A lot of the arguments against both XML and JSON seem to boil down to "here's why XML sucks..."
The reality is, for whatever reason, good or bad, a lot of people prefer to parse complex data in XML. There's a big market for it. Supporting both formats doesn't add horrible complexity. -George On Jun 2, 2011, at 11:41 PM, Mark Nottingham wrote: > The problem I mentioned before, though, is that XML Schema brings more issues > to the table than it solves. > > 1) People inevitably use schema to generate bindings to [insert language], > and because of the complexity of the underlying data model of XML (Infoset), > the mapping of information items to objects can happen in a variety of > different ways. This is an endless source of bugs. > > 2) It's very, very hard to define an XML Schema that's reasonably extensible; > unless you use exactly the right design patterns in your schema (which are > absurdly convoluted, btw), you'll end up locking out future > backwards-compatible changes. The authority in this space is Dave Orchard; > see his conclusions at > <http://www.pacificspirit.com/Authoring/Compatibility/ProvidingCompatibleSchemaEvolution.html>. > > 3) An XML Schema can never express all of the constraints on the format. So, > you'll still need to document those that aren't captured in the schema. > > I suppose the central question is what people are using the schema for. If > it's just to document the format, that's great; we can have a discussion > about how to do that. If they're using it for databinding, I'd suggest that > JSON is far superior, as a separate databinding step isn't needed. Finally, > if they're using it for runtime validation, I'd agree with Jay below; it's > much easier to use json parse + runtime value checks for validation > (especially in HTTP, where clients always have to be ready for errors anyway). > > Just my .02. > > Cheers, > > > On 03/06/2011, at 5:20 AM, Jorge Williams wrote: > >> It's not just about the service itself validating it, its as Joseph said, >> making sure that the data structures themselves are documented in detail to >> the client. To my knowledge there is no accepted schema language in JSON >> though JSON schema is starting to catch on. >> >> At the end of the day it should be a matter of providing our customers with >> a representation that they can readily use. It could be that my perception >> is wrong, but it seems to me that there's support for both representations. >> I'll try to get some data to back this up. >> >> -jOrGe W. >> >> >> On Jun 2, 2011, at 2:00 PM, Jay Pipes wrote: >> >>> On Thu, Jun 2, 2011 at 1:54 PM, Rick Clark <r...@openstack.org> wrote: >>>> Hi All, >>>> Is it required for new openstack API's to support both JSON and XML, or >>>> would it be acceptable to only support JSON? >>> >>> Glance currently does not support XML and I have no plans in the >>> immediate future to add support for it. >>> >>> IMHO, JSON can be validated just as easily as XML. Simply >>> json.loads(req.body) and then, if parsing succeeds, compare the >>> mapping against a model. No need for XSDs, WADLs, or any other >>> acronym. >>> >>> -jay >> >> >> _______________________________________________ >> Mailing list: https://launchpad.net/~openstack >> Post to : openstack@lists.launchpad.net >> Unsubscribe : https://launchpad.net/~openstack >> More help : https://help.launchpad.net/ListHelp > > -- > Mark Nottingham http://www.mnot.net/ > > > > > _______________________________________________ > Mailing list: https://launchpad.net/~openstack > Post to : openstack@lists.launchpad.net > Unsubscribe : https://launchpad.net/~openstack > More help : https://help.launchpad.net/ListHelp -- George Reese - Chief Technology Officer, enStratus e: george.re...@enstratus.com t: @GeorgeReese p: +1.207.956.0217 f: +1.612.338.5041 enStratus: Governance for Public, Private, and Hybrid Clouds - @enStratus - http://www.enstratus.com To schedule a meeting with me: http://tungle.me/GeorgeReese
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