C2DM background technology

I need further information about C2DM on android. The informations on http://code.google.com/intl/de-DE/android/c2dm/inde开发者_StackOverflow中文版x.html are not clear about the background technology.

Which protocolls are used? How does the Google server find my cell phone?

I need such informations.

You can get some info about C2DM internals from Google I/O 2010 video: Building push applications for Android

C2DM maintains an open TCP socket connection to the messaging server. Its really rather simple, other than keeping the socket open, which is no exactly trivial.