Question

Let’s say I have deployed an NSB endpoint that subscribes to events A,B, and C.
6 months later, version 1.1 of the endpoint adds a handler for event D, but the handler for event B is removed. What is a sensible process for removing the persisted subscription record for event B? I presume there is no automagic way for this to happen, and my choices would be:

1. Delete the entire contents of the subscription table and restart all endpoints.
2. Delete selectively based on what I know about the delta
3. Have some shutdown mode where my subscriber would call Unsubscribe on all its message types on the way down (and therefore would start with a clean slate on the way up)

Has anyone implemented any of these strategies, or am I missing some alternative?

Answer 1

The best solution would probably be option 1. The operational overhead involved in this would be fairly small:

1. Shut down publisher host
2. Clear down subscriptions db
3. Bounce all subscribers
4. Start up publisher host

Option 3 would also be possible but would involve making an unsubscribe call from every subscriber which is IMO much higher overhead (plus would require a redeployment if unscubscribe call not already implemented and then a shutdown to trigger the call).

Option 2 seems a bit hacky but would be lowest cost as you can just run a sql statement against the publisher db and bob’s your mother’s brother.

I would recommend option 1.