EJB 2.0 Interoperability Goals

The Relationship Between CORBA and Enterprise JavaBeans

The interoperability mechanisms in EJB 2.0 are based on several different specifications from CORBA. Besides the server-to-server interoperability requirements, J2EE applications also must be able to communicate with components hosted in a CORBA environment.

CORBA is a specification that was developed to provide a standard for creating distributed object systems. The standard allows for systems to be written in a multitude of languages and on many different operating systems. It was first developed by the OMG in the late 1980s. The OMG is made up of many different partners , all of which have a vested interest in moving the standards along.

EJB and CORBA are similar in that both are specifications and not actual implementations . Both describe ways of building distributed software systems, and both are platform neutral. EJB owes many of its ideas to the various CORBA specifications. There are some differences, however. CORBA is language independent and EJB uses Java exclusively. EJB is more of a component-based architecture, whereas CORBA wasn't originally designed that way. In 1999, OMG did agree to add a CORBA Component Model (CCM) to address limitations with the CORBA object model. These new features will allow CORBA application developers to implement, manage, configure, and deploy components that can take advantage of common services such as security, persistence, and transactional support in a standard environment.

Some see EJB and CORBA competing for the same market space. This might be true for some industries, but not for all. The two technologies really are very complementary of each other and typically are used in different circumstances. Because CORBA is language-neutral, it's very easy to build systems in CORBA that can communicate with other enterprise systems built with C++, for example. CORBA also is good for talking to legacy systems because there are many CORBA adapters available to allow mainframe and other legacy systems to communicate with CORBA applications. Enterprise JavaBeans can use the connector architecture, but the connector architecture is still immature and not many organizations are jumping on the connector bandwagon yet.

With all the benefits that CORBA has to offer and the number of enterprise systems built using CORBA, the designers of EJB were correct to try to leverage those benefits by being able to interoperate with those systems.

The interoperability requirements for J2EE and EJB applications can be divided into four distinct requirement areas:

• Remote invocation interoperability

• Transactional interoperability

• Naming interoperability

• Security interoperability

The extensions supporting distributed transaction propagation, security, and naming service access are all based on OMG standards.