> 3: RESTful. It should speak the language of HTTP verbs: GET, PUT, POST, PATCH, UPDATE, DELETE.

I know it's slightly off-topic, but when one of the early points of an article contains an incorrect piece of information, that really makes me not want to read on further

Restful API's are a recent "fad" that, even though_do_ have their place in mainly basic CRUD apps, RPC still reigns very popular. See [1] for a pretty good explanation of REST-styled vs RPC-styled APIs.

[1] https://www.linkedin.com/pulse/rest-vs-rpc-soa-showdown-josh...