Best practice for persistent mobile connections on Android?

Question

I'm considering using a persistent connection to a "cloud service" from an Android app. This would run all the time in a background service (or something like that).

I'm thinking of using web sockets or XMPP to keep the connection, basically looking for a light weight connection that won't drain battery. I want to be able to push notifications in real time to this connection, so periodic polling is not desired. I am aware of C2DM and other commercial solutions, but am looking to roll my own. This is why a web socket (or other light weight connection) is what I'm investigating. So if I go this route, what are some best practices I should be aware of?

I'm thinking of stuff like:

1. how to prevent the battery from draining,
2. How to handle IP address changes, etc?

Answer 1

This might not be the answer you are looking for but I think you may want to rethink your architecture.

Things you can expect out of a mobile platform

• Your IP address to change randomly
• Your physical internet connection to be lost randomly
• The OS to decide your not doing anything useful and killing your process
• The connection type changing randomly (from WIFI to 4G to 3G to edge) and thus your IP to change

Basically your app needs to be able to handle a loss of connection, because its almost guaranteed to happen.

That being said, it is totally doable depending on your definition of real-time. If your willing to continually check that there is still a viable connection, you could keep any delays down to the minutes range. But this will drain the battery and there is not much you can do about it.

Answer 2

Some things just don't go well together. That is "push notifications in real time" and "prevent battery draining". You sure have to make compromises here.

I can only recommend to try some Android Apps that use XMPP to get a feeling how they handle persistent connections, IP address changes and battery consumption. If they are open-source you can also view the code and learn from it. Yaxim, Project MAXS and Beem to name a few. Maybe you shoud also have a look at XEP-0286: XMPP on Mobile Devices

That said, are you sure that you want to reinvent the wheel when Google offers you C2DM? Which is optimized for this use case. I think that it has some delay, so it's no where "real-time". But again, either you will end up with an solution that tries aggressivly to establish a persisent connection and drains the battery, or you will have to live with some kind of delay (~ 0-30 min).