Java Easy SSE (Server-Sent Events) implementation (at server side).
Features:
- Minimal footprint, with no 3rd-party dependencies.
- Easily integrable with plain HTTP servlets or Vertx verticles (see below examples)
- Asynchronous operation: don't spend your server threads.
- Broadcasting mode with automatic, thread-safe management of subscribers
<dependency>
<groupId>info.macias</groupId>
<artifactId>jeasse-servlet3</artifactId>
<version>0.11.3</version>
</dependency>
(You also need to provide the servlet-api [3.0.1,) dependencies)
<dependency>
<groupId>info.macias</groupId>
<artifactId>jeasse-vertx3</artifactId>
<version>0.11.3</version>
</dependency>
(You also need to provide vertx-core and vertx-web [3.1.0,) dependencies.
Basic, one-to-one subscription:
@WebServlet(asyncSupported = true)
public class ExampleServlet1 extends HttpServlet {
EventTarget target;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
target = new ServletEventTarget(req).ok().open();
}
public void onGivenEvent(String info) {
target.send("givenEvent",info);
}
}
Subscription to broadcast messages:
@WebServlet(asyncSupported = true)
public class ExampleServlet2 extends HttpServlet {
EventBroadcast broadcaster = new EventBroadcast();
// Attaches a subscriber
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
broadcaster.addSubscriber(new ServletEventTarget(req));
}
// Broadcasts a message to all the subscribers
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
broadcaster.broadcast("message","broadcasting that I received a POST message from somebody");
}
}
Subscription to broadcast messages, with individial welcome message (MessageEvent API used):
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
MessageEvent welcome = new MessageEvent.Builder().setData("Welcome to the broadcasting service").build();
broadcaster.addSubscriber(new ServletEventTarget(req),welcome);
}
Basic, one-to-one subscription:
Router router = Router.router(vertx);
EventTarget target;
router.get("/subscribe").handler(ctx -> {
target = new VertxEventTarget(ctx.request());
});
router.get("/ongivenevent").handler(ctx -> {
target.send("givenEvent","I inform you that I received a some event");
});
Subscription to broadcast messages:
Router router = Router.router(vertx);
EventBroadcast broadcaster = new EventBroadcast();
// Subscription request
router.get("/subscribe").handler(ctx -> {
try {
broadcaster.addSubscriber(new VertxEventTarget(ctx.request());
} catch (Exception e) {
e.printStackTrace();
}
});
// Message send request
router.post("/msg").handler(ctx -> {
broadcaster.broadcast("message","broadcasting that I have received a POST message");
});
Subscription to broadcast messages, with individial welcome message (MessageEvent API used):
router.get("/subscribe").handler(ctx -> {
try {
broadcaster.addSubscriber(new VertxEventTarget(ctx.request()),
new MessageEvent.Builder().setData("Welcome to the broadcasting service").build()
);
} catch (Exception e) {
e.printStackTrace();
}
});
To see the easiness of integration of jEaSSe, you can see a simple chat web application in the examples folder.
At the moment I do not provide any client-side library. You can use other cool libraries:
- Jersey's EventInput
- Javascript's EventSource (Enabled by default in all browsers excepting Internet Explorer/MS Edge)