C#异步套接字服务器接收问题

Question

我已经在这里实现了关于这篇文章的服务器应用程序:http://www.codeguru.com/csharp/csharp/cs_network/sockets/article.php/c8781#Client1

总结:我正在使用异步套接字ala BeginAccept(..),BeginReceive(..).我的服务器能够处理多个客户端,一切正常,直到客户端执行两个或更多同步发送操作,而无需等待一段时间.客户端没有收到任何错误,因此没有得到通知,服务器没有收到第二条消息!如果客户等待约.第一次发送操作后100ms,一切正常.我认为当我使用TCP时,我可以确保服务器收到消息.(除了抛出异常)!你能帮我解决一下吗？

这是我在服务器中实现的WaitForData(..)和OnDataReceive(..)方法

public void WaitForData(MyClient client)
{
    try
    {
        if (pfnCallBack == null)
        {
            pfnCallBack = new AsyncCallback(OnDataReceived);
        }

        iarResult = client.Socket.BeginReceive(client.DataBuffer,
                                                0, client.DataBuffer.Length,
                                                SocketFlags.None,
                                                pfnCallBack,
                                                client);
    }
    catch (SocketException se)
    {
        MessageBox.Show("SocketException@WaitForData" + se.Message);
    }
}
public void OnDataReceived(IAsyncResult asyn)
{
    try
    {
        MyClient user= (MyClient)asyn.AsyncState;
        int iRx = user.Socket.EndReceive(asyn);

        byte[] receivedData = user.DataBuffer;

        MemoryStream memStream = new MemoryStream();
        BinaryFormatter binForm = new BinaryFormatter();
        memStream.Write(receivedData, 0, receivedData.Length);
        memStream.Seek(0, SeekOrigin.Begin);
        MyMessage msg = (MyMessage)binForm.Deserialize(memStream);

        switch (msg.Command)
        {
            case (MyMessage.MyCommand.ConnId):
                this.connId = (int) msg.MyObject;
                tsslConnStatus.Text += " | ID: " + connId.ToString();
            break;

            case (MyMessage.MyCommand.Text):
                MessageBox.Show(msg.MyObject.ToString());
                break;
        }
        WaitForData(server);
    }
    catch (ObjectDisposedException ode)
    {
        MessageBox.Show("ObjectDisposedException@OnReceiveData" + ode.Message);
    }
    catch (SocketException se)
    {
        MessageBox.Show("SocketException@OnReceiveData" + se.Message);
    }
}

客户端调用同步SEND METHOD TWICE或更多!服务器INSTANCEOF MyClient

if (server.Socket.Connected)
{
    BinaryFormatter bf = new BinaryFormatter();
    MemoryStream ms = new MemoryStream();
    bf.Serialize(ms, message);
    MyMessage = new MyMessage(something);
    server.Socket.Send(ms.ToArray());
}

所以,我认为这段代码片段必须足以让你得到我试图使用的想法!如果您需要更多详细信息或代码片段,请告诉我我会发布它!

感谢名单!

Answer 1

TCP是基于流的,而不是基于消息的.一个Read可以包含以下任何替代方案:

• 消息的一个小小的weeny部分
• 半信息
• 一条消息
• 一个半消息
• 两条消息

因此,您需要使用某种方法来查看是否已到达完整的消息.最常见的方法是:

• 添加一个页脚(例如一个空行),表示消息结束
• 添加包含消息长度的固定长度标头

更新

简单示例只有标题长度.

服务器端:

var buffer = binaryFormmater.Serialize(myobj);
var length = buffer.Length;
networkStream.Send(length);
networkStream.Send(buffer, 0, buffer.Length);

客户端:

var header = new buffer[4];
// TODO: You need to make sure that 4 bytes have been read.
networkStream.Read(header, 0, 4);
var length = BitConverter.ToInt32(buffer);

var readbuffer= new byte[65535];
var bytesLeft = length;
var messageStream = new MemoryStream();
while (bytesLeft > 0)
{
     var read = networkStream.Read(readbuffer, 0, bytesLeft);
     messageStream.Write(readbuffer, 0, read);
     bytesLeft -= read,
}

messageStream.Seek(0, SeekOrigin.Begin);
MyMessage msg = (MyMessage)binForm.Deserialize(messageStream);