persistence.xml with Glassfish 3.1.1 - jpa

Question

I am very new to glassfish, JPA and so on and I have really problems with setting that up. What I am planning to do is a simple RESTful service with a persistent backend. I am using glassfish3 as application server and already deployed a simple REST service with the jersey-library. Now I want to provide access to a database via JPA. Glassfish is shipped with JavaDB/derby and EclipseLink, is that right? So, I want to use that :-)
I created a persistence.xml in META-INF:
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
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
http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
<persistence-unit name="myPU" transaction-type="JTA">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties>
<property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.ClientDataSource" /> <!-- org.apache.derby.jdbc.EmbeddedDriver -->
<property name="javax.persistence.jdbc.url" value="jdbc:derby://localhost:1527/sample;create=true" />
<property name="javax.persistence.jdbc.user" value="APP" />
<property name="javax.persistence.jdbc.password" value="APP" />
<property name="eclipselink.ddl-generation" value="create-tables" />
</properties>
</persistence-unit>
</persistence>
Then I created a field in my resource, where I want to access/store som data:
#PersistenceUnit(unitName = "myPU")
EntityManagerFactory emf;
But "emf" is always NULL :-(
I guess that my persistence.xml is not configured appropriate.
Would be really glad if someone has a hint, what I am doing wrong...
thanks!

Answer 1

I think it is better to create JNDI for db connection . You can do it easly with GlassFish.
Firstly create connection pool (you will set db connection settings);
Resources->JDBC->JDBC Connection Pools
After that crate JNDI name for this pool ;
Resources->JDBC->JDBC Resources
So lets say you set JNDI name as "dbCon"
And here your persistence.xml ;
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" 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 http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="myPU" transaction-type="JTA">
<jta-data-source>dbCon</jta-data-source>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties/>
</persistence-unit>
</persistence>
Note : You must copy your jdbc jar to \glassfish-3.1.1\glassfish\domains\domain1\lib\ext

Answer 2

I have the solution now for my problem.
Here is the corresponding configuration:
glassfish 3.1.1
built-in JavaDB/derby database: jdbc/__default
glassfish's JPA, which is eclipselink
(JAX RS: Jersey, which is shipped with glassfish)
So, you have to create the folder "META-INF" wihtin your src folder and put the persistence.xml there:
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
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
http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
<persistence-unit name="myPU" transaction-type="JTA">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<jta-data-source>jdbc/__default</jta-data-source>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties>
<property name="eclipselink.ddl-generation" value="drop-and-create-tables" />
</properties>
</persistence-unit>
</persistence>
I created the .xml previously in the META-INF of WebContent, and that is wrong.
You also do not have to reference any additional libraries, since you have the glassfish modules added.
Now I have created a JavaBean, where I do inject the PersistenceUnit:
#Stateless
public class StorageService {
#PersistenceContext(unitName = "myPU")
EntityManager em;
...
}
And this one is injected in my Resource-Classes of the Jersey-Servlets:
#Path("/someres")
#Produces(MediaType.APPLICATION_XML)
#Stateless
public class SomeRes {
#EJB
StorageService storageService;
...
}
The injections do only work if the classes are marked as "#Stateless".

Answer 3

I have not tried with RESTful service, but I guess that should not matter. I noticed you are using persistence.xml for version 1. Any specific reason?
Following persistence.xml works for me:
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" 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
http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="myPU">
<properties>
<property name="eclipselink.ddl-generation" value="create-tables" />
<property name="eclipselink.ddl-generation.output-mode"
value="database" />
</properties>
</persistence-unit>
</persistence>
Hope this helps.