[cdi-dev] CDI + transactions query

[Tom Jenkinson]

That sounds like a good plan to me

On 2012-08-22T16:44:30 BST, Pete Muir wrote:
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> On 22 Aug 2012, at 15:29, Tom Jenkinson wrote:
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>> Hi Pete,
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>> Would it make sense to maintain the same restrictions as JMS?
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>> 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.
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> Yes, that makes sense.
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>>
>> 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!
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> No, I think this is right.
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> In that case, what I would suggest we do is:
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> * explicitly make controlling transactions from observers non-portable (which allows implementors to experiment with such a feature without breaking spec compliance)
> * raise a feature request in CDI to consider adding something like what you describe in the future
>
>> Tom
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>> 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
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>>> 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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