Add events for subscribe/unsubscribe stomp commands [SPR-11813]

[spring-projects-issues]

Vinicius Carvalho opened SPR-11813 and commented

We are missing subscribe/unsubscribe events on this module.

One good case for it would be the ability to perform some house cleaning on those events.

When using the StompBrokerRelay with RabbitMQ for example, once a client disconnects, we could remove the queue (for some reason rabbit 3.3.4 creates durable queues)

And because StompBrokerRelayMessageHandler is not a spring bean, not even using spring AOP was a choice for me when using the framework.

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Affects: 4.0.4

Referenced from: commits 1c91a52

[spring-projects-issues]

Jeffrey Barrus commented

I have a clean up use case for these events, the event would need to contain information about subscription destination though. Right now I cannot find any possible way to figure out the destination for an unsubscribe event. I tried using an interceptor that looks for unsubscribe events, but the unsubscribe events only have a subscription id, not a destination. Also, the DefaultSubscriptionRegistry does not provide any public method of finding out the destination for a given subscription id.

If the unsubscribe event doesn't have the destination, it would be nice if the DefaultSubscriptionRegistry had more public methods to find destinations for a sessionid/subscription id or subscriptions for a destination.

[spring-projects-issues]

Rossen Stoyanchev commented

I have a clean up use case for these events, the event would need to contain information about subscription destination though. Right now I cannot find any possible way to figure out the destination for an unsubscribe event.

I guess this behavior can vary depending on the client. According to the spec, the subscription id should be sufficient and unique within a session. We could expose a method on the SubscriptionRegistry but that only covers the simple broker so it's only a partial solution. Perhaps your implementation could be adapted to rely more on the subscription id vs the subscription destination? Otherwise you can also create a lookup of subscription id to destination (separated by session).