In your topic, suppose that I don't want to send charater, but I want to send a binary file. To do this, I read an image from harddisk and then transfer it to binary array.

When I send the Image binary array, I got a problem. When I know the server finish receiving data ?

Hello -

Using your code - i sometimes come across an issue.

During the operation of the application, the CPU will
max out at 99%.

It stays like that until i end the app (of course)

I'm not sure where the code block is maxing out at.

has anyone come across this issue before?

thanks
tony

Hi,

Iam doing a socket application,facing some problem in that.The issue is the remote host is sending some 10 messages means the client machine is able to capture only 3 to 4 messages.

i need help terribly.anyone pls help.thanks in advance

That's Great! But, How can you show me the way to transaction betwen two computer over internet. Especially, in this example! Can you modify code for me to have connection betwen Server and Client over Internet!  :(

Any more, I have some question want to have any help from you for design : :)

First: Game Online! Tell me the way to solve this kind of Programming! Server - Client!

Second: Mobile sendding data between PC and Mobile like Yahoo! Please help me explain my question in detail! :rolleyes:

Thank you so much for you reading!

hi,
I try to build a network sniffer in .net framework 2
and use the socketname.beginReceive(buffer,0,bufferLength,......);
like raw socket.
but when I convert the value in the buffer in to string ,there are meaningless staffs.
Can you help me please..

The following source code example has some un-safe thread issues.

Within the public method OnDataReceived(IAsyncResult asyn)

txtDataRx.Text = txtDataRx.Text + szData;

 

Nice tutorial on Sockets.
i've been developing and small network app and this article was very helpfull but i have problems implementing the comunication part, i can connect, receive and send data the problem arise when i try to send several message or objects(via serialization) i found that i get half of the object on the receiving stream, making imposible de deserialization of the object, i don't know if there is a workaround to this or i need to implement tokens in the message to know when to deserialize the object, any help or ideas will be apreciate :)

also i like to know if there is a way to detect when the remotehost have been disconnected after calling the Socket.BeginReceive() method.

Sorry for the bad english... Duke

Hi,

I am new to this forum but I am trying to do exactly what you may have achieved!

I am trying to connect multiple clients to Server!

Any Help is appriciated

AG

Hello,

I'm currently working on the both the server and multiple clients with tcp port connections. A port has been opened at server side for listening. Have tried multiple clients connections upto 120 clients. But in certain times, new client connections to the server are failed, but the existing client connection to server side are stil working fine if they're still connected, once they disconnected it, they cant do reconnection.
Meaning to say that the server side doesnt respond to any new client tcp connection after some times. No specific error message could be found. Do you have any idea on this? Any possibilities for this matter to happen?
Look forward to your helps. Thanks in advance.

Cheers.

Hi

how can i acknowledege an sending message in  asynchronous  socket program????

thank you

I was having the same problem until some minutes ago. The code below worked for me. See the bold section. Take a look at the help for Socket.Poll. This will return True only if there is still data to be received in the connected socket. If there's not, it sends the OK message.

I'll also post the whole code for the Client and Server classes. It may be useful for someone. I spend several hours researching and testing to come up with this...

I know we are in a C# area, but the code is very easy to translate.






Private Sub ReceiveCallback(ByVal ar As IAsyncResult)
        Try
            'Retrieve the state object and the client socket
            'from the asynchronous state object.
            Dim state As StateObject = CType(ar.AsyncState, StateObject)
            Dim client As Socket = state.workSocket
            'Read data from the remote device.
            Dim bytesRead As Integer = client.EndReceive(ar)
            If bytesRead > 0 Then
                'There might be more data, so store the data received so far.
                state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead))
                'Get the rest of the data.
                client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, New AsyncCallback(AddressOf ReceiveCallback), state)












                'Check if there is no more data to be received. If not an OK message is sent to the client.
                If Not client.Poll(1000000, SelectMode.SelectRead) Then
                    Send(client, "OK" & vbCrLf)
                End If



            Else
                'All the data has arrived;
                'Signal that all bytes have been received.
                receiveDone.Set()
                InvokeDelegate(state.sb.ToString)
            End If
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try








    End Sub


###See the complete solution below:
_____________________________________________________________________________


Public Delegate Sub StringReceivedHandlerDelegate(ByVal sRemoteAddress As String)

Public Class Server

    Private _PortNumber As Integer
    Private DataReceived As StringReceivedHandlerDelegate
    Private listener As Socket

    Sub New(ByVal PortNumber As Integer)
        _PortNumber = PortNumber
    End Sub

    Public Sub StartServer()
        Listen()
    End Sub

    Public Sub StopServer()
        If Not listener Is Nothing Then
            listener.Close()
        End If
    End Sub

    Public Class StateObject
        'Client socket.
        Public workSocket As Socket = Nothing
        'Size of receive buffer.
        Public Const BufferSize As Integer = 8192
        'Receive buffer.
        Public buffer() As Byte = New Byte(BufferSize - 1) {}
        'Received data string.
        Public sb As New StringBuilder
    End Class

    'ManualResetEvent instances signal completion.
    Private Shared connectDone As New ManualResetEvent(False)
    Private Shared sendDone As New ManualResetEvent(False)
    Private Shared receiveDone As New ManualResetEvent(False)

    Private Sub Listen()
        Try
            Dim remoteEP As New IPEndPoint(IPAddress.Any, _PortNumber)
            listener = New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
            listener.Bind(remoteEP)
            listener.Listen(10)
            listener.BeginAccept(New AsyncCallback(AddressOf ConnectCallback), listener)
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub

    Private Sub ConnectCallback(ByVal ar As IAsyncResult)
        Try
            'Retrieve the socket from the state object.
            Dim client As Socket = CType(ar.AsyncState, Socket)
            'Complete the connection.
            client = client.EndAccept(ar)
            Console.WriteLine("Socket connected to {0}", client.RemoteEndPoint.ToString())
            'Start Receiving
            Receive(client)
            'Signal that the connection has been made.
            connectDone.Set()
            listener.BeginAccept(New AsyncCallback(AddressOf ConnectCallback), listener)
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub

    Private Sub Receive(ByVal client As Socket)
        Try
            'Create the state object.
            Dim state As New StateObject
            state.workSocket = client
            'Begin receiving the data from the remote device.
            client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, New AsyncCallback(AddressOf ReceiveCallback), state)
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub

    Private Sub ReceiveCallback(ByVal ar As IAsyncResult)
        Try
            'Retrieve the state object and the client socket
            'from the asynchronous state object.
            Dim state As StateObject = CType(ar.AsyncState, StateObject)
            Dim client As Socket = state.workSocket
            'Read data from the remote device.
            Dim bytesRead As Integer = client.EndReceive(ar)
            If bytesRead > 0 Then
                'There might be more data, so store the data received so far.
                state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead))
                'Get the rest of the data.
                client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, New AsyncCallback(AddressOf ReceiveCallback), state)
                'Check if there is no more data to be received an OK message is sent to the client
                If Not client.Poll(1000000, SelectMode.SelectRead) Then
                    Send(client, "OK" & vbCrLf)
                End If
            Else
                'All the data has arrived;
                'Signal that all bytes have been received.
                receiveDone.Set()
                InvokeDelegate(state.sb.ToString)
            End If
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub

    Private Sub Send(ByVal client As Socket, ByVal data As String)
        Try
            'Convert the string data to byte data using ASCII encoding.
            Dim byteData As Byte() = Encoding.ASCII.GetBytes(data)
            'Begin sending the data to the remote device.
            client.BeginSend(byteData, 0, byteData.Length, 0, New AsyncCallback(AddressOf SendCallback), client)
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub

    Private Sub SendCallback(ByVal ar As IAsyncResult)
        Try
            'Retrieve the socket from the state object.
            Dim client As Socket = CType(ar.AsyncState, Socket)
            'Complete sending the data to the remote device.
            Dim bytesSent As Integer = client.EndSend(ar)
            Console.WriteLine("Sent {0} bytes to server.", bytesSent)
            'Signal that all bytes have been sent.
            sendDone.Set()
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub

    Public Sub SetStringInputHandler(ByVal pMethod As StringReceivedHandlerDelegate)
        Try
            Monitor.Enter(Me)
            If DataReceived Is Nothing Then
                DataReceived = pMethod
            End If
            Monitor.Exit(Me)
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub

    Private Sub InvokeDelegate(ByVal sData As String)
        Try
            DataReceived.Invoke(sData)
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub

End Class

____________________________________________________________________________

Public Class Client

    Private _RemoteHost As String
    Private _RemotePort As Integer
    Private _NetworkStream As NetworkStream
    Dim _TCPClient As TcpClient

    Sub New(ByVal RemoteHost As String, ByVal RemotePort As Integer)
        _RemoteHost = RemoteHost
        _RemotePort = RemotePort
    End Sub

    Public Function SendStringMessage(ByVal Message As String) As String
        Try
            _TCPClient = New TcpClient(_RemoteHost, _RemotePort)
            _NetworkStream = _TCPClient.GetStream()
            '_NetworkStream.WriteTimeout = 10000
            '_NetworkStream.ReadTimeout = 10000
            Dim strResponse As String
            ' Send a string (newline terminated) to the server.
            Dim writer As New System.IO.StreamWriter(_NetworkStream)
            Dim reader As New System.IO.StreamReader(_NetworkStream)
            writer.Write(Message)
            writer.Flush()
            ' Read server response (up to a newline).
            Try
                strResponse = reader.ReadLine
            Catch ex As Exception
                strResponse = Nothing
            End Try
            'Close
            writer.Close()
            reader.Close()
            _NetworkStream.Close()
            Return strResponse
        Catch ex As Exception
            Return Nothing
        Finally
            If Not _TCPClient Is Nothing Then
                _TCPClient.Close()
                _TCPClient = Nothing
            End If
        End Try
    End Function

End Class

Holpe it helped.

Regards,

Afas.