TcpListener problem

[AliAmjad]

        Dim listener As New TcpListener(System.Net.IPAddress.Any, 7778)

        'start it
        listener.Start()

        Dim bytes(1024) As Byte
        Dim Command As String = Nothing

        While True

            Console.WriteLine("Waiting for a connection... ")
            Dim client As TcpClient = listner.AcceptTcpClient()
            Console.WriteLine("Client connected... ")
            Console.WriteLine("Please Wait... ")

            Dim ns As NetworkStream = client.GetStream()

            Command = Nothing

            Dim i As Integer

            i = ns.Read(bytes, 0, bytes.Length)
            While (i <> 0)


                Command = System.Text.Encoding.ASCII.GetString(bytes, 0, i)

                Console.WriteLine(Command)

                i = ns.Read(bytes, 0, bytes.Length) 'stopper

            End While

            ns.Close()
            client.Close()

            Console.WriteLine("...")

        End While

Can anyone please help me why the execution stops at the bold line. Compiler don't execute anything after this line?

AliAmjad(MCP) First make it Run THEN make it Run Fast!

[DaveAuld]

When you say stops, do you mean it throws an exception? What is the exception? have you looked at the networkstream class documentation, you should be testing it canread before trying to read. look at the read method docs. [modified text] i just noticied that you have basically copied the example in the MSDN for the TCPListener, i have found in the past that these are not always reliable, and basically just show how everything hooks together, you still then need to look at each of the classes you are using to get more of the specific requirements (like the canread etc.)

Dave GoogleWave: dave.m.auld[at]googlewave.com Who am I?: Web|Facebook|Twitter|LinkedIn|Bebo

modified on Saturday, January 30, 2010 3:34 AM

[AliAmjad]

Thank you for your reply daveauld. Actually it didn't throw any exception at all just stops the execution and won't continue the loop or the remaining statements after the loop which is kind of weird. Do you have any idea what's wrong with the above code???

AliAmjad(MCP) First make it Run THEN make it Run Fast!

[DaveAuld]

I would change the read part to match the example in the networkstream.read example in the docs so;

Do
numberOfBytesRead = myNetworkStream.Read(myReadBuffer, 0, myReadBuffer.Length)
Loop While myNetworkStream.DataAvailable

Dave GoogleWave: dave.m.auld[at]googlewave.com Who am I?: Web|Facebook|Twitter|LinkedIn|Bebo

[Luc Pattyn]

Hi, Stream.Read() is a blocking call. Read the documentation, it contains: "read; however, if an exception occurs, the current position within the stream remains unchanged. Implementations return the number of bytes read. The return value is zero only if the position is currently at the end of the stream. The implementation will block until at least one byte of data can be read, in the event that no data is available. Read returns 0 only when there is no more data in the stream and no more is expected (such as a closed socket or end of file)." So your program is waiting inside the Read() method for more data to become available. You may have to restructure your communication, maybe use asyncrhonous calls, another thread, a time-out, it all depends on the circumstances. :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]

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I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that.
[The QA section does it automatically now, I hope we soon get it on regular forums as well]

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[Dave Kreskowiak]

It stops because .Read is a blocking call and won't return until it has actually read something. Since there's nothing more to read, the .Read call will sit there until there is something.

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[AliAmjad]

Thanks for your answers guys now i got the reason for this kind of behavior.

AliAmjad(MCP) First make it Run THEN make it Run Fast!