[infinispan-dev] Re: Query API, JPA and a fine-grained model

[Emmanuel Bernard]

All the JPA-QL grammar complexity comes from joins and navigation so I  
think if you restrict yourself to no join or limited joins this should  
be straightforward for someone that understands ANTLR.


On  May 12, 2009, at 11:27, Manik Surtani wrote:

> So the plan is that we would implement a new fine-grained model to  
> replace POJO Cache.  Rather than AOP, we would use a JPA-like  
> session-style interface where we can track changes made to state in  
> a session to detect field changes [1].  This hugely simplifies the  
> implementation and makes things more robust, plus provides people  
> with a familiar JPA API to use.
>
> Now considering the query API, if we are already providing a JPA  
> interface, this is another reason for the query API to support JPA- 
> QL rather than just Lucene queries.
>
> The other reason, of course, is easy migration off using databases  
> for persistence to using a data grid for persistence [2].  Now,  
> naturally, the designs outlined in [2] can easily be achieved using  
> Hibernate and a good distributed cache, but what happens when you  
> don't actually want to persist your data at all, just want it to  
> live in a grid (because you think your grid is "good enough" to not  
> be unavailable, and/or your data is transient or can be  
> recalculated), but you still want to use a JPA interface because  
> either you are more familiar with it, or you started off storing  
> this state in JPA and are now rethinking your persistence needs but  
> don't want to rewrite your app.
>
> Of course, supporting JPA-QL in a distributed cache query API is not  
> trivial.  We know we can do this fairly easily with Lucene queries.   
> Does anyone know of a mechanism to translate between these easily  
> enough?  If need be, this is something we could build.  JPA-QL  
> grammar is finite and an ANTLR [3] definition to translate these to  
> Lucene query objects shouldn't be too hard ...
>
> Thoughts?
> Manik
>
> [1] http://www.jboss.org/community/wiki/NewFineGrainedReplicationAPIDesign
> [2] http://web2.sys-con.com/node/951117
> [3] http://www.antlr.org/
> --
> Manik Surtani
> manik at jboss.org
> Lead, Infinispan
> Lead, JBoss Cache
> http://www.infinispan.org
> http://www.jbosscache.org
>
>
>
>