Decouple backend processing from a frontend host, where backend processing needs to be asynchronous, but the frontend still needs a clear response : https://docs.microsoft.com/en-us/azure/architecture/patterns/async-request-reply
Context and problem
Need a response quickly enough to arrive back over the same connection and avoid latency to the response and fake the appearance of asynchronous processing (recommended for I/O-bound operations).
But, the work done by backend may be long-running (seconds, minutes, or even hours). So, Queue-Based Load Leveling could he helpful.
Http response is the key in this kind of pattern : HTTP 202 (Accepted) status code, acknowledging that the request has been received for processing.Solution
If the backend in ARR may be slow (more seconds, more minutes, even hours), then Queue-Based Load Leveling pattern may be the solution.
Challenges
3.1) Asynchronous Request/Reply
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)
3.2) Queue-Based Load Leveling