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POWait until the complete message has arrived
 

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  1. POWait until the complete message has arrived
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    <p>I have to integrate 2 systems in a project with TCP communication - a custom protocol was developed. </p> <p>A message sent over the protocol will look as follows:</p> <pre><code>MsgLength - 10 positions (in chars, not bytes) MessageType - 20 positions Message Number - 9 positions Timestamp - 19 positions version - 2 positions Body - variable (depending on first field) </code></pre> <p>I am looking into Socket programming but I am wondering what's the best approach to wait for the complete msg to arrive. Probably I need to do a conversion of bytes to number of characters left. Because the socket API only works with bytes.</p> <p>All tips, code samples, blog posts are welcome :-)</p> <p>Edit: This is my first version of my code, I am using Async methods because multiple clients can connect at the same time. </p> <pre><code> private static void Listen() { while (true) { //TcpClient client = _listener.AcceptTcpClient(); allDone.Reset(); _listener.BeginAcceptTcpClient(new AsyncCallback(AcceptCallback), _listener); allDone.WaitOne(); } } public static void AcceptCallback(IAsyncResult ar) { // Signal the main thread to continue. allDone.Set(); // Get the socket that handles the client request. //TcpListener listener = (TcpListener)ar.AsyncState; TcpClient handler = _listener.EndAcceptTcpClient(ar); // Create the state object. StateObject state = new StateObject(); state.client = handler; handler.GetStream().BeginRead(state.buffer, 0, StateObject.BufferSize, new AsyncCallback(ReadCallback), state); } public static void ReadCallback(IAsyncResult ar) { String content = String.Empty; Encoding enc = Encoding.GetEncoding("ISO-8859-1"); // Retrieve the state object and the handler socket // from the asynchronous state object. StateObject state = (StateObject)ar.AsyncState; TcpClient handler = state.client; int bytesRead = handler.GetStream().EndRead(ar); state.TotalHeaderBytesRead += bytesRead; if (bytesRead == 60) { string header = enc.GetString(state.buffer); Header h = HeaderParser.Parse(header); //todo read the body byte[] bodyBuffer = new byte[((HeaderPlaPo)h).Length - 60]; state.buffer = bodyBuffer; handler.GetStream().BeginRead(state.buffer, 0, bodyBuffer.Length, new AsyncCallback(ReadBodyCallback), state); Logger.Log(string.Format("received header {0}", header), System.Diagnostics.TraceLevel.Info); } else { // Not all data of header received. Get more. handler.GetStream().BeginRead(state.buffer, 0, StateObject.BufferSize - state.TotalHeaderBytesRead, new AsyncCallback(ReadHeaderCallback), state); } } public static void ReadBodyCallback(IAsyncResult ar) { Encoding enc = Encoding.GetEncoding("ISO-8859-1"); // Retrieve the state object and the handler socket // from the asynchronous state object. StateObject state = (StateObject)ar.AsyncState; TcpClient handler = state.client; int bytesRead = handler.GetStream().EndRead(ar); int bytesRead = handler.GetStream().EndRead(ar); state.TotalBodyBytesRead += bytesRead; if (state.buffer.Length == state.TotalBodyBytesRead) </code></pre> <p>{ //todo we received all string body = enc.GetString(state.buffer); Logger.Log(string.Format("received body {0}", body), System.Diagnostics.TraceLevel.Info); } else { handler.GetStream().BeginRead(state.buffer, bytesRead, state.buffer.Length - state.TotalBodyBytesRead, ReadBodyCallback, state); } }</p> <p>public class StateObject { // Client socket. public TcpClient client = null; // Size of receive buffer. public static int BufferSize = 60; // Receive buffer. public byte[] buffer = new byte[BufferSize]; // Received data string public StringBuilder sb = new StringBuilder(); //Header public Header header; public Body body; public Int32 TotalBodyBytesRead; public Int32 TotalHeaderBytesRead; }</p> <p>This code works for clients that send data and close the connection, but when using a connected client to send multiple times, the data is not read -> should I close the connection after reading the complete body? </p>
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    1. USmsjonathan
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    1. COPlease explain what you mean by "positions" (positions are chars, not bytes??? What does this mean?)
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    2. COPositions are chars e.g. MsgLengt: "0000012345"
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      1. USmsjonathan
 

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