Introducing Other Connectivity Technologies

So far in today's lesson, you have learned about the J2EE Connector architecture, how it allows J2EE application components to interact with EISs, and how to code against these EISs. This is just one element of the Java technologies that allows you to connect to legacy systems and non-Java systems. There are other Java technologies that allow you to integrate Java applications with non-Java applications. The remainder of today's lesson provides an overview of three of these Java technologies:

• Java IDL

• RMI over IIOP

• Java Native Interface (JNI)

The first two technologies allow you to create and interact with objects that comply with the Common Object Request Broker Architecture (CORBA). If you don't know about CORBA, don't worry because the next section of today's lesson provides a brief overview of it. The most important aspect of these Java technologies is that they allow you to write code that interacts with either local or remote objects that are written in languages other than Java.

The third technology, JNI, also allows you to write code that interacts with code written in languages other than Java. Unlike the previous technologies, JNI allows you to interact with applications and libraries that are written in other languages, rather than only CORBA objects written in other languages. For example, you can write code that uses JNI that utilizes C libraries or C++ classes. This means that you can call non-Java functions to provide services that are unavailable from Java. The integration that JNI allows works in both directions—both the Java and non-Java sides can create, update, and access Java objects.

After today's lesson introduces these technologies, it will provide you with a brief evaluation of these technologies to help you decide which best suit your application's needs.