diff --git a/conn.go b/conn.go
deleted file mode 100644
index 9678ccc..0000000
--- a/conn.go
+++ /dev/null
@@ -1,190 +0,0 @@
-package tcp
-
-import (
-	"errors"
-	"io"
-	"net"
-	"strings"
-	"sync"
-	"sync/atomic"
-	"time"
-)
-
-var (
-	ErrConnClosing = errors.New("use of closed network connection")
-	ErrBufferFull  = errors.New("the async send buffer is full")
-)
-
-type TCPConn struct {
-	callback CallBack
-	protocol Protocol
-
-	conn      *net.TCPConn
-	readChan  chan Packet
-	writeChan chan Packet
-	errChan   chan error
-
-	readDeadline  time.Duration
-	writeDeadline time.Duration
-	maxPacketSize uint32
-
-	exitChan  chan struct{}
-	closeOnce sync.Once
-	exitFlag  int32
-}
-
-func NewTCPConn(conn *net.TCPConn, callback CallBack, protocol Protocol) *TCPConn {
-	c := &TCPConn{
-		conn:     conn,
-		callback: callback,
-		protocol: protocol,
-
-		readChan:  make(chan Packet, readChanSize),
-		writeChan: make(chan Packet, writeChanSize),
-		errChan:   make(chan error, 10),
-
-		exitChan: make(chan struct{}),
-		exitFlag: 0,
-	}
-	return c
-}
-
-func (c *TCPConn) Serve() {
-	defer func() {
-		if r := recover(); r != nil {
-			logger.Println("tcp conn(%v) Serve error, %v ", c.GetRemoteIPAddress(), r)
-		}
-	}()
-	atomic.StoreInt32(&c.exitFlag, 1)
-	c.callback.OnConnected(c)
-	go c.readLoop()
-	go c.writeLoop()
-	go c.handleLoop()
-}
-
-func (c *TCPConn) readLoop() {
-	defer func() {
-		recover()
-		c.Close()
-	}()
-
-	for {
-		select {
-		case <-c.exitChan:
-			return
-		default:
-			if c.readDeadline > 0 {
-				c.conn.SetReadDeadline(time.Now().Add(c.readDeadline))
-			}
-			p, err := c.protocol.ReadPacket(c.conn)
-			if err != nil {
-				if err != io.EOF {
-					c.errChan <- err
-				}
-				return
-			}
-			c.readChan <- p
-		}
-	}
-}
-
-func (c *TCPConn) ReadPacket() (Packet, error) {
-	if c.protocol == nil {
-		return nil, errors.New("no protocol impl")
-	}
-	return c.protocol.ReadPacket(c.conn)
-}
-
-func (c *TCPConn) writeLoop() {
-	defer func() {
-		recover()
-		c.Close()
-	}()
-
-	for pkt := range c.writeChan {
-		if pkt == nil {
-			continue
-		}
-		if c.writeDeadline > 0 {
-			c.conn.SetWriteDeadline(time.Now().Add(c.writeDeadline))
-		}
-		if err := c.protocol.WritePacket(c.conn, pkt); err != nil {
-			c.errChan <- err
-			return
-		}
-	}
-}
-
-func (c *TCPConn) handleLoop() {
-	defer func() {
-		recover()
-		c.Close()
-	}()
-	for p := range c.readChan {
-		if p == nil {
-			continue
-		}
-		c.callback.OnMessage(c, p)
-	}
-}
-
-func (c *TCPConn) AsyncWritePacket(p Packet) error {
-	if c.IsClosed() {
-		return ErrConnClosing
-	}
-	select {
-	case c.writeChan <- p:
-		return nil
-	default:
-		return ErrBufferFull
-	}
-}
-
-func (c *TCPConn) Close() {
-	c.closeOnce.Do(func() {
-		close(c.exitChan)
-		close(c.errChan)
-		close(c.writeChan)
-		close(c.readChan)
-		c.callback.OnDisconnected(c)
-		atomic.StoreInt32(&c.exitFlag, 0)
-		c.conn.Close()
-	})
-}
-
-func (c *TCPConn) Errors() <-chan error {
-	return c.errChan
-}
-
-func (c *TCPConn) GetRawConn() *net.TCPConn {
-	return c.conn
-}
-
-func (c *TCPConn) IsClosed() bool {
-	return atomic.LoadInt32(&c.exitFlag) == 0
-}
-
-func (c *TCPConn) GetLocalAddr() net.Addr {
-	return c.conn.LocalAddr()
-}
-
-//LocalIPAddress 返回socket连接本地的ip地址
-func (c *TCPConn) GetLocalIPAddress() string {
-	return strings.Split(c.GetLocalAddr().String(), ":")[0]
-}
-
-func (c *TCPConn) GetRemoteAddr() net.Addr {
-	return c.conn.RemoteAddr()
-}
-
-func (c *TCPConn) GetRemoteIPAddress() string {
-	return strings.Split(c.GetRemoteAddr().String(), ":")[0]
-}
-
-func (c *TCPConn) setReadDeadline(t time.Duration) {
-	c.readDeadline = t
-}
-
-func (c *TCPConn) setWriteDeadline(t time.Duration) {
-	c.writeDeadline = t
-}
diff --git a/tcp_conn.go b/tcp_conn.go
index 9678ccc..4df98da 100644
--- a/tcp_conn.go
+++ b/tcp_conn.go
@@ -2,6 +2,7 @@ package tcp
 
 import (
 	"errors"
+	"fmt"
 	"io"
 	"net"
 	"strings"
@@ -26,7 +27,6 @@ type TCPConn struct {
 
 	readDeadline  time.Duration
 	writeDeadline time.Duration
-	maxPacketSize uint32
 
 	exitChan  chan struct{}
 	closeOnce sync.Once
@@ -49,17 +49,23 @@ func NewTCPConn(conn *net.TCPConn, callback CallBack, protocol Protocol) *TCPCon
 	return c
 }
 
-func (c *TCPConn) Serve() {
+func (c *TCPConn) Serve() error {
 	defer func() {
 		if r := recover(); r != nil {
 			logger.Println("tcp conn(%v) Serve error, %v ", c.GetRemoteIPAddress(), r)
 		}
 	}()
+	if c.callback == nil || c.protocol == nil {
+		err := fmt.Errorf("callback and protocol are not allowed to be nil")
+		c.Close()
+		return err
+	}
 	atomic.StoreInt32(&c.exitFlag, 1)
 	c.callback.OnConnected(c)
 	go c.readLoop()
 	go c.writeLoop()
 	go c.handleLoop()
+	return nil
 }
 
 func (c *TCPConn) readLoop() {
@@ -146,7 +152,9 @@ func (c *TCPConn) Close() {
 		close(c.errChan)
 		close(c.writeChan)
 		close(c.readChan)
-		c.callback.OnDisconnected(c)
+		if c.callback != nil {
+			c.callback.OnDisconnected(c)
+		}
 		atomic.StoreInt32(&c.exitFlag, 0)
 		c.conn.Close()
 	})