I recently learned about the ability of iPhone apps to receive nearly instantaneous notifications to apps.
This is provided in the form of push notifications, a bespoke protocol which keeps an always on data connection to the iPhone and messages binary packets to the app, which pops up alerts incredibly quickly, between 0.5 - 5 seconds from server app send to phone app response time. This is sent as data - rather than SMS - in very very small packets charged as part of the data plan not as incoming messages.
I would like to know if using Android there is either a similar facility, or whether it's possible to implement something close to this using Android APIs. To clarify I define similar as:
Not an SMS message, but some data driven solution
As real time as is possible
Is scalable - ie: as the server part of a mobile app, I could notify thousands of app instances in seconds
I appreciate the app could be pull based, HTTP request/response style, but ideally I don't want to to be polling that heavily just to check for notification .. besides which it's like drip draining the data plan.