> > these devices are a lot different: they're running on battery, sometimes on WiFi > but often on expensive (both in money and battery) 2G or 3G data n

> > these devices are a lot different: they're running on battery, sometimes on WiFi > but often on expensive (both in money and battery) 2G or 3G data networks, > and essentially "off" most of the time. > On iOS devices, applications are killed and evicted from memory when they attempt > to do too much background processing or use too much memory. > On Windows RT and Windows 8 Modern applications, when the application is not in > the foreground we only get a few seconds of CPU execution time every 15 minutes > and again, strict memory limitations if we want to stay loaded. > And when the Skype application is unloaded, it can no longer receive incoming > calls or IMs, rendering it a lot less useful. > This is pretty much why/how all IM clients for iphone/ipad/android work as well. ( i work on verbs.im, we're a team of 4 now, here's a link to our privacy policy http://includetech.co/privacy/verbs http://includetech.co/privacy/verbs) The server becomes a proxy for your account, and being able to send push notifications. Your apps become thinner clients needing lesser battery, bandwidth. Infact we've got a step further, and replaced XMPP/HTTP with MQTT to save even more battery. ( here's a nice article profiling power consumption of MQTT vs HTTP here across wifi/3g: http://stephendnicholas.com/archives/1217 http://stephendnicholas.com/archives/1217 ) That being said, the recent iOS 7 have introduced API's for longer running background apps ~B