What spec version does OpenEJB support?

OpenEJB supports the Enterprise JavaBeans 3.0 specification and previous versions 2.1, 2.0 and 1.1.

I don't plan to use EJBs, so why would I embed OpenEJB into Tomcat.

Adding OpenEJB to Tomcat gives servlets several new Java EE 5 capabilities such as JPA, JAX-WS, JMS, J2EE Connectors, transactions, and more as well as enhancing the injection features of Tomcat 6 to now support injection of JavaEE objects like Topics, Queues, EntityManagers, JMS ConnectionFactories, JavaMail Sessions, as well as simpler data types such as Dates, Classes, URI, URL, List, Map, Set, Properties, and more. In the case of Tomcat 5.5 which doesn't support dependency injection at all, even more is gained.

Can I run OpenEJB with a JVM for any vendor?

The Sun, Mac, and IBM vms are regularly tested, however any vm should work.

Which version of Java is required to run OpenEJB?

Java versions 5 or 6, aka Java 1.5 or 1.6.

Do I need Apache Maven to work with OpenEJB?

Definitely not. Most of the examples include both Maven and Ant build files. OpenEJB is usable as a plain library, much like an embedded database like Derby, so it is usable in any application regardless if that application is run via Maven, Ant, Intellij, Eclipse, NetBeans, JUnit, TestNG, etc.

Can I start and stop OpenEJB from an IDE? If yes, which IDE is

supported by OpenEJB?

The short answer is yes. The basic approach for all embedding scenarios is to 1) add OpenEJB to your classpath, and 2) construct your InitialContext using org.apache.openejb.client.LocalInitialContextFactory. The LocalInitialContextFactory will boot OpenEJB in your vm and all ejb applications visible in the classpath will be deployed. See for details on how to embed openejb in your application and IDE. See Application discovery via the classpath for various ways to have your applications discovered.

During embedded testing, how can I externalize all my DataSource


Create an openejb.xml file in any directory that gets added to your test classpath. For maven, something that winds up directly under "target/classes/" or "target/test-classes/" will work just fine. Then in your test case do this:

   protected void setUp() throws Exception {
       Properties properties = new Properties();


       URL config =

this.getClass().getClassLoader().getResource("openejb.xml"); properties.setProperty("openejb.configuration", config.toExternalForm());

       initialContext = new InitialContext(properties);

The file itself doesn't have to be called "openejb.xml", you could have a few different files like that for different testing scenarios each with a name that describes the basic setup.

Container-Managed Persistence

What engine does OpenEJB use for CMP?

The CMP engine is written as a layer over JPA with OpenJPA doing the persistence work.

What is the format for the CMP mapping files?

The standard JPA mapping file and annotations are also used for CMP mappings.