Play Framework SSE结束分块响应

Question

I'm trying to implement Server-Side Events server in Play Framework 1.2.5

How can I know if the client called EventSource.close() (or closed its browser window, for example)? This is a simplified piece of server code I'm using:

public class SSE extends Controller {

  public static void updater() {
    response.contentType = "text/event-stream";
    response.encoding = "UTF-8";
    response.status = 200;
    response.chunked = true;

    while (true) {
      Promise<String> promise = Producer.getNextMessage();
      String msg = await(promise);
      response.writeChunk("data: " + msg + "\n\n");
    }
  }
}

Producer should deal with queuing, Promise objects, and produce the output, but I should know when to stop it (filling its queue). I would expect some exception thrown by response.writeChunk() if the output stream is closed, but there's no any.

There's a similar example that does not deal with SSE, but only chunks instead, at http://www.playframework.com/documentation/1.2.5/asynchronous#HTTPresponsestreaming

Answer 1

Since play.mvc.Controller doesn't let me know if the output stream is closed during the execution, I solved the problem through the Producer itself:

1. In Producer.getNextMessage() , the current time is remembered.
2. In Producer.putMessage(String) , the time since last 'get' is checked. If it's greater than some threshold, we can consider that SSE channel is closed.

There's also this class play.libs.F.EventStream which can be useful within the Producer .

Plus, Producer might not be the right name here, since it's more of a dispatching queue...