embedded-jetty-websocket-chat

Atmosphere Chat — Embedded Jetty WebSocket

A real-time chat application using programmatic embedded Jetty with WebSocket. Demonstrates the lower-level @WebSocketHandlerService approach (as opposed to @ManagedService).

What It Demonstrates

• Embedded Jetty server with programmatic setup (no web.xml)
• @WebSocketHandlerService — lower-level WebSocket handler
• WebSocketStreamingHandlerAdapter — streaming text handling
• Jakarta WebSocket integration with Jetty's JakartaWebSocketServletContainerInitializer
• Record-based message model using JDK 21+ records

Server Side

EmbeddedJettyWebSocketChat.java

Programmatically configures a Jetty server:

Server server = new Server();
ServerConnector connector = new ServerConnector(server);
connector.setPort(8080);

// WebSocket must be initialized BEFORE AtmosphereServlet
JakartaWebSocketServletContainerInitializer.configure(context, null);

// AtmosphereServlet with annotation scanning
ServletHolder atmo = context.addServlet(AtmosphereServlet.class, "/chat/*");
atmo.setInitParameter(ANNOTATION_PACKAGE, "org.atmosphere.samples.chat");
atmo.setInitParameter(WEBSOCKET_SUPPORT, "true");

server.start();

WebSocketChat.java

Uses the lower-level WebSocket handler API instead of @ManagedService:

@WebSocketHandlerService(path = "/chat", broadcaster = SimpleBroadcaster.class)
public class WebSocketChat extends WebSocketStreamingHandlerAdapter {

    @Override
    public void onOpen(WebSocket webSocket) { /* add disconnect listener */ }

    @Override
    public void onTextStream(WebSocket webSocket, Reader reader) {
        // Parse JSON and broadcast to all
        webSocket.broadcast(mapper.writeValueAsString(
            mapper.readValue(br.readLine(), Data.class)));
    }

    public record Data(String author, String message, long time) { }
}

Client Side

Same vanilla JavaScript client as the WAR chat sample — connects to /chat with WebSocket transport, prompts for a name, and exchanges JSON messages.

Build & Run

# Build
mvn clean install

# Run the embedded server
mvn -Pserver

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

Project Structure

embedded-jetty-websocket-chat/
├── pom.xml                              # JAR packaging + exec plugin
└── src/main/
    ├── java/org/atmosphere/samples/chat/
    │   ├── EmbeddedJettyWebSocketChat.java  # Jetty server setup (main)
    │   └── WebSocketChat.java               # @WebSocketHandlerService handler
    └── webapp/
        ├── index.html                       # Chat UI
        └── assets/                          # Bundled atmosphere.js + chat client

Note: For annotation-driven development (@ManagedService, @RoomService), see the WAR chat, Spring Boot chat, or Quarkus chat samples instead.