APNS, C2DM heartbeat process, how to achieve it?

Hello everyone, I want to ask a question:
1, on APPLE's APNS platform, I know he's a heartbeat message is 15min, ask specifically how it processes the message, such as messages back and forth several times, each time the size of the message content and what is it?
QQ is the 300s as a heartbeat, every heartbeat is QQ client initiates a packet, then QQ server response data + confirm, and then the phone QQ client back to confirm the interaction of three packages to complete a heartbeat process. Will APNS is not it?
2, the same problem, C2DM the heart of it?

Reply:
c2dm you can capture and see.