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Question

I have an idea for an application and am trying to first get hold of a plan to implement it. I am planning to implement a java service on Google App Engine and this would be pushing messages to subscribers, i have a concept of channels, exactly the same thing Parse has. Unfortunately Parse is not supported on GAE and it only has an Android client.

Does GCM have channel based push notifications? Like one device can be subscribed to multiple channels and I can push messages through a channel and all subscribers of that channel alone get notifications?

Or do I have another option?

Answer 1

GCM does not support channel based notifications.

If you use GCM directly, you'll have to implement this functionality yourself: your server will have to manage the mapping between channels and devices (Registration IDs), and push to all the devices subscribed to a channel when you wish to push to that channel.

Answer 2

Note 1 : this is already done, APNS and GCM . Do you have any other features in mind that this two systems do not yet provide?

GAE does not support listening sockets, which prevents building any server-to-device persistent connection push system.

Note 2 : there is Channels API , but it's web only as it's wrapped in an opaque javascript wrapper and it's protocol is obscured on purpose.

Alternative 1 : use an existing external service like PubNub, Pusher, Amazon SNS, etc..

Alternative 2 : instead of GAE use Compute Engine , which has no such limitations. However it does not (yet) have any most of the GAE goodies: it's service APIs (datastore, queues, etc..).

Note 3 : your idea of persistent connections would only work while application on device is "alive", eg in the foreground (at least on iOS, on Android it's possible but would severely impact battery). For universal push-to-device you would need to combine your system with platform-provided async push system (eg APNS and GCM ).