Chat server principal class that listens on socket for new connections. More...

Collaboration diagram for ChatServer:

Classes
interface	Context
	Provides message presentation context to instance of `ChatServer`. More...
Public Member Functions
	ChatServer (int port, Context context)
	Creates instance of the chat server.
int	getClientCount ()
	Get number of active client back-ends.
void	broadcast (ChatServerClient from, String message)
	Broadcasts message (terminated with new line) to all clients.
void	wwhhoo (ChatServerClient from)
	Responds to "wwhhoo" message.
void	logEliza (String message, ChatServerClient to)
	Logs messages from Eliza sent to client.
void	addClient (Socket clientSocket)
	Adds new client's back-end to the list of back-ends.
void	removeClient (ChatServerClient cli)
	Removes existing client's back-end from the list of back-ends.
void	run ()
	Listens on socket for new connections.
Private Attributes
String	serverID
	Server identifier; concatenated host name with TCP port.
int	port
	TCP port that chat server listens for new connections.
ArrayList< ChatServerClient >	clients
	Collection of active threaded chat clients (instances of `ChatServerClient`).
volatile boolean	running
	Indicates if thread is (or should be) running.
Context	context
	Event (call-back) context for the instance.

Detailed Description

Chat server principal class that listens on socket for new connections.

It instantiates a new threaded client back-end for each new connection and keeps all such client connections in the list. Client back-end thread purges itself from the list after remote end is disconnected.

Author:: Mikica B Kocic

Definition at line 17 of file ChatServer.java.

Constructor & Destructor Documentation

ChatServer.ChatServer	(	int	port,
		Context	context
	)

Creates instance of the chat server.

Parameters:

port	TCP port to listen
context	context where to log messages and send status updates

Definition at line 73 of file ChatServer.java.

References clients, context, port, running, and serverID.

    {
        this.clients  = new ArrayList<ChatServerClient> ();
        this.port     = port;
        this.context  = context;
        this.running  = true;
        this.serverID = "";
    }

Member Function Documentation

void ChatServer.addClient ( Socket clientSocket )

Adds new client's back-end to the list of back-ends.

Definition at line 150 of file ChatServer.java.

References clients, context, ChatServer.Context.logStatus(), and serverID.

Referenced by run().

    {
        int n; // will contain number of client after removal, used for status message

        synchronized( clients )
        {
            ChatServerClient client = new ChatServerClient( this, clientSocket );

            clients.add( client );
            client.start ();
            n = clients.size ();
        }

        /* update context status message appropriately
         */
        context.logStatus( serverID +
                ( n == 0 ? ", idle" : 
                  n == 1 ? ", 1 client active " 
                         : ", " + n + " clients active" )
              );
    }

void ChatServer.broadcast	(	ChatServerClient	from,
		String	message
	)

Broadcasts message (terminated with new line) to all clients.

Parameters:

from	originator, if `null` means that system sends a message
message	textual message that should be broadcasted

Definition at line 99 of file ChatServer.java.

References clients, context, ChatServerClient.getClientName(), and ChatServer.Context.logMessage().

Referenced by ChatServerClient.respondToMessage(), and ChatServerClient.run().

    {
        if ( from == null ) { // Message from the system
            context.logMessage( message );
            message = "[System] :: " + message;
        }
        else {
            context.logMessage( "[" + from.getClientName() + "] " + message );
        }
        
        synchronized( clients )
        {
            for( ChatServerClient c: clients ) {
                c.send( message );
            }
        }
    }

int ChatServer.getClientCount ( )

Get number of active client back-ends.

Definition at line 85 of file ChatServer.java.

References clients.

Referenced by ChatServerClient.respondToMessage(), and ChatServerClient.run().

    {
        synchronized( clients )
        {
            return clients.size ();
        }
    }

void ChatServer.logEliza	(	String	message,
		ChatServerClient	to
	)

Logs messages from Eliza sent to client.

Parameters:

message	textual message that should be broadcasted
to	client

Definition at line 142 of file ChatServer.java.

References context, ChatServerClient.getClientName(), and ChatServer.Context.logMessage().

Referenced by ChatServerClient.sendFromEliza().

    {
        context.logMessage( "Eliza -> [" + to.getClientName() + "] " + message );
    }

void ChatServer.removeClient ( ChatServerClient cli )

Removes existing client's back-end from the list of back-ends.

Definition at line 175 of file ChatServer.java.

References clients, context, ChatServer.Context.logStatus(), and serverID.

Referenced by ChatServerClient.run().

    {
        int n; // will contain number of client after removal, used for status message
        
        synchronized( clients )
        {
            clients.remove( cli );
            n = clients.size ();
        }

        /* update context status message appropriately
         */
        context.logStatus( serverID +
                  ( n == 0 ? ", idle" : 
                    n == 1 ? ", 1 client active " 
                           : ", " + n + " clients active" )
                );
    }

void ChatServer.run ( )

Listens on socket for new connections.

After accepting new connection, instantiates a new threaded client back-end for that connection.

Definition at line 199 of file ChatServer.java.

References addClient(), context, ChatServer.Context.logMessage(), ChatServer.Context.logStatus(), port, running, and serverID.

    {
        ServerSocket socket = null;
        
        /* Create socket
         */
        try
        {
            socket = new ServerSocket( this.port );
        }
        catch( IOException e )
        {
            context.logMessage( e.toString () );
            running = false;
        }
        
        /* Setup server ID, if we have socket...
         */
        if ( running )
        {
            try {
                serverID = InetAddress.getLocalHost().getHostName ()
                         + ":" + socket.getLocalPort ();
            } catch( UnknownHostException e ) {
                serverID = "unknown:" + socket.getLocalPort ();
            }
            context.logStatus( serverID + ", idle" );
            context.logMessage( "Server at " + serverID 
                                + " ready to accept new clients..." );
        }

        /* Listen for new connections, accept clients and add them to the
         * list of back-ends.
         */
        while( running )
        {
            try
            {
                addClient( socket.accept () );
            }
            catch ( IOException e )
            {
                context.logMessage( e.toString () );
                running = false;
            }
        }
        
        /* Inform parent that we are dead. Note that <code>", dead"</code> will
         * trigger also change in color of the log area background.
         */
        context.logStatus( serverID + ":" + port + ", dead" );
        context.logMessage( "Done." );
    }

void ChatServer.wwhhoo ( ChatServerClient from )

Responds to "wwhhoo" message.

Broadcasts list of connected users to all connected users.

Definition at line 121 of file ChatServer.java.

References clients, context, ChatServerClient.getClientName(), and ChatServer.Context.logMessage().

Referenced by ChatServerClient.respondToMessage().

    {
        context.logMessage( "[" + from.getClientName() + "] wwhhoo" );

        synchronized( clients )
        {
            for( ChatServerClient c: clients ) {
                String message = "WWHHOO: " + c.getClientName();
                for( ChatServerClient c2: clients ) {
                    c2.send( message );
                }
            }
        }
    }