- From: David Carlisle <davidc@nag.co.uk>
- Date: Fri, 27 Jul 2012 12:00:49 +0100
- To: "Rushforth, Peter" <Peter.Rushforth@NRCan-RNCan.gc.ca>
- Cc: "public-xmlhypermedia@w3.org" <public-xmlhypermedia@w3.org>
On 27/07/2012 11:04, Rushforth, Peter wrote: > Hi David, > For example, Atom Publishing protocol makes use of various hypermedia > constructs, It's fine for Atom (or HTML) to do this, they are languages/vocabularies defined using XML syntax. That doesn't mean that it is OK for XML to do it. > >> XML isn't in itself a language, it is a framework for designing >> languages > > Well, what we design with XML aren't really languages, are they? > Maybe vocabularies would be more appropriate. Whatever words you prefer, XML is at a different level than atom or html. > Either way, vowels is the thing I think we're talking about here. > And that's exactly the point, XML should give the users of that > framework the tools to design their vocabularies appropriate to the > environment. Schemas and namespaces are one way. The other way is > the the way I'm proposing. XML should as far as possible not pollute the vocabularies defined using that syntax by forcing element and attribute names. > > Atom, for instance, does not use a schema, per se, just a public > specification with required / permitted content layout. I would say > it is a best practice for hypermedia design. Same is true of HTML in the latest versions. > As long as it is not the _only_ position, we can still talk. yes cuts both ways though, you should also be prepared to contemplate a mechanism that lets you declare that attributes have hypermedia properties that does not use the blunt instrument of predefining certain attribute names. > >> As I mentioned before, these reasons alone were the reasons for not >> using xlink on languages such as xhtml2 being developed at the >> time. > >> Chinese) or, closer to home, if all your attribute names did not >> have a colon. > > Well, I imagine "xml" happens to show up in the Chinese xml from time > to time, and what about xmlns etc? A little bit more won't hurt. > >> It also means (since only one such name is allocated) that you can >> not have two such attributes on the same element. > > We should ask the hypermedia community what *they* think. Not the > XML community, strictly, although there is obviously an > intersection. I am not sure who you see as being the "hypermedia community" but HTML claims to be the hypertext markup language so might be part of that community and certainly (although I wasn't in the WG) the fact that you could not model <img src="foo" longdesc="bar"/> in xlink because it requires two URI on the same element was a _major_ reason for blocking the adoption of xlink in (X)HTML at the time. > >> If you want to say attribute foo="example.com" is a link of a >> certain type, you should define a schema type representing that and >> then apply that schema to the instance. (Or if not XSD specify a >> different annotation mechanism). What you should not do is say "if >> you want to make a link the attribute has to have fixed name >> xxxxx". > > I personally have nothing against XSD, nor schemas of any kind in > general. In fact, the bugzilla bug I wrote included a schema to > describe these vowels. I'm a pointy bracket guy! But I think schemas > and namespaces are what we want to avoid in this case. If you want to > do that with your vocabulary, so as to have control over the names of > attributes, elements, what have you, go ahead, the facilities are > there already in XML. What we want here are some hypermedia > affordance vowels which reflect the architectural style of the web, > as we know it today, and that we can refer to in our vocabularies, > _by specification_, not schema. It doesn't have to be a schema: just some declarative method that lets you say which attributes have which properties. The HTML group at the time proposed an extended css declaration syntax as I recall as a counter-proposal to xlink. ah found it: "clink" eg this discussion http://lists.w3.org/Archives/Public/www-style/2004Mar/0060.html Or the original opera proposal from 2000 that states right up front: > There are three key differences between Clink and Xlink. First, > Clink is a much simpler language not capable of describing the more > advanced features of Xlink. Second, Clink does not require markup > languages to change their syntax in order to describe linking > behavior. Third, Xlink has some functionality which goes beyond > Xlink, namely HTML's longdesc attribute and base element. http://people.opera.com/howcome/2000/clink/2000-05-05.html You see, nothing I have said in this thread has not been said dozens of times before by different people in different decades. David ________________________________________________________________________ The Numerical Algorithms Group Ltd is a company registered in England and Wales with company number 1249803. The registered office is: Wilkinson House, Jordan Hill Road, Oxford OX2 8DR, United Kingdom. This e-mail has been scanned for all viruses by Star. The service is powered by MessageLabs. ________________________________________________________________________
Received on Friday, 27 July 2012 11:01:21 UTC