Utterances of a Zimboe

Programming the Internet.

Fill in: Atom is to RSS what ____ is to REST

with 4 comments

I guess I need to write this post now (eventually) as I’m still seeing some basic concepts being mixed up. As the ‘domain model’ goes, we can do something like Atom over REST over HTTP, Atom/SOAP/HTTP, Atom/XMPP, or APP (statically linked Atom/HTTP)—I don’t know why only REST was mentioned in the post linked above.

The ‘failed’ OSI layer modelAtom surely supplements WS-DeathStar, but it can hardly replace any of it. Atom is a content presentation protocol, and I don’t actually even know any web services standard which defines content presentation. Web services standards define service-access/consumption related metadata, not content. And as content is just one kind of a service, ie. a subset of it, you can use WS-* with Atom for eg. callbacks, authorization etc. If you want to transport content in some standard form—which I definitely recommend—Atom can suit you fine. It’s definitely and absolutely better than RSS; and this is not an opinion, thus ‘absolutely’. :)

Well, I’ll include the following stuff here as I’m too lazy to write a complete entry out of it. I just fail to understand why the RESTian folks got so excited over WADL? Weren’t the RESTful services supposed to work without interface descriptions? (Like, duh.) Doesn’t WADL make REST way too SOAP’y? WADL is exactly what WSDL is for SOAP, and the major criticism towards SOAP was due to the ‘rigid’ interface descriptions, namely WSDL.

And just as a sidenote, I personally happen to like C header files, WSDL’s, Java interfaces and all other kinds of interface descriptions, and I believe WADL is one of the best things happened to REST yet.

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PS. I was thinking SOAP as an answer to the title. Agree?

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Written by Janne Savukoski

May 2, 2007 at 4:07 pm

Posted in Internet

4 Responses

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  1. Hey Janne – You’re missing the fact that Atom includes both a syndication format and a publishing protocol. The publishing protocol is REST based and defines how to read, create, update and delete entries in a collection. Thus its Atom over AtomPub over HTTP.

    charlie

    May 3, 2007 at 7:36 am

  2. Hi Charlie!

    I did note the atompub (APP; too many names again..) in the beginning, and Atom with HTTP surely can be used for publishing/editing/syndicating/etc (simple) content entries. And it seems great for that! (‘Seems’ as in that it still needs some more adoption.) But it doesn’t bring anything new to the transport layer; well, it’s just an instance of the RESTful approach.

    So, the actual beef of Atom—within or outside atompub—is in the content. And regarding that, if the metadata facilities of Atom don’t suffice, the Atom content format just gets in the way. It’s not as widely applicable as the DeathStar.

    I tried to look up some examples for and against Atom, and I thought the Digg API would be a good candidate for Atom. But as you look at it, there’s a whole bunch of stuff that supports the use of a proprietary content format. A concrete question might then be, in which of these would Atom make more use than harm?

    Frankly, there’s not much DeathStar either. I guess all this brings us to the ultimate. XML rules, it’s everywhere. Like HTTP. They’re platform. XMPP? I hope someday. But I’m afraid Atom is too specific for getting there. I guess it could be regarded as a microformat, filling some nichés, embedded somewhere—like the DeathStar. The interfaces will remain more proprietary, but I just hope they’ll get described with WADL or WSDL (public/private services, respectively.)

    Janne Savukoski

    May 3, 2007 at 11:47 am

  3. There was some good reasoning in microformats mailing list regarding hAtom, and I believe it matches the issues discussed here also.

    http://microformats.org/discuss/mail/microformats-new/2007-May/000316.html

    Janne Savukoski

    May 3, 2007 at 11:59 pm

  4. Hi Janne,

    Ah, I see. Sorry I misunderstood. I agree that Atom and AtomPub are aiming at a lowest common denominator, and often times you’ll have extend them for your own purposes. However, I think that lowest common denominator provided by atom is a better platform to build on top of then what SOAP has provided. And as far as extensibility – I punt just like Atom does – just use XML namespaces to do your own thing. Not very satisfying, but I don’t know of anything better unless you are in the camp that RDF is the right approach to that problem (I sit on the fence on that one).

    Anyway, thanks for the great discussion.

    charlie

    May 7, 2007 at 2:41 am


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