JSR-107 and a JSR on data grids
In response to Antonio Goncalves' blog post on his wish list for Java EE 7 and particularly on his comments around the inactive JSR-107 JCACHE spec, I’d like to spend a few moments jotting down my thoughts on the subject.
To start with, I am on the JSR-107 expert group, representing Red Hat. I have also been in recent discussions with the JCP about the inactive JSR and what can be done about it.
My feel is JSR-107 needs to be axed. It’s been inactive for way too long, it is out of date, and the community is pretty jaded about it. We do, however, need a JSR around distributed caches and in-memory data grids. There is definitely a need in the Java EE 7 umbrella specification, particularly with increasing focus and alignment with cloud. Apps designed to scale would almost certainly need a distributed, in-memory data grid. If Java EE is to be the preferred platform to build Software-as-a-Service offerings, scalability is crucial.
So what should this data grid JSR look like? Well, let’s start with JSR-107. After all, I didn’t think there was anything wrong with JSR-107, just that it was too limiting/simplistic.
What’s in JSR-107? A quick summary:
Primary interface - javax.cache.Cache - extending j.u.c.ConcurrentMap
Adds ability to register, de-register and list event listeners
Defines a CacheLoader interface for loading/storing cached data
Defines an #evict(K) #method, as well as the support for different eviction algorithms
Defines a ServiceLocator approach to loading the appropriate implementation at runtime
Defines a CacheManager interface to construct and retrieve Cache instances
What JSR-107 does not cover - but should be included in a Data Grid JSR Over and above what JSR-107 proposed, I believe the following features are crucial to a useful data grid standard:
JTA interoperability. The ability to participate in transactions is necessary, both as an XA resource and as a simple cache to front a RDBMS, via JPA
Define behaviour at certain stages of a tx’s lifecycle, particularly with regards to recovery
Should play nice with JPA’s second level cache SPI
Define and mandate REPLICATION and DISTRIBUTION, as well as SYNCHRONOUS and ASYNCHRONOUS versions of network communications
These could be useful in the JSR, but needs more thought and discussion
An asynchronous, Future-based API (See Infinispan’s Async API)
XML-based config file standardisation (including an XSD)
Standardise programmatic config bean interfaces
Further interesting thoughts
These additional, NoSQL-like features would also be very interesting, but probably more sense in a later revision of this JSR - both for the sake of manageability as well as to allow more community adoption/feedback on such APIs.
I’d like to hear your thoughts and opinions around this - please comment away!
Tags: jcp data grids