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How to be made aware of incoming emails on GMail without frequent polling?

If I am developing an Android application, what is the most feasible way to get near real-time notifications about an incoming email? Is there a push-like mechanism, or can I hold my IMAP connection for a long time, or do I use IDLE command?
Consider that user is authorized to use GMail services via OAuth and I don't want to poll IMAP server madly.

Update:

  • I'm not using the phone's configured-in Google account. There is another account set up using OAuth.
  • I'm using Apache Commons Net to connect to IMAP/SMTP in my app. It's a bare-bone library for IMAP, but I can perhaps modify it to add IMAP commands/extensions.
Solution

  • Since IMAP does natively provide any sort of push notifications and the Google extensions don't either, you have to implement it yourself.

    One way is to use IDLE requests, which is still a cheap way to do polling. Of course, you can't expect your app to be running all the time, so you need to use a background service. An 'always-on' service is however an anti-pattern on Android and will drain the battery quickly and likely get you many 1-stars. Additionally the system may decide to kill it at any time. The other alternative is to use AlarmManager to start the service periodically, but starting it every couple of seconds or so is just as bad. So you are basically back to square one: polling.

    The other way is to get push notifications using GCM or a similar service. This does require you to have a server, and the server needs to have the authentication info for the user (which might be a problem), but there are no real constraints concerning keeping open connections and sending IDLEs each second, etc. On the Android side, if you want to implement push yourself, you need to keep an open socket to get notifications. This is not very easy to do if you are not a system app (see above), so that leaves GCM. The connection it uses is manged by the system (Google Services framework), it can do things a regular app cannot, and you basically get it for free, since it's already there. It receives small pieces of data when there is something to do, called 'tickles'. Those in turn trigger broadcasts, Google Play updates, etc.

    So, take your pick. Or just give up, register the account and use GMail and its labels Android API.