Apache Geronimo is developed and distributed under the Apache License, Version 2.0, which is a derivative of the BSD License. This means that any individual or commercial entity can distribute Apache Geronimo for free. The big difference from GPL licensed software is that derivative works that are distributed need not be open source. This makes Geronimo attractive to corporations and software houses. Some corporations actually pay their employees to work full time on Geronimo. However, a lot of people contribute to Geronimo as a hobby or as a way to learn how to write scalable software.
Anyone can contribute new features, raise defects, contribute documentation, or contribute bug fixes to Geronimo. This is encouraged, as a more vibrant community will help to make a better product. The procedure to follow is to open an issue in the Geronimo issue tracker (JIRA) and attach a patch file. You can generate the patch file by invoking the svn diff subcommand. Once you attach a patch file, one of the committers (people who can make changes to the source code in the Geronimo subversion repository) will review your patch and if he or she feels it is valid, will commit it to the source tree in subversion repository.
Eclipse from the Eclipse Foundation is a popular open source IDE written in Java that supports a variety of languages, including Java. Support for Java EE 5 is provided by a set of Eclipse plugins called the Web Tools Platform or WTP. WTP provides extension points for application server vendors to extend WTP to integrate with their servers and provide deployment and debug functionality during server-side Java EE development. Apache Geronimo provides a WTP server adapter or an Eclipse plugin that runs on top of WTP and provides Java EE developers with features to develop, deploy, and debug Java EE applications on Apache Geronimo. The Geronimo Eclipse Plugin (GEP) can be downloaded from the subprojects site at http://geronimo.apache.org/development-tools.html. The source code for the Geronimo Eclipse Plugin is available from https://svn.apache.org/repos/asf/geronimo/devtools/eclipse-plugin/.
Apache Geronimo provides a set of sample Java EE 5 applications that exercise almost all aspects of the Java EE 5 specification. These samples range from the most trivial web applications such as the Inventory sample to reasonably complex enterprise applications like the Day Trader. The samples for different versions of Apache Geronimo can be obtained from the URL http://cwiki.apache.org/GMOxSAMPLES/.
The Day Trader sample is actually checked into the subversion tree for Apache Geronimo. Users can download it from the Subversion repository and build it. The Subversion (SVN) URL is https://svn.apache.org/repos/asf/geronimo/daytrader/.
The other samples are also available in SVN at https://svn.apache.org/repos/asf/geronimo/samples/.