Wow, this is very nice! Kudos Jonas!

Cheers, Tim

On 09/06/2009 14:18, "Jonas Bonér" <jbo...@gmail.com> wrote:

> 
> Hey guys.
> 
> I have hacked together an early draft of the JTA transaction stuff.
> 
> I have wrapped it up in a monad. Here  are some examples of usage:
> 
>  for {
>    ctx <- TransactionContext.Required
>    entity <- updatedEntities
>    if !ctx.isRollbackOnly
>  } {
>    // transactional stuff
>    ctx.getEntityManager.merge(entity)
>  }
> 
> val users = for {
>    ctx <- TransactionContext.Required
>    name <- userNames
>  } yield {
>    // transactional stuff
>    val query = ctx.getEntityManager.createNamedQuery("findUserByName")
>    query.setParameter("userName", name)
>    query.getSingleResult
>  }
> 
> If you don't like the monadic approach you can just use the high-order
> functions:
> 
> TransactionContext.withTxRequired {
>     ... // REQUIRED semantics
> 
>   TransactionContext.withTxRequiresNew {
>     ... // REQUIRES_NEW semantics
>   }
> }
> 
> I have implemented the same semantics as used in the EJB spec.
> Required, RequiresNew, Mandatory, Supports, Never. All these are
> monadic objects in the TransactionContext object.
> I don't have a webapp to try this out, so I would be happy to get all
> kinds of feedback, but API wise and bug reports or fixes.
> 
> This API is hooked into Derek's Scala-JPA stuff. I had my own impl of
> this but replaced it with Derek's work.
> 
> Derek,
> please go through the integration to see if I have done it correctly,
> and where things code be improved.
> 
> All committers,
> feel free to hack and change this code anyway you want.
> 
> The code is in a branch (wip-jta-jonas), you can find it here:
> http://github.com/dpp/liftweb/tree/3783b9e2200cc57dd72baa1bd8cabdb1365ee923/li
> ft-jta
> 
> Check the ScalaDoc (or the source) for the documentation on usage,
> semantics etc.
> Also see the README for configuration in persistence.xml etc.
> 
> Currently it is hard-coded to use the Atomikos Transaction library and
> Hibernate JPA, that would have to be configurable + some other options
> as well. See the TODOs in the code.
> 
> As I said, this needs feedback and testing. Thanks.



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