Google Cloud Messaging send notification to all devices
android, google-cloud-messaging, notifications
Solution
Is there a way to send messages to all devices without pass the registrarions id?
No way. After successfully registering on GCM, you (the Android application) should send the registration id to your application server and store them somewhere, in a database for example. This registration id will be used to send a notification to a particular device.
To send a notification to all devices, would mean then to select all the registration ids from that database, and as you said, put them in an array and pass them further to GCM.
Update: With Firebase Cloud Messaging, it is now possible to use https://firebase.google.com/docs/cloud-messaging/android/topic-messaging to send notifications without explicitly specifying registration IDs.
Problem
I'm new in GCM. I would like to send an message to all devices that have the app installed. I read about registration_id: after the first connection to GCM, google send this unique string to device. I'm a beginner in server world but if I'm not mistaken, in server side, for sending a notification to devices I have to send array of registration_id and the message to google. Google knows how has the registration id? Is there a way to send messages to all devices without pass the registrarions id? Thank you.