About Google App Engine (GAE) and Ehcache
The ehcache-googleappengine module combines the speed of Ehcache with the scale of Google's memcache and provides the best of both worlds:
Speed - Ehcache cache operations take a few microseconds, versus around 60ms for Google's provided client-server cache, memcacheg.
Cost - Because it uses way less resources, it is also cheaper.
Object Storage - Ehcache in-process cache works with objects that are not serializable.
Compatibility
Ehcache is compatible and works with Google App Engine. Google App Engine provides a constrained runtime which restricts networking, threading and file system access.
Limitations
All features of Ehcache can be used except for the DiskStore and replication. Having said that, there are workarounds for these limitations. See
Use Cases. As of June 2009, Google App Engine appears to be limited to a heap size of 100MB. (See the article "The Limitations of Google App Engine" at
http://gregluck.com/blog/?s=limitations for the evidence of this).
Dependencies
Version 2.3 and higher of Ehcache are compatible with Google App Engine. Older versions will not work.