High-Level SSE Support

[glassfishrobot]

Experts,

Oracle's current SSE API proposal clearly is a good API for SSE. The question is, whether it really fulfils what application developers expert from JAX-RS in particular.

There might be programmers that don't like to explicitly learn a new (and rather complex) set of classes and methods just to get the additional benefit of update notifications, and that the style of the SSE API does not very well fit into the style of JAX-RS. SSE API is completely algorithmic, while server-side JAX-RS is mostly declarative. I could imagine that some programmers would love to get a high-level SSE support in JAX-RS that more looks like "SSE inside JAX-RS" and less like a standalone SSE API.

To illustrate, let me give an example. Think of a simple CRUD application that works pretty well in JAX-RS 2.0 already (@POST / @GET / @PUT / @DELETE). Now the developers decide that once data is updated (PUT) or deleted (DELETE), the client shall be notified about that immediately using SSE technology with minimal additional code. But the amount of additional code lines with the new SSE API is really heavy and clutters the previously clean application with lots of SSE special code.

So I wonder whether it might be beneficial to provide some high-level API that simplifies this use case?

For example, it could look like this (simplified for illustration purposes):

@SSE public class MyResource {

  @GET @SseInit public void notifications() {};

  @POST public void create() {…};

  @GET @Path("{id}") public MyObject read() {…};

  @PUT @SseNotify public void update() {…};

  @DELETE @SseNotify public void delete() {…};

}

The idea would be the SSE API as outlined by Oracle is used under the hood by the JAX-RS container. Once a requests to get SSE notifications by calling the @SseInit-annotated GETter, the JAX-RS container sets up an implied SSE subscription for that client with this resource. Whenever the JAX-RS container leaves the body of @SseNotify-annotated methods, it pushes notifications to that subscriptions (the messages as synthetically built from the HTTP method and the URL, so the client knows what the message means).

This is not as far as flexible as Oracle's full-blown SSE API, but it is only intended as sugar ontop for simple but frequent use cases.

-Markus

Affected Versions

[2.1]

[glassfishrobot]

• Issue Imported From: https://github.com/jax-rs/api/issues/549
• Original Issue Raised By:@glassfishrobot
• Original Issue Assigned To: @glassfishrobot

[glassfishrobot]

@glassfishrobot Commented Reported by mkarg

[glassfishrobot]

@glassfishrobot Commented mkarg said: Hi Marcus, Sergey, thanks for thinking about this topic and coming with an enhancement (or maybe extension is a better name). I believe the idea is a sound one. I also share Sergeys opinion that JAX-RS should provide SSE support on the level which is currently proposed. I know you won't like this, but.. can you please formalize your proposal as a jira ticket? We need to keep "closing" stuff instead of adding and I we don't even have any comprehensive review of the proposed SSE yet. If we'd include this as part of it, it would most likely significantly prolong the review period, not mentioning that it can be treated as completely separate feature. We can call it "High level SSE API". Also, the idea will need some work - currently, there is no mention of the message format (I believe it will need to be pluggable, we don't want to define any "standard" there), relation to the existing API (esp. broadcaster), etc. Having said that, please don't take it as "I don't want to hear your thoughts" - it's exactly the opposite. But I believe there is a general conclusion: "we want to have API similar to what has been proposed by JAX-RS Spec leads". Let's finish that one. We can build on top of it later. Thanks and regards, Pavel

On 03/02/2017 10:41, Sergey Beryozkin wrote: I think the proposed SSE API should stay (to let users control SSE flows in a fine grained manner when needed),

However offering the users an option to cover the basic SSE flows with the use of annotations is interesting which if accepted should be complementary IMHO

Cheers, Sergey

[glassfishrobot]

@glassfishrobot Commented mkarg said: My proposal actually is to add SSE API as-is, and then add the High-Level SSE Support ONTOP.

[glassfishrobot]

@glassfishrobot Commented This issue was imported from java.net JIRA JAX_RS_SPEC-544