Guide to Jetspeed-2 Component Architecture

The Jetspeed-2 architecture is build on a component architecture where as defined by Martin Fowler:

    By the term component, I mean a glob of software that's intended to be used, 
    without change, by application that is out of the control of the writers of 
    the component. By 'without change' I mean that the using application doesn't 
    change the source code of the components, although they may alter the component's 
    behavior by extending it in ways allowed by the component writers.

Jetspeed-2 uses dependency injection as a programming design pattern and architectural model to establish a level of abstraction via a public interface, and to remove dependency on the components' implementation. The architecture unites the components rather than the components linking themselves or being linked together. Dependency injection is a pattern in which responsibility for object creation and object linking is removed from the objects themselves and transferred to a factory. Dependency injection therefore is obviously inverting the control for object creation and linking, and can be seen to be a form of Inversion of Controls(IoC).

  engine = new JetspeedEngine(properties, applicationRoot, config,
      initializeComponentManager(config, applicationRoot, properties));