Multithreaded Socket Programming means that a Multithreaded Server can communicate with more than one clients at the same time .

MultiThreaded Server Socket Program here is a VB.NET Console based application , that can handle multiple clients at the same time. Here we create a Server Socket from TcpListener class and listen to PORT 8888 . When the server gets a request from Client , the Server pass the instance of the client request to a separate class handleClient . In handleClient class there is a Thread , handling the communication between the instance of Server side client and Client from outside .

For each request , in Server there is a new thread instant is create for communication , so we can connect more than one client at the same time to Server and communicate independently .

Create a new VB.NET Console Application project and put the following source code in the project.

VB.NET SourceCode

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

serverSocket.Start()
msg("Server Started")
counter = 0
While (True)
counter += 1
clientSocket = serverSocket.AcceptTcpClient()
msg("Client No:" + Convert.ToString(counter) + " started!")
Dim client As New handleClinet
client.startClient(clientSocket, Convert.ToString(counter))
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

Public Class handleClinet
Dim clientSocket As TcpClient
Dim clNo As String
Public Sub startClient(ByVal inClientSocket As TcpClient, _
ByVal clineNo As String)
Me.clientSocket = inClientSocket
Me.clNo = clineNo
Dim ctThread As Threading.Thread = New Threading.Thread(AddressOf doChat)
ctThread.Start()
End Sub
Private Sub doChat()
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)
serverResponse = "Server to clinet(" + clNo + ") " + rCount
sendBytes = Encoding.ASCII.GetBytes(serverResponse)
networkStream.Write(sendBytes, 0, sendBytes.Length)
networkStream.Flush()
msg(serverResponse)
Catch ex As Exception
MsgBox(ex.ToString)
End Try

End While

End Sub
End Class
End Module

You have to run Server program first and then Client program , then only you can communicate with Server and Client each other .

MultiThreaded Client Socket Program is a windows based application . Here the client program is connected to Server's PORT 8888 , and IP Address here we give Server Address as " 127.0.0.1 " , because Server and Client program run on the same machine.

clientSocket.Connect("127.0.0.1", 8888)

When the Client get conncted to the Server , the Server make a separate thread for Client's communication . So we can connect more than one client and communicate at the same time.

Create a new VB.NET Windows based application and put the following source code in the Project.

VB.NET SourceCode

Imports System.Net.Sockets
Imports System.Text
Public Class Form1
Dim clientSocket As New System.Net.Sockets.TcpClient()
Dim serverStream As NetworkStream

Private Sub Button1_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Button1.Click
Dim serverStream As NetworkStream = clientSocket.GetStream()
Dim buffSize As Integer
Dim outStream As Byte() = _
System.Text.Encoding.ASCII.GetBytes("Message from Client$")
serverStream.Write(outStream, 0, outStream.Length)
serverStream.Flush()

Dim inStream(10024) As Byte
buffSize = clientSocket.ReceiveBufferSize
serverStream.Read(inStream, 0, buffSize)
Dim returndata As String = _
System.Text.Encoding.ASCII.GetString(inStream)
msg("Data from Server : " + returndata)
End Sub

Private Sub Form1_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load
msg("Client Started")
clientSocket.Connect("127.0.0.1", 8888)
Label1.Text = "Client Socket Program - Server Connected ..."
End Sub

Sub msg(ByVal mesg As String)
TextBox1.Text = TextBox1.Text + Environment.NewLine + " >> " + mesg
End Sub
End Class