restructured eth rpc API

rpc/codec/codec.go

@@ -0,0 +1,47 @@
+package codec
+
+import (
+	"net"
+	"strconv"
+
+	"github.com/ethereum/go-ethereum/rpc/shared"
+)
+
+type Codec int
+
+// (de)serialization support for rpc interface
+type ApiCoder interface {
+	// Parse message to request from underlying stream
+	ReadRequest() (*shared.Request, error)
+	// Parse response message from underlying stream
+	ReadResponse() (interface{}, error)
+	// Encode response to encoded form in underlying stream
+	WriteResponse(interface{}) error
+	// Decode single message from data
+	Decode([]byte, interface{}) error
+	// Encode msg to encoded form
+	Encode(msg interface{}) ([]byte, error)
+	// close the underlying stream
+	Close()
+}
+
+// supported codecs
+const (
+	JSON Codec = iota
+	nCodecs
+)
+
+var (
+	// collection with supported coders
+	coders = make([]func(net.Conn) ApiCoder, nCodecs)
+)
+
+// create a new coder instance
+func (c Codec) New(conn net.Conn) ApiCoder {
+	switch c {
+	case JSON:
+		return NewJsonCoder(conn)
+	}
+
+	panic("codec: request for codec #" + strconv.Itoa(int(c)) + " is unavailable")
+}