Working with DataNucleus: How I solved the "No persistence providers available" problem.

[Cameron Wallace McKenzie]

I just published an article to TheServerSide that discusses how to set up and configure your development environment to use DataNucleus as the Java Persistence API (JPA) provider. I've linked to this thread from the article, hoping anyone who is having trouble running the example might post their question here and take advantage of the big brains that make up the JavaRanch community.

Anyways, the darnedest thing about putting together the tutorial was that during the writing, I kept getting this annoying error that said:

Exception in thread "main" javax.persistence.PersistenceException:
No persistence providers available for "PU" after trying the following discovered implementations:
org.datanucleus.jpa.PersistenceProviderImpl
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:180)
at javax.persistence.Persistence.createEntityManagerFactory

Anyways, I saw a few posts on the issue, but no solutions. I knew it had to be a simple mistake, and sure enough, it was. I had the incorrect entry in my persistence.xml file:

<!-- INCORRECT -->
<provider>org.datanucleus.jpa.EntityManagerFactoryImpl</provider>    

The correct entry for this application should have been:

 <provider>org.datanucleus.jpa.PersistenceProviderImpl</provider>   

The full persistence.xml file looked like this:

 
<?xml version="1.0" encoding="UTF-8" ?> 
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">
 <persistence-unit name="PU">
  <provider>org.datanucleus.jpa.PersistenceProviderImpl</provider> 
  <class>com.mcnz.model.GameSummary</class> 
  <exclude-unlisted-classes /> 
  <properties>
  <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost/rps" /> 
  <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" /> 
  <property name="javax.persistence.jdbc.user" value="root" /> 
  <property name="javax.persistence.jdbc.password" value="password" /> 
  </properties>
 </persistence-unit>
</persistence>   

Anyways, that fixed it, just in case anyone is having a similar issue.

-Cameron McKenzie

[Jignesh Patel]

Cameron,
I am trying to connect to HBase using JBoss 7.0.2 and data nucleus 3.0.2 and till now no success.

-Jignesh