How to implement Beluga or WhatsApp like messaging system in Android 2.1

Question

I am trying to develop a message app within my android app. The message will be like whatsapp and beluga. I googled it and found C2DM Android 2.2 can send the push notifications to the device. However, this is not available on Android 2.1. Anyone knows how whatsapp send the notifications for 2.1 devices?

Answer 1

For Android: Whatsapp is build upon C2DM and when the app opens it opens an XMPP connection to their service to deliver the messages instantly. They also might use MQTT as a protocol to minimize battery usage. That's basically it.

Edit: I learned more, Facebook uses MQTT in their messaging app. Whatsapp is build upon XMPP with their own extensions. Their server side runs on top of ejabbard (XMPP implementation in erlang). http://www.ejabberd.im/

On pre 2.1 devices WhatsApp probably keeps a connection open to their XMPP servers in the background but this is not really good for battery life.

Answer 2

C2DM is replaced by GCM (google cloud messaging) now . you can use it for delivering the notifications to your app . For the exchange of message one should rely on protocols like xmpp (whatsapp), mqtt(facebook messenger), mtproto (telegram) etc.

if you are looking to familiarize yourself with GCM . try out this tutorial by appsrox - Create an Instant Messaging app using Google Cloud Messaging (GCM)

they are using GCM for the message delivery as well. it won't suit for production, but its an excellent resource for people who want to develop an instant messaging android app .