REST. Getting closer to the lightbulb moment.

by Matt 14. June 2007 07:13

Does REST need a service description language? Great question. And one I would have initially said a most emphatic "yes" to. Now I'd probably so "no". Or more accurately - "you're asking the wrong question".

I think some of the fundamental differences between WS-* and REST are finally beginning to sink in. I've been viewing them as pretty much the same thing, just with different formats and tool support and stuff. But conceptually, they're actually pretty orthogonal.

WS-* is all about messaging. You send and receive messages to and from an endpoint. That endpoint is simply a processor - by and of itself, it means nothing. It's just an address. The interesting stuff is in the message. This tells the service what to do and with what data. The reply message contains the data relevant to the operation - what happened, the returned data, whatever.

REST is all about interacting with resources. You POST, PUT, GET or DELETE resources. The url is all-important - this identifies the resource. As the above post mentions:

The consequence of [this] is that there isn't much to describe; there aren't any methods or signatures thereof to document, since access to resources is uniform and governed by the verbs defined in RFC 2616 (in the case of HTTP, anyway)

You don't need a service description language, because there isn't a service. You're accessing and operating on resources. The service is pretty much implicit in the HTTP verb.

What you do need is a specification for the media type. And preferably in a machine readable format that can be used to generate code for interacting with the resource's data.

This is the question you should be asking.

The Atom Publishing Protocol is one such media type, and there are libraries (not necessarily tools) for working with that. Interestingly, following the small flurry of (*cough*knee-jerk*cough*) reactions to Dare Obasanjo's posts on Google's (out of date) implementation of the APP spec, (and without reading the spec at all!) it looks like APP is able to act as a kind of REST envelope. By which I mean when you POST a new customer to a resource (such as a collection of users), you can get an Atom doc back detailing the url of the newly added resource (customer). My knee-jerk reaction - is APP REST's SOAP?

I'm being kinda oblique with this - I know I need to study the APP before I can really make remarks like this, and I think this example was how to use the Atom Publishing Protocol to publish non Atom (as in RSS-like media type) entries. But if the cap fits...

(One point made that I really like is how the http protocol provides the optimistic concurrency for the updates via the humble etag. Very clever of the http people, and this really helped with defining the REST ideals for me. But it does mean state is maintained at the transport level, rather than at the resource level, something which SOAP has worked around by trying to be transport neutral. Another difference for you to weigh up.)

I don't buy that a client shouldn't know about the URI space of the server. For individual resources, yes. But for collections, or resources such as locks or printers, then surely the client needs to know about these (or how else does it add a new customer? Print?) So a description/discovery language of some sort is needed here too - at the least a means of knowing what media type + verb a particular resource endpoint accepts. Perhaps this is where WADL comes in (but I have to agree with Don Box's analysis of WADL vs WSDL)?

And I don't know how security and authentication is solved, either. Whatever happens, this will demand a spec at the least.

So, with all of this, is REST any simpler than WS-*? Or is it just an orthogonal concept, but just as complex?


Comments (22) -

suv comparison
suv comparison
7/20/2011 10:34:44 PM #

Per il tuo bambino scegli Moncler. Una scelta di capi, estivi ed invernali, eccezionali. Tuo figlio sarà sempre alla moda e potrà muoversi in totale comodità.


best hybrid cars 2011
best hybrid cars 2011
7/22/2011 3:50:38 AM #

it ti permette di orientarti con semplicità nel pulviscolare niverso di Moncler.Troverai le indicazioni per lo spaccio o negozio Moncler più vicino a casa tua felpe moncler, pantaloni e abbigliamento sportivo.


Philix United States
11/22/2015 5:51:16 AM #

Ace Web Site.


Philix United States
11/28/2015 12:30:05 AM #

Ace Web Site.


Cornelius Styborski
Cornelius Styborski United States
1/15/2016 4:56:49 AM #

Congrats! So glad to see this site getting the recognition it deserves, the world can always use a little more awesome.


Douglas Ramler
Douglas Ramler United States
1/15/2016 6:24:03 AM #

I love the dolphin saving you one.


Antony Goren
Antony Goren United States
1/15/2016 6:44:17 AM #

Thaaaat IS awesome! lol hehe


Solomon Trudics
Solomon Trudics United States
1/15/2016 7:19:43 AM #

this is awesome like the book of awesome


Raleigh Maarx
Raleigh Maarx United States
1/15/2016 8:29:41 AM #

Printing out an essay or paper, reading the first line and realizing there aren't any mistakes.<br />AWESOME!


Betsy Ragans
Betsy Ragans United States
1/15/2016 8:59:42 AM #

yeah, except the "dolphin saving you" one


Jessie Souvannakhiry
Jessie Souvannakhiry United States
2/15/2016 8:39:44 AM #

I need 2 set up wordpess through a webhost.... . i know i have to download wordpress but whats a good host to go with? and after i set up an account with a host, how difficult is the set up before I can begin building a site? and last but not least, can i still import the free wordpress templates?.


amazing sex videos
amazing sex videos United States
2/6/2017 10:01:29 AM #

This website was... how do you say it? Relevant!! Finally I have found something which helped me. Thanks a lot!


Having read this I believed it was very enlightening. I appreciate you finding the time and effort to put this short article together. I once again find myself spending way too much time both reading and commenting. But so what, it was still worthwhile!


so real 8 inch realistic dong
so real 8 inch realistic dong United States
9/12/2018 5:28:38 PM #

Oh my goodness! an amazing write-up dude. Thank you However I will be experiencing trouble with ur rss . Do not know why Can not register for it. Perhaps there is any person acquiring identical rss difficulty? Anybody who knows kindly respond. Thnkx


專業技術支援 United States
10/8/2018 5:10:00 AM #


杏仁 United States
10/12/2018 2:12:10 AM #



從暴食症變運動網紅 Emi:「快速減肥法?講都唔好信!」    Marie Claire (HK) Edition  打開Instagram搜尋Emi Wong,會看到一個有近90k追蹤者的帳號,內裡有很多Emi做運動的照片、短片,亦有她四處遊歷吃喝的玩樂照。受歡迎,因為她透過相片帶給人們健康的訊息,覺得這    




醫學美容 乳霜
醫學美容 乳霜 United States
10/16/2018 4:09:02 PM #

LANCOME 蘭蔻 【絕對完美系列】絕對完美唇膏 L'Absolu Rouge的商品介紹   LANCOME 蘭蔻,絕對完美系列,絕對完美唇膏 L'Absolu Rouge7       


MISSHA 【基礎底妝】零妝感柔光持久粉底液SPF17PA++ The style art Designing Foundation 12hrs的商品介紹   MISSHA,基礎底妝,零妝感柔光持久粉底液SPF17PA++ The style art Designing Foundation 12hrs       


眼妝 United States
10/18/2018 1:31:29 AM #

CLINIQUE 倩碧線上購物官網。瀏覽Clinique倩碧官方網站,了解更多線上購物、護膚、彩粧、香氛及禮品詳情。通過過敏性測試,百分百不含香料。


產後圓臉拉提成V臉!音波拉提加強版-埋線拉提紀錄  菜叫空姐Doris  淨妍醫美  玻尿酸(hyaluronic acid)又名透明質酸,呈透明膠狀,存在人體的結締組織及真皮層。玻尿酸在醫學上可填充凹陷處如山根。玻尿酸隆鼻,自然安全還可讓臉看起來更立體更小!      


Add comment

  • Comment
  • Preview


Month List