Evaluation of Integration Technologies

Today's lesson has provided you with an introduction to a number of approaches to integrating legacy and non-Java code or applications into your J2EE applications. Sometimes you may find it quite clear which approach to adopt, but sometimes the approach to adopt might not be immediately obvious. The following guidelines will assist you in making that choice.

• Connector Architecture— This is your primary choice when you want to allows J2EE components to call on the functions an EIS provides. Typically, these EISs include ERP systems, mainframe transaction processing systems, and databases (not to the exclusion of JDBC).

• JavaIDL and RMI-IIOP— If you want to utilize non-Java objects and the remote system is incapable of running a stable JVM or runs existing CORBA objects, you will use CORBA. You should use Java IDL if your existing code-base makes use of Java IDL, or you are an experienced CORBA programmer wanting to use Java. In most other instances, you will find it simpler and more effective to use RMI-IIOP.

• JNI— You should wrap code by using JNI when that code is a local non-Java application, library, or time critical sections of code that you want to implement in a lower-level programming language. In addition, you can wrap remote non-Java code by using JNI, and then export it as RMI remote objects. Note that to adopt this approach, you must have a JVM on both the client and the server.