Push notification server
apple-push-notifications, google-cloud-messaging, push-notification
Solution
AirNotifier, stand alone notification server supports APNS, GCM, MPNS/WNS(windows phone) and SMS, it's written in python with Restful APIs and easy to use web interface.
Problem
I'll need to implement server-side push-notification service for at least APNS, GCM. Any trustable open source project which is suitable for production environment I can start with?