17

I need to implement an inter-process communication between C# applications. I decided to use named pipes and wrote the following code:

Server

while (true)
{
    using (var server = new NamedPipeServerStream("some_pipe"))
    {
        server.WaitForConnection();
        using (var reader = new StreamReader(server))
        {
            string line = reader.ReadLine();
            MessageBox.Show(line);
        }
    }
}

Client

using (var client = new NamedPipeClientStream("some_pipe"))
{
    client.Connect();

    using (var writer = new StreamWriter(client))
    {
        writer.AutoFlush = true;
        writer.WriteLine(path);
        client.WaitForPipeDrain();
    }
}

I have the following questions about it:

  • Is this solution correct at all? Is there any issues or bugs you already see?
  • What will happen if the second client will try to connect to this server? Will it wait for the first client to finish or just send its message along with another client's instance resulting in garbage?
  • Should I really create another instance of NamedPipeServerStream class every time? If I move its construction from the while (true) loop it gives me an exception "Cannot access a closed pipe". How can I avoid it? If I can't avoid it and should re-create this object every time, what will happen if there is no NamedPipeServerStream at the moment when client will try to connect to it?
Andrew Diamond
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FrozenHeart
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  • I'd put the server pipe in it's own `AppDomain`. Network clients can prevent the server from re-creating the pipe if they are still using it. Unloading the domain and the pipe gets around that –  Aug 24 '15 at 09:20
  • @Micky Duncan Can you give me an example pls? – FrozenHeart Aug 24 '15 at 09:22
  • I tried the same thing...It seemed that the client is closed when the StreamWriter is disposed. – Mike Jan 17 '17 at 14:52

1 Answers1

11

This will not work. Multiple clients connecting to just one NamedPipeServerStream is a feature not available. Its name with "...ServerStream" is misleading. Pipes are 1 to 1 connections. You must have multiple server instances serving the same pipe for many clients. This Code Project shows how to implement a Server Pipes and may help you.

Fidel Orozco
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    But [here on MSDN](https://msdn.microsoft.com/en-us/library/bb762927(v=vs.110).aspx) it says "Named pipes can be one-way or duplex. They support message-based communication and allow multiple clients to connect simultaneously to the server process using the same pipe name". – Robert Synoradzki Feb 12 '17 at 19:59
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    @ensisNoctis To the same server *process*, not the same `NamedPipeServerStream`. The server process needs to start as many `NamedPipeServerStream`s as there are clients. – Asad Saeeduddin Mar 01 '18 at 02:36