Overview
Connections gives you sixteen words and four hidden themes, and the only way through is to see the link before you run out of attempts. Turning it into a networked game is where it gets interesting: everyone connected plays the same game, at the same time, on a timer the server owns.
The exam asked for a client–server system in Java. The server runs one global game, authenticates users, scores proposals, keeps the leaderboard and persists everything to disk; the client holds a TCP connection for requests and listens on UDP for the notification that the round has closed and a new one has started.
What I built
- A multithreaded server: a TCP front end on an ExecutorService thread pool, a UDP server on its own dedicated thread, and a game scheduler that closes each round at timeout, scores it and opens the next one automatically.
- A non-blocking TCP client built on Java NIO, speaking JSON: register, log in, submit a proposal, ask for game info, personal stats or the leaderboard.
- Asynchronous push over UDP, so a player learns the round has ended without polling for it.
- The scoring rules: +6, +12 or +18 points for one, two or three groups found, −4 for every wrong proposal, and a game lost after four mistakes.
- File-based persistence of users and finished games, written atomically through temporary files so a crash mid-write cannot corrupt the store.
In pictures
Play a round
Real puzzles from the server's data file
Sixteen words, four hidden themes. Pick four that belong together and submit. Four wrong guesses and the game is over — the same rules the Java server enforces, scoring included.
Dealing the words…
The real thing runs on a server: one global game for everyone, a timer, a leaderboard and UDP notifications when the round closes. This is just the board.