The Avalon project is Apache's Java Server Framework. It is separated into five sub projects: Framework, Excalibur, LogKit, Cornerstone, and Phoenix. Its purpose is to simplify server side programming for Java based projects. It formalizes serveral best of breed practices and patterns for server side programming.
For more information about Avalon, please go to http://jakarta.apache.org/avalon.
The Avalon Framework formalizes the contracts and patterns used in the other Avalon projects. It is derived from modern software engineering techniques and aims to provide a solid basis on which to build server products.
What that means is that we define the central interface Component. We also define the relationship (contract) a component has with peers, ancestors and children. This documentation introduces you to those patterns, interfaces, and relationships.
The Avalon Framework raises the abstraction level from Object-Oriented Programming concept one notch to the Component-Oriented Programming model. This enables programmers to concern themselves with assemblies of classes, rather than the classes themselves--thus reducing the number of things the programmer must keep in mind, and speeding up application development.
The Avalon Framework is already used in Cocoon2, an XML publishing framework. The Avalon Framework is also used in Apache JAMES, a Java(tm) Mail Server. Another project that is built on Avalon Framework is Jestkop, a cross-platform replacement for your ordinary desktop. If you are evaluating Avalon and want the proof that it's claims are valid check them out.
For more information about Avalon Framework 4.1, please go to http://jakarta.apache.org/avalon/framework.