Need help with socket listener to stay active

I have a server used to get info from SAPGUI. Everything works fine for a first request but nothing after that. The first iteration waits for a socket event. Once the socket is read for the first time it just loops without reading the receive buffer. I am assuming I need to reset the listener but am having trouble doing so.

'first iteration it works as expected but readbyte is always 0 after that even though it loops through fine. 'what I don't get is that the first iteration it waits for data to come down the socket, but after that it just loops 'and doesn't retreive anything.

Code:

---

          Dim listenerSocket As Socket = New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
    Dim ipend As IPEndPoint = New IPEndPoint(IPAddress.Parse("127.0.0.1"), 8888)
    listenerSocket.Bind(ipend)
    listenerSocket.Listen(0)
    Dim clientSocket As Socket = listenerSocket.Accept()
    Dim Buffer As Byte() = New Byte(clientSocket.SendBufferSize - 1) {}
    Dim readByte, sendByte As Integer
    Dim Sbuffer As Byte() = System.Text.Encoding.ASCII.GetBytes("Some form of SAP response!")
    Dim clientError As System.Net.Sockets.SocketError
    Console.WriteLine("Waiting for connection : ")



  For infinitecounter = 1 To 3
      infinitecounter = 1
      readByte = clientSocket.Receive(Buffer)

        While (True)
            If readByte > 0 Then
                Dim rData As Byte() = New Byte(readByte - 1) {}
                Array.Copy(Buffer, rData, readByte)


              SAPrq = System.Text.Encoding.UTF8.GetString(rData)
                SAPpar = Left(SAPrq, 1)

                SAPpar1 = InStr(SAPrq, "%")

                If SAPpar = 1 Then
                    SAPnwk = Mid(SAPrq, 3)

                    xy = Getbam(SAPnwk)' this is a function that talks to SAP and it works on first loop

                End If



        End While
     
    Next`

---

I tried adding setting infinitecounter = 2 before the next statement and adding an if statement to reset the listener but failed.

I am not that good at VB.NET so even if there may be related posts , I am too inexperienced to hack them to fit my needs.
I've been working on a solution for a while and can't find a solution on my own.

Pete

I am open to an alternative but since Ièm not used to VB.net , I'd need some help with coding that!

Thanks

Pete

It looks like your While loop is just going to go on forever. Nothing is going to make it exit. Is it meant to be While(readByte > 0) instead of While(True) ?

I was thinking of using non blocking Sockets or Async mode but have no clue as to how to implement it!

Thanks

Hi Peter,

I don't know exactly what your code is doing but what I see is that loop inside the For loop is endless.. I mean it will go on forever. There is no way to get out of that loop...so the readByte is always 0

You must get out of the loop..

maybe:

Code:

---

While (True)
    readByte = clientSocket.Receive(Buffer)
    If readByte > 0 Then
        ' you recieved data and is doing something with it
    Else
        ' No more data so exit the loop
        Exit While
    End If
End While

---

This line looks very sus to me

Code:

---

    Dim clientSocket As Socket = listenerSocket.Accept()

---

A server should be accepting sockets (calling Accept on listener socket to create new sockets) on new incomming client connection Events only, so that you you get separate clientSocket for second, third and so on clients.

Currently you get/accept a clientSocket for the first client, handle communication/protocol in the While loop and then exit procedure without waiting for any more incomming traffic (i.e. other consequtive connections) which is probably not what you wanted to do.

cheers,
</wqw>

You were correct as I added this last night and all works great now!
If infinitecounter = 2 Then

listenerSocket.Accept()
clientSocket = listenerSocket.Accept()

End If
Peter