PowerShell Named Pipe: no connection? - powershell

Question

I need a named pipe to read and write.
In a program I create the pipe server using from kernel32.dll:
string PipeName = "\\\\.\\pipe\\myMT4";
int PipeMode = PIPE_TYPE_MESSAGE|PIPE_READMODE_MESSAGE|PIPE_WAIT; # tried too: PIPE_NOWAIT
int hPipe = CreateNamedPipeW(
PipeName,
PIPE_ACCESS_DUPLEX,
PipeMode,
PIPE_UNLIMITED_INSTANCES,1024,1024,
NMPWAIT_USE_DEFAULT_WAIT,NULL);
The handle hPipe is valid - every things seems to be ok here!
But in a PowerShell-script I want to open a client, connect and open the writer -
and cannot connect => timed out
function connect{
Param ([PSObject] $h)
...
$h.Pipe = New-Object -TypeName System.IO.Pipes.NamedPipeClientStream "\\.\pipe\PipeTest"
$h.Pipe.Connect( 5000 )
$h.Writer = New-Object -TypeName System.IO.StreamWriter $h.Pipe, $h.Encode
I really would prefer this way to have a similar access when reading and writen
either from/to the pipe and sockets e.g.:
function write{
Param ([PSObject] $h, [string] $line )
try {
$h.Writer.Write($line)
}
What is wrong?
Thanks in advance,
Gooly.
PS:
It seems that the program cannot deal with pipe-servers - I have to open a pipe-client, and that works but that causes other problems:
I define for the PowerShell-pipe-server :
$pipeName = "testpipe"
$pipeDir = [System.IO.Pipes.PipeDirection]::InOut
$pipeMsg = [System.IO.Pipes.PipeTransmissionMode]::Message
$pipeOpti = [System.IO.Pipes.PipeOptions]::Asynchronous
$pipe = New-Object system.IO.Pipes.NamedPipeServerStream(
$pipeName, $pipeDir, 1, $pipeMsg, $pipeOpti )
$pipe.WaitForConnection() #
$sw = new-object System.IO.StreamWriter $pipe
$sw.AutoFlush = $true
$sw.WriteLine("Server pid is $pid")
$sw.Dispose()
$pipe.Dispose()
1) My first problem is now that the powerShell-pipe-server is blocked by
$pipe.WaitForConnection()
until a client connects but it must handle 2 different sockets independently meanwhile and
2) if the client closes the connection I was unable to tell the client to open the same pipe again and the client gets the Windows-error: ERROR_PIPE_BUSY 231
Form the program I connect to the server with the kernel32.dll-function:
int CallNamedPipeW(string PipeName,
string outBuffer, int outBufferSz,
uint& inBuffer[], int inBufferSz,
int& bytesRead[], int timeOut
);
Any ideas?

Answer 1

Hmm, I can get named pipes to work between two different PowerShell sessions so I don't think it is an inherent PowerShell limitation:
Here is the server script:
$pipe = new-object System.IO.Pipes.NamedPipeServerStream 'testpipe','Out'
$pipe.WaitForConnection()
$sw = new-object System.IO.StreamWriter $pipe
$sw.AutoFlush = $true
$sw.WriteLine("Server pid is $pid")
$sw.Dispose()
$pipe.Dispose()
Here is the client script:
$pipe = new-object System.IO.Pipes.NamedPipeClientStream '.','testpipe','In'
$pipe.Connect()
$sr = new-object System.IO.StreamReader $pipe
while (($data = $sr.ReadLine()) -ne $null) { "Received: $data" }
$sr.Dispose()
$pipe.Dispose()
Client outputs:
Received: Server pid is 22836