mixing spring-data-rest with spring websocket implementation [DATAREST-232]

Peter Butkovic opened DATAREST-232 and commented

Let me put it in a StackOverflow way (to prevent reformulating my dilemmas to some perfectly designed solution proposal):

I'd like to synchronize the state to all the clients interested in particular entity changes. so I'd like to achieve something like:

• exposing CRUD API on entity (via HTTP/REST and websockets)
• and routing the response (of the modifying calls) to websockets topic

So technically, I'd be interested in ideas to mix spring-data-rest with spring websockets implementation to achieve something like spring-data-websocket.

It would be nice if spring-data-rest could support websocket annotations "somehow" :) out of the box. Marking my rest exposed methods via anotations (taking care of websocket message routing would be perfect).

Otherwise, there are a two solutions coming to my mind, in fact in both would be:

• spring-data-rest to expose my entities via REST/HTTP API
• websocket controllers (used for the modification calls on entities)

websocket controllers would look like this:

@Controller
public class EntityAWebSocketController {
      @MessageMapping("/EntityA/update")
      @SendTo("/topic/EntityA/update")
      public EntityA update(EntityA entityA) throws Exception {
           // persist,....
           return entityA;
     }
}

Scenario 1: Websocket API called from REST/HTTP API

Rules:

• client request is always REST/HTTP API
• response is REST/HTTP API for all the operations
• moreover for modifying operations the websocket message comes as well

Technically, could be achieved, by:

• calling the websocket controllers from the spring-rest-data events (namely in the AfterCreateEvent, AfterSaveEvent, AfterLinkSaveEvent, AfterDeleteEvent)

Still it seems quite sick to me, as I'd be going for:

1. client A ==HTTP request==> Server (spring-data-rest controller)
2. Server (AfterXXXEvent in the spring-data-rest controller) ==websocket message==> Spring websocket controller
3. Spring websocket controller ==websocket message via topic==> all Clients interested in the topic
4. Server (spring-data-rest controller) ==HTTP response==> client A

Scenario 2: Websocket API independent from REST API

Rules:

• client request is REST/HTTP API for non-modifying operations only
• response is REST/HTTP API for non-modifying operations only
• client sends websocket message for all the modifying operations
• websocket message to client for all the modifying operations only

Well, if no other ideas come up, I'd go for the later one, but still, it would be great if I could have somehow generated C(R)UD methods exposed via websockets as well, something like spring-data-websockets and handle in my implementation only the routes.

As I feel like I'd have to manually expose (via *WebSocketControllers) all the CUD methods for all my entities. And I might be too lazy for that.

Ideas?

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Affects: 2.0 M1 (Codd)

Reference URL: https://stackoverflow.com/questions/21278307/mixing-spring-data-rest-with-spring-websocket-implementation

8 votes, 9 watchers