Programming Tutorials

Chat Server in VB.net

By: Issac in VB.net Tutorials on 2009-02-22  

A chat server program is one which listens to the connection request from clients and broadcasts the msg to all clients that are connected to it at that instant.

The VB.NET Multithreaded Chat Server Program has two sections.

• Chat Server
• Chat Client

Chat server keeps listening to PORT 8888 for any request from clients, once a request is received it adds the name of the client into a client list maintained (in this code it is a Hash table) and then creates a new thread for communication with server. When the Server gets a message from a client, it selects all the Clients from clientsList and sends the message to all Clients (ie we can say Broadcast) in the clientsList. So each Client can see the message each other and they can communicate through Chat Server.

The client list we implemented here in a HashTable. The clientsList stores the Client Name (ie the first message from Client) and an instance of the Client Socket.

When a Chat Client connected to Server, the Server creates a new Thread for communication. Here we implement a Class handleClient for handling Client as a separate Thread. The Class handleClient has a function doChat () is handling the communication between the Server side Client Socket and the incoming Client Socket.

When Server gets a message from any of the currently connected Chat Client, the Server Broadcast the message to all Clients using broadcast method for sending messages to all Clients.

Create a new VB.NET Console based application and put the following source code into the Project..

Imports System.Net.Sockets
Imports System.Text
Module Module1
    Dim clientsList As New Hashtable
    Sub Main()
        Dim serverSocket As New TcpListener(8888)
        Dim clientSocket As TcpClient
        Dim counter As Integer

        serverSocket.Start()
        msg("Chat Server Started ....")
        counter = 0

        While (True)
            counter += 1
            clientSocket = serverSocket.AcceptTcpClient()

            Dim bytesFrom(10024) As Byte
            Dim dataFromClient As String

            Dim networkStream As NetworkStream = _
            clientSocket.GetStream()
networkStream.Read(bytesFrom, 0, CInt(clientSocket.ReceiveBufferSize))
dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom)
            dataFromClient = _
            dataFromClient.Substring(0, dataFromClient.IndexOf("$"))

            clientsList(dataFromClient) = clientSocket

            broadcast(dataFromClient + " Joined ", dataFromClient, False)

            msg(dataFromClient + " Joined chat room ")
            Dim client As New handleClinet
            client.startClient(clientSocket, dataFromClient, clientsList)
        End While

        clientSocket.Close()
        serverSocket.Stop()
        msg("exit")
        Console.ReadLine()
    End Sub

    Sub msg(ByVal mesg As String)
        mesg.Trim()
        Console.WriteLine(" >> " + mesg)
    End Sub
    Private Sub broadcast(ByVal msg As String, _
    ByVal uName As String, ByVal flag As Boolean)
        Dim Item As DictionaryEntry
        For Each Item In clientsList
            Dim broadcastSocket As TcpClient
            broadcastSocket = CType(Item.Value, TcpClient)
            Dim broadcastStream As NetworkStream = _
                    broadcastSocket.GetStream()
            Dim broadcastBytes As [Byte]()

If flag = True Then
broadcastBytes = Encoding.ASCII.GetBytes(uName + " says : " + msg)
Else
broadcastBytes = Encoding.ASCII.GetBytes(msg)
End If

        broadcastStream.Write(broadcastBytes, 0, broadcastBytes.Length)
            broadcastStream.Flush()
        Next
    End Sub

    Public Class handleClinet
        Dim clientSocket As TcpClient
        Dim clNo As String
        Dim clientsList As Hashtable

        Public Sub startClient(ByVal inClientSocket As TcpClient, _
        ByVal clineNo As String, ByVal cList As Hashtable)
            Me.clientSocket = inClientSocket
            Me.clNo = clineNo
            Me.clientsList = cList
Dim ctThread As Threading.Thread = New Threading.Thread(AddressOf doChat)
            ctThread.Start()
        End Sub

        Private Sub doChat()
            'Dim infiniteCounter As Integer
            Dim requestCount As Integer
            Dim bytesFrom(10024) As Byte
            Dim dataFromClient As String
            Dim sendBytes As [Byte]()
            Dim serverResponse As String
            Dim rCount As String
            requestCount = 0

            While (True)
                Try
                    requestCount = requestCount + 1
                    Dim networkStream As NetworkStream = _
                            clientSocket.GetStream()
networkStream.Read(bytesFrom, 0, CInt(clientSocket.ReceiveBufferSize))
dataFromClient = System.Text.Encoding.ASCII.GetString(bytesFrom)
                    dataFromClient = _
            dataFromClient.Substring(0, dataFromClient.IndexOf("$"))
        msg("From client - " + clNo + " : " + dataFromClient)
                    rCount = Convert.ToString(requestCount)

                    broadcast(dataFromClient, clNo, True)
                Catch ex As Exception
                    MsgBox(ex.ToString)
                End Try
            End While
        End Sub

    End Class
End Module