All the notifications come from a server?

Question

When an app show a notification, this come from a server?

Is there a way to send a notification from "inside of the app"?

What happens is there are not internet connection?

The notification never comes?

Answer 1

Its depends on app. if its a static notification you can use Services,Timers,DataBase(Predefined Notification data store) to generate the Notification from app itself without internet. Ex: Predefined Notification to intimate scheduling for every 3 hours.

If you need Dynamic data you need to fetch it from server.

Answer 2

It is possible to send mobile to mobile PUSH NOTIFICATION USING gcm.One mobile will send a message to gcm which in turn will send the message to the destination mobile using IMEI number.You can get more details here http://androidexample.com/Device_To_Device_Messaging_Using_Google_Cloud_Messaging_GCM_-_Android_Example/index.php?view=article_discription&aid=122&aaid=142

And as far as I know it is not possible to send a push notification without internet.