[seam-dev] Persistence Module Overview

[Shane Bryzak]

  Great work, thanks Stuart.

I was wondering about one thing though - why is @Transactional not an 
interceptor binding?  The way it is now, you can't use it in a 
stereotype (though you can probably use 
@TransactionalInterceptorBinding, but this is in the impl module not the 
api, and having to use it instead of @Transactional seems inconsistent).

Shane

On 15/10/10 09:05, Stuart Douglas wrote:
> I just though I would send out a quick overview of exactly what is in
> the persistence module at the moment:
>
>
> Transactions:
>
> It provides a SeamUserTransaction object that extends the JTA
> UserTransaction (this means a dependency on the jta API).
>
> Three default implementations will be provided
> - The default EE version that either looks up UserTransaction in JNDI
> or retrieves it from the EJBContext if a CMT is active
> - An implementation that uses EntityTransaction, this is retrieved from the SMPC
> - An implementation that uses hibernate's transaction API (to be done)
>
> It does not use the CDI's ability to inject the UserTransaction for a
> number of reason:
> - It is not available in all environments
> - It is not available in EJB's that use CMT
>
> It provides a transaction interceptor, this allows you to use
> @TransactionAttribute on managed beans the same way you would on
> EJB's.
> It provides @Transactional and @SeamApplicationException for
> environments where these API's are not available.
>
> Managed Persistence Contexts
>
> - Defined as follows:
>
> @SeamManaged
> @Produces
> @ConversationScoped
> @PersistenceUnit("myPu")
> EntityManagerFactory enf;
>
> - This will work even in environments where @PersistenceUnit injection
> is not directly supported, as seam-persistence will bootstrap it for
> you.
>
> - The SMPC provides the following:
> - Automatic transaction enlistment
> - Ability to use EL in queries
> - Automatic hibernate search integration, if available
> - Ability to set manual flush mode if required
> - Event is fired when the SMPC is created, to allow for additional
> configuration such as adding hibernate filters.
>
> It also provides @TransactionScoped for transaction scoped beans
> (forgot to put this in the reference guide, oops)
>
> There are currently tests for jboss-as, jetty, and jetty+openjpa (with
> no hibernate classes present on the classpath). I am planning on also
> adding glassfish, glassfish+hibernate, and probably a few more as
> well.
>
> I have also added seam managed transactions to the faces module, this
> is similar to seam 2, however it has two notable improvements:
> - It can be controlled on per view basis (including using wildcards)
> - it can be enabled only for the RENDER_RESPONSE, so you have manual
> transaction control in your business logic, and then seam opens a
> transaction for you when rendering to prevent LIE's (this also can be
> configured on a per view basis).
>
> I think that just about covers it. If anyone has any questions or
> comments fire away.
>
> Stuart
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