Interchange is the open source alternative to commercial e-commerce servers and "best of breed" application server/component applications. Interchange is one of the most powerful tools available to automate and database-enable your web site or build online applications. It's also one of the easiest tools to learn, plus it's open source, making it the most open and least expensive solution to implement. For some documentation and resources for it have a look at http://www.interchange.rtfm.info/