The GridSphere project is building on experience in the Java-based Astrophysics Simulation Collaboratory and GPDK portal toolkits. It now has a reasonable uptake in Europe and to some extent Canada.

GridSphere provides a "white-box" framework (you edit the code) in which users can override base classes and "hook" in their own methods. It therefore requires users to become familiar with core framework interfaces which are however based on the community standard API JSR-168. Heavy use is made of design patterns which provide template solutions to commonly recurring software design problems. They also provides a common language that makes the code easier to read and understand. The Model View Control (MVC) pardigm is used to separate logic from presentation as in other portlet frameworks.

For more information see http://www.gridsphere.org/gridsphere/gridsphere