Ica :
I want make a push notification when there is data insert to table of the database. I use REST API in android using retrofit. Could it possibly to make push notification every "insert" to all devices without firebase cloud messaging???
Peter Fortuin :
FCM is just a framework that allows you to send push notifications. I know that Samsung has their own framework that they use. And maybe there are others. So, technically it's possible to create your own framework to do this, but I would never recommend it. There is so much to consider to get this done correctly (power use, security, registration of devices, etc. etc.) and using FCM is quite easy.