There are five versions of Jini: 1.0, 1.1, 1.2, 2.0, and now 2.1. The core classes are the same in each version. In this book, we'll deal only with the new version, 2.1. Jini 2.1 requires Java Development Kit (JDK) 1.4 or later, not earlier versions of Java. It will work with JDK 1.5 but does not require it.

The changes for 2.1 are listed in the document jini2_1/doc/release-notes/new.html.

The main classes that have changed for 2.0 are as follows:

The main new classes are as follows:

If you get syntax errors or runtime errors relating to these classes, it is possible that you are using Jini 1 instead of Jini 2. If you get "deprecated" warnings, it is likely that you are using the Jini 1 classes in a Jini 2 environment. The old classes are supported for now, but are not approved.