Java Enterprise in a Nutshell, Third Edition

Appendix G. IDL Reference

This chapter serves as a quick reference for CORBA’s language-independent Interface Definition Language (IDL). It also gives a summary of the Java mapping of IDL (i.e., how IDL interface definitions are mapped by an IDL-to-Java compiler into equivalent Java interfaces.) For a complete, definitive reference on IDL and the Java mapping of IDL, consult the IDL specification issued by the OMG.

Since this reference combines an IDL reference with an overview of the Java mapping of IDL, we’ll be using a combination of IDL and Java examples throughout. In order to make it clear which language is being used in each example, we’ve stolen a convention from the CORBA standards documents: a comment preceding the example code indicates which language is in use.

IDL, as the name implies, is a language for defining object interfaces. IDL is language-neutral, so interfaces defined in IDL can be converted to objects implemented in any language with an IDL mapping. One way to think of the role that IDL plays is to imagine that you already have a set of interacting objects defined, and IDL is a way to export a subset of those interfaces so that they can be accessed by remote entities. Any member variables or operations that you define in the IDL interfaces will be visible and accessible by remote entities, providing they can obtain a reference to instances of these interfaces (refer to Chapter 14 for more details on the use of CORBA objects). If you proceed this way, the definitions ...