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  • Sequential access to asynchronous sockets

    - by Lars A. Brekken
    I have a server that has several clients C1...Cn to each of which there is a TCP connection established. There are less than 10,000 clients. The message protocol is request/response based, where the server sends a request to a client and then the client sends a response. The server has several threads, T1...Tm, and each of these may send requests to any of the clients. I want to make sure that only one of these threads can send a request to a specific client at any one time, while the other threads wanting to send a request to the same client will have to wait. I do not want to block threads from sending requests to different clients at the same time. E.g. If T1 is sending a request to C3, another thread T2 should not be able to send anything to C3 until T1 has received its response. I was thinking of using a simple lock statement on the socket: lock (c3Socket) { // Send request to C3 // Get response from C3 } I am using asynchronous sockets, so I may have to use Monitor instead: Monitor.Enter(c3Socket); // Before calling .BeginReceive() And Monitor.Exit(c3Socket); // In .EndReceive I am worried about stuff going wrong and not letting go of the monitor and therefore blocking all access to a client. I'm thinking that my heartbeat thread could use Monitor.TryEnter() with a timeout and throw out sockets that it cannot get the monitor for. Would it make sense for me to make the Begin and End calls synchronous in order to be able to use the lock() statement? I know that I would be sacrificing concurrency for simplicity in this case, but it may be worth it. Am I overlooking anything here? Any input appreciated.

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  • UDP Tracker not responding

    - by kelton52
    Alright, so I'm trying to connect to UDP trackers using c#, but I never get a response. I also don't get any errors. Here's my code. namespace UDPTester { class MainClass { public static bool messageReceived = false; public static Random Random = new Random(); public static void LOG(string format, params object[] args) { Console.WriteLine (format,args); } public static void Main (string[] args) { LOG ("Creating Packet..."); byte[] packet; using(var stream = new MemoryStream()) { var bc = new MiscUtil.Conversion.BigEndianBitConverter(); using(var br = new MiscUtil.IO.EndianBinaryWriter(bc,stream)) { LOG ("Magic Num: {0}",(Int64)0x41727101980); br.Write (0x41727101980); br.Write((Int32)0); br.Write ((Int32)Random.Next()); packet = stream.ToArray(); LOG ("Packet Size: {0}",packet.Length); } } LOG ("Connecting to tracker..."); var client = new System.Net.Sockets.UdpClient("tracker.openbittorrent.com",80); UdpState s = new UdpState(); s.e = client.Client.RemoteEndPoint; s.u = client; StartReceiving(s); LOG ("Sending Packet..."); client.Send(packet,packet.Length); while(!messageReceived) { Thread.Sleep(1000); } LOG ("Ended"); } public static void StartReceiving(UdpState state) { state.u.BeginReceive(ReceiveCallback,state); } public static void ReceiveCallback(IAsyncResult ar) { UdpClient u = (UdpClient)((UdpState)(ar.AsyncState)).u; IPEndPoint e = (IPEndPoint)((UdpState)(ar.AsyncState)).e; Byte[] receiveBytes = u.EndReceive(ar, ref e); string receiveString = Encoding.ASCII.GetString(receiveBytes); LOG("Received: {0}", receiveString); messageReceived = true; StartReceiving((UdpState)ar.AsyncState); } } public class UdpState { public UdpClient u; public EndPoint e; } } I was using a normal BinaryWriter, but that didn't work, and I read somewhere that it wants it's data in BigEndian. This doesn't work for any of the UDP trackers I've found, any ideas why I'm not getting a response? Did they maybe change the protocol and not tell anyone? HTTP trackers all work fine. Trackers I've tried udp://tracker.publicbt.com:80 udp://tracker.ccc.de:80 udp://tracker.istole.it:80 Also, I'm not interested in using MonoTorrent(and when I was using it, the UDP didn't work anyways). Protocol Sources http://xbtt.sourceforge.net/udp_tracker_protocol.html http://www.rasterbar.com/products/libtorrent/udp_tracker_protocol.html

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  • Reading off a socket until end of line C#?

    - by Omar Kooheji
    I'm trying to write a service that listens to a TCP Socket on a given port until an end of line is recived and then based on the "line" that was received executes a command. I've followed a basic socket programming tutorial for c# and have come up with the following code to listen to a socket: public void StartListening() { _log.Debug("Creating Maing TCP Listen Socket"); _mainSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); IPEndPoint ipLocal = new IPEndPoint(IPAddress.Any, _port); _log.Debug("Binding to local IP Address"); _mainSocket.Bind(ipLocal); _log.DebugFormat("Listening to port {0}",_port); _mainSocket.Listen(10); _log.Debug("Creating Asynchronous callback for client connections"); _mainSocket.BeginAccept(new AsyncCallback(OnClientConnect), null); } public void OnClientConnect(IAsyncResult asyn) { try { _log.Debug("OnClientConnect Creating worker socket"); Socket workerSocket = _mainSocket.EndAccept(asyn); _log.Debug("Adding worker socket to list"); _workerSockets.Add(workerSocket); _log.Debug("Waiting For Data"); WaitForData(workerSocket); _log.DebugFormat("Clients Connected [{0}]", _workerSockets.Count); _mainSocket.BeginAccept(new AsyncCallback(OnClientConnect), null); } catch (ObjectDisposedException) { _log.Error("OnClientConnection: Socket has been closed\n"); } catch (SocketException se) { _log.Error("Socket Exception", se); } } public class SocketPacket { private System.Net.Sockets.Socket _currentSocket; public System.Net.Sockets.Socket CurrentSocket { get { return _currentSocket; } set { _currentSocket = value; } } private byte[] _dataBuffer = new byte[1]; public byte[] DataBuffer { get { return _dataBuffer; } set { _dataBuffer = value; } } } private void WaitForData(Socket workerSocket) { _log.Debug("Entering WaitForData"); try { lock (this) { if (_workerCallback == null) { _log.Debug("Initializing worker callback to OnDataRecieved"); _workerCallback = new AsyncCallback(OnDataRecieved); } } SocketPacket socketPacket = new SocketPacket(); socketPacket.CurrentSocket = workerSocket; workerSocket.BeginReceive(socketPacket.DataBuffer, 0, socketPacket.DataBuffer.Length, SocketFlags.None, _workerCallback, socketPacket); } catch (SocketException se) { _log.Error("Socket Exception", se); } } public void OnDataRecieved(IAsyncResult asyn) { SocketPacket socketData = (SocketPacket)asyn.AsyncState; try { int iRx = socketData.CurrentSocket.EndReceive(asyn); char[] chars = new char[iRx + 1]; _log.DebugFormat("Created Char array to hold incomming data. [{0}]",iRx+1); System.Text.Decoder decoder = System.Text.Encoding.UTF8.GetDecoder(); int charLength = decoder.GetChars(socketData.DataBuffer, 0, iRx, chars, 0); _log.DebugFormat("Read [{0}] characters",charLength); String data = new String(chars); _log.DebugFormat("Read in String \"{0}\"",data); WaitForData(socketData.CurrentSocket); } catch (ObjectDisposedException) { _log.Error("OnDataReceived: Socket has been closed. Removing Socket"); _workerSockets.Remove(socketData.CurrentSocket); } catch (SocketException se) { _log.Error("SocketException:",se); _workerSockets.Remove(socketData.CurrentSocket); } } This I thought was going to be a good basis for what I wanted to do, but the code I have appended the incoming characters to a text box one by one and didn't do anything with it. Which doesn't really work for what I want to do. My main issue is the decoupling of the OnDataReceived method from the Wait for data method. which means I'm having issues building a string (I would use a string builder but I can accept multiple connections so that doesn't really work. Ideally I'd like to look while listening to a socket until I see and end of line character and then call a method with the resulting string as a parameter. What's the best way to go about doing this.

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  • C# Asynchronous Network IO and OutOfMemoryException

    - by The.Anti.9
    I'm working on a client/server application in C#, and I need to get Asynchronous sockets working so I can handle multiple connections at once. Technically it works the way it is now, but I get an OutOfMemoryException after about 3 minutes of running. MSDN says to use a WaitHandler to do WaitOne() after the socket.BeginAccept(), but it doesn't actually let me do that. When I try to do that in the code it says WaitHandler is an abstract class or interface, and I can't instantiate it. I thought maybe Id try a static reference, but it doesnt have teh WaitOne() method, just WaitAll() and WaitAny(). The main problem is that in the docs it doesn't give a full code snippet, so you can't actually see what their "wait handler" is coming from. its just a variable called allDone, which also has a Reset() method in the snippet, which a waithandler doesn't have. After digging around in their docs, I found some related thing about an AutoResetEvent in the Threading namespace. It has a WaitOne() and a Reset() method. So I tried that around the while(true) { ... socket.BeginAccept( ... ); ... }. Unfortunately this makes it only take one connection at a time. So I'm not really sure where to go. Here's my code: class ServerRunner { private Byte[] data = new Byte[2048]; private int size = 2048; private Socket server; static AutoResetEvent allDone = new AutoResetEvent(false); public ServerRunner() { server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); IPEndPoint iep = new IPEndPoint(IPAddress.Any, 33333); server.Bind(iep); Console.WriteLine("Server initialized.."); } public void Run() { server.Listen(100); Console.WriteLine("Listening..."); while (true) { //allDone.Reset(); server.BeginAccept(new AsyncCallback(AcceptCon), server); //allDone.WaitOne(); } } void AcceptCon(IAsyncResult iar) { Socket oldserver = (Socket)iar.AsyncState; Socket client = oldserver.EndAccept(iar); Console.WriteLine(client.RemoteEndPoint.ToString() + " connected"); byte[] message = Encoding.ASCII.GetBytes("Welcome"); client.BeginSend(message, 0, message.Length, SocketFlags.None, new AsyncCallback(SendData), client); } void SendData(IAsyncResult iar) { Socket client = (Socket)iar.AsyncState; int sent = client.EndSend(iar); client.BeginReceive(data, 0, size, SocketFlags.None, new AsyncCallback(ReceiveData), client); } void ReceiveData(IAsyncResult iar) { Socket client = (Socket)iar.AsyncState; int recv = client.EndReceive(iar); if (recv == 0) { client.Close(); server.BeginAccept(new AsyncCallback(AcceptCon), server); return; } string receivedData = Encoding.ASCII.GetString(data, 0, recv); //process received data here byte[] message2 = Encoding.ASCII.GetBytes("reply"); client.BeginSend(message2, 0, message2.Length, SocketFlags.None, new AsyncCallback(SendData), client); } }

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  • Help with Silverlight Sockets and Message delivery

    - by pixel3cs
    There are 4 months since I stopped developing my Silverlight Multiplayer Chess game. The problem was a bug wich I couldn't reproduce. Sice I got some free time this week I managed to discover the problem and I am now able to reproduce the bug. It seems that if I send 10 messages from client, one after another, with no delay between them, just like in the below example // when I press Enter, the client will 10 messages with no delay between them private void textBox_KeyDown(object sender, KeyEventArgs e) { if (e.Key == Key.Enter && textBox.Text.Length > 0) { for (int i = 0; i < 10; i++) { MessageBuilder mb = new MessageBuilder(); mb.Writer.Write((byte)GameCommands.NewChatMessageInTable); mb.Writer.Write(string.Format("{0}{2}: {1}", ClientVars.PlayerNickname, textBox.Text, i)); SendChatMessageEvent(mb.GetMessage()); //System.Threading.Thread.Sleep(100); } textBox.Text = string.Empty; } } // the method used by client to send a message to server public void SendData(Message message) { if (socket.Connected) { SocketAsyncEventArgs myMsg = new SocketAsyncEventArgs(); myMsg.RemoteEndPoint = socket.RemoteEndPoint; byte[] buffer = message.Buffer; myMsg.SetBuffer(buffer, 0, buffer.Length); socket.SendAsync(myMsg); } else { string err = "Server does not respond. You are disconnected."; socket.Close(); uiContext.Post(this.uiClient.ProcessOnErrorData, err); } } // the method used by server to receive data from client private void OnDataReceived(IAsyncResult async) { ClientSocketPacket client = async.AsyncState as ClientSocketPacket; int count = 0; try { if (client.Socket.Connected) count = client.Socket.EndReceive(async); // THE PROBLEM IS HERE // IF SERVER WAS RECEIVE ALL MESSAGES SEPARATELY, ONE BY ONE, THE COUNT // WAS ALWAYS 15, BUT BECAUSE THE SERVER RECEIVE 3 MESSAGES IN 1, THE COUNT // IS SOMETIME 45 } catch { HandleException(client); } client.MessageStream.Write(client.Buffer, 0, count); Message message; while (client.MessageStream.Read(out message)) { message.Tag = client; ThreadPool.QueueUserWorkItem(new WaitCallback(this.processingThreadEvent.ServerGotData), message); totalReceivedBytes += message.Buffer.Length; } try { if (client.Socket.Connected) client.Socket.BeginReceive(client.Buffer, 0, client.Buffer.Length, 0, new AsyncCallback(OnDataReceived), client); } catch { HandleException(client); } } there are sent only 3 big messages, and every big message contain 3 or 4 small messages. This is not the behavior I want. If I put a 100 milliseconds delay between message delivery, everything is work fine, but in a real world scenario users can send messages to server even at 1 millisecond between them. Are there any settings to be done in order to make the client send only one message at a time, or Even if I receive 3 messages in 1, are they full messages all the time (I dont't want to receive 2.5 messages in one big message) ? because if they are, I can read them and treat this new situation

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