[Proposal] New generic Action for calling an API and returning the result as XML

Hi, I'm writing a treeview (using the yahoo treeview javascript api) to display the list of all pages of a wiki and in order to have good performances I need to call a server-side method for getting all children pages of a given page (so that the nodes or the treeview are loaded dynamically). In order to implement this I thus need a new XWiki Action. Now I think it would be good to generalize this common need. As we add more Ajax to our UIs we'll need more and more calls from JS to the server side. I'm thus proposing a generic ExecuteXMLAction (or AjaxAction or another name) that would do the following: * Get the class, method and parameter to execute from the HTTP request * Verify that the class is in the api package (to prevent security issues) * Call the method using introspection * Return the result as XML using XStream (it generates automatically XML from any java object) Note: I'd need to define the format for sending the information in the request. Not sure about which format to use. WDYT? Thanks -Vincent