From the PicoContainer site --http://www.picocontainer.org/PicoContainer is a small, simple container for arbitrary components. It is embeddable and extentensible. PicoContainer is designed for server and client side, for small and enterprise applications. There are already quite a few diverse containers that deliver the PicoContainer design. Components can be created for it without importing or extending any interfaces or classes outside of the java.* package. Components also have no meta-info specification. i.e. no XML. Most importantly of all, components for PicoContainer can be used without PicoContainer for good old-fashioned hard-coded deployments.