Windows Server AppFabric uses notifications to update cache clients about the changes that are made to the cache cluster. These notifications are sent asynchronously and can be subscribed at the level of granularity that suits the cache client's requirements. For local cache, these notifications serve as automatic means of cache invalidation.
The Windows Server AppFabric development team made a design choice that caches will have to opt in for notifications. This is so cache notifications are not switched on by default and also so the cache clients can subscribe for notifications at the level of granularity that is required.
Cache clusters can publish notifications for the following cache operations (defined at the region and cache level respectively):
1. Region level:
When a new region is created
When all the cache items in a region are cleared/removed
When the region is removed
2. Cache level:
When a new item is added to the cache
When an existing cache item is replaced...