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Comment by teddyh | Hacker News Reader

In my opinion, you can't really understand REST until you understand HATEOAS - the two concepts work together and REST (and the restrictions it imposes) isn't really very meaningful without HATEOAS.

Twilio Conference 2011: Steve Klabnik, Everything You Know About REST Is Wrong: http://vimeo.com/30764565

REST APIs must be hypertext-driven: http://roy.gbiv.com/untangled/2008/rest-apis-must-be-hyperte...

Hypermedia APIs - Jon Moore: http://vimeo.com/20781278

Designing a RESTful Web API: http://blog.luisrei.com/articles/rest.html

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I might be unlucky but I've personaly never encountered a single REST API that implements HATEOAS (among many third party APIs I've integrated into softwares I've been working on on).

If almost nobody who implements a REST API has HATEOAS in mind, doesn't it mean that REST is de facto independent from HATEOAS, no matter what the initial theoretician said about what REST should contain ?

In other words, if REST mean something different for almost everybody than REST for the author (and a minority of people aware of the author's first intention), then in my opinion it doesn't mean that everybody is wrong about REST, it just mean that the word «REST» has evolved to a slightly more relaxed definition.

This is also the claim of this talk: https://www.youtube.com/watch?v=6UXc71O7htc

A while ago people started referring to 'true' REST APIs as Hypermedia APIs so on-topic discussion could be googled again.

Accepting the redefinition of terms merely because they are popularly misunderstood is literally putting the inmates in charge of the asylum. wink

> If almost nobody who implements a REST API has HATEOAS in mind, doesn't it mean that REST is de facto independent from HATEOAS

If it's independent of HATEOAS what is in REST? If it's just doing HTTP, why not call it HTTP?

> If it's independent of HATEOAS what is in REST?

Using GET/POST/PUT/DELETE with a defined semantic, the confidence that GET is idempotent, and the proper use of HTTP status codes.

Back in 2005, it was really common to have only GET routes even for update of deletion, or worst: to have a single url: http://example.org/action which concentrated all the API surface, different behavior being triggered by the type of the payload (JSON or even XML). Also, all the errors where `200 OK` but with a payload which contained the error. It was all done on top of HTTP but nothing was really using the HTTP tools (route + method + status code).

Every single API / webservice had its own logic & semantic, working with 3rth party was a nightmare … It's exactly this kind of mess that the modern trend of «non-dogmatic REST» really solved.

> If it's just doing HTTP, why not call it HTTP?

Is it really REST ? No.

Is everybody calling it REST ? Yes.

Can we change how everybody calls it ? I don't think so, and I don't really think it matters.

Many things are poorly named[1], but as soon as it gets to the popular language we need to use it for what it mean for people, not for ourselves.

[1] Is a «quantum leap» a nano-scale step forward ? Where is the isomorphism in an Isomorphic web app ?

> Using GET/POST/PUT/DELETE with a defined semantic, the confidence that GET is idempotent, and the proper use of HTTP status codes.

That's literally got nothing to do with REST though, that's straight out of RFC 7231 (sections 4 "request methods" and 6 "response status codes") and the IANA HTTP Method Registry.

You're right and wrong at the same time:

- Technically REST and HTTP are two different things, I totally agree with you.

- Historically, before REST became popular, people where doing complete nonsense on top of HTTP, with no respect of the spec whatsoever (see my comment above). This madness was stopped because of REST ! It's only when REST gained in popularity that people started to learn HTTP, and since then people developed a lot of semantically valid HTTP interface and called them REST API.

To sum up my previous points : REST as imagined by Roy Fielding never caught, and the word REST is now almost unanimously used to describe «HTTP-compliant API». May HATEOAS rest in peace :)

The first time I heard about HATEOAS is from the authoer of intercooler.js, and these tow of his blog posts were insiprable:

HATEOAS is for Humans :(http://intercoolerjs.org/2016/01/18/rescuing-rest.html)

Rescuing REST From the API Winter: (http://intercoolerjs.org/2016/05/08/hatoeas-is-for-humans.ht...)

From your second link:

> A REST API must not define fixed resource names or hierarchies (an obvious coupling of client and server). Servers must have the freedom to control their own namespace.

I'm not getting it. We have an API layer serving both mobile and web clients. When we change the API layer, we have to be careful to not remove any fields willy-nilly that mobile might be using. Instead we hard-deprecate mobile versions and remove fields later. It keeps the application stable but makes future architecture depend on past architecture.

Server instruction on URL construction seems to be doing a lot of work in order to not fix the problem. It does not buy us the ability to just switch around field names and relations and hierarchy without concerns for what consumers were using the old system.

That's the real problem with server / client coupling, not that the client needs to magically know which route a created resource has. Sticking a link in the response body just seems silly.

Without reinventing SOAP in JSON form, by this I mean providing machine-readable schema information via the API, I can't see a way through this. But even that wouldn't solve the problem, you'd need some kind of intelligence on the client side for managing an API that might shift around under it without warning.

If we change a field from createdDate to createDate, is there a way to use HATEOAS to communicate the name change?

> I'm not getting it.

It's just saying that the "URLs" are not fixed in the client (aside from the one root URL) and are provided by the server and dereferenced from content types.

> If we change a field from createdDate to createDate, is there a way to use HATEOAS to communicate the name change?

No. In REST/HATEOAS, the content types are fixed and documented, the hierarchy is mobile. Content type alterations impact clients which may not be generic over type contents.

OK, I understand better now, thanks.

What does a mobile hierarchy buy me?

Edit: nevermind, I think I can see the idea. Thanks!

Came here looking for a comment like this. If you're not discussing HATEOAS at all, you will be losing out on many of the benefits that REST provides.

It's the 'central dogma' of RESTful services.

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