How to identify if a request type is synchronous or asynchronous

Question

Actually, my requirement is, client can call my rest based services in both synchronous (request-response) or in asynchronous (request-acknowledgment-response) mode. Now, based on the request type, I have to follow the mode.

Now, my question is, is there any way, from the request itself, by default, is there any indicator, which will tells the clients desire request-response model. Service protocol is http.

if not possible, then what will be the best practice, to handle this type of scenario.

Answer 1

You can have the client specify its preference to receive an asynchronous response via a header:

Prefer: respond-async

You can find details here: https://www.rfc-editor.org/rfc/rfc7240#section-4.1. I am not aware of any way to explicitly request the opposite, a synchronous response.