Info2: Exercise 04: Chatterbox

Learning Goals

After this lab you should be able to agree with each of the following statements.

I can use the Socket API for TCP connections:

I can create a server that listens for and accepts connections
I can create a client that makes a connection request to the server
I can send text from a client to a server via streams
I can send text from a server to a client via streams
I can use multithreading to simultaneously process tcp requests and input from the user
(if you do the “for the bored” part: I can use multithreading for the server to handle multiple connection requests)

Write down the code for the following questions and be able to explain what is happening.

P1. How do you set up a connection with Sockets between two computers in Java?

P2. Write a method to read from a connection in Java.

P3. Write a method to write to a connection in Java.

P4. How do you create concurrent threads?

Note: use the plain TCP Socket and ServerSocket classes for this exercise! See: Lesson: All About Sockets (The Java™ Tutorials > Custom Networking)

Note that you can also use telnet to test your Server implementations without having the Client ready.

Start your chatterbox by writing a method that listens for a Socket connection on a port. This is your Chatterbox server. For now, just echo what you have read to the console.
Now write a client that connects to it and writes to a port.
Test your methods on your own machine.
If you are not in the lab with the others: Follow the instructions to connect to an HTW lab computer at https://imi-bachelor.htw-berlin.de/studium/labore/hinweise/entfernter-zugriff-auf-labor-pcs-ueber-vpn-und-remote-desktop/ and copy your code onto your lab computer. It is recommended you use a ganymed computer. Share your address and port with others and see whether you can chat with each other. You might need to change the default ports of your program to ports between 8000 and 8010.

Extend your Server such that you can enter messages on the Server side as well, and extend your Client to receive and display those messages.

Now extend your Chatterbox such that it can simultaneously receive and send messages using Java Threads.

The Zuul Game uses standard input and output as user interface. This can easily be exchanged with the Input- and Output Stream comming from a Socket!

Extract the input- and output streams System.in and System.out as fields initialized by parameters e.g. in the Game constructor.
Take the Server from Step 2 and attach a Game instance for processing the messages received by the client.
There isn’t really a need to implement a special client, telnet works just fine.
Done! you now can play Zuul remotely. In order to move it towards a multiplayer game, you would need a thread running a game instance for each connected client - just like for a multiuser chat in the “for the bored” part.

Create a Chat Server that can handle connections from more than one client using one Thread for each connected client.
Change the Server to dispatch incoming messages to all connected clients.

All info on the lab reports can be found on the Labs page.