Android Cloud to Device Messaging Framework
Android Cloud to Device Messaging (C2DM) is a service that helps developers send data
from servers to their applications on Android devices. The service provides a simple,
lightweight mechanism that servers can use to tell mobile applications to contact the server directly,
to fetch updated application or user data.
The C2DM service handles all aspects of queueing of messages and delivery
to the target application running on the target device.