Synchronous CacheStore vs BackingMapListener

Question

For partitioned caches (with backup-count=0), I need to react to cache entries being mutated (or inserted) synchronously (i.e - the mutating call should return after listeners are called). From what I understand, there are 2 mechanisms available to do this (and I have no experience with these features, so please bear with my ignorance in this regard):
1. CacheStore - set write-delay to 0 in the read-write-backing-map-scheme
or
2. BackingMapListener. No way to make this synchronous, but I am not sure.
Questions:
1. How are the 2 mechanisms different?
2. Which approach is better?
3. My understanding is that a BackingMapListener is a plain MapListener, just happens to be registered with a backing map. If there are 3 storage-enabled members, it needs to be registered 3 times?
Thanks
Ghanshyam

Answer 1

Hi Ghanshyam,
grpatel20 wrote:
For partitioned caches (with backup-count=0), I need to react to cache entries being mutated (or inserted) synchronously (i.e - the mutating call should return after listeners are called). From what I understand, there are 2 mechanisms available to do this (and I have no experience with these features, so please bear with my ignorance in this regard):
1. CacheStore - set write-delay to 0 in the read-write-backing-map-scheme
or
2. BackingMapListener. No way to make this synchronous, but I am not sure.
BackingMapListeners are always synchronous, AFAIK.
>
Questions:
1. How are the 2 mechanisms different?
I believe, backing map listeners have access to the binary form, cache-store on the other hand is geared for persistence, and entry is always deserialized.
Also, I expect that a backing map listener executes after a cache element is determined to change, and a cache store can actually prevent a change by throwing an exception (although at the cost of throwing the exception back to the client) which also prevent a backing map listener from being notified.
2. Which approach is better?
For this particular case, backing map listeners are probably better... :-)
3. My understanding is that a BackingMapListener is a plain MapListener, just happens to be registered with a backing map. If there are 3 storage-enabled members, it needs to be registered 3 times?
Backing map listeners are supposed to be registered in the cache configuration file. This also implies that it is defined only once, and Coherence takes care of the registration.
Thanks
GhanshyamBest regards,
Robert