using System; 
using System.IO; 
using System.Collections; 
using System.Runtime.Remoting; 
using System.WinForms ; 
using System.Runtime.Remoting.Channels.HTTP; 
namespace com.icommware.PublishSubscribe 
{ 
public class Topic : MarshalByRefObject 
{ 
ArrayList userlist = new ArrayList() ; 
ArrayList textboxlist = new ArrayList() ; 
ArrayList listboxlist = new ArrayList() ; 
///<summary> 
/// Input : string username (by value) and RichTextBox , ListBox (by refrence) 
/// Output: bool 'true' if username is unique else 'false ' 
///</summary> 
public bool addUser(string user, ref RichTextBox textBox1, ref ListBox listBox1) 
{ 
//check is username is present in the userlist 'ArrayList' 
bool test=userlist.Contains(user) ; 
if(test) 
{ 
//if present then Give the message to use and return 'false' 
textBox1.Text+="This Nick has already been taken, try changing your Nick \n" ; 
return false ; 
} 
else
{ 
//user is unique hence add him to the userlist 
userlist.Add(user) ; 
//add the RichTextBox reference to textboxlist 
textboxlist.Add(textBox1); 
//add to existing users list 
foreach(ListBox lb in listboxlist) 
{ 
lb.Items.Add(user) ; 
} 
//add the ListBox reference to listboxlist 
listboxlist.Add(listBox1) ; 
//Send to message only to the client connected 
textBox1.Text+="Connected to server... \n" ; 
//send message to everyone . 
sendMessage(user+" has Joined Chat") ; 
//add all the usernames in the ListBox of the client 
foreach(string users in userlist) 
{ 
listBox1.Items.Add(users) ; 
} 
return true ; 
} 
} 
///<summary> 
/// Input: string username 
/// It is called when the user quits chat 
///</summary> 
public void removeUser(string user) 
{ 
//check is the user is present in the userlist 
try
{ 
if(userlist.Contains(user)) 
{ 
//get the position of user in userlist 
int i=userlist.IndexOf(user) ; 
//remove user from userlist 
userlist.Remove(user) ; 
//remove user's RichTextBox reference from textboxarray 
textboxlist.RemoveAt(i) ; 
//remove user's ListBox refrence from listboxarray 
listboxlist.RemoveAt(i) ; 
//Inform all users about user quiting 
sendMessage(user+" has quit Chat") ; 
//remove the user from all users ListBox 
foreach(ListBox lb in listboxlist) 
{ 
lb.Items.Remove((object)user) ; 
} 
} 
} 
catch(Exception ed) 
{ 
Console.WriteLine(ed) ; 
} 
} 
///<summary> 
/// Input: string message 
/// it sends the message to all users connected to the server 
///<summary> 
public void sendMessage(string message) 
{ 
//write the message on the server console 
Console.WriteLine ("Added Message : {0}", message); 
//for each user connected, send the message to them 
foreach(RichTextBox rf in textboxlist) 
{ 
rf.Text+=message+"\n" ; 
} 
} 
} 
public class TheServer 
{ 
public static void Main () 
{ 
int listeningChannel = 1099; 
// Create a New HTTP Channel that listens on Port listeningChannel 
// TCPChannel channel = new TCPChannel (listeningChannel); 
HTTPChannel channel = new HTTPChannel (listeningChannel); 
// Register the channel with the runtime 
ChannelServices.RegisterChannel (channel); 
// Expose the Calculator Object from this Server 
RemotingServices.RegisterWellKnownType ("Server", 
"com.icommware.PublishSubscribe.Topic", 
"Topic.soap", 
WellKnownObjectMode.Singleton); 
// Keep the Server running until the user presses enter 
Console.WriteLine ("The Topic Server is up and running on port {0}", 
listeningChannel); 
Console.WriteLine ("Press enter to stop the server..."); 
Console.ReadLine (); 
} 
} 
} 
// That's all ... it's all easy if you are willing understand ! 
// Make a printout of it & open your .net sdk for better understanding :) 

The Client Code: The client code reside in newFormclient.cs.

/** 
* Article: Channels and .NET Remoting 
* Copyright (c) 2000, Gopalan Suresh Raj. All Rights Reserved. 
* ... Thanks Saurabh for great help to make it lively .... thanks :) 
* ... Thanks Mahesh for Loading it on Site .... It Rocks :) 
* ... Thanks to You for Reading it You know better who you are :) 
* ... The Main Heart of the program is taken from the sample program of Gopalan 
Suresh Raj 
* ... modified as per requirement & presented in front of you.... Hope it would be helpful for somebody 
*/ 
// Win32Form1.cs 
namespace Win32Form1Namespace 
{ 
using System; 
using System.Drawing; 
using System.ComponentModel; 
using System.WinForms; 
using System.Runtime.Remoting; 
using System.Runtime.Remoting.Channels.HTTP; 
using com.icommware.PublishSubscribe; 
using System.Collections; 
///<summary> 
/// Summary description for Win32Form1. 
///</summary> 
public class Win32Form1 : System.WinForms.Form 
{ 
///<summary> 
/// Required by the Win Forms designer 
///</summary> 
private System.ComponentModel.Container components; 
private System.WinForms.Button nickname_btn; 
private System.WinForms.TextBox nickname_txtbox; 
private System.WinForms.Label nickname; 
private System.WinForms.Button btnListname; 
private System.WinForms.Button button1; 
private System.WinForms.TextBox textBox2; 
private System.WinForms.Label label1; 
private System.WinForms.GroupBox groupBox1; 
//useing RichTextBox insted of TextBox since It supports many more enhancements private System.WinForms.RichTextBox textBox1; 
private System.WinForms.ListBox listBox1; 
private Topic topic ; 
private string username ; 
private bool connected=false ; 
private HTTPChannel channel ; 
public Win32Form1() 
{ 
// Required for Win Form Designer support 
InitializeComponent(); 
// TODO: Add any constructor code after InitializeComponent call 
} 
///<summary> 
/// Clean up any resources being used 
///</summary> 
public override void Dispose() 
{ 
quitclient() ; 
base.Dispose(); 
components.Dispose(); 
} 
///<summary> 
/// The main entry point for the application. 
///</summary> 
public static void Main(string[] args) 
{ 
Application.Run(new Win32Form1()); 
} 
///<summary> 
/// Required method for Designer support - do not modify 
/// the contents of this method with an editor 
///</summary> 
private void InitializeComponent() 
{ 
this.components = new System.ComponentModel.Container(); 
this.button1 = new System.WinForms.Button(); 
this.listBox1 = new System.WinForms.ListBox(); 
this.groupBox1 = new System.WinForms.GroupBox(); 
this.label1 = new System.WinForms.Label(); 
this.nickname_btn = new System.WinForms.Button(); 
this.textBox2 = new System.WinForms.TextBox(); 
this.nickname = new System.WinForms.Label(); 
this.nickname_txtbox = new System.WinForms.TextBox(); 
this.btnListname = new System.WinForms.Button(); 
this.textBox1 = new System.WinForms.RichTextBox(); 
//@design this.TrayHeight = 0; 
//@design this.TrayLargeIcon = false; 
//@design this.TrayAutoArrange = true; 
button1.Location = new System.Drawing.Point(136, 64); 
button1.Size = new System.Drawing.Size(72, 24); 
button1.TabIndex = 4; 
button1.Text = "Send"; 
button1.Click += new System.EventHandler(button1_Click); 
listBox1.Location = new System.Drawing.Point(320, 0); 
listBox1.Size = new System.Drawing.Size(152, 329); 
listBox1.TabIndex = 0; 
groupBox1.Location = new System.Drawing.Point(16, 232); 
groupBox1.TabIndex = 0; 
groupBox1.TabStop = false; 
groupBox1.Text = "Add Message"; 
groupBox1.Size = new System.Drawing.Size(240, 104); 
label1.Location = new System.Drawing.Point(16, 32); 
label1.Text = "Message"; 
label1.Size = new System.Drawing.Size(56, 23); 
label1.TabIndex = 0; 
nickname_btn.Location = new System.Drawing.Point(16, 392); 
nickname_btn.Size = new System.Drawing.Size(224, 24); 
nickname_btn.TabIndex = 2; 
nickname_btn.Text = "Connect"; 
nickname_btn.Click += new System.EventHandler(nickname_btn_Click); 
textBox2.Location = new System.Drawing.Point(72, 32); 
textBox2.TabIndex = 3; 
textBox2.Size = new System.Drawing.Size(160, 20); 
textBox2.Click += new System.EventHandler(button1_Click); 
nickname.Location = new System.Drawing.Point(16, 360); 
nickname.Text = "Nick Name"; 
nickname.Size = new System.Drawing.Size(72, 16); 
nickname.TabIndex = 0; 
nickname_txtbox.Location = new System.Drawing.Point(88, 360); 
nickname_txtbox.TabIndex = 1; 
nickname_txtbox.Size = new System.Drawing.Size(152, 20); 
nickname_txtbox.Click += new System.EventHandler(nickname_btn_Click); 
btnListname.Location = new System.Drawing.Point(344, 336); 
btnListname.Size = new System.Drawing.Size(96, 32); 
btnListname.TabIndex = 5; 
btnListname.Text = "Disconnect"; 
btnListname.Enabled=false ; 
btnListname.Click += new System.EventHandler(btnListname_Click); 
textBox1.Location = new System.Drawing.Point(24, 8); 
textBox1.Multiline = true; 
textBox1.TabIndex = 0; 
textBox1.Size = new System.Drawing.Size(288, 208); 
textBox1.BackColor = System.Drawing.SystemColors.Info; 
this.Text = "Client"; 
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13); 
this.ClientSize = new System.Drawing.Size(496, 425); 
groupBox1.Controls.Add(button1); 
groupBox1.Controls.Add(textBox2); 
groupBox1.Controls.Add(label1); 
this.Controls.Add(nickname_btn); 
this.Controls.Add(nickname_txtbox); 
this.Controls.Add(nickname); 
this.Controls.Add(btnListname); 
this.Controls.Add(groupBox1); 
this.Controls.Add(textBox1); 
this.Controls.Add(listBox1); 
} 
///<summary> 
/// Does the cleaning up when client diconnects 
///</summary> 
private void quitclient() 
{ 
if(topic!=null) 
{ 
try
{ 
//remove the user from the server 
topic.removeUser(username) ; 
connected=false ; 
//set the buttons 
btnListname.Enabled=false; 
nickname_txtbox.Enabled=true ; 
nickname_btn.Enabled=true ; 
listBox1.Items.Clear() ; 
//unregister to channel so we can connect some other place 
ChannelServices.UnregisterChannel(channel) ; 
} 
catch(Exception ed) 
{ 
//this exception will occur when a 2 clients are running on the same machine and 
//one try's to disconnect. 
//Since both are using the same port (i.e. '0') to conect to server 
//if you see above we are calling 'ChannelServices.UnregisterChannel(channel)' 
//this will try to close the port '0' but since another client is 
//using this port a exception will occur 
Console.WriteLine(ed) ; 
} 
} 
} 
protected void nickname_btn_Click(object sender, System.EventArgs e) 
{ 
try
{ 
// codeing manipulation starts here ... 
if(!connected) 
{ 
int listeningChannel = 0; 
// Create and register a channel to communicate to the server 
// The Client will use the port passed in as args to listen for callbacks 
channel = new HTTPChannel (listeningChannel); 
ChannelServices.RegisterChannel (channel); 
// Create an instance on the remote server and call a method remotely 
topic = (Topic) Activator.GetObject (typeof (Topic), // type to create 
"http://localhost:1099/Topic.soap" // URI 
); 
username = nickname_txtbox.Text ; 
//add the user to the server 
bool check = topic.addUser(nickname_txtbox.Text, ref textBox1 ,ref listBox1) ; 
if(!check) 
{ 
//if server rejected user then do cleanup 
connected=false ; 
btnListname.Enabled=false; 
nickname_txtbox.Enabled=true ; 
nickname_btn.Enabled=true ; 
ChannelServices.UnregisterChannel (channel); 
topic=null ; 
nickname_txtbox.Text="" ; 
} 
else
{ 
//set up variables and buttons 
connected=true ; 
btnListname.Enabled=true; 
nickname_txtbox.Enabled=false ; 
nickname_btn.Enabled=false ; 
this.Text="Client "+username+" Connected" ; 
} 
} 
} 
catch(Exception ed) 
{ 
MessageBox.Show(this, "Exception occured"+ed.ToString()); 
} 
} 
protected void btnListname_Click(object sender, System.EventArgs e) 
{ 
//call the mothod to quit rom server 
quitclient() ; 
} 
protected void button1_Click(object sender, System.EventArgs e) 
{ 
//send the message to everyone 
if(textBox2.Text!="")
{ 
topic.sendMessage(username+": "+textBox2.Text) ; 
textBox2.Text=""; 
} 
} 
} 
}