Develop Reference

Creating a Socket Connection in Store App not Working

I have just released an app to the Windows Phone Store, after thoroughly debugging, and the functionality when testing in debug and release mode is not the same as when I use the app that was downloaded from the store. When testing in debug and release mode from my solution I have no issues (on device or on emulator) and everything works great. After downloading from the store I only return the SocketError.NetworkDown error?
I am creating a Socket connection to gather network interface information.
private async void UpdateCurrentInterface()
{
Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
// To run this application you should specify the name of a server on your network that is running
// the required service.
string serverName = "www.bing.com";
// This identifies the port over which to communicate.
int portNumber = 80;
// Create DnsEndPoint.
DnsEndPoint hostEntry = new DnsEndPoint(serverName, portNumber);
// Create a SocketAsyncEventArgs object to be used in the connection request.
SocketAsyncEventArgs socketEventArg = new SocketAsyncEventArgs();
socketEventArg.RemoteEndPoint = hostEntry;
socketEventArg.UserToken = socket;
socketEventArg.Completed += ShowNetworkInterfaceInformation1;
// // Make an asynchronous Connect request over the socket.
socket.ConnectAsync(socketEventArg);
}
/// <summary>
/// Display the network information using the GetCurrentNetworkInterface extension method on the socket.
/// </summary>
/// <remarks>This is the callback from the ConnectAsync method.</remarks>
private void ShowNetworkInterfaceInformation1(object s, SocketAsyncEventArgs e)
{
// When ConnectAsync was called it was passed the socket object in
// the UserToken field of the socketEventArg. This context is retrieved once
// the ConnectAsync has completed.
Socket socket = e.UserToken as Socket;
// Only call GetCurrentNetworkInterface if the connection was successful.
if (e.SocketError == SocketError.Success)
{
NetworkInterfaceInfo netInterfaceInfo = socket.GetCurrentNetworkInterface();
// We are making UI updates, so make sure these happen on the UI thread.
Dispatcher.BeginInvoke(() =>
{
currentTypeTextBlock.Text = GetInterfaceTypeString(netInterfaceInfo.InterfaceType);
currentNameTextBlock.Text = name = netInterfaceInfo.InterfaceName;
string change = "";
if (netInterfaceInfo.InterfaceState.ToString() == "Connected")
currentStateTextBlock.Text = "connected";
else
currentStateTextBlock.Text = "disconnected";
});
}
else if (e.SocketError == SocketError.NetworkDown)
{
DisplayMessage("Could not connect.", "Network Down Error", MessageBoxButton.OK);
}
// Close our socket since we no longer need it.
socket.Close();
}

Include ID_CAP_NETWORKING as a capability within WMAppManifest.

Multithreading: passing different custom control properties between threads (or using them asynchronously)

I'm trying to develop a project where I can have multiple clients making their own server requests for the purpose of stress testing. I'm having a lot of difficulty figuring out how I can manipulate custom control properties when I make a new thread and want that thread to do the work. I have upwards of 100 controls; so ideally 100 individual clients. The problem is my controls are part of the GUI and I don't know how to allow that thread in question get access from that relative control.
Here's what I have:
// Custom project.class to get access to a custom base of properties created within the tool itself.
List<custom_control_project.custom_control_widget> controlList = new List<custom_control_project.custom_control_widget>();
private async void btnStart_Click(object sender, EventArgs e)
{
...// control property initializations
foreach (var control in controlList)
{
if (control.Enabled)
{
Thread thread = new Thread(() => StartClient());
thread.Start();
// Loop until worker thread activates.
while (!thread.IsAlive);
... // Ideally the GUI updates would happen from these threads. Simple updates to labels based on status code responses and expected xml parameters received.
}
}
My StartClient() is largely based off Microsofts asynchronous socket client example here: http://msdn.microsoft.com/en-us/library/bew39x2a%28v=vs.110%29.aspx
I was running these clients asynchronously but the program was not my end result. I have made a few changes, including resetting the ManualResetEvents. However, when I run my application, all the controls still run one after the other, and I'd like them to be independent. Do I have the right approach by making new threads with the StartClient()?
Referencing microsofts example, the part I'm most interested in is the ReceiveCallback(IAsyncResult ar) method:
public class StateObject
{
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 1024;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
}
// ManualResetEvent instances signal completion.
private ManualResetEvent connectDone =
new ManualResetEvent(false);
private ManualResetEvent sendDone =
new ManualResetEvent(false);
private ManualResetEvent receiveDone =
new ManualResetEvent(false);
// The response from the remote device.
private String response = String.Empty;
public void StartClient()
{
// Connect to a remote device.
try
{
// Establish the remote endpoint for the socket.
// The name of the
// remote device is "host.contoso.com".
//IPHostEntry ipHostInfo = Dns.Resolve("host.contoso.com");
//IPAddress ipAddress = ipHostInfo.AddressList[0];
//IPEndPoint remoteEP = new IPEndPoint(ipAddress, port);
// Create a TCP/IP socket.
Socket client = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Connect to the remote endpoint.
client.BeginConnect(asyncServerHolder, asyncPortHolder,
new AsyncCallback(ConnectCallback), client);
connectDone.WaitOne();
// Send test data to the remote device.
Send(client, (Upload)); //POST HTTP string + xml parameters
sendDone.WaitOne();
// Receive the response from the remote device.
Receive(client);
receiveDone.WaitOne();
// Write the response to the console.
//MessageBox.Show("Response received : " + response);
// Release the socket.
client.Shutdown(SocketShutdown.Both);
client.Close();
// Reset all manual events for next instance.
connectDone.Reset();
sendDone.Reset();
receiveDone.Reset();
}
catch (Exception)
{
//MessageBox.Show(e.ToString());
}
}
private void ConnectCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket client = (Socket)ar.AsyncState;
// Complete the connection.
client.EndConnect(ar);
//MessageBox.Show("Socket connected to " + client.RemoteEndPoint.ToString());
// Signal that the connection has been made.
connectDone.Set();
}
catch (Exception)
{
//MessageBox.Show(e.ToString());
}
}
private void Receive(Socket client)
{
try
{
// Create the state object.
StateObject state = new StateObject();
state.workSocket = client;
// Begin receiving the data from the remote device.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
catch (Exception)
{
//MessageBox.Show(e.ToString());
}
}
private void ReceiveCallback(IAsyncResult ar)
{
try
{
// Retrieve the state object and the client socket
// from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket client = state.workSocket;
// Read data from the remote device.
int bytesRead = client.EndReceive(ar);
if (bytesRead > 0)
{
// There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));
// Get the rest of the data.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
else
{
// All the data has arrived; put it in response.
if (state.sb.Length > 1)
{
response1 = state.sb.ToString();
///
///
/// **THIS IS WHERE I WANT ALL THE PROCESSING TO BE DONE**
/// **AFTER THE RESPONSE IS COMPLETE!!**
///
///
}
// Signal that all bytes have been received.
receiveDone.Set();
}
}
catch (Exception)
{
//MessageBox.Show(e.ToString());
}
}
private void Send(Socket client, String data)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);
// Begin sending the data to the remote device.
client.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), client);
}
private void SendCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket client = (Socket)ar.AsyncState;
// Complete sending the data to the remote device.
int bytesSent = client.EndSend(ar);
//MessageBox.Show("Sent " + bytesSent + " bytes to server.");
// Signal that all bytes have been sent.
sendDone.Set();
}
catch (Exception)
{
//MessageBox.Show(e.ToString());
}
}
How am I able to get the relative control from my foreach statement passed into the method and then amend my GUI (invoking somehow?) based on the outcome? Also, is it even possible to make each client independent, and have multiple client to server to client requests simultaneously? That is my main objective.
If this is a far fetched or very discouraged way of attempting this, please say so. Without diving into too much programming jargon (for understanding purposes, I'm fairly new to programming), how would you go about doing this?
Thanks in advance!

Well, you can sort of manipulate any control from a different thread by using the BeginInvoke function on the control, passing the action you want to execute. The action will be executed on the UI thread.
But your main problem here is that you're failing to separate the concerns. You UI code can for sure make actions happen, but these actions should be distinct from any UI code. You should design your actions in such a way to make them reusable. In other words, if you decide to rewrite your UI from scratch, you should still be able to reuse your actions as-is.
To make this possible, your actions should not reference any UI, they even should not be aware of the existence of any UI. This will make your code more manageable. So extract all that stuff in a different class, and then use something like events for instance to communicate back with the UI. The UI code then would make the BeginInvoke call.

TCP server in C# causing 100% CPU usage after 2-3 days

Here's my code for a very simple TCP Server (basically the sample Asynchronous Server Socket example - http://goo.gl/Ix5C - modified slightly):
public static void InitiateListener()
{
try
{
allDone = new ManualResetEvent(false);
configFile = new XmlConfig();
StartListening();
}
catch (Exception exc)
{
LogsWriter f = new LogsWriter(configFile.ErrorLogsPath);
f.WriteToFile(exc.Message);
f.CloseFile();
}
}
private static void StartListening()
{
try
{
IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Any, configFile.Port);
Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
listener.Bind(localEndPoint);
listener.Listen(100);
while (true)
{
// Set the event to nonsignaled state.
allDone.Reset();
// Start an asynchronous socket to listen for connections.
listener.BeginAccept(new AsyncCallback(AcceptCallback), listener);
// Wait until a connection is made before continuing.
allDone.WaitOne();
}
}
catch (Exception exc)
{
throw exc;
}
}
public static void AcceptCallback(IAsyncResult ar)
{
allDone.Set(); // Signal the main thread to continue.
// Get the socket that handles the client request.
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);
// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state);
}
public static void ReadCallback(IAsyncResult ar)
{
string hexData = string.Empty;
// Retrieve the state object and the handler socket from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket handler = state.workSocket;
try
{
// Read data from the client socket.
int bytesRead = handler.EndReceive(ar);
if (bytesRead > 0)
{
hexData = BitConverter.ToString(state.buffer);
if (hexData.Contains("FA-F8")) //heartbeat - echo the data back to the client.
{
byte[] byteData = state.buffer.Take(bytesRead).ToArray();
handler.Send(byteData);
}
else if (hexData.Contains("0D-0A")) //message
{
state.AsciiData = Encoding.ASCII.GetString(state.buffer, 0, bytesRead);
state.ParseMessage(configFile);
}
}
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state);
}
catch (Exception)
{
handler.Shutdown(SocketShutdown.Both);
handler.Close();
}
}
This is all in a Windows service. And the CPU maxes to 100% after about 2 and a half days of running perfectly acceptably. This has happened 3 times now - the windows service always works fine and functions as it's supposed to, utlizing almost no CPU resources but sometime on the 3rd day goes to 100% and stays there until the service is resarted.
I get very simple CSV packets, that I parse quickly and send it off to a database via a webservice in this method:
state.ParseMessage(configFile);
Even when the CPU is 100%, the database gets filled up pretty reliably. But I understand this could be one place where I need to investigate?
Which other areas of the code seem like they could be causing the problem? I'm new to async programming, so I don't know if I need to close threads manually. Also, this might be another problem:
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state);
Calling that line within ReadCallback itself. I do this to maintain the connection with the client and continue to receive the data, but maybe I should close to the socket and force a new connection?
Could you please offer some suggestions? Thanks

Instead of loop while(true) in startlistening method we need to call
listener.BeginAccept(new AsyncCallback(AcceptCallback), listener);
from AcceptCallback method once completion of accepting new client.

You need to detect disconnection through bytesRead == 0. Right now you don't and instead issue another read.
Looks like you have copied MSDN sample code. I can tell because of the insightless combination of async IO and events. All this code becomes simpler when you use synchronous IO.

Socket Programming multiple client one server

I am just starting out Socket Programming in C# and am now a bit stuck with this problem.
How do you handle multiple clients on a single server without creating a thread for each client?
The one thread for each client works fine when there are say 10 clients but if the client number goes up to a 1000 clients is creating a thread for every single one of them advisable? If there is any other method to do this can someone please tel me?

Try to use asynchronous server.
The following example program creates a server that receives connection requests from clients. The server is built with an asynchronous socket, so execution of the server application is not suspended while it waits for a connection from a client. The application receives a string from the client, displays the string on the console, and then echoes the string back to the client. The string from the client must contain the string <EOF> to signal the end of the message.
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
// State object for reading client data asynchronously
public class StateObject {
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 1024;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
}
public class AsynchronousSocketListener {
// Thread signal.
public static ManualResetEvent allDone = new ManualResetEvent(false);
public AsynchronousSocketListener() {
}
public static void StartListening() {
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];
// Establish the local endpoint for the socket.
// The DNS name of the computer
// running the listener is "host.contoso.com".
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);
// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp );
// Bind the socket to the local endpoint and listen for incoming connections.
try {
listener.Bind(localEndPoint);
listener.Listen(100);
while (true) {
// Set the event to nonsignaled state.
allDone.Reset();
// Start an asynchronous socket to listen for connections.
Console.WriteLine("Waiting for a connection...");
listener.BeginAccept(
new AsyncCallback(AcceptCallback),
listener );
// Wait until a connection is made before continuing.
allDone.WaitOne();
}
} catch (Exception e) {
Console.WriteLine(e.ToString());
}
Console.WriteLine("\nPress ENTER to continue...");
Console.Read();
}
public static void AcceptCallback(IAsyncResult ar) {
// Signal the main thread to continue.
allDone.Set();
// Get the socket that handles the client request.
Socket listener = (Socket) ar.AsyncState;
Socket handler = listener.EndAccept(ar);
// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive( state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
public static void ReadCallback(IAsyncResult ar) {
String content = String.Empty;
// Retrieve the state object and the handler socket
// from the asynchronous state object.
StateObject state = (StateObject) ar.AsyncState;
Socket handler = state.workSocket;
// Read data from the client socket.
int bytesRead = handler.EndReceive(ar);
if (bytesRead > 0) {
// There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(
state.buffer,0,bytesRead));
// Check for end-of-file tag. If it is not there, read
// more data.
content = state.sb.ToString();
if (content.IndexOf("<EOF>") > -1) {
// All the data has been read from the
// client. Display it on the console.
Console.WriteLine("Read {0} bytes from socket. \n Data : {1}",
content.Length, content );
// Echo the data back to the client.
Send(handler, content);
} else {
// Not all data received. Get more.
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
}
}
private static void Send(Socket handler, String data) {
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);
// Begin sending the data to the remote device.
handler.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), handler);
}
private static void SendCallback(IAsyncResult ar) {
try {
// Retrieve the socket from the state object.
Socket handler = (Socket) ar.AsyncState;
// Complete sending the data to the remote device.
int bytesSent = handler.EndSend(ar);
Console.WriteLine("Sent {0} bytes to client.", bytesSent);
handler.Shutdown(SocketShutdown.Both);
handler.Close();
} catch (Exception e) {
Console.WriteLine(e.ToString());
}
}
public static int Main(String[] args) {
StartListening();
return 0;
}
}
That's will be the best solution.

Threads can work fine but rarely scales well to that many clients. There are two easy ways and lots of more complex ways to handle that, here's some pseudocode for how the easier two are usually structured to give you an overview.
select()
This is a call to check which sockets have new clients or data waiting on them, a typical program looks something like this.
server = socket(), bind(), listen()
while(run)
status = select(server)
if has new client
newclient = server.accept()
handle add client
if has new data
read and handle data
Which means no threads are needed to handle multiple clients, but it doesn't really scale well either if handle data take a long time, then you won't read new data or accept new clients until that's done.
Async sockets
This is another way of handling sockets which is kind of abstracted above select. You just set up callbacks for common events and let the framework do the not-so-heavy lifting.
function handleNewClient() { do stuff and then beginReceive(handleNewData) }
function handleNewData() { do stuff and then beginReceive(handleNewData) }
server = create, bind, listen etc
server.beginAddNewClientHandler(handleNewClient)
server.start()
I think this should scale better if your data handling take a long time. What kind of data handling will you be doing?

This could be a good starting point. If you want to avoid 1 thread <-> 1 client; then you should use async socket facilities provided in .NET. Core object to use here is SocketAsyncEventArgs.

C#: Crash on ManualResetEvent

I wrote my code using this article at msdn as a primary helper
My code:
private ManualResetEvent _AllDone = new ManualResetEvent(false);
internal void Initialize(int port,string IP)
{
IPEndPoint _Point = new IPEndPoint(IPAddress.Parse(IP), port);
Socket _Accpt = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
_Accpt.Bind(_Point);
_Accpt.Listen(2);
while (true)
{
_AllDone.Reset();
_Accpt.BeginAccept(null, 0, new AsyncCallback(Accept), _Accpt);
_AllDone.WaitOne(); <<crash here
}
}
This is what happens,I set a breakpoint at BeginAccept(I thought there's the problem),but it steps it normally.However,when I try to step "_AllDone.WaitOne()" - the server crash.
If _allDone can't be used in a win32 form application - how do I make my project?
EDIT
I forgot to mention I wrote _AllDone.Reset() in Accept(),but It doesn't go there,I set a breakpoint there,but it won't go.
private void Accept(IAsyncResult async)
{
_AllDone.Set();
Socket _Accpt = (Socket)async.AsyncState;
Socket _Handler = _Accpt.EndAccept(async);
StateObject _State = new StateObject();
_State.workSocket = _Handler;
_Handler.BeginReceive(_State.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), _State);
}

So if I get it right, you want to re-start Accept as soon as a socket connection is received, and not wait until Accept is done, and that's why you don't use the sync version of Accept.
So you are saying that it does not fire your Accept method when you connect a socket to the specified address and port? Because that's what Accept does: it accepts a new incoming connection, waiting until a client connects. So that may be why you are thinking that it "crashed" and why it never reaches your code in your Accept method.
Hint: maybe also have a look at Socket.AcceptAsync
Edit: To set up an async server listening to incoming connections, you don't need any ManualWaitEvent:
internal void Initialize(int port,string IP) {
IPEndPoint _Point = new IPEndPoint(IPAddress.Parse(IP), port);
Socket _Accpt = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
_Accpt.Bind(_Point);
_Accpt.Listen(2);
_Accpt.BeginAccept(null, 0, new AsyncCallback(Accept), _Accpt);
}
private void Accept(IAsyncResult async) {
Socket _Accpt = (Socket)async.AsyncState;
Socket _Handler;
try {
_Handler = _Accpt.EndAccept(async);
} finally {
_Accpt.BeginAccept(null, 0, new AsyncCallback(Accept), _Accpt);
}
StateObject _State = new StateObject();
_State.workSocket = _Handler;
_Handler.BeginReceive(_State.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), _State);
}
Note: You will also need an exit condition, so that the BeginAccept is not called (for instance when you want to shut down the server).

I think that Lucero is trying to say, that the application works normally, you may ask how come.
Well when you are using a server side socket application, what you basically do is to ask the server to liseten to a port and wait for a conection to arrive. when the connection arrives then you do the rest of the code.
What Lucero was saying is, that while no message is arriving to the server the server keeps lisetning and waiting, which might look for you as if it's freezes.
Is it the case in your code?