I was interested in developing a clock widget for the homescreen and upon reading Home Screen Widgets tutorial, is there a pre-existing Service I could reference for updating the current time rather than re-inventing the wheel?

I have currently Retro Clock on my android phone and noticed that when I click it, it pops up the Alarm Clock settings, but with the default Google Analog Clock widget, upon click does nothing.

Is that because the Retro Clock widget implements the Alarm Clock service? If so, how can I go about referencing that service? Or do I have this all wrong and misunderstood?

Any help is appreciated.

EDIT:

I believe implementing the service to update the clock would drain the battery life tremendously, any ideas on a work around or help shed some light on any performance issues with using Service?