abhirockzz / websocket-chat

Sample code for the 'Java WebSocket API Handbook'

The is a chat application (a canonical use case for WebSocket) built using the Java WebSocket API (JSR 356). This is meant to help understand the API usage and try it hands on (this is not a full-blown chat service)

Components

• Uses the Tyrus implementation for the core logic
• Leverages the Grizzly container support available in Tyrus
• Packaged as a standalone JAR

Build & run

The application is a Maven project

• To build, just execute mvn clean install which will produce an independent (fat/uber) JAR
• Run it using java -jar target/websocket-chat.jar

Features

Here is what you can do with the chat application

• Join the chat room
• Send public messages
• Send private messages
• Get notified about new users joining
• Leave the chat room
• Get notified another user leaves the chat room

Code

Before you explore the source code yourself, here is quick overview

Class(es)	Category	Description
ChatServer	Core	It contains the core business logic of the application
WebSocketServerManager	Bootstrap	Manages bootstrap and shutdown process of the WebSocket container
ChatMessage, DuplicateUserNotification, LogOutNotification, NewJoineeNotification, Reply, WelcomeMessage	Domain objects	Simple POJOs to model the application level entities
ChatMessageDecoder	Decoder	Converts chats sent by users into Java (domain) object which can be used within the application
DuplicateUserMessageEncoder ,LogOutMessageEncoder, NewJoineeMessageEncoder, ReplyEncoder, WelcomeMessageEncoder	Encoder(s)	Converts Java (domain) objects into native (text) payloads which can be sent over the wire using the WebSocket protocol

Unit tests: The unit tests use the Java client API implementation in Tyrus

Try it out

You would need a WebSocket client for this example - try the Simple WebSocket Client which is a Chrome browser plugin. Here is a transcript

• Users foo and bar join the chatroom. To do so, you need to connect to the WebSocket endpoint URL e.g. ws://localhost:8080/chat/foo/ (do the same for user bar). foo gets notified about bar
• User john joins (ws://localhost:8080/chat/john/). foo and bar are notified
• foo sends a message to everyone (public). Both bar and john get the message
• bar sends a private message to foo. Only foo gets it
• In the meanwhile, john gets bored and decides to leave the chat room. Both foo and bar get notified