Register webhooks to set up the communication between the App migration platform and your cloud app. This enables the App migration platform to notify your cloud app when specific events happen on your server app during migration. Use the Notification API to register webhooks with the App migration platform.
Your cloud app
Your app installed on the cloud site
The framework that your cloud app uses to interact with the App migration platform and the cloud products, and contains all the endpoints for migration
Provides endpoints to register/deregister your cloud app, and to receive notifications about migration events
Documentation is here: link
Read more about pre-migration steps in our docs.