Web Interface and XML binding

Hi, at the moment I'm thinking about a new project. The project will need a Web API to communicate with an iphone. To me it is quite obvious to implement the API part as a request handler. But when it comes to generation of e.g. XML I'm not sure what is the best way to do. Sure, the seaside way to do it is to create my own canvas and every object needs to draw itself onto the canvas. But then I have magritte and a lot could be done automatically. Using xpath in the descriptions I could use Pastell to deserialize objects. To produce the output there could be a similar way. This would be some kind of XML binding then. I wanted to ask if there is anything already available that could help me on my way or if there dedicated ideas how to solve this in seaside. thanks in advance, Norbert