...
In some scenarios, you might want to provide a way for clients to cancel a long-running request. In that case, the backend service must support some form of cancellation instruction.
Return appropriate status code
Implement with legacy clients (i.e implement a facade over the asynchronous API to hide the asynchronous processing from the client. Logic Apps could help for that)
Predict the volume of requests to the service at any time.
3.2) Queue-Based Load Leveling