EhCache: Replicated vs Distributed Cache Configuration

Question

So in EhCache we have three major classes:

• Cache,
• CacheManager, and
• Store

Under a replicated setup, which of these is actually being replicated? The Cache, the CacheManager or the Store? Calling a Cache's cache(K,V) method places that entry into whatever underlying Store it has been configured with (memory, disk, etc.), but then what replicated mechanism syncs this entry with other replicated mechanisms?

Once I understand that, I will be able to understand how those same "replicated mechanisms" change roles when we have a distributed cache configured. So my next question would be: under what circumstances would one choose replicated over distributed? Distributed seems to be the more powerful option all the way.

Final question: is replication and/or distribution available in the open source EhCache distro? From the documentation I can't tell if EhCache uses the term "enterprise" as a synonym for "proprietary" or "licensed".

Answer 1

Both replicated & distributed Ehcache are OSS. Enterprise comes with other features such as BigMemory & Active-Active Terracotta Server Array for example.

Replicated does its best at replicating all data to all nodes, while distributed does ... distribute the data across all nodes, while keeping the data that is relevant to your a particular node on it (as far as resources allow). Also atomic operations and the like are only available using distributed caches.