CMSC691D Design Patterns In Java

Fall 1999

Project 2

RMI Chat Server

Additional Requirements For CMSC691D Students

Due Date: December 8, 1999

Additional Project Requirements

To allow clients to register for specific chat topics, the ChatServer interface is modified as follows:

      public interface ChatServer extends Remote {
         public void registerClient(ChatClient client, String topic) 
            throws RemoteException;
         public void unregisterClient(ChatClient client, String topic) 
            throws RemoteException;
         public void broadcast(String msg, String topic) 
            throws RemoteException;
         public String[] getHistory(int n, String topic) 
            throws RemoteException;
      }

These methods do the following:

• public void registerClient(ChatClient client, String topic) - registers the client with the chat server for the specified topic. If the chat topic does not yet exist, it is created. Note that the object registered is a remote reference to a ChatClient object on the client host.
• public void unregisterClient(ChatClient client, String topic) - unregisters the client with the chat server for the specified topic.
• public void broadcast(String msg, String topic) - add the String msg to the history of the chat session for the specified topic and notifies all registered clients of that topic of the new message. Notification is done by invoking the update() method of the remote ChatClient objects.
• public String[] getHistory(int n, String topic) - returns the n most recent mesages added to the chat session for the specified topic.

Test your application with at least three clients, a server and two different topics as chat sessions. Have a least one client register for both topics.