some news about web service from HQ:
We recently added an easy access to the full API documentation. You need to connect as admin and go to Block Admin > Plugins > Web services > API Documentation. All your web service functions (enabled or not) are listed.
We also wrote a Web Service API Roadmap, to have an idea of the next web service functions that will be implemented: http://docs.moodle.org/dev/Web_services_Roadmap
We also looked at the most common issues reported in the forum and decided to work in the next weeks on the following points:
1- new naming convention (based on the one listed in the Roadmap) - current function will still be working but just marked as deprecated.
2- Making "Access control exception" more explicit when debug mode is set to developer on the server.
3- Making the exception message of "invalid return value" more explicit too - at least knowing which attribut of the return value is concerned.
4- Deliver PHP - SOAP/XMLRPC demo clients in a zip that don't require Moodle to be run. Rewrite the client documentation using these clients.
5- Making the REST server return JSON values if the new "alt" param is set to "json". Otherwise the REST server still keep returning the current XML.
Finally we will start to add more of the Roadmap functions, and later we'll tackle the JAVA/.Net SOAP compatibility: MDL-28988.