[wildfly-dev] Favour jboss-persistence.xml if present

[Brian Stansberry]

On 1/29/14, 3:20 PM, Scott Marlow wrote:
> On 01/29/2014 03:17 PM, Jason Greene wrote:
>>
>> On Jan 29, 2014, at 2:11 PM, Scott Marlow <smarlow at redhat.com> wrote:
>>
>>> On 01/29/2014 02:44 PM, David M. Lloyd wrote:
>>>> On 01/29/2014 01:39 PM, Klein, Christopher wrote:
>>>>> Hey guys,
>>>>> I already filled out a feature request in JIRA (https://issues.jboss.org/browse/WFLY-2816).
>>>>>
>>>>> We have the situation that our development environment (currently JBoss AS 7.1.1) differs from the production instance (WebSphere 8.5). Our persistence.xml has to be adjusted for production environment: different jta-data-source, different properties. The dirty solution for this problem would be to generate separate build artifacts for both environments. As you can imagine I don't like the idea of having two binaries just because of a few different settings. Other options (WildFly or WebSphere specific JPA properties; extending Hibernate persistence provider) do not work.
>>>>>
>>>>> A much nicer solution would be: WildFly checks on deployment process for the existence of a jboss-persistence.xml. If it does, the jboss-persistence.xml is used for configuring the JPA subsystem. Otherwise it falls back to the standard persistence.xml. The jboss-persistence.xml would use the XML schema from persistence.xml.
>>>>>
>>>>> I lookup into the WildFly sources and this change should be an easy patch which I would provide.
>>>>>
>>>>> So here are my questsions:
>>>>> 1. Are you generally interested in accepting such a pull request or is it a feature you don't want?
>>>>> 2. Does another solution exists to my problem apart from generating different artifacts which makes this pull request needless?
>>>>
>>>> It sounds like a reasonable idea that actually applies generally.  If I
>>>> recall correctly, we have something of a mix today of descriptors which
>>>> override versus supplementing existing configuration.  But overall the
>>>> unofficial policy for new descriptors has been to add them in to
>>>> jboss-all.xml as subdescriptors, FWIW.
>>>>
>>>
>>> I'm not sure that jboss-all.xml would be a good place for the
>>> persistence unit definitions.
>>
>> I would agree that this is probably impractical.
>>
>>>
>>> I think that the proposed jboss-persistence.xml (or
>>> wildfly-persistence.xml) could be helpful for anyone that wants to only
>>> develop on WildFly but deploy on other application servers.  I suppose
>>> this could help someone that wants to migrate off of WildFly as well (to
>>> prepare for a switch to something else).  Is that what you mean by the
>>> proposed solution applying generally?
>>
>> It does sound a lot like a vendor specific alt-dd feature. We have some other solutions as well that might be relevant:
>>
>> 1) Deployment overlay feature - This allows you to override the descriptors in a deployment without modifying the deployment. These are added in a separate management op with a match pattern, and preserved outside the lifecycle of the deployment. Available in WildFly 8 and EAP 6.2 (can’t recall if it made EAP 6.1).
>
> I was just reading
> https://docs.jboss.org/author/display/WFLY8/Deployment+Overlays but I'm
> not sure that would help with this use case.  Since the deployment will
> fail due to the persistence.xml targeting WebSphere (persistence unit
> property "hibernate.transaction.manager_lookup_class" is set to
> "org.hibernate.transaction.WebSphereExtendedJTATransactionLookup").
>

The persistence.xml that is the deployment overlay would not include 
those settings. The deployment overlay feature hides the original 
persistence.xml in the deployment archive from the deployment 
processors; they only see the overlay.

> What might help is if we could ignore (or auto-magically remove during
> deployment) certain persistence unit property settings that we know will
> cause the deployment to fail.
>
>>
>> 2) Property Substituion - There is a flag you can optionally enable in standalone/domain.xml that allows descriptors to contain property expressions. However, this only works for this use case if all venders are using the same expression language (unlikely). I just thought I would mention it.
>>
>>
>>>
>>>
>>>
>>>
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>>> wildfly-dev at lists.jboss.org
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>>
>> --
>> Jason T. Greene
>> WildFly Lead / JBoss EAP Platform Architect
>> JBoss, a division of Red Hat
>>
>
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-- 
Brian Stansberry
Senior Principal Software Engineer
JBoss by Red Hat