| Re: [eclipselink-dev] Loading multiple persistence.xml files |
Hi Carl,
Is the number of mapping files you get known or constrained? If so, it may be possible to build jar files containing your domain classes and orm.xml files and point to them in the persistence.xml file using <jar-file>.
As for the "classloader trick"... Although I have not heard of it, it is plausible that it might work. If you are in a JavaSE-type deployment, EclipseLink processes the persistence.xml and as long as it is available to System.getResources("META-INF/persistence.xml") when we bootstrap, I can't see why it wouldn't work. There is even some API that allows you to tell us what classloader to use. The only issue I can think of in this type of deployment is that the dynamic weaving we can do for performance might not work.
JavaEE-type deployments would likely depend on what application server you are running since the app-server controls the processing of persistence.xml.
-Tom
Carl Hall wrote:
That works out fine. Our system pulls in jars that are self contained projects. I don't have a way to know what mapping files are available without querying the classloader.
e.g.
Sakai ClassLoader sees:
project1.jar!META-INF/persistence.xml <-- defines "default" UoW
project1.jar!META-INF/orm.xml
project2.jar!META-INF/persistence.xml <-- also defines "default" UoW
project2.jar!META-INF/orm.xml
etc.
The classloader "trick" I've seen is to query for all these files then inject into getResources() such that either, on-the-fly, 1) create a persistence.xml that contains a mapping entry for each orm.xml found or 2) merge all orm.xml files into 1 file and return a reference.
<mailto:tom.ware@xxxxxxxxxx> <mailto:tom.ware@xxxxxxxxxxOn Wed, Dec 17, 2008 at 11:07, Tom Ware <tom.ware@xxxxxxxxxx <mailto:tom.ware@xxxxxxxxxx>> wrote:
Hi Carl,
What issues are you seeing when you specify several orm files
within the same persistence unit definition in one persistence.xml file?
e.g.
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
persistence_1_0.xsd" version="1.0">
<persistence-unit name="default" transaction-type="RESOURCE_LOCAL">
<provider>
org.eclipse.persistence.jpa.PersistenceProvider
</provider>
<mapping-file>META-INF/advanced-entity-mappings.xml</mapping-file>
<mapping-file>META-INF/inheritance-entity-mappings.xml</mapping-file-->
<mapping-file>META-INF/inherited-entity-mappings.xml</mapping-file>
<mapping-file>META-INF/relationships-entity-mappings.xml</mapping-file>
etc....
-Tom
Carl Hall wrote:
Hi, Tom.
You've nailed it. Each persistence.xml is trying to create the
same persistence unit ("default"). Is there a nice way to load
1 persistence unit from multiple orm.xml files? I've seen some
classloader tricks to accomplish this but don't want to head
down that rabbit hole unless necessary.
Thanks,
Carl
On Wed, Dec 17, 2008 at 10:55, Tom Ware <tom.ware@xxxxxxxxxx
<mailto:tom.ware@xxxxxxxxxx>>> wrote:
Hi Carl,
Are you using separate EntityManagers for each persistence unit?
An EntityManager represents one persistence unit - when the
EntityManagerFactory is created, you get it by persistence unit
name. Any EntityManager created by that factory will
represent that
persistence unit.
The name of a persistence unit is specified in the
persistence.xml
and only one persistence.xml may be used to define a given
persistence units. It is an error to have multiple
persistence.xml
that define the same persistence unit and the behavior is
undefined
- I am not surprised that if you are doing this, you get the last
one loaded.
To access different persistence units, create an
EntityManager for
each.
-Tom
Carl Hall wrote:
I have a setup where multiple project come into a shared
classloader. Each project can have its own model files and
thusly its own persistence.xml and orm.xml files. When I
create
an EntityManager, I see in the logs that each persistence.xml
file is found (3) and each orm.xml file loads with the
expected
entities. When I try to query or persist using this
EntityManager, only the entities from the lastly loaded
persistence.xml is found. Am I loading this correctly? Am I
trying to access things incorrectly?
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