Thank you. This is one that I've been puzzling over for years. If anyone has a straightforward answer, and can provide example REST responses with and without "HATEOAS", I'd really appreciate it.
See the 'Richardson Maturity Model' levels [1], and contrast level 2 with 3. Level 3, satisfying the HATEOAS constraint, has hyperlinks leading to other resources, and the relationship between the origin and destination resource is qualified (with link relations [2]).
Essentially, everything is a graph, resources are the nodes, and the labels on edges are the relations, also serving as an inventory of state transitions.
The "HATEOAS debate" is the trope that says people will inevitably debate whether a particular API that claims to adhere to REST does in fact adhere to REST, because many APIs that namedrop REST don't satisfy the HATEOAS constraint. This is rarely a practical debate, but the fact that it keeps coming up -- and people take the time to explain -- is part of the problem with REST. This was the author's point.
I think the problem I have a hard time with HATEOAS is that I really can't see what difference it makes to the API. I mean I get that it's always better to return a URI rather than simply an ID. But the link relations feel like they are from a time when we all thought the semantic web (RDF and OWL) was going to be a very big deal.
