For your problem I would take a look into Jifty::Plugin::REST which allows access to models and actions using various formats.
Let me just say that Jifty doesn't have terrible documentation. However, most of included documentation is API documentation, but there is very low-noise mailing list which has useful tips and links to applications.
Wiki at http://jifty.org/ is another resource which has useful bits.
If your goal is to make video store (my favorite benchmark for 4GLs and CRUD frameworks) in afternoon, it's really worth a look!
