A simple Multi-Threaded Server Client Instant Messenger Application

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Introduction

Got Bored.

The Library Project

I created a ChatLibrary that will contain the valid commands and a Message that will contain the parsing.

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public enum Command

{

   Login = 0,

   PersonalMessage = 1,    

   ClientList = 2,        

   Conference = 3,

   Logout = 4        

};



public class Message

{

string strSender;

string strReceiver;

Command cmdMessageCommand;

string strMessageDetail;

public Message ()

{

}

public Message (byte [] rawMessage)

{

  string strRawStringMessage = System.Text.Encoding.ASCII.GetString (rawMessage);   

  string [] strRawStringMessageArray = strRawStringMessage.Split(new char []{'|'});

  this.strSender = strRawStringMessageArray[1];

  this.strReceiver = strRawStringMessageArray[2];

  this.cmdMessageCommand = (Command) Convert.ToInt32(strRawStringMessageArray[3]);

  this.MessageDetail = strRawStringMessageArray[4];

}

...



public byte [] GetRawMessage ()

{

   System.Text.StringBuilder sbMessage = new System.Text.StringBuilder ("John");

   sbMessage.Append("|");

   sbMessage.Append(strSender);

   sbMessage.Append("|");

   sbMessage.Append(strReceiver);

   sbMessage.Append("|");

   sbMessage.Append((int)cmdMessageCommand);

   sbMessage.Append("|");

   sbMessage.Append(strMessageDetail);

   sbMessage.Append("|");

   return System.Text.Encoding.ASCII.GetBytes(sbMessage.ToString());

}

...

The Server Project

I created a SocketServer that calls the TCPListener.Start() method

IPEndPoint endPoint = new IPEndPoint (ipaAddress, iPort);

listener = new TcpListener (endPoint);

listener.Start();

Upon calling Listen, a new thread will be created that will listen for incoming clients

thrListenForClients = new Thread(new ThreadStart(ListenForClients));

thrListenForClients.Start();

The ListenForClients method will wait for connections and will assign the incoming socket to a new Client instance.

Client acceptClient = new Client();

acceptClient.Socket = listener.AcceptTcpClient();

listenForMessageDelegate = new ListenForMessageDelegate (ListenForMessages);

listenForMessageDelegate.BeginInvoke(acceptClient, new AsyncCallback(ListenForMessagesCallback), "Completed");

The Client, by the way is a class that contains a TCPClient, so we can keep track of our connections

public class Client {

   string strName;

   TcpClient tcpClient;

   public Client()

   {

   }

   public string Name 

   {

    get{return strName;}

    set{ this.strName = value;}            

   }

   public TcpClient Socket

   {

    get{return tcpClient;}

    set{ this.tcpClient = value;}

   }

   public void SendMessage (Message sendMessage)

   {

    NetworkStream stream = tcpClient.GetStream();

    stream.Write(sendMessage.GetRawMessage() , 0, sendMessage.GetRawMessage().Length);            

   }

}

Our server is now ready to listen for incoming messages. To do this, we pass the client socket that we received, then make a loop. We use a NetworkStream to read the message

NetworkStream stream = client.Socket.GetStream();

byte [] bytAcceptMessage = new byte [1024];

stream.Read(bytAcceptMessage, 0, bytAcceptMessage.Length);

Message message = new ChatLibrary.Message(bytAcceptMessage);

Once we receive the message, we can do anything that we want

txtStatus.Text += "rn" + strDisplayMessageType + strWriteText.TrimStart(new char[]{'r','n'});

My SocketServer makes use of a few events that makes coding a little easier

public event ClientConnectedEventHandler ClientConnected;

public event ClientDisconnectingEventHandler ClientDisconnecting;

public event MessageReceivedEventHandler MessageReceived;

In my ServerForm codes, what I did was I kept a copy of each connected Client in a ClientCollection that inherits from System.Collections.CollectionBase. With this, I can iterate through the Clients.

The Client Project

The Client does basically the same thing. I created a ClientSocket that will create a TCPListener and call Connect()

IPEndPoint serverEndpoint = new IPEndPoint (ipaAddress , iPort);

tcpClient = new TcpClient ();

tcpClient.Connect(serverEndpoint);

thrListenForMessages = new Thread (new ThreadStart(ListenForMessages));

thrListenForMessages.Start();

What ListenForMessages will do is to loop with NetworkStream.Read()

stream = tcpClient.GetStream();

byte [] bytRawMessage = new byte [1024];

stream.Read(bytRawMessage, 0, bytRawMessage.Length);

ChatMessage receivedMessage = new ChatLibrary.Message (bytRawMessage);

Then we do the same process, create a Message using the received bytes.

Again, my goal is to create a YM/MSN - looking Instant Messenger, so I made two UI forms. The MessengerForm and the ClientWindow. The MessengerForm is the class that instantiates the ClientSocket and receives the messages. upon receiving a message, it calls the MessengerWindow that should display the text.

Note that I didn't do a regular instantiation. I called Invoke to be able to make my controls thread safe

this.Invoke(createNewClientDelegate, new object []{receivedMessage});

History

June 2006 : Initial Version

License

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About the Author

massivegas

John lives in the Philippines with his family, working as a programmer. He used to program VB6 but is now... ummm... trying to learn C# .Net. Occupation: Web Developer Location: Philippines