title: How to create a subscriber with PubSub on Google Cloud App Engine that listens to a message via Publisher from a Google Cloud App Engine Flex?
body: <p>I have a Django Application running on Google App Engine. There is another time consuming application running in Google App Engine Flex that is triggered from the Google App Engine Application.</p>
  
  <p>When the Google App Engine Flex Application finished its execution, I want it to trigger a message and send it to Google App Engine Django Application, so Django can update the database item accordingly.</p>
  
  <p>How can I use Google Cloud PubSub to achieve this?</p>