Push Notification using GCM

GCM, Google's version of Push Notification, allows your application to receive messages. The idea is similar to SMS messages, but much more flexible. There are three components to GCM:

• Your server (this is where you initiate the message)
• Google's GCM server
• Android device (although GCM is also available on other platforms)

When the user starts your application, your code needs to connect to the GCM server and obtain a device token, then send that token to your server. Your server is responsible for initiating the message and passing it to the GCM server. Your server needs to track the device tokens that have to be sent when initiating the message. (Your server tells the GCM server which device tokens needs to be sent.)

You can implement your own server or choose to use one of many services available. The next chapter, Backend Service Options, will look at several BaaS options, many of which also offer Push Notification. (The Simple Testing Option section...