[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: xml:href, xml:rel and xml:type
On Tue, 2012-04-17 at 12:05 +0000, Rushforth, Peter wrote: [...] > Web crawlers, to take one example, can't crawl xml, because there is no reliable static > markup to identify links in all xml. There's also no way to mark what's content, which elements break phrases, how to make elements bold or italic, which elements are titles, that Web crawlers need to generate result snippets. Arch Forms were the HyTime/Eliot-Compatible Approach (HTECA). > The existence of xml:href solves that problem. > Unless they are Kreskin crawlers they won't know what to do with the xml when they find it. > That is what @xml:type is there for. While application/xml does not tell you too > much, there are sub sub media types, media type parameters etc to tell you how > to process the representation once you retrieve it. Also, it does not have to be xml :-). Media type tells you what something is, not how to process it. There are lots of things you can do with an SVG image, for example, besides simply rendering it. > > Finally, applications which use xml on the web need a way to decide / let the > client decide what state is the next state for the client. That is what @xml:rel > is for. > > How is this different from xlink? For one thing, it is static shared markup that > can be reliably used by the entire community. For another, xlink:type and xml:type are > different. xlink:type describes the processing of the link, while xml:type advertises > the media type that may be negotiable from the server (no guarantees, after all its > the server's resource). Putting media types in static content is generally not a good architecture. The remote Web server will send a media type as an HTTP header and that is what should be used - it is normative, authoritative. This is why, in HTML, it's <a href="foo"> and not <a href="fo" type="text/html"> Indeed, different HTTP clients (browsers) might receive different formats, depending on the Accept: HTTP headers they send. > > Why is xml:lang needed for xml itself? or xml:base for that matter? > Why is linking less important? Where you start and stop is fairly arbitrary. We didn't do xml:id in the first spec either. Peter, the people you need to persuade here mostly fall into two broad camps - (1) people happy with XML and namespaces and who generally see little or no problem with XLink. XLink already has the ability to describe the "state of the cilent" as you call it, to specify link relationships (like the rel attribute on "a" and "link" in HTML), and does not have the Web-architecture-breakage of putting media types into links ;-)... and (2) people who have no interest in using XML on the Web today, and for whom the difference between xlink:href and xml:href is like saying, buy a Jeep because the rear axle leaf spring bushings are polyurethane whereas in a Toyota they're aluminium. The biggest barrier to XML on the Web today is that when Aunt Tillie tries it, and leaves quotes of her attribute values, she gets a really confusing error message. The next biggest is lack of architectural forms for search crawlers and ad servers to use. Without ads, and with strict syntax, we're not about to take over the world. That's actually fine, too. XML is used in televisions, in DVD players, in music players, in 'plane navigation systems, in shoes, in car engines, all over the world. OK, not in _all_ shoes, but there were some. Honest ;) We are limited in the ways we can change XML itself, although we can change the layers above more easily. Liam -- Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/ Pictures from old books: http://fromoldbooks.org/
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