How to add html/js query to gwt app using gwt-rpc?

We have a web client built with GWT that talks to a server via gwt-rpc. One part of the app will now use html/js to replace the GWT GUI and we want that part to talk to the server but not via gwt-rpc. What ways are there to migrate a gwt-rpc call to something that will work with a none a gwt client? Today we send and receive java collections that contain object graphs like a list of order objects that have them self order detail objects and so on.

Thanks

via Chebli Mohamed