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From Andy Jefferson <a...@jpox.org>
Subject Re: [DISCUSS] Named PMF proposal (JDOHelper enhancements)
Date Wed, 28 Feb 2007 06:37:18 GMT
> Call it what you want -- I only proposed these names.  I wouldn't call
> it persistence.xml, as the contents are not the same as the
> JPA-specified content.  If the persistence.xml is found, its contents
> are of course interpretable by the JDO implementation according to our
> JPA alignment verbage defined in JDO 2.1.

ok. So a JDO2.1 impl has to understand both "persistence.xml" (JPA format) and 
this "jdo.xml" ? No problem if that is the case but just want to understand 
what we're specifying here since not everyone was on this conf call.

> >2. Why not just use same definition of "persistence.xml" from
> >aforementioned JPA spec ?
> > When JDO2.1 has annotations not everything is
> >always defined in a
> >jdo(/orm/jdoquery) file, so would be nice to have the ability
> >to specify classes, or jars.
>
> Because it's not the same as the persistence.xml.  If we're missing the
> ability to specify classes or jars, let's add it!

ok. 

> >4. Why do we need "persistence-manager-factory" class="..." ?
>
> Basically, for backward similarity only, not necessarily backward
> compatibility.  It was only a suggestion as well, since we could just go
> with a <property name="javax.jdo.PersistenceManagerFactoryClass"
> value="..."/> element.  It's just that this property is almost always
> present, so I thought a convenient shortcut would be nice.

ok.

> >We could use the
> >same boot idea as JPA and have a META-INF/services/javax.jdo.XXX file
> >defining the PMF(s) available, and it takes the one that
> >claims it supports
> >the required "persistence-unit" (or PMF)
>
> I like this suggestion!  I assume the following would be true -- please
> correct where I've got it wrong.
>
> * The name of this file is
> "META-INF/services/javax.jdo.PersistenceManagerFactory"
> 	* This is a text file
> 	* The contents of the file would be the name of the provider's
> implementation class of javax.jdo.PersistenceManagerFactory

Yes. See a mail by Erik to the lists on 19/01/2007 called "Proposal for 
Service Discovery". JDOHelper would then have the job of finding all services 
files of this name ("javax.jdo.PersistenceManagerFactory"), and from the 
contents finding the relevant PMF to instantiate for a particular PMF name.


Since this appears to be an extension to JDO and not the simple mapping across 
of terminology JDO-JPA (being able to read a "persistence.xml"), I'd ask are 
we just confusing users by having "persistenceUnitName" and "transactionType" 
for when a JDO impl reads a "persistence.xml", yet here we also have a PMF 
name (which is the same as a persistence-unit name) for when we use this 
file.



-- 
Andy

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