How do I make named pipes work between c++ and .NET?

Question

I just had a really tough time making Named Pipes work between c++ and .NET. I had no problems creating Named Pipes that worked between 2 c++ apps, or between 2 .NET apps.

Wow, fast responses. Sorry guys I planning to post the answer to the problem right after asking it (to help other people), but got distracted and it took longer than expected to answer it. Thanks for your concern. — Solx, Feb 10 '11 at 18:54
Welcome to Stack Overflow! The average time between asking a question and getting an answer that turns out to be correct, is about six minutes. — Greg Hewgill, Feb 10 '11 at 18:59

score 2 · Accepted Answer · answered Feb 10 '11 at 18:35

I dont have problem with this communication, i use this scenario in some project.

C++ side:

LPTSTR lpszPipename = TEXT("\\\\.\\pipe\\pipename");
CHAR chReadBuf[1024];
DWORD cbRead;
BOOL fResult;  

fResult = CallNamedPipe( 
    lpszPipename,          // pipe name 
    _Message,              // message to server 
    strlen(_Message),      // message length 
    chReadBuf,             // buffer to receive reply 
    sizeof(chReadBuf),     // size of read buffer 
    &cbRead,               // number of bytes read 
    NMPWAIT_WAIT_FOREVER); // wait;-)

At C# side:

    public string GetMessageFromPipe()
    {
        int _lenght = 0;

        /*
         * Pipe Control Block
         */
        _pipeserver.WaitForConnection();

        do
        {
            _lenght += _pipeserver.Read(_buffer, _lenght, _buffer.Length);
        }
        while (!_pipeserver.IsMessageComplete);

        _pipeserver.Disconnect();
        /*
         * End of Pipe Control Block
         */

        if (_lenght == 0)
        {
            throw new ArgumentException("Message is empty ;-(");
        }

        return Encoding.UTF8.GetString(_buffer, 0, _lenght);
    }

Pipe Creation:

_pipeserver = new NamedPipeServerStream("pipename",
  PipeDirection.InOut, 254, PipeTransmissionMode.Message,
  PipeOptions.Asynchronous, 262144, 262144);

This works, and please see my answer as well. The issue was that the pipe name string is different in .NET and c++. — Solx, Feb 10 '11 at 18:50
That last param to Read really should be: '_buffer.Length-_lenght' — Cameron, Jun 01 '17 at 23:04

score 1 · Answer 2 · answered Feb 10 '11 at 18:48

I found that I could use ProcessExplorer to see the names of the pipes that I was opening. Even though I used the exact same name in both c++ and .NET, ProcessExplorer showed that they were different.

I ended up using these names: In .NET: "\\.\pipe\XXXDebug"

In c++: "\\.\pipe\pipe\XXXDebug"

What I saw in ProcessExplorer for both of these was: \Device\NamedPipe\pipe\XXXDebug

One more thing, I opened the pipe in .NET via:

NamedPipeServerStream pipe = new NamedPipeServerStream(_pipeName, PipeDirection.InOut, 1, PipeTransmissionMode.Byte);

And I opened the pipe in c++ via:

    g_hPipe = CreateFile(
        _pipeName,
        GENERIC_WRITE,
        0,
        NULL,
        OPEN_EXISTING,
        FILE_ATTRIBUTE_NORMAL,
        NULL);

All this time, all it was...was an extra pipe prefix...SERIOUSLY M$?! SERIOUSLY?! — Alexandru, Jan 13 '14 at 20:19

How do I make named pipes work between c++ and .NET?

2 Answers2

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