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How to communicate between two Unity apps with TCP?

Update
I figured out what the problem was. I was trying to move too much data over TCP, and it was causing freeze-ups. For some reason, this wasn't manifesting in the editor...who knows for what reason. If anyone else stumbles upon this problem (in a program like Unity, where functions are looping constantly and data is always being processed), consider that you're moving too much irrelevant data.
Original Post
I've run into quite the problem, and I'm hoping I can receive some guidance.
In short, I'm wondering how to use TCP to communicate two Unity apps over the same computer. I've gotten it functioning in editor, but when both apps are built, communication quickly breaks down.
This is really stumping me, because I don't understand why an app would work in the Editor environment, but not in the official build.
When I use TCP to communicate between two Unity apps (on the same computer), it works so long as one of them is kept in the Unity environment. That is, if I build one app, and open the other in the Unity editor, TCP communication works flawlessly.
Here is some more background: One of my apps is functioning as a User Interface, and the other is interfacing with a Looking Glass to provide a holographic display of in-game objects. Originally, they were combined into one App - but I had a lot of trouble getting Unity's multidisplay support to function between two monitors of different resolutions. Looking Glass factory even provides a prefab to do just this, but it is broken in the current SDK. So I have resorted to using sockets to interface between two apps, one for each monitor.
I'm using C#'s TCP listener class: https://learn.microsoft.com/en-us/dotnet/api/system.net.sockets.tcplistener?view=netframework-4.8
And TCP client class: https://learn.microsoft.com/en-us/dotnet/api/system.net.sockets.tcpclient?view=netframework-4.8
Presently, the UI is acting as the TCPListener, and the application that produces holograms is the TCPClient. Within each of these applications, I'm using two Queues - an IncomingMessages queue and an Outgoing Messages queue - which are global variables shared between the main thread and the networking thread.
TCP Listener:
private void Start()
{
incomingMessages = new Queue();
outgoingMessages = new Queue();
Application.runInBackground = true;
thread = new Thread(new ThreadStart(Receive));
thread.Start();
//stuff happens that's irrelevant to this question. And then...
}
void Receive()
{
TcpListener server = null;
try
{
// Set the TcpListener on port 13000.
Int32 port = 13000;
IPAddress localAddr = IPAddress.Parse("127.0.0.1");
// TcpListener server = new TcpListener(port);
server = new TcpListener(localAddr, port);
// Start listening for client requests.
server.Start();
// Buffer for reading data
Byte[] bytes = new Byte[256];
String data = null;
// Enter the listening loop.
Debug.Log("About to reenter main while in Server...");
while (threadContinue)
{
Debug.Log("Waiting for a connection... ");
// Perform a blocking call to accept requests.
// You could also user server.AcceptSocket() here.
TcpClient client = server.AcceptTcpClient();
Debug.Log("Connected!");
data = null;
// Get a stream object for reading and writing
NetworkStream stream = client.GetStream();
int i;
// Loop to receive all the data sent by the client.
while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
{
// Translate data bytes to a ASCII string.
data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
Debug.Log("Received from Client: " + data);
lock (this)
incomingMessages.Enqueue(data);
string response = supplyData();
byte[] msg = System.Text.Encoding.ASCII.GetBytes(response);
// Send back a response.
stream.Write(msg, 0, msg.Length);
Debug.Log("Sent to Client: " + response);
}
// Shutdown and end connection
client.Close();
}
}
catch (SocketException e)
{
Debug.Log("SocketException: ");
Debug.Log(e);
}
finally
{
// Stop listening for new clients.
server.Stop();
}
Debug.Log("Exiting 'Receive'");
}
And here is the TCP Client. It attempts to connect a regular intervals, and also whenever new data is available. This is so that it can receive information from the server regularly and share new data whenever it is available:
void Start()
{
//prepare networking
Application.runInBackground = true;
outgoingMessages = new Queue();
incomingMessages = new Queue();
thread = new Thread(new ThreadStart(Connect));
thread.Start();
//stuff happens that's irrelevant to this question...
}
private void Connect()
{
String server = "127.0.0.1";
Int32 port = 13000;
string message = "";
while (threadContinue == true)
{
if (timeToConnect())
{
lastConnection = ourTime;
if (outgoingMessages.Count > 0)
message = outgoingMessages.Dequeue().ToString();
else
message = "Nothing to report.";
try
{
// Create a TcpClient.
// Note, for this client to work you need to have a TcpServer
// connected to the same address as specified by the server, port
// combination.
client = new TcpClient(server, port);
// Translate the passed message into ASCII and store it as a Byte array.
Byte[] data = System.Text.Encoding.ASCII.GetBytes(message);
// Get a client stream for reading and writing.
// Stream stream = client.GetStream();
stream = client.GetStream();
// Send the message to the connected TcpServer.
stream.Write(data, 0, data.Length);
Debug.Log("Sent to Server: " + message);
// Buffer to store the response bytes.
data = new Byte[256];
// String to store the response ASCII representation.
String responseData = String.Empty;
// Read the first batch of the TcpServer response bytes.
Int32 bytes = stream.Read(data, 0, data.Length);
responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes);
lock (this)
incomingMessages.Enqueue(responseData);
Debug.Log("Received from Server: " + responseData);
stream.Close();
client.Close();
}
catch (ArgumentNullException e)
{
Debug.Log("ArgumentNullException: ");
Debug.Log(e);
outgoingMessages.Enqueue(message);
}
catch (SocketException e)
{
Debug.Log("SocketException: ");
Debug.Log(e);
outgoingMessages.Enqueue(message);
}
}
}
}
private bool timeToConnect()
{
if ((ourTime - lastConnection > NETWORK_DELAY) || (outgoingMessages.Count > 0))
return true;
return false;
}
Instantiated in separate threads so that Unity's main thread can continue unhindered.
Again - it works in Editor, but when I build it, it breaks.

Update
I figured out what the problem was. I was trying to move too much data over TCP, and it was causing freeze-ups. For some reason, this wasn't manifesting in the editor...just in the exported app. Who knows for what reason. If anyone else stumbles upon this problem...where you're bypassing Unity's multidisplay functionality by building multiple apps that communicate over network...consider that you're burdening your queues with too much data.

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.

TCPClient not receiving data

I want to use StreamReader and StreamWriter to receive and send data over TCPClient.NetworkStream. The code is depicted below:
Client code:
using (TcpClient client = new TcpClient())
{
IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 9001);
client.Connect(localEndPoint);
client.NoDelay = true;
using(NetworkStream stream = client.GetStream())
{
using (StreamWriter writer = new StreamWriter(stream))
{
writer.AutoFlush = true;
using (StreamReader reader = new StreamReader(stream))
{
string message = "Client says: Hello";
writer.WriteLine(message);
// If I comment the line below, the server receives the first message
// otherwise it keeps waiting for data
string response = reader.ReadToEnd();
Console.WriteLine(response);
}
;
}
}
}
Note: If I comment the reader.ReadToEnd(); then the server receives the message, otherwise the server keeps waiting for data from the client. Is ReadToEnd the problem?
Server code accepts a connection asynchronously, but handles the data in a synchronous manner:
class Program
{
private static AsyncCallback tcpClientCallback;
static void Main(string[] args){
IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"),9001);
TcpListener listener = new TcpListener(localEndPoint);
listener.Start();
tcpClientCallback = new AsyncCallback(ConnectCallback);
AcceptConnectionsAysnc(listener);
Console.WriteLine("Started Aysnc TCP listener, press any key to exit (server is free to do other tasks)");
Console.ReadLine();
}
private static void AcceptConnectionsAysnc(TcpListener listener)
{
listener.BeginAcceptTcpClient(tcpClientCallback, listener);
}
static void ConnectCallback(IAsyncResult result)
{
Console.WriteLine("Received a conenct request");
TcpListener listener = (TcpListener)result.AsyncState;
// We are starting a thread which waits to receive the data
// This is not exactly scalable
Task recieveTask = new Task(() => { HandleRecieve(result, listener); });
recieveTask.Start();
AcceptConnectionsAysnc(listener);
}
// This makes a blocking call - that means until the client is ready to
// send some data the server waits
private static void HandleRecieve(IAsyncResult result, TcpListener listener)
{
Console.WriteLine("Waiting for data");
using (TcpClient client = listener.EndAcceptTcpClient(result))
{
client.NoDelay = true;
using (NetworkStream stream = client.GetStream())
{
using (StreamReader reader = new StreamReader(stream))
{
using (StreamWriter writer = new StreamWriter(stream))
{
writer.AutoFlush = true;
Stopwatch watch = new Stopwatch();
watch.Start();
string data = reader.ReadToEnd();
watch.Stop();
Console.WriteLine("Time: " + watch.Elapsed.TotalSeconds);
Console.WriteLine(data);
// Send a response to client
writer.WriteLine("Response: " + data);
}
}
}
}
}
}

A stream doesn't end until it is closed. Currently, both client and server are holding their connections open, and both is trying to read to the end from the other - and when they do, will close themselves. This is a deadlock: neither will ever get to the end, so neither will ever close (which would allow the other to get to the end).
Options:
use raw sockets, and have the client close the outbound stream after sending:
socket.Shutdown(SocketShutdown.Send);
this lets the server read to completion, which lets the server close, which lets the client read to completion; the client can still read from the inbound stream after closing the outbound socket.
use a different termination metaphor than ReadToEnd; for text-based protocols, end-of-line is the most common (so: ReadLine); for binary protocols, a length-prefix of the message is the most common. This allows each end to read the next message, without ever having to read to the end of the stream. In this scenario it would only be a single message, but the strategy still works.
use a different protocol if you find the above tricky; http is good for single request/response operations, and can be handled at the server via HttpListener.
Additionally, I'd be very careful about using ReadToEnd on a server (or even ReadLine) - that could be a good way of locking up threads on the server. If the server needs to cope with high throughput and lots of connections, async-IO based on raw sockets would be preferred.

Manage several/multiple tcp connections

I have a server application and client application with the functionality already working. Let me show you how I connect my client application to my server app:
//SERVER
// instantiate variables such as tempIp, port etc...
// ...
// ...
server = new TcpListener(tempIp, port); //tempIp is the ip address of the server.
// Start listening for client requests.
server.Start();
// Buffer for reading data
Byte[] bytes = new Byte[MaxChunkSize];
String data = null;
// Enter the listening loop.
while (disconect == false)
{
Console.Write("Waiting for a connection... ");
// Perform a blocking call to accept requests.
// You could also user server.AcceptSocket() here.
client = server.AcceptTcpClient(); // wait until a client get's connected...
Console.WriteLine("Connected!");
// Get a stream object for reading and writing
stream = client.GetStream();
// now that the connection is established start listening though data
// sent through the stream..
int i;
try
{
// Loop to receive all the data sent by the client.
while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
{
// Translate data bytes to a ASCII string.
data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
Console.WriteLine("Received: {0}", data);
// etc..
....
ok now on the client side lets say I want to establish a connection then send some data through the stream
//Client
client = new TcpClient(serverIP, port);
// Get a client stream for reading and writing.
stream = client.GetStream();
//then if I wish to send the string hello world to the server I would do:
sendString(stream, "Hello world");
protected void sendString(NetworkStream stream, string str)
{
sendBytes(stream, textToBytes(str));
}
protected void sendBytes(NetworkStream stream, Byte[] data)
{
// Send the message to the connected TcpServer.
stream.Write(data, 0, data.Length);
}
protected static Byte[] textToBytes(string text)
{
return System.Text.Encoding.ASCII.GetBytes(text);
}
since I am able to send bytes I am able to send files or everything that I want. the technique that I use is that if I send the string file for example to the server then the server will start listening for a file. It will open a stream and write the received bytes to that file. If a different keyword is send the server will start listening on a different method etc..
So when dealing with one server and one client everything works great. Now I want to add more clients and need them to also connect to the server. I know that several connections can be establish on the same port just like we do it with por 80 on websites... I do not know how to manage several connections. so one thing I was thinking was to leave everything as it is. if a connection is established then tell the server to start another thread listening for other connections on the same port. with this technique I will have several threads running plus I just know the basics of multrythreading. If this technique is my best option I will start implementing it. You guys out there are really knowledgeable about all this so it will be nice if someone can point me on the right direction. Or maybe I should listen on several ports. if the server is already connected on port 7777 for example then do not accept connections from that port and start listening on port 7778 for example. I mean there could be so many different ways of achieving what I need and you guys probably know the best way. I just know the basics of networking...

You could use threading:
var client = server.AcceptTcpClient();
var t = new Thread(new ParameterizedThreadStart(AccentClient));
t.Start(client);
The target method would look like this
public void AccentClient(object clientObj)
{
var client = clientObj as TcpClient;
// Do whatever you need to do with the client
}
If you are not familiar with multithreading, it is important you learn at least the basics first.

You could implement a class that encapsulates TCP behavior. Check this class:
public class SimpleListener
{
private System.Net.Sockets.TcpListener _tcpListen;
//declare delegate to handle new connections
public delegate void _new_client(System.Net.Sockets.TcpClient tcpclient);
//declare a clients container (or something like...). OPTION 1
List<System.Net.Sockets.TcpClient> _connected_clients;
//declare an event and event handler (the same for _new_client) for new connections OPTION 2
public event _new_client new_tcp_client;
//public (The list of connected clients).
public List<System.Net.Sockets.TcpClient> ConnectedClients { get { return _connected_clients; } }
public SimpleListener(string ip, int listenport)
{
System.Net.IPAddress ipAd = System.Net.IPAddress.Parse(ip);
_tcpListen = new System.Net.Sockets.TcpListener(new System.Net.IPEndPoint(ipAd,listenport));
_connected_clients = new List<System.Net.Sockets.TcpClient>();
}
//Fire this method to start listening...
public void Listen()
{
_tcpListen.Start();
_set_listen();
}
//... and this method to stop listener and release resources on listener
public void Stop()
{
_tcpListen.Stop();
}
//This method set the socket on listening mode...
private void _set_listen()
{
//Let's do it asynchronously - Set the method callback, with the same definition as delegate _new_client
_tcpListen.BeginAcceptTcpClient(new AsyncCallback(_on_new_client), null);
}
//This is the callback for new clients
private void _on_new_client(IAsyncResult _async_client)
{
try
{
//Lets get the new client...
System.Net.Sockets.TcpClient _tcp_cl = _tcpListen.EndAcceptTcpClient(_async_client);
//Push the new client to the list
_connected_clients.Add(_tcp_cl);
//OPTION 2 : Fire new_tcp_client Event - Suscribers will do some stuff...
if (new_tcp_client != null)
{
new_tcp_client(_tcp_cl);
}
//Set socket on listening mode again... (and wait for new connections, while we can manage the new client connection)
_set_listen();
}
catch (Exception ex)
{
//Do something...or not
}
}
}
You could use this in your code:
//SERVER
// instantiate variables such as tempIp, port etc...
// ...
// ...
SimpleListener server = new SimpleListener(tempIp, port); //tempIp is the ip address of the server.
//add handler for new client connections
server.new_tcp_client += server_new_tcp_client;
// Start listening for client requests.
server.Listen();
.... //No need to loop. The new connection is handled on server_new_tcp_client method
void server_new_tcp_client(System.Net.Sockets.TcpClient tcpclient)
{
// Buffer for reading data
Byte[] bytes = new Byte[MaxChunkSize];
String data = null;
Console.WriteLine("Connected!");
// Get a stream object for reading and writing
System.IO.Stream stream = tcpclient.GetStream();
// now that the connection is established start listening though data
// sent through the stream..
int i;
try
{
// Loop to receive all the data sent by the client.
while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
{
// Translate data bytes to a ASCII string.
data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
Console.WriteLine("Received: {0}", data);
// etc..
....
}

Cannot get string data to pass through NamedPipeServerStream and NamedPipeClientStream

I'm trying to achieve bi-directional, named pipe communication on my Win-XP workstation using two simple C# forms solutions. One for the client and one for the server. They appear almost identical and use NamedPipeServerStream and NamedPipeClientStream (.NET 3.5). Both client and server are set to bidirectional comms via PipeDirection.InOut
The order of start-up events is:
1) Start the server. It waits for a connection from the client.
2) Start the client and it immediately finds and connects to the server. The server, likewise, completes its connection to the client.
3) Both client and server launch their "Read" threads which in turn create instances of streamreader. These threads then call ReadLn() and block - waiting for data. In all instances, autoflush is true.
I then use streamwriter.WriteLn() to send string data from the server to the client (or vice-versa). However, the execution never returns from that call. I don't know why and any insights would be greatfully received.
I have spent considerable time studying all that there is on this subject but I'm still missing something.
Client and server code snippets are shown:
SERVER:
private void ListenForClients()
{
// Only one server as this will be a 1-1 connection
m_pipeServerStream = new NamedPipeServerStream(PipeName, PipeDirection.InOut, 1);
// Wait for a client to connect
m_pipeServerStream.WaitForConnection();
// Ccould not create handle - server probably not running
if (!m_pipeServerStream.IsConnected)
return;
// Create a stream writer which flushes after every write
m_pipeServerWriter = new StreamWriter(m_pipeServerStream);
m_pipeServerWriter.AutoFlush = true;
Connected = true;
// Start listening for messages
if (m_pipeServerStream.CanRead)
{
ReadThread = new Thread(new ParameterizedThreadStart(Read));
ReadThread.Start(m_pipeServerStream);
}
}
/// <summary>
/// Reads data from the client
/// </summary>
/// <param name="serverObj"></param>
private void Read(object serverObj)
{
NamedPipeServerStream pipeStream = (NamedPipeServerStream)serverObj;
using (StreamReader sr = new StreamReader(pipeStream))
{
while (true)
{
string buffer;
try
{
buffer = sr.ReadLine();
}
catch
{
//read error has occurred
break;
}
//client has disconnected
if (buffer.Length == 0)
break;
//fire message received event
if (MessageReceived != null)
{
MessageReceived(buffer);
}
}
}
}
/// <summary>
/// Sends a message to the connected client
/// </summary>
/// <param name="message">the message to send</param>
public void SendMessage(string message)
{
if (m_pipeServerWriter != null)
{
m_pipeServerWriter.WriteLine(message);
m_pipeServerWriter.Flush();
}
}
CLIENT:
private void ConnectToServer()
{
// Seek out the one server
m_pipeClientStream = new NamedPipeClientStream(".", PipeName, PipeDirection.InOut);
// Connect to the waiting server
m_pipeClientStream.Connect();
// Ccould not create handle - server probably not running
if (!m_pipeClientStream.IsConnected)
return;
// Create a stream writer which flushes after every write
m_pipeClientWriter = new StreamWriter(m_pipeClientStream);
m_pipeClientWriter.AutoFlush = true;
Connected = true;
// Start listening for messages
if (m_pipeClientStream.CanRead)
{
ReadThread = new Thread(new ParameterizedThreadStart(Read));
ReadThread.Start(m_pipeClientStream);
}
}
/// <summary>
/// Reads data from the server
/// </summary>
private void Read(object serverObj)
{
NamedPipeClientStream pipeStream = (NamedPipeClientStream)serverObj;
using (StreamReader sr = new StreamReader(pipeStream))
{
while (true)
{
string buffer;
try
{
buffer = sr.ReadLine();
}
catch
{
//read error has occurred
break;
}
//client has disconnected
if (buffer.Length == 0)
break;
//fire message received event
if (MessageReceived != null)
{
MessageReceived(buffer);
}
}
}
}
/// <summary>
/// Sends a message to the connected server
/// </summary>
/// <param name="message"></param>
public void SendMessage(string message)
{
if (m_pipeClientWriter != null)
{
m_pipeClientWriter.WriteLine(message);
m_pipeClientWriter.Flush();
}
}

Try setting the Async flag on the streams:
NamedPipeClientStream(".", PipeName, PipeDirection.InOut, PipeOptions.Asynchronous);

I've now given up and moved to the safe, obvious technique of using two pipes, one for each direction of communication. They work fine.

I am not sure if this will help but I am also experiencing the same problem. First of all, I don't know why any reference to m_pipeServerStream.IsConnected will break the pipe. I tested this with just a simple MessageBox.Show(m_pipeServerStream.IsConnected.ToString()) and that broke my pipe!
Secondly, another weird thing is that your streamreader call will never return if you are using a duplex named pipe. You will need to read it manually like this
const int BufferSize = 4096;
Decoder decoder = Encoding.UTF8.GetDecoder();
StringBuilder msg = new StringBuilder();
char[] chars = new char[BufferSize];
byte[] bytes = new byte[BufferSize];
int numBytes = 0;
MessageBox.Show("before do while loop");
numBytes = pipeServer.Read(bytes, 0, BufferSize);
if (numBytes > 0)
{
int numChars = decoder.GetCharCount(bytes, 0, numBytes);
decoder.GetChars(bytes, 0, numBytes, chars, 0, false);
msg.Append(chars, 0, numChars);
}
MessageBox.Show(numBytes.ToString() + " " + msg.ToString());
MessageBox.Show("Finished reading, now starting writing");
using (StreamWriter swr = new StreamWriter(pipeServer))
{
MessageBox.Show("Sending ok back");
swr.WriteLine("OK");
pipeServer.WaitForPipeDrain();
}
Anyway, it doesn't seem to like the behavior of StreamReader, but this will work for now... I got this off this link http://social.msdn.microsoft.com/forums/en-US/csharpgeneral/thread/23dc2951-8b59-48e4-89fe-d2b435db48c6/
I'm not following every single step because I just needed to find out why it keeps hanging at StreamReader.ReadLine(). it's not returning from this function. StreamWriter does not seem to have this problem.
I am actually communicating between native dll and a managed windows service. Imagine my surprise when I found out that it was the managed part that was the problem, not the unmanaged part since they has such good examples in msdn...

I am no expert on Named Pipes or Anonymous Pipes but I will give it my best shot at trying to help others out even though you have a work around to your problem.
Client Server Communications is the best way to think of how this process should be achieved.
Server Starts and Listens for a Connection --> Client initiates a connection to a Server -->Server accepts the connection -->Client makes a request -->Server makes a response --> Connection is closed.
Server Starts and Listens for a Connection:
try
{
namedPipeServerStream = new NamedPipeServerStream(PipeName, PipeDirection.InOut, 1, PipeTransmissionMode.Byte, PipeOptions.Asynchronous);
// Wait for a connection here...
namedPipeServerStream.BeginWaitForConnection(new AsyncCallback(ConnectionCallBack), namedPipeServerStream);
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
}
Client Connects, then makes a Request:
try
{
namedPipeClientStream = new NamedPipeClientStream(".", PipeName, PipeDirection.InOut, PipeOptions.Asynchronous);
// Connect with timeout...
namedPipeClientStream.Connect(TimeOut);
byte[] buffer = Encoding.UTF8.GetBytes(DataToSend);
namedPipeClientStream.BeginWrite(buffer, 0, buffer.Length, ConnectionCallBack, namedPipeClientStream);
}
catch (TimeoutException ex)
{
Debug.WriteLine(ex.Message);
}
ConnectionCallBack is an Asynchronous CallBack. This Method (this is on the Client) is where the Connection is managed:
private void ConnectionCallBack(IAsyncResult iAsyncResult)
{
try
{
// Get the pipe
NamedPipeClientStream namedPipeClientStream = (NamedPipeClientStream)iAsyncResult.AsyncState;
// End the write
namedPipeClientStream.EndWrite(iAsyncResult);
namedPipeClientStream.Flush();
// Get Server Response...
GetServerResponse(namedPipeClientStream);
// Flush Data and Close Pipe...
namedPipeClientStream.Flush();
namedPipeClientStream.Close();
namedPipeClientStream.Dispose();
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
}
}
The Server handles the Client Request and formulates a Response and sends it:
// Response Methods...
public void SendResponse(string ServerResponse)
{
try
{
// Fill Buffer with Server Response Data...
byte[] Buffer = Encoding.UTF8.GetBytes(ServerResponse);
// Begin Async Write to the Pipe...
namedPipeServerStream.BeginWrite(Buffer, 0, Buffer.Length, SendResponseCallBack, namedPipeServerStream);
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
}
}
private void SendResponseCallBack(IAsyncResult iAsyncResult)
{
try
{
// Get the Pipe Handle...
NamedPipeServerStream namedPipeServerStream = (NamedPipeServerStream)iAsyncResult.AsyncState;
// End the Write and Flush...
namedPipeServerStream.EndWrite(iAsyncResult);
namedPipeServerStream.Flush();
// Close the Connection and Dispose...
namedPipeServerStream.Close();
namedPipeServerStream.Dispose();
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
}
}
This is called from the Client Request Handler:
private void ClientRequestHandler(string clientRequest)
{
try
{
if (this.InvokeRequired)
{
this.Invoke(new InvokedDelegate(ClientRequestHandler), clientRequest);
}
else
{
ProcessClientRequest(clientRequest);
}
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
}
}
private void ProcessClientRequest(string clientRequest)
{
// Display the Client Request...
richTextBox1.Text = clientRequest;
PipeServer.SendResponse("Server has received Client Request at: " + DateTime.Now);
}
The Client has initiated a Connection to the Server, at the point where the Asynchronous CallBack Method see's this:
// Get Server Response...
GetServerResponse(namedPipeClientStream);
The Connection is still open. The Client Request was made and the Pipe was Flushed and is ready for the Client to Read the Server Response mentioned above:
private void GetServerResponse(NamedPipeClientStream namedPipeClientStream)
{
byte[] buffer = new byte[255];
namedPipeClientStream.Read(buffer, 0, buffer.Length);
// Convert byte buffer to string
string ResponseData = Encoding.UTF8.GetString(buffer, 0, buffer.Length);
// Pass message back to calling form
ServerResponse.Invoke(ResponseData);
}
The Response is received and then the Connection is again Flushed and Closed ready for the Client to Initiate another Connection.
The code is a little more complex than just this but essentially this is how it works. While you have a connection initiated, use it. Once you close it, and then try to re-initialise it, you will need to wait for a period of time for it to dispose properly or you will get all sorts of semaphore errors and so on. Don't Smoke your connection when you don't need to!!!
Please see: Code Project - C# Async Named Pipes for an excellent example