PubNub is a SaaS platform that lets us build realtime applications fairly quick by taking implementing websockets and a neat pub/sub API based model along with several other nice features. It’s supported across all sorts of platforms that you can think of like PHP, Ruby, Python, Android, iOS, Java, embedded systems, etc. I’ve covered how to setup it’s Android SDK and the basic usage before. In this tutorial I’d like to cover how we can use it to send Push Notifications via its own REST APIs as well as Google Cloud Messaging (GCM). I’ve already covered Android messaging (showing up as Notifications) via GCM before.