I'm new with Android GCM and I downloaded the appengine demo application provided by Google. I was looking at the server side and first I thought that the servlets (HomeServlet, RegisterServlet, etc.) were part of GCM, but when I looked into client side I saw that first it's called GCMRegistrar.register and, if it's successfull, then a post request is sent to the register servlet on the server side.
So I guess that these servlets should be replaced with my server application (it's currently running without GCM) and I only need to call GCMRegistrar.register in my client side for the device to be registered. Am I right?