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Comment by grandalf | Hacker News Reader

As a designer you might enjoy the way I explain REST to people:

Think of the URL as part of the User Interface. REST offers conventions that make it easy to guess the URL of what you are looking for, just as you would guess where to click/navigate to get it.

I realize this only covers one aspect of REST, but I like it because I think the idea of an address as a resource which has a certain appearance (its URL) is quite powerful.

edit: I realize that rest could just as easily use meaningless identifiers, but it is often the case that meaningful identifiers are used such that the user can GET desired items by guessing the URL.

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NO. NO.

REST is absolutely not about being able to guess URLs -- it's about never having to guess a URL. Repeat after me: Hypertext. As. The. Engine. Of. Application. State.

Clean, meaningful, organized / structured URLs are unrelated to REST, and their presence tends to lead to the predominant anti-pattern of 'API Specifications'. Leave that bullshit in SOAP's failure pile.

Uh ... I didn't say guessing state, I said guessing what is behind the URL. as in /users/greg vs /users/davis

rather than /u.exe?23q4234q34q34234234asdfa&query=true&xml=false&screen=home

The point I was trying to make is that with REST, URLs have meaning in and of themselves, not dependent on the presence/absence of a variety of other aspects of state embodied in the URL... The protocol (and REST verbs) is how you add that additional meaning... and a different URL thus means something different. Hence, for some universe of items, if one has an obvious meaning, the rest should.

If you are using the protocol in the right way then your resource will not change depending on which verb you are using.

It sounds like you're commenting on what REST is without ever having read Roy's dissertation. You can fix that, you know.

What was inaccurate about my statement?

I think the point that the previous posters were making is that pure REST should not rely on out-of-band information. The client should not have to guess or create URLs from knowledge they may have to look up in some other place. A pure REST API should be discoverable and subsequently navigable without having to rely on any other information not contained inside the request.

In practice this can increase the amount of requests required to get at the information you want, and also the size of each request, as it must then include information about the actions that can be taken on the resource. It could be argued that this constraint is more for the benefit of systems or programs that need to interact with the API without knowing anything but the initial URL, and not necessarily a programmer who can work these things out. owever, if a REST API uses this constraint, and application developers follow it, deep changes can be made to the URL structure of the API without breaking the applications that use it.

thanks for clarifying

It's not so much that it was inaccurate (although it was) as that it was missing the point.

fair enough... I guess the reason I have though of the idea is b/c of the resource focus of REST... where a URL means something... I realize that isn't the point of REST, but it's nice.

You said: "REST offers conventions that make it easy to guess the URL of what you are looking for, just as you would guess where to click/navigate to get it."

In your earlier comment it does seem as though you are talking about guessing the URL.

What the other comment was alluding to with "Hypertext. As. The. Engine. Of. Application. State." (or HATEOAS, one of the main principles of REST) is that your application should never have to guess a URL. The possible URLs your application can next GET/POST/PUT/DELETE to should be given in the response to the last action it took.

There is nothing in the original description of REST that says anything about URLs being human readable. That's a pleasant side-effect of a sensible design but isn't the main aim.

As the original post describes, the importance of REST is to make simpler for machines (not humans) to manipulate services on the web.

You should probably read a bit more about the principles of REST before confusing people with your own interpretation of what you think it is.

edit: mistakenly thought HN understood markdown. edit: mistakenly thought HN understood HTML.

ok thanks for clarifying

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