Blogs A new data grid JSR

A new data grid JSR

Following up on my previous response to Antonio Goncalves' blog post, I have submitted a JSR to the JCP on a data grid standard, titled "Java Data Grids".  It has yet to be assigned a number by the JCP, but I thought I’d talk about it a little here anyway.

Here is the description of the JSR that I have submitted:

This specification proposes to provide an API for accessing, storing, and managing data in a distributed data grid. The primary API will build upon and extend JSR-107 (JCACHE) API. In addition to it’s genericized Map-like API to access a Cache, JSR-107 defines SPIs for spooling in-memory data to persistent storage, an API for obtaining a named Cache from a CacheManager and an API to register event listeners. Above and beyond JSR-107, this JSR will define characteristics and expectations from eviction, replication and distribution, and transactions (via the JTA specification). Further, it would define an asynchronous, non-blocking API as an alternative to JSR-107’s primary API, as non-blocking access to data becomes a concern when an implementation needs to perform remote calls, as in the case of a data grid. This specification builds upon JSR-107, which is not yet complete. We intend to work with the JSR-107 EG to ensure that their schedule is compatible with the schedule for this JSR. If JSR-107 is unable to complete, we propose merging the last available draft into this specification.

Data grids are gaining prominence and importance in enterprise Java, particularly as cloud-style deployments gain popularity:

  • Characteristics such as high availability, along with removal of single points of failure become increasingly important, since cloud infrastructure is inherently unreliable and can be re-provisioned with minimal notice; applications deployed on cloud need to be resilient to this.  

  • Further, one of the major benefits of cloud-style deployments is elasticity.  The ability to scale out (and back in) quickly and easily.  Again, data grids have a role to play here.  

  • Finally, with scalable middleware comes additional stress on the data tier (traditionally an RDBMS), as middleware nodes scale out to cope with load.  Data grids - used as a distributed cache - can help with mitigating database bottlenecks.

With one of Java EE 7’s stated goals being "cloud-friendliness", the above are powerful arguments for the inclusion of a distributed data grid standard in Java EE 7.

What about JSR-107?  JSR-107 - the temporary caching API proposed in 2001 - certainly has a role to play in Java EE too.  Temporary caches are an important part of enterprise middleware, but yet a standard has been sadly missing from a Java EE umbrella specification for far too long.  Spring, having identified the need as well, has a temporary caching abstraction in their current development versions.  Several other non-Java frameworks define temporary caching APIs too (Ruby on Rails, Django for Python, .NET).  There is no denying JSR-107 is necessary, and necessary as a part of Java EE.

But JSR-107 isn’t a data grid.  JSR-107 falls short as a standard for data grids, specifically as it doesn’t take into account characteristics of distribution and replication of data, and doesn’t define a contract that implementations would have to adhere to when it comes to moving data around a cluster.  Crucial things for a data grid that, if not baked into a specification, will hinder portability and render the standard itself useless and impotent.

Further, with remote capabilities in mind, a data grid should also expose a non-blocking API, since network calls can be a limiting factor.  Invoking methods that involve remote calls should be able to be done in an asynchronous fashion.  Stuff that is irrelevant to a temporary caching API like JSR-107.

So with all that in mind, I’d love to hear your thoughts on the data grid JSR.  In addition to Red Hat, the JSR is currently backed by a major Java EE and data grid vendor which cannot be named at this stage, along with independent JCP members with relevant interest and background.

Cheers Manik

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