If you are a developer interested in contributing to the GlassFish effort, here are a few things you should probably know.

Understand the Code

Developing an application server is a big deal. Below are the links that help us organize the development of a project of this size.

Build It

Starting with GlassFish v3, the build infrastructure is entirely based on Maven (2).
This wiki page should have all the details and steps required to build GlassFish.

Test It

There are several different tests that are currently available in GlassFish. QuickLook tests run in a short time and cover a broad set of features in the app server. Developer tests are also available for the different modules. Each module has more information about running those tests.

For more information, see the GlassFish Quality Portal.

Contribute Code

Contributing to project GlassFish can be done in various ways: bug fixes, enhancements, new features, or even whole modules.

Contribute GlassFish Packages

GlassFish uses IPS/pkg(5) as its modules systems accessible using the update center feature of the product.
We welcome contributions of additional packages. For more information:

Contribute Samples

We welcome good quality samples that demonstrate a feature or aspect of GlassFish or Java EE technology.
Join the GlassFish Samples Project and see your contributions making a difference.

All contributors must sign and return a Contributor Agreement.

Contribute Documentation

One mark of a quality product is its supporting documentation. There are many ways to contribute GlassFish documentation, most of which are listed on the documentation home page. Also see the Community Docs page on the GlassFish wiki, which focuses on the specifics of community doc contributions. Explore these pages, think about how you'd like to get involved, then do so! We welcome and encourage your contributions. Questions about how or what to contribute? Contact the documentation mailing list.