> What the subsystem does when it receives a suspend command, and
> considers itself suspended will vary, but in the common case it will
> immediatly start rejecting external requests (e.g. Undertow will start
> responding with a 503 to all new requests).
I think there will need to be some mechanism for coordination between
subsystems here. For example, I doubt mod_cluster will want Undertow
deciding to start sending 503s before it gets a chance to get the LB sorted.
Maybe this needs to be a two step process.
Basically preSuspend() gets called for each container, and they notify
when this is done (which would be mod_cluster notifying the load
balancer), then the actual suspend takes place.
I don't think we need anything any more complex.