它取决于你的需求是什么，你必须做的。

Its Depend on your requirement what you have to do.

here是C2DM 的示例：在此示例Android设备被注册wtih服务器服务器后发送按摩到所有的设备。所以单向通信（服务器到Android设备）

here is sample of C2DM: in this sample android device is registered wtih server after that server send massage to all device. so there is one way communication(server to Android device)

因此​​，所有的东西都在服务器端完成。只要下载这个教程。这两种服务器端（PHP）和Android code是可用。

So all things are done at server side. just download this tutorial. Both Server side(PHP) and Android code are available.

您得到了来自谷歌的服务，你必须把在服务器端应用的关键。

you got application key from Google services which you have to put at server side.

SENDER_ID - 谷歌的项目编号，你要当你想注册服务器设备发送

SENDER_ID – Google project id which you have to send when you want to register your device with server.