I want to send push notification in my app (Android) using Google Cloud Messaging. I am using firebase for backend. As firebase do not support inbuilt push notification i am using Google App Engine.
I do not have any idea on Google App Engine. Right now i am using a template provided by google for sending push notification. Google Cloud Messaging Template Github
Till now i have deployed my app in Google App Engine and i am able to send push notification to all devices that are registered (From Web) An HTML page i get when i use GCM template.
What i want to do is , to Listen for Firebase data change and send push notification to user who is not online or has closed the app.
How can i run a servlet in background so that it keeps running in background and send push to user who is not online/connected.
As i have only push notification logic in Google App Engine Should i use servlet or struts.
Thanks in Advance