diff --git a/client/call.go b/client/call.go
new file mode 100644
index 0000000..167bb05
--- /dev/null
+++ b/client/call.go
@@ -0,0 +1,68 @@
+package client
+
+import (
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+var callStatePool sync.Pool
+var zeroTime time.Time
+
+type CallState struct {
+	ID       interface{}
+	Method   string
+	Args     interface{}
+	Result   interface{}
+	Error    error
+	DoneChan chan *CallState
+
+	canceled uint32
+}
+
+func (cs *CallState) done() {
+	select {
+	case cs.DoneChan <- cs:
+		// ok
+	default:
+		// We don't want to block here. It is the caller's responsibility to make
+		// sure the channel has enough buffer space. See comment in Go().
+		// if debugLog {
+		// 	log.Println("rpc: discarding Call reply due to insufficient Done chan capacity")
+		// }
+	}
+}
+
+// Cancel cancels async call.
+//
+// Canceled call isn't sent to the server unless it is already sent there.
+// Canceled call may successfully complete if it has been already sent
+// to the server before Cancel call.
+//
+// It is safe calling this function multiple times from concurrently
+// running goroutines.
+func (cs *CallState) Cancel() {
+	atomic.StoreUint32(&cs.canceled, 1)
+}
+
+func (cs *CallState) IsCanceled() bool {
+	return atomic.LoadUint32(&cs.canceled) != 0
+}
+
+func retainCallState() *CallState {
+	v := callStatePool.Get()
+	if v == nil {
+		return &CallState{}
+	}
+	return v.(*CallState)
+}
+
+func releaseCallState(cs *CallState) {
+	cs.Method = ""
+	cs.Args = nil
+	cs.Result = nil
+	cs.Error = nil
+	cs.DoneChan = nil
+
+	callStatePool.Put(cs)
+}
diff --git a/client/client.go b/client/client.go
new file mode 100644
index 0000000..4a4d77f
--- /dev/null
+++ b/client/client.go
@@ -0,0 +1,339 @@
+package client
+
+import (
+	"fmt"
+	"io"
+	"runtime"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"git.loafle.net/commons_go/rpc/protocol"
+)
+
+func New(ch ClientHandler) Client {
+	c := &client{
+		ch: ch,
+	}
+	return c
+}
+
+type Client interface {
+	Start(rwc io.ReadWriteCloser)
+	Stop()
+	Notify(method string, args interface{}) error
+	Call(method string, args interface{}, result interface{}) error
+	CallTimeout(method string, args interface{}, result interface{}, timeout time.Duration) error
+}
+
+type client struct {
+	ch ClientHandler
+
+	rwc io.ReadWriteCloser
+
+	pendingRequestsCount uint32
+
+	requestQueueChan chan *CallState
+
+	stopChan chan struct{}
+	stopWg   sync.WaitGroup
+}
+
+func (c *client) Start(rwc io.ReadWriteCloser) {
+	c.ch.Validate()
+
+	if nil == rwc {
+		panic("RWC(io.ReadWriteCloser) must be specified.")
+	}
+
+	if c.stopChan != nil {
+		panic("Client: the given client is already started. Call Client.Stop() before calling Client.Start() again!")
+	}
+
+	c.rwc = rwc
+	c.stopChan = make(chan struct{})
+	c.requestQueueChan = make(chan *CallState, c.ch.GetPendingRequests())
+
+	c.stopWg.Add(1)
+	go handleRPC(c)
+}
+
+func (c *client) Stop() {
+	if c.stopChan == nil {
+		panic("Client: the client must be started before stopping it")
+	}
+	close(c.stopChan)
+	c.stopWg.Wait()
+	c.stopChan = nil
+}
+
+func (c *client) Notify(method string, args interface{}) error {
+	_, err := c.send(method, args, nil, false, true)
+	return err
+}
+
+func (c *client) Call(method string, args interface{}, result interface{}) error {
+	return c.CallTimeout(method, args, result, c.ch.GetRequestTimeout())
+}
+
+func (c *client) CallTimeout(method string, args interface{}, result interface{}, timeout time.Duration) (err error) {
+	var cs *CallState
+	if cs, err = c.send(method, args, result, true, true); nil != err {
+		return
+	}
+
+	t := retainTimer(timeout)
+
+	select {
+	case <-cs.DoneChan:
+		result, err = cs.Result, cs.Error
+		releaseCallState(cs)
+	case <-t.C:
+		cs.Cancel()
+		err = getClientTimeoutError(c, timeout)
+	}
+
+	releaseTimer(t)
+
+	return nil
+}
+
+func (c *client) send(method string, args interface{}, result interface{}, hasResponse bool, usePool bool) (cs *CallState, err error) {
+	if !hasResponse {
+		usePool = true
+	}
+
+	if usePool {
+		cs = retainCallState()
+	} else {
+		cs = &CallState{}
+	}
+
+	cs.Method = method
+	cs.Args = args
+
+	if hasResponse {
+		cs.ID = c.ch.GetRequestID()
+		cs.Result = result
+		cs.DoneChan = make(chan *CallState, 1)
+	}
+
+	select {
+	case c.requestQueueChan <- cs:
+		return cs, nil
+	default:
+		// Try substituting the oldest async request by the new one
+		// on requests' queue overflow.
+		// This increases the chances for new request to succeed
+		// without timeout.
+		if !hasResponse {
+			// Immediately notify the caller not interested
+			// in the response on requests' queue overflow, since
+			// there are no other ways to notify it later.
+			releaseCallState(cs)
+			return nil, getClientOverflowError(c)
+		}
+
+		select {
+		case rcs := <-c.requestQueueChan:
+			if rcs.DoneChan != nil {
+				rcs.Error = getClientOverflowError(c)
+				//close(rcs.DoneChan)
+				rcs.done()
+			} else {
+				releaseCallState(rcs)
+			}
+		default:
+		}
+
+		select {
+		case c.requestQueueChan <- cs:
+			return cs, nil
+		default:
+			// Release m even if usePool = true, since m wasn't exposed
+			// to the caller yet.
+			releaseCallState(cs)
+			return nil, getClientOverflowError(c)
+		}
+	}
+}
+
+func handleRPC(c *client) {
+	defer c.stopWg.Done()
+
+	stopChan := make(chan struct{})
+
+	pendingRequests := make(map[interface{}]*CallState)
+	var pendingRequestsLock sync.Mutex
+
+	writerDone := make(chan error, 1)
+	go rpcWriter(c, pendingRequests, &pendingRequestsLock, stopChan, writerDone)
+
+	readerDone := make(chan error, 1)
+	go rpcReader(c, pendingRequests, &pendingRequestsLock, readerDone)
+
+	var err error
+
+	select {
+	case err = <-writerDone:
+		close(stopChan)
+		c.rwc.Close()
+		<-readerDone
+	case err = <-readerDone:
+		close(stopChan)
+		c.rwc.Close()
+		<-writerDone
+	case <-c.stopChan:
+		close(stopChan)
+		c.rwc.Close()
+		<-readerDone
+		<-writerDone
+	}
+
+	if err != nil {
+		//c.LogError("%s", err)
+		err = &ClientError{
+			Connection: true,
+			err:        err,
+		}
+	}
+
+}
+
+func rpcWriter(c *client, pendingRequests map[interface{}]*CallState, pendingRequestsLock *sync.Mutex, stopChan <-chan struct{}, writerDone chan<- error) {
+	var err error
+	defer func() {
+		writerDone <- err
+	}()
+
+	for {
+		var cs *CallState
+
+		select {
+		case cs = <-c.requestQueueChan:
+		default:
+			// Give the last chance for ready goroutines filling c.requestsChan :)
+			runtime.Gosched()
+
+			select {
+			case <-stopChan:
+				return
+			case cs = <-c.requestQueueChan:
+			}
+		}
+
+		if cs.IsCanceled() {
+			if nil != cs.DoneChan {
+				// cs.Error = ErrCanceled
+				// close(m.done)
+				cs.done()
+			} else {
+				releaseCallState(cs)
+			}
+			continue
+		}
+
+		if nil != cs.DoneChan {
+			pendingRequestsLock.Lock()
+			n := len(pendingRequests)
+			pendingRequests[cs.ID] = cs
+			pendingRequestsLock.Unlock()
+			atomic.AddUint32(&c.pendingRequestsCount, 1)
+
+			if n > 10*c.ch.GetPendingRequests() {
+				err = fmt.Errorf("Client: The server didn't return %d responses yet. Closing server connection in order to prevent client resource leaks", n)
+				return
+			}
+		}
+
+		if nil == cs.DoneChan {
+			releaseCallState(cs)
+		}
+
+		if err = c.ch.GetCodec().Write(c.rwc, cs.Method, cs.Args, cs.ID); nil != err {
+			err = fmt.Errorf("Client: Cannot send request to wire: [%s]", err)
+			return
+		}
+	}
+}
+
+func rpcReader(c *client, pendingRequests map[interface{}]*CallState, pendingRequestsLock *sync.Mutex, readerDone chan<- error) {
+	var err error
+	defer func() {
+		if r := recover(); r != nil {
+			if err == nil {
+				err = fmt.Errorf("Client: Panic when reading data from server: %v", r)
+			}
+		}
+		readerDone <- err
+	}()
+
+	for {
+		crn, err := c.ch.GetCodec().NewResponseOrNotify(c.rwc)
+		if nil != err {
+			err = fmt.Errorf("Client: Cannot decode response or notify: [%s]", err)
+			return
+		}
+
+		if crn.IsResponse() {
+			err = responseHandle(c, crn.GetResponse(), pendingRequests, pendingRequestsLock)
+		} else {
+			err = notifyHandle(c, crn.GetNotify())
+		}
+		if nil != err {
+			return
+		}
+	}
+
+}
+
+func responseHandle(c *client, codecResponse protocol.ClientCodecResponse, pendingRequests map[interface{}]*CallState, pendingRequestsLock *sync.Mutex) error {
+	pendingRequestsLock.Lock()
+	cs, ok := pendingRequests[codecResponse.ID()]
+	if ok {
+		delete(pendingRequests, codecResponse.ID())
+	}
+	pendingRequestsLock.Unlock()
+
+	if !ok {
+		return fmt.Errorf("Client: Unexpected ID=[%v] obtained from server", codecResponse.ID())
+	}
+
+	atomic.AddUint32(&c.pendingRequestsCount, ^uint32(0))
+
+	cs.Result = codecResponse.Result()
+	if err := codecResponse.Error(); nil != err {
+		// cs.Error = &ClientError{
+		// 	Server: true,
+		// 	err:    fmt.Errorf("gorpc.Client: [%s]. Server error: [%s]", c.Addr, wr.Error),
+		// }
+	}
+
+	cs.done()
+
+	return nil
+}
+
+func notifyHandle(c *client, codecNotify protocol.ClientCodecNotify) error {
+	_, err := c.ch.GetRPCRegistry().Invoke(codecNotify)
+
+	return err
+}
+
+func getClientTimeoutError(c *client, timeout time.Duration) error {
+	err := fmt.Errorf("Client: Cannot obtain response during timeout=%s", timeout)
+	//c.LogError("%s", err)
+	return &ClientError{
+		Timeout: true,
+		err:     err,
+	}
+}
+
+func getClientOverflowError(c *client) error {
+	err := fmt.Errorf("Client: Requests' queue with size=%d is overflown. Try increasing Client.PendingRequests value", cap(c.requestQueueChan))
+	//c.LogError("%s", err)
+	return &ClientError{
+		Overflow: true,
+		err:      err,
+	}
+}
diff --git a/client/client_handler.go b/client/client_handler.go
new file mode 100644
index 0000000..49874b1
--- /dev/null
+++ b/client/client_handler.go
@@ -0,0 +1,25 @@
+package client
+
+import (
+	"time"
+
+	"git.loafle.net/commons_go/rpc"
+	"git.loafle.net/commons_go/rpc/protocol"
+)
+
+type ClientHandler interface {
+	OnStart()
+	OnStop()
+
+	GetContentType() string
+	GetCodec() protocol.ClientCodec
+	GetRPCRegistry() rpc.Registry
+	GetRequestTimeout() time.Duration
+	GetPendingRequests() int
+
+	GetRequestID() interface{}
+	Send()
+	Validate()
+
+	addWrite(cs *CallState)
+}
diff --git a/client/client_handlers.go b/client/client_handlers.go
new file mode 100644
index 0000000..e6dea91
--- /dev/null
+++ b/client/client_handlers.go
@@ -0,0 +1,80 @@
+package client
+
+import (
+	"sync"
+	"time"
+
+	"git.loafle.net/commons_go/rpc"
+	"git.loafle.net/commons_go/rpc/protocol"
+)
+
+type ClientHandlers struct {
+	ContentType string
+	Codec       protocol.ClientCodec
+	// Maximum request time.
+	// Default value is DefaultRequestTimeout.
+	RequestTimeout time.Duration
+	// The maximum number of pending requests in the queue.
+	//
+	// The number of pending requsts should exceed the expected number
+	// of concurrent goroutines calling client's methods.
+	// Otherwise a lot of ClientError.Overflow errors may appear.
+	//
+	// Default is DefaultPendingMessages.
+	PendingRequests int
+
+	RPCRegistry rpc.Registry
+
+	requestID    uint64
+	requestIDMtx sync.Mutex
+}
+
+func (ch *ClientHandlers) OnStart() {
+	// no op
+}
+
+func (ch *ClientHandlers) OnStop() {
+	// no op
+}
+
+func (ch *ClientHandlers) GetContentType() string {
+	return ch.ContentType
+}
+
+func (ch *ClientHandlers) GetCodec() protocol.ClientCodec {
+	return ch.Codec
+}
+
+func (ch *ClientHandlers) GetRPCRegistry() rpc.Registry {
+	return ch.RPCRegistry
+}
+
+func (ch *ClientHandlers) GetRequestTimeout() time.Duration {
+	return ch.RequestTimeout
+}
+
+func (ch *ClientHandlers) GetPendingRequests() int {
+	return ch.PendingRequests
+}
+
+func (ch *ClientHandlers) GetRequestID() interface{} {
+	var id uint64
+	ch.requestIDMtx.Lock()
+	ch.requestID++
+	id = ch.requestID
+	ch.requestIDMtx.Unlock()
+
+	return id
+}
+
+func (ch *ClientHandlers) Validate() {
+	if "" == ch.ContentType {
+		panic("ContentType must be specified.")
+	}
+	if ch.RequestTimeout <= 0 {
+		ch.RequestTimeout = DefaultRequestTimeout
+	}
+	if ch.PendingRequests <= 0 {
+		ch.PendingRequests = DefaultPendingMessages
+	}
+}
diff --git a/client/constants.go b/client/constants.go
new file mode 100644
index 0000000..a741697
--- /dev/null
+++ b/client/constants.go
@@ -0,0 +1,12 @@
+package client
+
+import "time"
+
+const (
+	// DefaultRequestTimeout is the default timeout for client request.
+	DefaultRequestTimeout = 20 * time.Second
+
+	// DefaultPendingMessages is the default number of pending messages
+	// handled by Client and Server.
+	DefaultPendingMessages = 32 * 1024
+)
diff --git a/client/error.go b/client/error.go
new file mode 100644
index 0000000..e10be8d
--- /dev/null
+++ b/client/error.go
@@ -0,0 +1,26 @@
+package client
+
+// ClientError is an error Client methods can return.
+type ClientError struct {
+	// Set if the error is timeout-related.
+	Timeout bool
+
+	// Set if the error is connection-related.
+	Connection bool
+
+	// Set if the error is server-related.
+	Server bool
+
+	// Set if the error is related to internal resources' overflow.
+	// Increase PendingRequests if you see a lot of such errors.
+	Overflow bool
+
+	// May be set if AsyncResult.Cancel is called.
+	Canceled bool
+
+	err error
+}
+
+func (e *ClientError) Error() string {
+	return e.err.Error()
+}
diff --git a/client/timer.go b/client/timer.go
new file mode 100644
index 0000000..9ad91b1
--- /dev/null
+++ b/client/timer.go
@@ -0,0 +1,34 @@
+package client
+
+import (
+	"sync"
+	"time"
+)
+
+var timerPool sync.Pool
+
+func retainTimer(timeout time.Duration) *time.Timer {
+	tv := timerPool.Get()
+	if tv == nil {
+		return time.NewTimer(timeout)
+	}
+
+	t := tv.(*time.Timer)
+	if t.Reset(timeout) {
+		panic("BUG: Active timer trapped into retainTimer()")
+	}
+	return t
+}
+
+func releaseTimer(t *time.Timer) {
+	if !t.Stop() {
+		// Collect possibly added time from the channel
+		// if timer has been stopped and nobody collected its' value.
+		select {
+		case <-t.C:
+		default:
+		}
+	}
+
+	timerPool.Put(t)
+}
diff --git a/encode/encode.go b/encode/encode.go
index e198fd6..544c99d 100644
--- a/encode/encode.go
+++ b/encode/encode.go
@@ -2,10 +2,11 @@ package encode
 
 import "io"
 
-// Encoder interface contains the encoder for http response.
+// Encoder interface contains the encoder for response.
 // Eg. gzip, flate compressions.
 type Encoder interface {
 	Encode(w io.Writer) io.Writer
+	Decode(r io.Reader) io.Reader
 }
 
 type encoder struct {
@@ -15,4 +16,8 @@ func (_ *encoder) Encode(w io.Writer) io.Writer {
 	return w
 }
 
+func (_ *encoder) Decode(r io.Reader) io.Reader {
+	return r
+}
+
 var DefaultEncoder = &encoder{}
diff --git a/encode/selector.go b/encode/selector.go
index 2c749b9..30f6c56 100644
--- a/encode/selector.go
+++ b/encode/selector.go
@@ -7,13 +7,18 @@ import "io"
 // figure out client capabilities.
 // Eg. "Accept-Encoding" tells about supported compressions.
 type EncoderSelector interface {
-	Select(r io.Reader) Encoder
+	SelectByReader(r io.Reader) Encoder
+	SelectByWriter(w io.Writer) Encoder
 }
 
 type encoderSelector struct {
 }
 
-func (_ *encoderSelector) Select(_ io.Reader) Encoder {
+func (_ *encoderSelector) SelectByReader(_ io.Reader) Encoder {
+	return DefaultEncoder
+}
+
+func (_ *encoderSelector) SelectByWriter(_ io.Writer) Encoder {
 	return DefaultEncoder
 }
 
diff --git a/protocol/client_codec.go b/protocol/client_codec.go
new file mode 100644
index 0000000..ecee9c5
--- /dev/null
+++ b/protocol/client_codec.go
@@ -0,0 +1,32 @@
+package protocol
+
+import (
+	"io"
+)
+
+// ClientCodec creates a ClientCodecRequest to process each request.
+type ClientCodec interface {
+	Write(w io.Writer, method string, args interface{}, id interface{}) error
+	NewResponseOrNotify(rc io.Reader) (ClientCodecResponseOrNotify, error)
+}
+
+// ClientCodecResponseOrNotify encodes a response or notify using a specific
+// serialization scheme.
+type ClientCodecResponseOrNotify interface {
+	IsResponse() bool
+	IsNotify() bool
+	GetResponse() ClientCodecResponse
+	GetNotify() ClientCodecNotify
+	Complete()
+}
+
+type ClientCodecResponse interface {
+	ID() interface{}
+	Result() interface{}
+	Error() error
+	Complete()
+}
+
+type ClientCodecNotify interface {
+	RegistryCodec
+}
diff --git a/protocol/codec.go b/protocol/codec.go
deleted file mode 100644
index 02f7642..0000000
--- a/protocol/codec.go
+++ /dev/null
@@ -1,29 +0,0 @@
-package protocol
-
-import (
-	"io"
-)
-
-// ----------------------------------------------------------------------------
-// Codec
-// ----------------------------------------------------------------------------
-
-// Codec creates a CodecRequest to process each request.
-type Codec interface {
-	// NewRequest is constructor of new request object
-	// error io.ErrUnexpectedEOF or io.EOF
-	NewRequest(rc io.Reader) (CodecRequest, error)
-}
-
-// CodecRequest decodes a request and encodes a response using a specific
-// serialization scheme.
-type CodecRequest interface {
-	// Reads the request and returns the RPC method name.
-	Method() (string, error)
-	// Reads the request filling the RPC method args.
-	ReadRequest(interface{}) error
-	// Writes the response using the RPC method reply.
-	WriteResponse(io.Writer, interface{}) error
-	// Writes an error produced by the server.
-	WriteError(w io.Writer, status int, err error) error
-}
diff --git a/protocol/json/client.go b/protocol/json/client.go
index 48af5d7..bce8333 100644
--- a/protocol/json/client.go
+++ b/protocol/json/client.go
@@ -2,8 +2,12 @@ package json
 
 import (
 	"encoding/json"
+	"fmt"
 	"io"
-	"math/rand"
+	"sync"
+
+	"git.loafle.net/commons_go/rpc/encode"
+	"git.loafle.net/commons_go/rpc/protocol"
 )
 
 // ----------------------------------------------------------------------------
@@ -23,58 +27,167 @@ type clientRequest struct {
 
 	// The request id. This can be of any type. It is used to match the
 	// response with the request that it is replying to.
-	ID uint64 `json:"id"`
+	ID interface{} `json:"id"`
 }
 
 // clientResponse represents a JSON-RPC response returned to a client.
 type clientResponse struct {
 	Version string           `json:"jsonrpc"`
 	Result  *json.RawMessage `json:"result"`
-	Error   *json.RawMessage `json:"error"`
+	Error   interface{}      `json:"error"`
+	ID      interface{}      `json:"id"`
 }
 
-// EncodeClientRequest encodes parameters for a JSON-RPC client request.
-func EncodeClientRequest(method string, args interface{}) ([]byte, error) {
-	c := &clientRequest{
-		Version: Version,
-		Method:  method,
-		Params:  args,
-		ID:      uint64(rand.Int63()),
-	}
-	return json.Marshal(c)
+// clientRequest represents a JSON-RPC request sent by a client.
+type clientNotify struct {
+	// JSON-RPC protocol.
+	Version string `json:"jsonrpc"`
+
+	// A String containing the name of the method to be invoked.
+	Method string `json:"method"`
+
+	// Object to pass as request parameter to the method.
+	Params *json.RawMessage `json:"params"`
 }
 
-// EncodeClientNotify encodes parameters for a JSON-RPC client notification.
-func EncodeClientNotify(method string, args interface{}) ([]byte, error) {
-	c := &clientRequest{
-		Version: Version,
-		Method:  method,
-		Params:  args,
-	}
-	return json.Marshal(c)
+// ----------------------------------------------------------------------------
+// Codec
+// ----------------------------------------------------------------------------
+
+// NewCustomClientCodec returns a new JSON Codec based on passed encoder selector.
+func NewCustomClientCodec(encSel encode.EncoderSelector) *ClientCodec {
+	return &ClientCodec{encSel: encSel}
 }
 
-// DecodeClientResponse decodes the response body of a client request into
-// the interface reply.
-func DecodeClientResponse(r io.Reader, reply interface{}) error {
-	var c clientResponse
-	if err := json.NewDecoder(r).Decode(&c); err != nil {
+// NewClientCodec returns a new JSON Codec.
+func NewClientCodec() *ClientCodec {
+	return NewCustomClientCodec(encode.DefaultEncoderSelector)
+}
+
+// ClientCodec creates a ClientCodecRequest to process each request.
+type ClientCodec struct {
+	encSel encode.EncoderSelector
+}
+
+func (cc *ClientCodec) Write(w io.Writer, method string, args interface{}, id interface{}) error {
+	req := retainClientRequest(method, args, id)
+	defer func() {
+		if nil != req {
+			releaseClientRequest(req)
+		}
+	}()
+
+	encoder := json.NewEncoder(cc.encSel.SelectByWriter(w).Encode(w))
+	if err := encoder.Encode(req); nil != err {
 		return err
 	}
-	if c.Error != nil {
-		jsonErr := &Error{}
-		if err := json.Unmarshal(*c.Error, jsonErr); err != nil {
-			return &Error{
-				Code:    E_SERVER,
-				Message: string(*c.Error),
-			}
-		}
-		return jsonErr
-	}
 
-	if c.Result == nil {
-		return ErrNullResult
-	}
-
-	return json.Unmarshal(*c.Result, reply)
+	return nil
+}
+
+// NewResponse returns a ClientCodecResponse.
+func (cc *ClientCodec) NewResponseOrNotify(r io.Reader) (protocol.ClientCodecResponseOrNotify, error) {
+	return newClientCodecResponseOrNotify(r, cc.encSel.SelectByReader(r))
+}
+
+// newCodecRequest returns a new ServerCodecRequest.
+func newClientCodecResponseOrNotify(r io.Reader, encoder encode.Encoder) (protocol.ClientCodecResponseOrNotify, error) {
+	// Decode the request body and check if RPC method is valid.
+	var raw json.RawMessage
+	dec := json.NewDecoder(r)
+	err := dec.Decode(&raw)
+
+	if err == io.ErrUnexpectedEOF || err == io.EOF {
+		return nil, err
+	}
+	if err != nil {
+		err = &Error{
+			Code:    E_PARSE,
+			Message: err.Error(),
+			Data:    raw,
+		}
+	}
+
+	ccrn := retainClientCodecResponseOrNotify()
+
+	if res, err := newClientCodecResponse(raw, dec); nil != err {
+		notify, err := newClientCodecNotify(raw, dec)
+		if nil != err {
+			releaseClientCodecResponseOrNotify(ccrn)
+			return nil, fmt.Errorf("Is not response or notification [%v]", raw)
+		}
+		ccrn.notify = notify
+	} else {
+		ccrn.response = res
+	}
+
+	return ccrn, nil
+}
+
+type ClientCodecResponseOrNotify struct {
+	notify   protocol.ClientCodecNotify
+	response protocol.ClientCodecResponse
+}
+
+func (ccrn *ClientCodecResponseOrNotify) IsResponse() bool {
+	return nil != ccrn.response
+}
+
+func (ccrn *ClientCodecResponseOrNotify) IsNotify() bool {
+	return nil != ccrn.notify
+}
+
+func (ccrn *ClientCodecResponseOrNotify) GetResponse() protocol.ClientCodecResponse {
+	return ccrn.response
+}
+
+func (ccrn *ClientCodecResponseOrNotify) GetNotify() protocol.ClientCodecNotify {
+	return ccrn.notify
+}
+
+func (ccrn *ClientCodecResponseOrNotify) Complete() {
+	if nil != ccrn.notify {
+		ccrn.notify.Complete()
+	}
+	if nil != ccrn.response {
+		ccrn.response.Complete()
+	}
+	releaseClientCodecResponseOrNotify(ccrn)
+}
+
+var clientRequestPool sync.Pool
+
+func retainClientRequest(method string, params interface{}, id interface{}) *clientRequest {
+	v := clientRequestPool.Get()
+	if v == nil {
+		return &clientRequest{}
+	}
+	cr := v.(*clientRequest)
+	cr.Method = method
+	cr.Params = params
+	cr.ID = id
+	return cr
+}
+
+func releaseClientRequest(cr *clientRequest) {
+	cr.Method = ""
+	cr.Params = nil
+	cr.ID = nil
+
+	clientRequestPool.Put(cr)
+}
+
+var clientCodecResponseOrNotifyPool sync.Pool
+
+func retainClientCodecResponseOrNotify() *ClientCodecResponseOrNotify {
+	v := clientCodecResponseOrNotifyPool.Get()
+	if v == nil {
+		return &ClientCodecResponseOrNotify{}
+	}
+	return v.(*ClientCodecResponseOrNotify)
+}
+
+func releaseClientCodecResponseOrNotify(cr *ClientCodecResponseOrNotify) {
+
+	clientCodecResponseOrNotifyPool.Put(cr)
 }
diff --git a/protocol/json/client_notify.go b/protocol/json/client_notify.go
new file mode 100644
index 0000000..158f773
--- /dev/null
+++ b/protocol/json/client_notify.go
@@ -0,0 +1,92 @@
+package json
+
+import (
+	"encoding/json"
+	"fmt"
+	"sync"
+
+	"git.loafle.net/commons_go/rpc/protocol"
+)
+
+// ----------------------------------------------------------------------------
+// ClientCodecNotify
+// ----------------------------------------------------------------------------
+
+// newCodecRequest returns a new ClientCodecNotify.
+func newClientCodecNotify(raw json.RawMessage, decoder *json.Decoder) (protocol.ClientCodecNotify, error) {
+	// Decode the request body and check if RPC method is valid.
+	ccn := retainClientCodecNotify()
+	err := decoder.Decode(&ccn.notify)
+	if err != nil {
+		releaseClientCodecNotify(ccn)
+		return nil, err
+	}
+	if "" == ccn.notify.Method {
+		releaseClientCodecNotify(ccn)
+		return nil, fmt.Errorf("This is not ClientNotify")
+	}
+
+	if ccn.notify.Version != Version {
+		ccn.err = &Error{
+			Code:    E_INVALID_REQ,
+			Message: "jsonrpc must be " + Version,
+			Data:    ccn.notify,
+		}
+	}
+
+	return ccn, nil
+}
+
+// ClientCodecNotify decodes and encodes a single notification.
+type ClientCodecNotify struct {
+	notify clientNotify
+	err    error
+}
+
+func (ccn *ClientCodecNotify) Method() string {
+	return ccn.notify.Method
+}
+
+func (ccn *ClientCodecNotify) ReadParams(args interface{}) error {
+	if ccn.err == nil && ccn.notify.Params != nil {
+		// Note: if scr.request.Params is nil it's not an error, it's an optional member.
+		// JSON params structured object. Unmarshal to the args object.
+		if err := json.Unmarshal(*ccn.notify.Params, args); err != nil {
+			// Clearly JSON params is not a structured object,
+			// fallback and attempt an unmarshal with JSON params as
+			// array value and RPC params is struct. Unmarshal into
+			// array containing the request struct.
+			params := [1]interface{}{args}
+			if err = json.Unmarshal(*ccn.notify.Params, &params); err != nil {
+				ccn.err = &Error{
+					Code:    E_INVALID_REQ,
+					Message: err.Error(),
+					Data:    ccn.notify.Params,
+				}
+			}
+		}
+	}
+	return ccn.err
+}
+
+func (ccn *ClientCodecNotify) Complete() {
+	releaseClientCodecNotify(ccn)
+}
+
+var clientCodecNotifyPool sync.Pool
+
+func retainClientCodecNotify() *ClientCodecNotify {
+	v := clientCodecNotifyPool.Get()
+	if v == nil {
+		return &ClientCodecNotify{}
+	}
+	return v.(*ClientCodecNotify)
+}
+
+func releaseClientCodecNotify(ccn *ClientCodecNotify) {
+	ccn.notify.Version = ""
+	ccn.notify.Method = ""
+	ccn.notify.Params = nil
+
+	clientCodecNotifyPool.Put(ccn)
+}
diff --git a/protocol/json/client_response.go b/protocol/json/client_response.go
new file mode 100644
index 0000000..8c12bda
--- /dev/null
+++ b/protocol/json/client_response.go
@@ -0,0 +1,79 @@
+package json
+
+import (
+	"encoding/json"
+	"fmt"
+	"sync"
+
+	"git.loafle.net/commons_go/rpc/protocol"
+)
+
+// ----------------------------------------------------------------------------
+// ClientCodecResponse
+// ----------------------------------------------------------------------------
+
+// newClientCodecResponse returns a new ClientCodecResponse.
+func newClientCodecResponse(raw json.RawMessage, decoder *json.Decoder) (protocol.ClientCodecResponse, error) {
+	// Decode the request body and check if RPC method is valid.
+	ccr := retainClientCodecResponse()
+	err := decoder.Decode(&ccr.response)
+	if err != nil {
+		releaseClientCodecResponse(ccr)
+		return nil, err
+	}
+	if nil == ccr.response.ID {
+		releaseClientCodecResponse(ccr)
+		return nil, fmt.Errorf("This is not Response")
+	}
+
+	if ccr.response.Version != Version {
+		ccr.err = &Error{
+			Code:    E_INVALID_REQ,
+			Message: "jsonrpc must be " + Version,
+			Data:    ccr.response,
+		}
+	}
+
+	return ccr, nil
+}
+
+// ClientCodecResponse decodes and encodes a single request.
+type ClientCodecResponse struct {
+	response clientResponse
+	err      error
+}
+
+func (ccr *ClientCodecResponse) ID() interface{} {
+	return ccr.response.ID
+}
+
+func (ccr *ClientCodecResponse) Result() interface{} {
+	return ccr.response.Result
+}
+
+func (ccr *ClientCodecResponse) Error() error {
+	return ccr.response.Error.(error)
+}
+
+func (ccr *ClientCodecResponse) Complete() {
+	releaseClientCodecResponse(ccr)
+}
+
+var clientCodecResponsePool sync.Pool
+
+func retainClientCodecResponse() *ClientCodecResponse {
+	v := clientCodecResponsePool.Get()
+	if v == nil {
+		return &ClientCodecResponse{}
+	}
+	return v.(*ClientCodecResponse)
+}
+
+func releaseClientCodecResponse(ccr *ClientCodecResponse) {
+	ccr.response.Version = ""
+	ccr.response.Result = nil
+	ccr.response.Error = nil
+	ccr.response.ID = nil
+
+	clientCodecResponsePool.Put(ccr)
+}
diff --git a/protocol/json/constants.go b/protocol/json/constants.go
new file mode 100644
index 0000000..b642d1d
--- /dev/null
+++ b/protocol/json/constants.go
@@ -0,0 +1,5 @@
+package json
+
+const (
+	Version = "2.0"
+)
diff --git a/protocol/json/server.go b/protocol/json/server.go
index 6327a8f..566c1d6 100644
--- a/protocol/json/server.go
+++ b/protocol/json/server.go
@@ -3,13 +3,13 @@ package json
 import (
 	"encoding/json"
 	"io"
+	"sync"
 
 	"git.loafle.net/commons_go/rpc/encode"
 	"git.loafle.net/commons_go/rpc/protocol"
 )
 
 var null = json.RawMessage([]byte("null"))
-var Version = "2.0"
 
 // ----------------------------------------------------------------------------
 // Request and Response
@@ -55,34 +55,54 @@ type serverResponse struct {
 // Codec
 // ----------------------------------------------------------------------------
 
-// NewcustomCodec returns a new JSON Codec based on passed encoder selector.
-func NewCustomCodec(encSel encode.EncoderSelector) *Codec {
-	return &Codec{encSel: encSel}
+// NewCustomServerCodec returns a new JSON Codec based on passed encoder selector.
+func NewCustomServerCodec(encSel encode.EncoderSelector) *ServerCodec {
+	return &ServerCodec{encSel: encSel}
 }
 
-// NewCodec returns a new JSON Codec.
-func NewCodec() *Codec {
-	return NewCustomCodec(encode.DefaultEncoderSelector)
+// NewServerCodec returns a new JSON Codec.
+func NewServerCodec() *ServerCodec {
+	return NewCustomServerCodec(encode.DefaultEncoderSelector)
 }
 
-// Codec creates a CodecRequest to process each request.
-type Codec struct {
-	encSel encode.EncoderSelector
+// ServerCodec creates a ServerCodecRequest to process each request.
+type ServerCodec struct {
+	encSel    encode.EncoderSelector
+	notifyMtx sync.Mutex
+	notify    clientRequest
 }
 
-// NewRequest returns a CodecRequest.
-func (c *Codec) NewRequest(r io.Reader) (protocol.CodecRequest, error) {
-	return newCodecRequest(r, c.encSel.Select(r))
+// NewRequest returns a ServerCodecRequest.
+func (sc *ServerCodec) NewRequest(r io.Reader) (protocol.ServerCodecRequest, error) {
+	return newServerCodecRequest(r, sc.encSel.SelectByReader(r))
+}
+
+// WriteNotify send a notification from server to client.
+func (sc *ServerCodec) WriteNotify(w io.Writer, method string, args interface{}) error {
+	sc.notifyMtx.Lock()
+
+	sc.notify.Version = Version
+	sc.notify.Method = method
+	sc.notify.Params = args
+
+	encoder := json.NewEncoder(sc.encSel.SelectByWriter(w).Encode(w))
+	err := encoder.Encode(&sc.notify)
+	sc.notifyMtx.Unlock()
+	// Not sure in which case will this happen. But seems harmless.
+	if err != nil {
+		return err
+	}
+	return nil
 }
 
 // ----------------------------------------------------------------------------
-// CodecRequest
+// ServerCodecRequest
 // ----------------------------------------------------------------------------
 
-// newCodecRequest returns a new CodecRequest.
-func newCodecRequest(r io.Reader, encoder encode.Encoder) (protocol.CodecRequest, error) {
+// newCodecRequest returns a new ServerCodecRequest.
+func newServerCodecRequest(r io.Reader, encoder encode.Encoder) (protocol.ServerCodecRequest, error) {
 	// Decode the request body and check if RPC method is valid.
-	req := new(serverRequest)
+	req := retainServerRequest()
 	err := json.NewDecoder(r).Decode(req)
 	if err == io.ErrUnexpectedEOF || err == io.EOF {
 		return nil, err
@@ -102,24 +122,29 @@ func newCodecRequest(r io.Reader, encoder encode.Encoder) (protocol.CodecRequest
 		}
 	}
 
-	return &CodecRequest{request: req, err: err, encoder: encoder}, nil
+	return retainServerCodecRequest(req, err, encoder), nil
 }
 
 // CodecRequest decodes and encodes a single request.
-type CodecRequest struct {
+type ServerCodecRequest struct {
 	request *serverRequest
 	err     error
 	encoder encode.Encoder
 }
 
+// Complete is callback function that end of request.
+func (scr *ServerCodecRequest) Complete() {
+	if nil != scr.request {
+		releaseServerRequest(scr.request)
+	}
+	releaseServerCodecRequest(scr)
+}
+
 // Method returns the RPC method for the current request.
 //
 // The method uses a dotted notation as in "Service.Method".
-func (c *CodecRequest) Method() (string, error) {
-	if c.err == nil {
-		return c.request.Method, nil
-	}
-	return "", c.err
+func (scr *ServerCodecRequest) Method() string {
+	return scr.request.Method
 }
 
 // ReadRequest fills the request object for the RPC method.
@@ -135,40 +160,36 @@ func (c *CodecRequest) Method() (string, error) {
 // absence of expected names MAY result in an error being
 // generated. The names MUST match exactly, including
 // case, to the method's expected parameters.
-func (c *CodecRequest) ReadRequest(args interface{}) error {
-	if c.err == nil && c.request.Params != nil {
-		// Note: if c.request.Params is nil it's not an error, it's an optional member.
+func (scr *ServerCodecRequest) ReadParams(args interface{}) error {
+	if scr.err == nil && scr.request.Params != nil {
+		// Note: if scr.request.Params is nil it's not an error, it's an optional member.
 		// JSON params structured object. Unmarshal to the args object.
-		if err := json.Unmarshal(*c.request.Params, args); err != nil {
+		if err := json.Unmarshal(*scr.request.Params, args); err != nil {
 			// Clearly JSON params is not a structured object,
 			// fallback and attempt an unmarshal with JSON params as
 			// array value and RPC params is struct. Unmarshal into
 			// array containing the request struct.
 			params := [1]interface{}{args}
-			if err = json.Unmarshal(*c.request.Params, &params); err != nil {
-				c.err = &Error{
+			if err = json.Unmarshal(*scr.request.Params, &params); err != nil {
+				scr.err = &Error{
 					Code:    E_INVALID_REQ,
 					Message: err.Error(),
-					Data:    c.request.Params,
+					Data:    scr.request.Params,
 				}
 			}
 		}
 	}
-	return c.err
+	return scr.err
 }
 
 // WriteResponse encodes the response and writes it to the ResponseWriter.
-func (c *CodecRequest) WriteResponse(w io.Writer, reply interface{}) error {
-	res := &serverResponse{
-		Version: Version,
-		Result:  reply,
-		ID:      c.request.ID,
-	}
-	return c.writeServerResponse(w, res)
+func (scr *ServerCodecRequest) WriteResponse(w io.Writer, reply interface{}) error {
+	res := retainServerResponse(Version, reply, nil, scr.request.ID)
+	return scr.writeServerResponse(w, res)
 }
 
 // WriteError encodes the response and writes it to the ResponseWriter.
-func (c *CodecRequest) WriteError(w io.Writer, status int, err error) error {
+func (scr *ServerCodecRequest) WriteError(w io.Writer, status int, err error) error {
 	jsonErr, ok := err.(*Error)
 	if !ok {
 		jsonErr = &Error{
@@ -176,18 +197,19 @@ func (c *CodecRequest) WriteError(w io.Writer, status int, err error) error {
 			Message: err.Error(),
 		}
 	}
-	res := &serverResponse{
-		Version: Version,
-		Error:   jsonErr,
-		ID:      c.request.ID,
-	}
-	return c.writeServerResponse(w, res)
+	res := retainServerResponse(Version, nil, jsonErr, scr.request.ID)
+	return scr.writeServerResponse(w, res)
 }
 
-func (c *CodecRequest) writeServerResponse(w io.Writer, res *serverResponse) error {
+func (scr *ServerCodecRequest) writeServerResponse(w io.Writer, res *serverResponse) error {
+	defer func() {
+		if nil != res {
+			releaseServerResponse(res)
+		}
+	}()
 	// ID is null for notifications and they don't have a response.
-	if c.request.ID != nil {
-		encoder := json.NewEncoder(c.encoder.Encode(w))
+	if scr.request.ID != nil {
+		encoder := json.NewEncoder(scr.encoder.Encode(w))
 		err := encoder.Encode(res)
 
 		// Not sure in which case will this happen. But seems harmless.
@@ -200,3 +222,70 @@ func (c *CodecRequest) writeServerResponse(w io.Writer, res *serverResponse) err
 
 type EmptyResponse struct {
 }
+
+var serverCodecRequestPool sync.Pool
+
+func retainServerCodecRequest(request *serverRequest, err error, encoder encode.Encoder) *ServerCodecRequest {
+	v := serverCodecRequestPool.Get()
+	if v == nil {
+		return &ServerCodecRequest{}
+	}
+
+	scr := v.(*ServerCodecRequest)
+	scr.request = request
+	scr.err = err
+	scr.encoder = encoder
+
+	return scr
+}
+
+func releaseServerCodecRequest(scr *ServerCodecRequest) {
+	scr.request = nil
+	scr.err = nil
+	scr.encoder = nil
+
+	serverCodecRequestPool.Put(scr)
+}
+
+var serverRequestPool sync.Pool
+
+func retainServerRequest() *serverRequest {
+	v := serverRequestPool.Get()
+	if v == nil {
+		return &serverRequest{}
+	}
+	return v.(*serverRequest)
+}
+
+func releaseServerRequest(sr *serverRequest) {
+	sr.Method = ""
+	sr.Params = nil
+	sr.ID = nil
+
+	serverRequestPool.Put(sr)
+}
+
+var serverResponsePool sync.Pool
+
+func retainServerResponse(version string, result interface{}, err *Error, id *json.RawMessage) *serverResponse {
+	v := serverResponsePool.Get()
+	if v == nil {
+		return &serverResponse{}
+	}
+	sr := v.(*serverResponse)
+	sr.Version = version
+	sr.Result = result
+	sr.Error = err
+	sr.ID = id
+
+	return sr
+}
+
+func releaseServerResponse(sr *serverResponse) {
+	sr.Version = ""
+	sr.Result = nil
+	sr.Error = nil
+	sr.ID = nil
+
+	serverResponsePool.Put(sr)
+}
diff --git a/protocol/registry_codec.go b/protocol/registry_codec.go
new file mode 100644
index 0000000..4446be5
--- /dev/null
+++ b/protocol/registry_codec.go
@@ -0,0 +1,13 @@
+package protocol
+
+// ----------------------------------------------------------------------------
+// Codec
+// ----------------------------------------------------------------------------
+// RegistryCodec creates a RegistryCodecRequest to process each request.
+type RegistryCodec interface {
+	// Reads the request and returns the RPC method name.
+	Method() string
+	// Reads the request filling the RPC method args.
+	ReadParams(interface{}) error
+	Complete()
+}
diff --git a/protocol/server_codec.go b/protocol/server_codec.go
new file mode 100644
index 0000000..bffb9c6
--- /dev/null
+++ b/protocol/server_codec.go
@@ -0,0 +1,18 @@
+package protocol
+
+import (
+	"io"
+)
+
+// ServerCodec creates a ServerCodecRequest to process each request.
+type ServerCodec interface {
+	NewRequest(r io.Reader) (ServerCodecRequest, error)
+}
+
+// ServerCodecRequest decodes a request and encodes a response using a specific
+// serialization scheme.
+type ServerCodecRequest interface {
+	RegistryCodec
+	WriteResponse(w io.Writer, reply interface{}) error
+	WriteError(w io.Writer, status int, err error) error
+}
diff --git a/registry.go b/registry.go
index 5135e30..f563b7e 100644
--- a/registry.go
+++ b/registry.go
@@ -1,10 +1,7 @@
 package rpc
 
 import (
-	"fmt"
-	"io"
 	"reflect"
-	"strings"
 
 	"git.loafle.net/commons_go/rpc/protocol"
 )
@@ -19,38 +16,24 @@ Network connection
 
 */
 
-type WriteHookFunc func(io.Writer)
-
 // NewRPCRegistry returns a new RPC registry.
 func NewRegistry() Registry {
 	return &rpcRegistry{
-		codecs:   make(map[string]protocol.Codec),
 		services: new(serviceMap),
 	}
 }
 
 type Registry interface {
-	RegisterCodec(codec protocol.Codec, contentType string)
 	RegisterService(receiver interface{}, name string) error
 	HasMethod(method string) bool
-	Invoke(contentType string, reader io.Reader, writer io.Writer, beforeWrite WriteHookFunc, afterWrite WriteHookFunc) error
+	Invoke(codec protocol.RegistryCodec) (result interface{}, err error)
 }
 
 // RPCRegistry serves registered RPC services using registered codecs.
 type rpcRegistry struct {
-	codecs   map[string]protocol.Codec
 	services *serviceMap
 }
 
-// RegisterCodec adds a new codec to the server.
-//
-// Codecs are defined to process a given serialization scheme, e.g., JSON or
-// XML. A codec is chosen based on the "Content-Type" header from the request,
-// excluding the charset definition.
-func (rr *rpcRegistry) RegisterCodec(codec protocol.Codec, contentType string) {
-	rr.codecs[strings.ToLower(contentType)] = codec
-}
-
 // RegisterService adds a new service to the server.
 //
 // The name parameter is optional: if empty it will be inferred from
@@ -86,36 +69,15 @@ func (rr *rpcRegistry) HasMethod(method string) bool {
 // Codecs are defined to process a given serialization scheme, e.g., JSON or
 // XML. A codec is chosen based on the "Content-Type" header from the request,
 // excluding the charset definition.
-func (rr *rpcRegistry) Invoke(contentType string, r io.Reader, w io.Writer, beforeWrite WriteHookFunc, afterWrite WriteHookFunc) error {
-	var codec protocol.Codec
-	if contentType == "" && len(rr.codecs) == 1 {
-		// If Content-Type is not set and only one codec has been registered,
-		// then default to that codec.
-		for _, c := range rr.codecs {
-			codec = c
-		}
-	} else if codec = rr.codecs[strings.ToLower(contentType)]; codec == nil {
-		return fmt.Errorf("Unrecognized Content-Type: %s", contentType)
-	}
-
-	// Create a new codec request.
-	codecReq, errNew := codec.NewRequest(r)
-	if nil != errNew {
-		return errNew
-	}
-	// Get service method to be called.
-	method, errMethod := codecReq.Method()
-	if errMethod != nil {
-		return write(codecReq, w, beforeWrite, afterWrite, nil, errMethod)
-	}
-	serviceSpec, methodSpec, errGet := rr.services.get(method)
+func (rr *rpcRegistry) Invoke(codec protocol.RegistryCodec) (result interface{}, err error) {
+	serviceSpec, methodSpec, errGet := rr.services.get(codec.Method())
 	if errGet != nil {
-		return write(codecReq, w, beforeWrite, afterWrite, nil, errGet)
+		return nil, errGet
 	}
 	// Decode the args.
 	args := reflect.New(methodSpec.argsType)
-	if errRead := codecReq.ReadRequest(args.Interface()); errRead != nil {
-		return write(codecReq, w, beforeWrite, afterWrite, nil, errRead)
+	if errRead := codec.ReadParams(args.Interface()); errRead != nil {
+		return nil, errRead
 	}
 	// Call the service method.
 	reply := reflect.New(methodSpec.replyType)
@@ -133,32 +95,8 @@ func (rr *rpcRegistry) Invoke(contentType string, r io.Reader, w io.Writer, befo
 	}
 
 	if errResult != nil {
-		return write(codecReq, w, beforeWrite, afterWrite, nil, errResult)
+		return nil, errResult
 	}
 
-	return write(codecReq, w, beforeWrite, afterWrite, reply.Interface(), nil)
-}
-
-func write(codecReq protocol.CodecRequest, w io.Writer, beforeWrite WriteHookFunc, afterWrite WriteHookFunc, result interface{}, err error) error {
-	if nil != beforeWrite {
-		beforeWrite(w)
-	}
-
-	var wErr error
-
-	if err == nil {
-		wErr = codecReq.WriteResponse(w, result)
-	} else {
-		wErr = codecReq.WriteError(w, 400, err)
-	}
-
-	if nil != wErr {
-		return wErr
-	}
-
-	if nil != afterWrite {
-		afterWrite(w)
-	}
-
-	return nil
+	return reply.Interface(), nil
 }
diff --git a/server/server.go b/server/server.go
new file mode 100644
index 0000000..5615d8d
--- /dev/null
+++ b/server/server.go
@@ -0,0 +1,89 @@
+package server
+
+import (
+	"io"
+	"sync"
+
+	"git.loafle.net/commons_go/rpc/protocol"
+)
+
+func New(sh ServerHandler) Server {
+	s := &server{
+		sh: sh,
+	}
+	return s
+}
+
+type Server interface {
+	Start()
+	Stop()
+	Handle(r io.Reader, w io.Writer) error
+}
+
+type server struct {
+	sh ServerHandler
+
+	stopChan chan struct{}
+	stopWg   sync.WaitGroup
+}
+
+func (s *server) Start() {
+	if nil == s.sh {
+		panic("Server: server handler must be specified.")
+	}
+	s.sh.Validate()
+
+	if s.stopChan != nil {
+		panic("Server: server is already running. Stop it before starting it again")
+	}
+	s.stopChan = make(chan struct{})
+
+}
+
+func (s *server) Stop() {
+	if s.stopChan == nil {
+		panic("Server: server must be started before stopping it")
+	}
+	close(s.stopChan)
+	s.stopWg.Wait()
+	s.stopChan = nil
+}
+
+func (s *server) Handle(r io.Reader, w io.Writer) error {
+	contentType := s.sh.GetContentType(r)
+	codec, err := s.sh.getCodec(contentType)
+	if nil != err {
+		return err
+	}
+
+	var codecReq protocol.ServerCodecRequest
+
+	defer func() {
+		if nil != codecReq {
+			codecReq.Complete()
+		}
+	}()
+
+	s.sh.OnPreRead(r)
+	// Create a new codec request.
+	codecReq, errNew := codec.NewRequest(r)
+	if nil != errNew {
+		return errNew
+	}
+	s.sh.OnPostRead(r)
+
+	result, err := s.sh.invoke(codecReq)
+
+	if nil != err {
+		s.sh.OnPreWriteError(w, err)
+		codecReq.WriteError(w, 400, err)
+		s.sh.OnPostWriteError(w, err)
+		return nil
+	}
+
+	s.sh.OnPreWriteResult(w, result)
+	codecReq.WriteResponse(w, result)
+	s.sh.OnPostWriteResult(w, result)
+
+	return nil
+}
diff --git a/server/server_handler.go b/server/server_handler.go
new file mode 100644
index 0000000..53f848c
--- /dev/null
+++ b/server/server_handler.go
@@ -0,0 +1,27 @@
+package server
+
+import (
+	"io"
+
+	"git.loafle.net/commons_go/rpc/protocol"
+)
+
+type ServerHandler interface {
+	RegisterCodec(codec protocol.ServerCodec, contentType string)
+
+	GetContentType(r io.Reader) string
+
+	OnPreRead(r io.Reader)
+	OnPostRead(r io.Reader)
+
+	OnPreWriteResult(w io.Writer, result interface{})
+	OnPostWriteResult(w io.Writer, result interface{})
+
+	OnPreWriteError(w io.Writer, err error)
+	OnPostWriteError(w io.Writer, err error)
+
+	getCodec(contentType string) (protocol.ServerCodec, error)
+	invoke(codec protocol.RegistryCodec) (result interface{}, err error)
+
+	Validate()
+}
diff --git a/server/server_handlers.go b/server/server_handlers.go
new file mode 100644
index 0000000..a9441c7
--- /dev/null
+++ b/server/server_handlers.go
@@ -0,0 +1,81 @@
+package server
+
+import (
+	"fmt"
+	"io"
+	"strings"
+
+	"git.loafle.net/commons_go/rpc"
+	"git.loafle.net/commons_go/rpc/protocol"
+)
+
+type ServerHandlers struct {
+	Registry rpc.Registry
+
+	codecs map[string]protocol.ServerCodec
+}
+
+// RegisterCodec adds a new codec to the server.
+//
+// Codecs are defined to process a given serialization scheme, e.g., JSON or
+// XML. A codec is chosen based on the "Content-Type" header from the request,
+// excluding the charset definition.
+func (sh *ServerHandlers) RegisterCodec(codec protocol.ServerCodec, contentType string) {
+	if nil == sh.codecs {
+		sh.codecs = make(map[string]protocol.ServerCodec)
+	}
+	sh.codecs[strings.ToLower(contentType)] = codec
+}
+
+func (sh *ServerHandlers) GetContentType(r io.Reader) string {
+	return ""
+}
+
+func (sh *ServerHandlers) OnPreRead(r io.Reader) {
+	// no op
+}
+
+func (sh *ServerHandlers) OnPostRead(r io.Reader) {
+	// no op
+}
+
+func (sh *ServerHandlers) OnPreWriteResult(w io.Writer, result interface{}) {
+	// no op
+}
+
+func (sh *ServerHandlers) OnPostWriteResult(w io.Writer, result interface{}) {
+	// no op
+}
+
+func (sh *ServerHandlers) OnPreWriteError(w io.Writer, err error) {
+	// no op
+}
+
+func (sh *ServerHandlers) OnPostWriteError(w io.Writer, err error) {
+	// no op
+}
+
+func (sh *ServerHandlers) Validate() {
+	if nil == sh.Registry {
+		panic("Registry(RPCRegistry) must be specified.")
+	}
+}
+
+func (sh *ServerHandlers) getCodec(contentType string) (protocol.ServerCodec, error) {
+	var codec protocol.ServerCodec
+	if contentType == "" && len(sh.codecs) == 1 {
+		// If Content-Type is not set and only one codec has been registered,
+		// then default to that codec.
+		for _, c := range sh.codecs {
+			codec = c
+		}
+	} else if codec = sh.codecs[strings.ToLower(contentType)]; codec == nil {
+		return nil, fmt.Errorf("Unrecognized Content-Type: %s", contentType)
+	}
+
+	return codec, nil
+}
+
+func (sh *ServerHandlers) invoke(codec protocol.RegistryCodec) (result interface{}, err error) {
+	return sh.Registry.Invoke(codec)
+}
diff --git a/service_map.go b/service_map.go
index 0e76035..33cf571 100644
--- a/service_map.go
+++ b/service_map.go
@@ -31,6 +31,7 @@ type serviceMethod struct {
 	replyType reflect.Type   // type of the response argument
 }
 
+
 // ----------------------------------------------------------------------------
 // serviceMap
 // ----------------------------------------------------------------------------