chat

Atmosphere Chat — WAR Deployment

A real-time chat application deployed as a standard WAR file. Uses @ManagedService with WebSocket and automatic long-polling fallback.

What It Demonstrates

• @ManagedService annotation-driven handler with @Ready, @Disconnect, @Heartbeat, @Message
• Jackson encoding/decoding via @Message(encoders = ..., decoders = ...)
• Dependency injection of BroadcasterFactory, AtmosphereResource, Broadcaster
• WAR packaging with web.xml configuration
• WebSocket with transparent long-polling fallback

Server Side

Chat.java

The entire server is one annotated class:

@ManagedService(path = "/chat", atmosphereConfig = MAX_INACTIVE + "=120000")
public class Chat {

    @Inject private BroadcasterFactory factory;
    @Inject private AtmosphereResource r;

    @Ready
    public void onReady() { /* client connected */ }

    @Disconnect
    public void onDisconnect() { /* client left */ }

    @Message(encoders = {JacksonEncoder.class}, decoders = {JacksonDecoder.class})
    public Message onMessage(Message message) {
        return message; // returning broadcasts to all subscribers
    }
}

web.xml

Registers AtmosphereServlet with annotation scanning:

<servlet>
    <servlet-class>org.atmosphere.cpr.AtmosphereServlet</servlet-class>
    <init-param>
        <param-name>org.atmosphere.cpr.packages</param-name>
        <param-value>org.atmosphere.samples</param-value>
    </init-param>
    <load-on-startup>0</load-on-startup>
    <async-supported>true</async-supported>
</servlet>
<servlet-mapping>
    <url-pattern>/chat/*</url-pattern>
</servlet-mapping>

Client Side

application.js

Vanilla JavaScript using atmosphere.js 5.0 (no framework dependencies):

1. Subscribes to /chat with WebSocket transport and long-polling fallback
2. On first connection, prompts the user for a name
3. Sends JSON messages: { author, message }
4. Receives and displays messages with timestamps and author attribution

subscription = await atmosphere.atmosphere.subscribe(
    { url: '/chat', transport: 'websocket', fallbackTransport: 'long-polling' },
    {
        open:    (res) => { /* show connected status */ },
        message: (res) => { /* parse JSON, display message */ },
        close:   ()    => { /* show disconnected */ },
    }
);

subscription.push(JSON.stringify({ author: 'Alice', message: 'Hello!' }));

Build & Run

# Build
mvn clean install

# Run with embedded Jetty via Maven plugin
mvn jetty:run

Open http://localhost:8080/atmosphere-chat/ in multiple browser tabs to chat.

Deploying to a Servlet Container

Build the WAR and deploy to any Servlet 6.0+ container:

mvn clean package
# Deploy target/atmosphere-chat.war to Tomcat, GlassFish, Jetty, etc.

Project Structure

chat/
├── pom.xml                              # WAR packaging
└── src/main/
    ├── java/org/atmosphere/samples/chat/
    │   ├── Chat.java                    # @ManagedService handler
    │   ├── Message.java                 # Message POJO
    │   ├── JacksonEncoder.java          # Message → JSON
    │   └── JacksonDecoder.java          # JSON → Message
    └── webapp/
        ├── WEB-INF/web.xml              # AtmosphereServlet config
        ├── index.html                   # Chat UI
        └── assets/                      # Bundled atmosphere.js + chat client