	"io"
+	"reflect"
+
+	"github.com/docker/libchan"
+)
+
+// ChannelFactory represents an object which is able to create new
+// channels and streams. This interface is used by an encoder
+// create a channel or stream, copy the encoded type, and
+// encode the identifier.
+type ChannelFactory interface {
+	// CreateSender creates a new send channel and returns
+	// the identifier associated with the sender. This
+	// identifier can be used to get the Receiver on
+	// the receiving side by calling GetReceiver.
+	CreateSender() (libchan.Sender, uint64, error)
+
+	// CreateReceiver creates a new receive channel and
+	// returns the identifier associated with the receiver.
+	// This identifier can be used to get the Sender on
+	// the receiving side by calling GetSender.
+	CreateReceiver() (libchan.Receiver, uint64, error)
+
+	// CreateStream createsa  new byte stream and returns
+	// the identifier associate with the stream.  This
+	// identifier can be used to get the byte stream
+	// by calling GetStream on the receiving side.
+	CreateStream() (io.ReadWriteCloser, uint64, error)
+}
+
+// ChannelReceiver represents an object which is able to receive
+// new channels and streams and retrieve by an integer identifer.
+type ChannelReceiver interface {
+	// GetSender gets a remotely created sender referenced
+	// by the given identifier.
+	GetSender(uint64) (libchan.Sender, error)
+
+	// GetReceiver gets a remotely created receiver referenced
+	// by the given identifier.
+	GetReceiver(uint64) (libchan.Receiver, error)
+
+	// GetStream gets a remotely created byte stream
+	// referenced by the given identifier.
+	GetStream(uint64) (io.ReadWriteCloser, error)
+}
+
+// Encoder represents an object which can encode an interface
+// into data stream to be decoded. This Encoder must be able
+// to encode interfaces by converting to libchan channels and
+// streams and encoding the identifier.
+type Encoder interface {
+	Encode(v ...interface{}) error
+}
+
+// Decoder represents an object which can decode from a data
+// stream into an interface. The decoder must have support
+// for decoding stream and channel identifiers into a libchan
+// Sender or Receiver as well as io Readers and Writers.
+type Decoder interface {
+	Decode(v ...interface{}) error
+}
+
+// ChannelCodec represents a libchan codec capable of encoding
+// Go interfaces into data streams supporting libchan types as
+// well as decode into libchan supported interfaces. In addition
+// to encoding and decoding, the codec must provide a transit
+// type which is capable of copying a data stream in order to
+// delay decoding into an object until finally received.
+// The RawMessage must return an object similar to json.RawMessage
+// with the capability of decoding itself into an object.
+type ChannelCodec interface {
+	NewEncoder(io.Writer, ChannelFactory) Encoder
+	NewDecoder(io.Reader, ChannelReceiver, reflect.Type, reflect.Type, reflect.Type) Decoder
+	NewRawMessage() Decoder
+}