C# 异步SOCKET问题

异步接收函数如下：
private void ReadCallback(IAsyncResult ar)
{
    StateObject state = (StateObject)ar.AsyncState;
    Socket handler = state.workSocket;
    try
    {
         int bytesRead = handler.EndReceive(ar);
         if (bytesRead > 0)
         {
              GetDataEvent(state.buffer, bytesRead, handler.Handle);
              //handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                    //    new AsyncCallback(ReadCallback), state);
          }
          catch (Exception ex)
          { }
    ｝
｝
异步发送函数如下：
private void SendCallback(IAsyncResult ar)
{
      Socket handler = null;
      try
      {
          handler = (Socket)ar.AsyncState;
          int bytesSent = handler.EndSend(ar);
          StateObject state = new StateObject();
          state.workSocket = handler;
          handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
            new AsyncCallback(ReadCallback), state);
      }
      catch (Exception e)
      { }
}

StateObject结构如下：
public class StateObject
  {
        //Client socket.
        public Socket workSocket = null;
        //Size of receive buffer.
        public const int BufferSize = 1500;
        //Receive buffer.
        public byte[] buffer = new byte[BufferSize];
  }

我现在要用SOCKET传输文件，传输方式是，客户端发一次请求数据，服务器返回一次数据，然后客户端再发送数据，服务器再返回一次数据，一直到文件传输完。在这个过程中，如果在ReadCallback和SendCallback中同时调用BeginReceive方法，则在传输过程中内在会一直增大；如果去掉ReadCallback中的BeginReceive调用，不调用SendCallback函数就收不到后续的数据；如果去掉SendCallback中的Beginreceive调用，只保留ReadCallback中的调用，则在调用SendCallback后就不能接收数据，请问这个问题要怎么处理？望高手指点！

补充：.NET技术 ,  C#