Python script (App Server) to post a downstream message to a particular device using FireBase Cloud Messaging.

FireBasePushMessage.py

import urllib2
import json

payload = {'data': {'name':'Robby', 'dept':'HRD'},'to':'<Token-Generated-In-Device>'}

url = 'https://fcm.googleapis.com/fcm/send'
headers = {'Content-Type': 'application/json', 'Authorization': 'key=<YourServerKey>'}

# When request body has to be plain text
# headers = {'Content-Type': 'application/x-www-form-urlencoded;charset=UTF-8', 'Authorization': 'key=<YourServerKey>'}

data = json.dumps(payload)
print(data)

req = urllib2.Request(url, data, headers)
response = urllib2.urlopen(req)
the_page = response.read()
print(the_page)