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Some CDI layer for SSE using Tomcat Websocket
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mvn clean install

CDI Tomcat Event

It adds some CDI events corresponding to Websocket events.

typically you can observe the following events:

public void onOpen(final @Observes OnOpenEvent event);
public void onClose(final @Observes OnCloseEvent event);
public void onMessage(final @Observes TextMessageEvent event);
public void onMessage(final @Observes ByteMessageEvent event);

All events inherit from WebSocketEvent. This class offers you a stateful storage linked to the connection:

MyData data =;

And some communication shortcut to send data to the client:

event.writeBinaryMessage(new byte[] { 1, 2, 3});

CDI Tomcat SSE


SSE is the fact to send from the server data to the client. This is often done using a servlet with an infinite loop and the content type text/event-stream.

However using a servlet is not a good solution for common cases.

With the new websocket technology we can answer the same need a bit differently using them to send from the server to the client with a kind of pub/sub mecanism.


First define a com.github.rmannibucau.sse.SSEWebSocket (either in web.xml or through servlet 3 annotations):

@WebServlet(urlPatterns = "/impl")
public class SSEImpl extends SSEWebSocket {}

If you extend the SSEWebSocket (not mandatory) you have access to some hooks linked to client connections:

protected void onOpen();
protected void onClose(final int status);

Then you can inject (needs CDI) a SSESender which will broadcast information you want to all client:

private SSESender sse;

The client are matched from the @SSE parameter (url patterns/mapping).

This means you can have a client page with several update zone without any issues.

On the client side simply use websocket API as usual to connect on the websocket endpoint and update your page in onmessage callback.

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