I'm new to Salesforce, and am looking for advice on how to best approach a scenario where a Salesforce runtime communicates with an external REST-service that is under my control. My background is web-development, so I assumed to just run a POST-request from Salesforce and wait for the response. My colleagues told me that that's not the "Salesforce-way" because it would be a synchronous workload, and proposed to modify the service such that it writes its response into the Salesforce-db instead.
I dislike that approach, but am having difficulties sifting through the docpages in order to come up with an alternative. What I was hoping to find was a way to define an external resource, when to call it, and where to write its response, without writing the code to make it async and let Salesforce handle that.