openjpa | Apache OpenJPA | Object-Relational Mapping library

A few misundestandings.

I have tried using only openjpa-maven-plugin without maven-compiler-plugin, but it did not help.

Maven's pom.xml is considered a "project object model" That means, for your "project" it is the "object" that "models" the build process. This object is sub-classed from a "parent pom.xml" that is embedded inside of Maven, which defines a default build; so, if you remove the "maven-compiler-plugin" you will get the default "maven-compiler-plugin" configuration. Odds are that configuration is quite old, being shipped with Maven, and you probably are better off including an "override" which brings it up to date.

Eclpise and Maven work together; but, until you know how they work together, you will have a lot of problems.

Eclipse reads the pom.xml file and generates a Eclipse configuration that should perform the same steps as the pom.xml file, in the same ways. When you compile with Eclipse, it doesn't run mvn compile, it builds off of the Eclipse configuration, which might be older than the recently edited pom.xml. For this reason, you should reread your project configuration after every edit of pom.xml when using ecplise.

If you want to look at a different IDE that is similar to Eclipse; but, one that calls mvn compile instead of calling it's own interperted version of "should be the same, but often isn't", look at NetBeans. https://netbeans.apache.org/download/nb122/index.html Unlike Ecplipse, it doesn't contain its own "mirror image of commands" for Maven plugins (or its own embedded compiler), it uses the mvn command and the javac compiler and launches them with configurations to generate a lot of output messages, which it then reads to update it's "IDE side" of things.

The reason I point this out, is because you might be following the instructions, and if you are, you might be seeing correct output on a mvn package from the command line, but not within Eclipse (because of the need to refresh the eclipse project from the source pom.xml)

You need to add openjpa:enhance to the POM itself. Then you just run mvn clean install.

Found out that org.apache.derby.jdbc.EmbeddedDriver class is not in derby artifactid dependency (it has derby and derbyshared jar's). It is in derbytools, so including derbytools to dependencies solve issue abbout missing EmbeddedDriver class:

Found out that required classes were in java.sql and and java.instrument module, so adding these to module-info solve my issue. module-info.java should look like this:

as OpenJpa documentation Section 2, “ Integrating with the Transaction Manager ” says, I should add to persistence.xml.
By this property, OpenJpa understands that should uses container's managed transaction.
In case of weblogic, I do not need to configure "openjpa.ManagedRuntime " property.
and according to Section 2.1, “ Managed and XA DataSources ”. "When using a managed DataSource, you should also configure a second unmanaged DataSource that OpenJPA can use to perform tasks that are independent of the global transaction. The most common of these tasks is updating the sequence table OpenJPA uses to generate unique primary key values for your datastore identity objects. "
So, this is my persistence.xml:

• Generally, a standard (such as JPA) will generally avoid dictating implementation decisions and instead dictate required behaviors expected of implementations.
• JPA is a data access pattern, somewhere between a database gateway (EntityManager) and a data mapper. Because JPA presents managed Entities to core code, realize that database interactions aren't necessarily restricted to a data access layer: records with implicit updates and (possibly) implicit queries for sub records.

I encourage anyone to seek to understand the pattern that JPA is - it is an interesting one. Not universal (are there any universal data access patterns?), but a terrific tool to have in your toolbox.

I had the same issue on a project of mine and I solved it by adding the full path to the openejb-javaagent-4.6.0.jar. If you install the jar via Maven (you can see the dependencies to add here) it is in the target/ directory of your project.

I found out after some researching/intuition that in pom.xml were missing some surefire plugin dependencies.I integreted them and now it works fine!

The javax.rmi package was contain in the system library (in Java 9 and 10 in the module java.corba) until it was removed in Java 11 by JEP 320.

For Java 11 or higher you need to add a plugin/bundle containing the package javax.rmi to your target platform since it is required by the org.apache.openjpa plugin/bundle you have. Or maybe there is a newer version of org.apache.openjpa that contains the javax.rmi package or does not require it anymore.