[cdi-dev] CDI + transactions query

Tom Jenkinson tom.jenkinson at redhat.com
Wed Aug 22 10:29:58 EDT 2012

Hi Pete,

Would it make sense to maintain the same restrictions as JMS?

In JMS you can initiate a new transaction from onMessage, analogous to 
a method decorated with @Observes. If the method returns without 
completing the transaction then an error is logged and the transaction 
rolled back.

Flowing a transaction from an event producer to an event consumer isn't 
a great idea (it doesn't work in JMS either). But allowing a consumer 
to control their own transaction does seem to make sense to me.

Admittedly this is a gut reaction, I read through the Jira and the doc 
you linked to though, and used my JEE experience to draw analogies, do 
let me know if I got the wrong end of the stick please!

On 2012-08-22T13:20:52 BST, Pete Muir wrote:
> Hi Paul, Tom, Mike,
> I have an open issue in CDI - https://issues.jboss.org/browse/CDI-213 - which I would like your input on.
> Events in CDI are very simple (you can read more at http://docs.jboss.org/weld/reference/latest/en-US/html/events.html) and provide a typesafe implementation of the observer/observable pattern. Currently the spec prohibits manipulating transactions from an observer method, but it doesn't say what happens if someone does try to do this [1].
> So, what I'm asking is really whether it really makes no sense to allow this, or whether it's best to say that it's "non-portable", which means that an implemenation might offer this as a feature above and beyond the spec. Furthermore, it may be that it's not really possible to disallow this, in which case we would need to go with non-portable as well.
> Thanks
> Pete
> [1] If we say that it leads to an exception, we can then check it in the TCK, which is good :-)

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