Updates

• Assignment deadline extended to Friday.
• Solution available: JavlleClient.java JavlleServer.java JavlleServerHandler.java

Due date
Friday, 24 September 1999 at 12:20pm.

Advice

• Start today.
• Make use of office hours and the newsgroup. Ask for help, clarification.
• Check the web site and newsgroup frequently for updates
• Don't copy. The consequences are severe.

Goal
In this assignment we will be hooking up our client boards together via a server. This will allow players to play Javlle on different machines across the network.

Client
On startup the client will create a new board and display the user interface. Additionally, our client will open a connection to the server and listen for messages. Each message is separated by a newline character, and is simply a board string. Upon receiving a message from the server, the client will update the board, thereby updating also the display. When the "Go" button is clicked the current board is sent to the server. If there is a communication error, the client just quits. A client can be initiated by typing "java a3testClient".

Server
The server is a "broadcast proxy". It starts up and waits for connections from clients. Internally, it stores the current board, which is the last board it has been sent by any client. The initial board is empty. When a connection is accepted, a handler is spawned off to take care of it. Multiple simultaneous connections should be possible. Upon connection the server sends the newly connected client the current board. Also, the board is sent to all connected clients (broadcast) whenever the board changes. If a communication error occurs with any given client, the handler should terminate quietly, yet the server should continue to run, and other connections remain unaffected. A server can be initiated by typing "java a3testServer".

Guide to solving assignment
JavlleClient: Provides the functionality required for client to communicate with server.

• constructor: opens connection to given (host,port), sets up streams, throws IOException if not successful
• boardSend: sends single given Board message to server, throws IOException on error
• boardListen: listens continuously and updates given board with server messages, throws IOException on error

• DEFAULT_PORT: constant default Javlle port, 2002.
• constructor: bind server socket to given port, if no port given then use default, throw IOException if not successful
• listen: accept connections and spawn handlers, throw IOException on error

• constructor: given socket, board will setup streams, etc...
• run: maintains connection open and follows above-mentioned protocol, returns on communication error
• update: notify client of updated board

Code
You are required to create the classes: JavlleClient, JavlleServer and JavlleServerHandler and their respective .java files. To start the server and two clients all at once type: "java a3test".

Submission
Before the assignment deadline you are expected to sumbit one file into your A3 directory:

• JavlleClient.java
• JavlleServer.java
• JavlleServerHandler.java