How to send a request and get a response using system.io.pipes - named-pipes

Question

I'm trying to write a client and server that communicate through named pipes. I need the the client to be able to send a query to the server and have the server send a response. All of the samples on the web for System.IO.pipes either send a single string to the client or a single string to the server. I have found some examples of how to do that with the old Win32 pipes. But, I can't use that.
Here is what I have so far. I know it is a lot of code. But, I think the issue may just be in one of the constructors for the pipe streams.
Client Code
Private Sub cmdSend_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdSend.Click
Dim strMsg As String = ""
Dim strRequest As String = "Send Key"
Dim strErrMsg As String = ""
PrintText("Creating new pipe client")
'pipeStream = New NamedPipeClientStream(strPipeName)
'pipeStream = New NamedPipeClientStream(strPipeName, PipeDirection.InOut, 1, PipeTransmissionMode.Message, PipeOptions.None)
pipeStream = New NamedPipeClientStream(strServerName, strPipeName, PipeDirection.InOut, PipeOptions.None, Security.Principal.TokenImpersonationLevel.None)
PrintText("Connecting to server")
pipeStream.Connect()
pipeStream.ReadMode = PipeTransmissionMode.Message
PrintText("Sending request")
'Send Request
If SendPipeMessage(pipeStream, strRequest, strErrMsg) Then
Else
PrintText(strErrMsg)
End If
PrintText("Receiving response")
'Process Response
If ReadPipeMessage(pipeStream, strMsg, strErrMsg) Then
PrintText(strMsg)
Else
PrintText(strErrMsg)
End If
pipeStream.Dispose()
pipeStream = Nothing
End Sub
Private Function SendPipeMessage(ByRef pipeStream As NamedPipeClientStream, ByVal strMsg As String, ByRef strErrMsg As String) As Boolean
Dim blnRetVal As Boolean = True
Dim bytMessage() As Byte = Nothing
Dim encoding As UTF8Encoding = Nothing
Try
encoding = New UTF8Encoding
bytMessage = encoding.GetBytes(strMsg)
pipeStream.Write(bytMessage, 0, bytMessage.Length)
Catch ex As Exception
blnRetVal = False
strErrMsg = ex.ToString
End Try
Return blnRetVal
End Function
Private Function ReadPipeMessage(ByRef pipeStream As NamedPipeClientStream, ByRef strPipeText As String, ByRef strErrMsg As String) As Boolean
Dim blnRetVal As Boolean = True
Dim strTextChunck As String = ""
Dim intNumBytes As Integer = 0
Dim intNumChars As Integer = 0
Dim bytMessage(10) As Byte
Dim chars(10) As Char
Dim decoder As Decoder = Nothing
Try
decoder = Encoding.UTF8.GetDecoder
strPipeText = ""
Do
strTextChunck = ""
Do
intNumBytes = pipeStream.Read(bytMessage, 0, bytMessage.Length)
intNumChars = decoder.GetChars(bytMessage, 0, intNumBytes, chars, 0)
strTextChunck = strTextChunck & New String(chars, 0, intNumChars)
Loop While Not pipeStream.IsMessageComplete
strPipeText = strPipeText & strTextChunck
Loop While intNumBytes <> 0
Catch ex As Exception
blnRetVal = False
strErrMsg = ex.ToString
End Try
Return blnRetVal
End Function
Server Code
Private Sub cmdListen_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdListen.Click
bw.RunWorkerAsync()
End Sub
Private Sub bw_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bw.DoWork
Dim strRequest As String = ""
Dim strErrMsg As String = ""
bw.ReportProgress(0, "Create new pipe server stream")
pipeStream = New NamedPipeServerStream(strPipeName, PipeDirection.InOut, 1, PipeTransmissionMode.Message, PipeOptions.None)
'Wait for connection
bw.ReportProgress(0, "Listening for connection")
pipeStream.WaitForConnection()
bw.ReportProgress(0, "Receiving request")
'Receive Request
If ReadPipeMessage(pipeStream, strRequest, strErrMsg) Then
bw.ReportProgress(0, "Request : " & strRequest)
Else
bw.ReportProgress(0, strErrMsg)
End If
'Get response
strResponse = GetResponse(strRequest)
bw.ReportProgress(0, "Sending response")
'Send Response
If SendPipeMessage(pipeStream, strResponse, strErrMsg) Then
bw.ReportProgress(0, "Sent response")
Else
bw.ReportProgress(0, strErrMsg)
End If
bw.ReportProgress(0, "Done!")
pipeStream.Disconnect()
pipeStream.Dispose()
pipeStream = Nothing
End Sub
Private Sub bw_ProgressChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles bw.ProgressChanged
PrintText(e.UserState)
End Sub
Private Sub bw_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles bw.RunWorkerCompleted
PrintText(e.Result)
End Sub
Private Function SendPipeMessage(ByRef pipeStream As NamedPipeServerStream, ByVal strMsg As String, ByRef strErrMsg As String) As Boolean
Dim blnRetVal As Boolean = True
Dim bytMessage() As Byte = Nothing
Dim encoding As UTF8Encoding = Nothing
Try
encoding = New UTF8Encoding
bytMessage = encoding.GetBytes(strMsg)
pipeStream.Write(bytMessage, 0, bytMessage.Length)
Catch ex As Exception
blnRetVal = False
strErrMsg = ex.ToString
End Try
Return blnRetVal
End Function
Private Function ReadPipeMessage(ByRef pipeStream As NamedPipeServerStream, ByRef strPipeText As String, ByRef strErrMsg As String) As Boolean
Dim blnRetVal As Boolean = True
Dim strTextChunck As String = ""
Dim intNumBytes As Integer = 0
Dim intNumChars As Integer = 0
Dim bytMessage(10) As Byte
Dim chars(10) As Char
Dim decoder As Decoder = Nothing
Try
decoder = Encoding.UTF8.GetDecoder
strPipeText = ""
Do
strTextChunck = ""
Do
intNumBytes = pipeStream.Read(bytMessage, 0, bytMessage.Length)
intNumChars = decoder.GetChars(bytMessage, 0, intNumBytes, chars, 0)
strTextChunck = strTextChunck & New String(chars, 0, intNumChars)
Loop While Not pipeStream.IsMessageComplete
strPipeText = strPipeText & strTextChunck
Loop While intNumBytes <> 0
Catch ex As Exception
blnRetVal = False
strErrMsg = ex.ToString
End Try
Return blnRetVal
End Function
When I start the client, it hangs on ReadPipMessage() and the server hangs on ReceivingRequest(). If I kill the client, the server reads in the request sent by the client. But, it bombs on sending the response because the client is no longer running.
Is it not possible for the server to send and receive a message in the same connection? I thought that was what PipeDirection.InOut meant.
Thanks,
Mike

Answer 1

You may want to look at the named pipes binding for WCF. There are many good examples of how to use it available out there, for instance: http://www.jmedved.com/2010/03/named-pipes-in-wcf/