TCP-IP Remoting

In order to expose server functionality we need to create a socket service that will listen on a specific TCP-IP port for incoming connection requests.

C#.Net
VB.Net

Imports System.Net.Sockets
Imports System.Threading
Imports System.Diagnostics
Imports System.Runtime.InteropServices
Imports System.Runtime.InteropServices.Marshal
Imports System.Net
Imports System.Reflection
Imports System.Runtime.Remoting.Metadata.W3cXsd2001

using System;

using System.Collections;

using System.Collections.Generic;

using System.Data;

using System.Diagnostics;

using System.Net.Sockets;

using System.Threading;

using System.Runtime.InteropServices;

using System.Runtime.InteropServices.Marshal;

using System.Net;

using System.Reflection;

using System.Runtime.Remoting.Metadata.W3cXsd2001;

If working with unmanaged com classes on the target process, ensure the above name spaces are imported.

Create a class to serve as TCP port listener

C#.Net
VB.Net

Public Class TCPGateway
    Public ProcessRunning As Boolean = True
    Dim serverSocket As TcpListener
    Dim serverSocketActive As Boolean = True
    Dim WithEvents clientSocket As TcpClient
    Public clientCounter As Integer = 0
    Shared _EngineStatus As String = "Free"
    Shared _CurrentOwner As String = ""
 
    Public Shared Property EngineStatus() As String
        Get
            EngineStatus = _EngineStatus
        End Get
        Set(ByVal value As String)
            _EngineStatus = value
        End Set
    End Property
 
    Public Shared Property CurrentOwner() As String
        Get
            CurrentOwner = _CurrentOwner
        End Get
        Set(ByVal value As String)
            _CurrentOwner = value
        End Set
    End Property
 
 
    Private Sub Form1_FormClosing(sender As Object, e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        ProcessRunning = False
    End Sub
 
 
    Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        Timer1.Start()
        StartTCP_IP()
    End Sub
 
 
#Region "TCP-IP"
    Sub StartTCP_IP()
        Dim myServerIP As IPAddress = IPAddress.Parse("xxx.xxx.xxx.xxx")
        Dim myServerPort As Integer = yyyy
        serverSocket = New TcpListener(myServerIP, myServerPort)
        Try
            serverSocket.Start()
            '// Start Client Connection Listener
            Dim tcpListener As New Threading.Thread(AddressOf Listener)
            tcpListener.Start()
            RichTextBox1.Text = RichTextBox1.Text & "Gateway running: " & myServerIP.ToString & " port: " & myServerPort & vbCrLf
        Catch ex As Exception
            RichTextBox1.Text = RichTextBox1.Text & ex.ToString & vbCrLf
            serverSocketActive = False
        End Try
    End Sub
 
    Delegate Sub WriteTextDelegate(ByVal Text As String)
    Public WriteTextInstance As New WriteTextDelegate(AddressOf WriteText)
    Sub WriteText(ByVal Text As String)
        Writer(Text)
    End Sub
    Sub Writer(ByVal text As String)
        Me.RichTextBox1.Text = Me.RichTextBox1.Text & text & vbCrLf
    End Sub
 
    Sub Listener()
        Do While True
            Threading.Thread.Sleep(10)
            Try
                clientCounter += 1
                clientSocket = serverSocket.AcceptTcpClient()
                clientSocket.LingerState.Enabled = False
                clientSocket.LingerState.LingerTime = 0
                clientSocket.ReceiveTimeout = 5000
                clientSocket.SendTimeout = 5000
                Dim client As New handleTCPClient
                client.startClient(clientSocket, Convert.ToString(clientCounter))
            Catch ex As Exception
                RichTextBox1.Text = RichTextBox1.Text & ex.ToString & vbCrLf
            End Try
            If Not ProcessRunning Then
                Exit Sub
            End If
        Loop
    End Sub
 
    Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Label1.Text = handleTCPClient.State
    End Sub
#End Region
End Class

    public class TCPGateway
{
    public bool ProcessRunning = true;
    TcpListener serverSocket;
    bool serverSocketActive = true;
    TcpClient clientSocket;
    public int clientCounter = 0;
    static string _EngineStatus = "Free";
    static string _CurrentOwner = "";
 
    public static string EngineStatus {
        get { return _EngineStatus; }
        set { _EngineStatus = value; }
    }
 
    public static string CurrentOwner {
        get { return _CurrentOwner; }
        set { _CurrentOwner = value; }
    }
 
    private void Form1_FormClosing(object sender, System.Windows.Forms.FormClosingEventArgs e)
    {
        ProcessRunning = false;
    }
 
    private void Form1_Load(object sender, System.EventArgs e)
    {
        Timer1.Start();
        StartTCP_IP();
    }
 
    #region "TCP-IP"
    public void StartTCP_IP()
    {
        IPAddress myServerIP = IPAddress.Parse("xxx.xxx.xxx.xxx");
        int myServerPort = yyyy;
        serverSocket = new TcpListener(myServerIP, myServerPort);
        try {
            serverSocket.Start();
            //// Start Client Connection Listener
            System.Threading.Thread tcpListener = new System.Threading.Thread(Listener);
            tcpListener.Start();
            RichTextBox1.Text = RichTextBox1.Text + "Gateway running: " + myServerIP.ToString + " port: " + myServerPort + Environment.NewLine;
 
        } catch (Exception ex) {
            RichTextBox1.Text = RichTextBox1.Text + ex.ToString() + Environment.NewLine;
 
            serverSocketActive = false;
        }
    }
 
    public delegate void WriteTextDelegate(string Text);
    public WriteTextDelegate WriteTextInstance = new WriteTextDelegate(WriteText);
 
    public void WriteText(string Text)
    {
        Writer(Text);
    }
 
    public void Writer(string text)
    {
        this.RichTextBox1.Text = this.RichTextBox1.Text + text + Environment.NewLine;
    }
 
    public void Listener()
    {
        while (true) {
            System.Threading.Thread.Sleep(10);
            try {
                clientCounter += 1;
                clientSocket = serverSocket.AcceptTcpClient();
                clientSocket.LingerState.Enabled = false;
                clientSocket.LingerState.LingerTime = 0;
                clientSocket.ReceiveTimeout = 5000;
                clientSocket.SendTimeout = 5000;
                handleTCPClient client = new handleTCPClient();
                client.startClient(clientSocket, Convert.ToString(clientCounter));
            } catch (Exception ex) {
                RichTextBox1.Text = RichTextBox1.Text + ex.ToString() + Environment.NewLine;
            }
            if (!ProcessRunning) {
                return;
            }
        }
    }
 
    private void Timer1_Tick(object sender, System.EventArgs e)
    {
        Label1.Text = handleTCPClient.State;
    }
    public TCPGateway()
    {
        Load += Form1_Load;
        FormClosing += Form1_FormClosing;
    }
    #endregion
}

The above code is launched when the application is started. The main routine StartTCP_IP() starts a new TcpListener on the IP xxx.xxx.xxx.xxx port yyyy.

An endless While loop keeps polling for incoming connections. The boolean 'ProcessRunning' flag is used to stop the process on application shutdown.

Once a connection is made, it hands it off to the class handleTCPClient, this spawns a new thread that initiates receiving and sending information. This class is also responsible for interfacing and communicating with the processes on the main server (the target application functionality).

In order to utilize server functionality we need to create a socket service that will call and connect on a specific TCP-IP port to the socket server.

C#.Net
VB.Net

Imports System.Net.Sockets
Imports System.Runtime.InteropServices
Imports System.Web.Script.Serialization

using System.Net.Sockets;
using System.Runtime.InteropServices;
using System.Web;
using System.Web.Script.Serialization;

On the client application ensure the above namespaces are loaded.

Client functionality is not as complex as the server side as all it needs to do is make a connection to the server. The code below shows a simple function that requests the remote severs status.

C#.Net
VB.Net

 Const FailCounter As Integer = 100
    Public Shared Function GerTCPServerStatus() As String
        Dim status As String = "Unknown"
        Dim CommandString As String = "Status#" & Environment.MachineName
        Dim Timeout As Integer = 100
        Dim RemoteAddress As String = ConfigurationManager.AppSettings("BridgeAddress")
        Dim RemotePort As String = ConfigurationManager.AppSettings("BridgePort")
        If ServerAvailable(RemoteAddress, RemotePort) Then
            Dim TcpClient As TcpClient
            Dim NetworkStream As NetworkStream
            TcpClient = New TcpClient
            TcpClient.SendTimeout = 5
            TcpClient.ReceiveTimeout = 5
            TcpClient.Connect(Net.IPAddress.Parse(RemoteAddress), ConfigurationManager.AppSettings("BridgePort"))
            If TcpClient.Connected Then
                TcpClient.NoDelay = True
                TcpClient.LingerState.Enabled = True
                TcpClient.LingerState.LingerTime = 50
                HttpContext.Current.Session.Contents("TcpClient") = TcpClient
                NetworkStream = TcpClient.GetStream()
                NetworkStream.ReadTimeout = 50
                HttpContext.Current.Session.Contents("NetworkStream") = NetworkStream
                If NetworkStream.CanWrite And NetworkStream.CanRead Then
                    '// Send request
                    Dim sendBytes As [Byte]() = Encoding.ASCII.GetBytes(CommandString)
                    NetworkStream.Write(sendBytes, 0, sendBytes.Length)
                    NetworkStream.Flush()
                    Threading.Thread.Sleep(10)
                    '// Get answer
wait:               Dim bytes(TcpClient.Available) As Byte
                    NetworkStream.Read(bytes, 0, CInt(TcpClient.Available))
                    Dim ReturnData As String = Encoding.ASCII.GetString(bytes)
                    Dim Array() As String = Split(ReturnData, "#")
                    If Array.Length < 2 Then
                        ' If Split(ReturnData, "#")(0) <> Environment.MachineName Then
                        Threading.Thread.Sleep(5)
                        GoTo wait
                    End If
                    status = Array(0)
                End If
                NetworkStream.Close()
                NetworkStream.Dispose()
            Else
                status = "No Engine Available"
            End If
        Else
            status = "Server not found."
        End If
        Return status
    End Function

const int FailCounter = 100;
public static string GerTCPServerStatus()
{
    string status = "Unknown";
    string CommandString = "Status#" + Environment.MachineName;
    int Timeout = 100;
    string RemoteAddress = ConfigurationManager.AppSettings("BridgeAddress");
    string RemotePort = ConfigurationManager.AppSettings("BridgePort");
 
    if (ServerAvailable(RemoteAddress, RemotePort)) {
        TcpClient TcpClient = default(TcpClient);
        NetworkStream NetworkStream = default(NetworkStream);
        TcpClient = new TcpClient();
        TcpClient.SendTimeout = 5;
        TcpClient.ReceiveTimeout = 5;
        TcpClient.Connect(System.Net.IPAddress.Parse(RemoteAddress), ConfigurationManager.AppSettings("BridgePort"));
 
        if (TcpClient.Connected) {
            TcpClient.NoDelay = true;
            TcpClient.LingerState.Enabled = true;
            TcpClient.LingerState.LingerTime = 50;
            HttpContext.Current.Session.Contents("TcpClient") = TcpClient;
            NetworkStream = TcpClient.GetStream();
            NetworkStream.ReadTimeout = 50;
            HttpContext.Current.Session.Contents("NetworkStream") = NetworkStream;
 
            if (NetworkStream.CanWrite & NetworkStream.CanRead) {
                //// Send request
                Byte[] sendBytes = Encoding.ASCII.GetBytes(CommandString);
                NetworkStream.Write(sendBytes, 0, sendBytes.Length);
                NetworkStream.Flush();
                System.Threading.Thread.Sleep(10);
                wait:
                //// Get answer
                byte[] bytes = new byte[TcpClient.Available + 1];
                NetworkStream.Read(bytes, 0, Convert.ToInt32(TcpClient.Available));
                string ReturnData = Encoding.ASCII.GetString(bytes);
                string[] Array = Strings.Split(ReturnData, "#");
                if (Array.Length < 2) {
                    // If Split(ReturnData, "#")(0) <> Environment.MachineName Then
                    System.Threading.Thread.Sleep(5);
                    goto wait;
                }
                status = Array[0];
            }
            NetworkStream.Close();
            NetworkStream.Dispose();
        } else {
            status = "No Engine Available";
        }
 
    } else {
        status = "Server not found.";
    }
    return status;
}

The IP address and port, in this case obtained from the application configuration settings must point the remote server IP and port.

The TCPClient will attempt to make a connection to the server. If successful the client't (now connected) stream is attached to a network stream.

If the networkstream is open for read and write operations, a command (string) is converted to a byte array and sent to the server. In this case the command is "Status#MachineName" (where MachineName is the name of the client computer, this is used by the server to identify the connected party).

After sending the command, the client waits for a reply, checking to make sure the information received is for it. In This case, responses from the server contain the MachineName of the client, so these should (must) match.

A live demo (if the development server is not in use for other purposes) of TCP remoting. It adds an extra twist to remote async services.

Purpose: Enable a web user to use remote value added services.

In this case we will make a simple 3D cube and use SolidWorks to achieve this, returning an image of the cube.

Width

Depth

Height

TCP-IP Remoting

Basic Requirements

TCP-IP Socket Server

TCP-IP Server Listener

TCP-IP Socket Client

TCP-IP Client

How the Client works

TCP-IP Remoting Demo

About Jeroen Steeman

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