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> > >FYI - as promised, the HTML Working Group has released a document that >begins to address issues with an alternative to XLink. That document is >available at http://www.w3.org/TR/hlink/ > >The chair of the HTML Working Group has sent out the following message >as well. > >Steven Pemberton wrote: > > > > XML has what you may call 'host languages', and what you may call > > 'integration languages'. A host language has a root element, and may host > > other languages. For instance XHTML can host Math or SVG or many others by > > allowing those languages to be integrated into its structure. Integration > > languages on the other hand are designed to be hosted by other languages; > > they typically don't have a root element (though they may): Xlink for > > instance, XForms, XML Events. These usually have elements and attributes > > intended to be used by other languages. Some languages can be both host and > > integration (SVG for instance, and XHTML is also used this way by some). > > > > 1) Suppose we have an integration language 'XML Handlers', that has an > > element > > > > <script> > > a=b > > </script> > > > > and as an option the <script> element may have an attribute pointing to an > > external resource: > > > > <script src="/scripts/pop" /> > > > > and someone complains that this should use XLink, so it gets changed to: > > > > <script xmlns:xlink="http://www.w3.org/1999/xlink" > > xlink:href="/scripts/pop" xlink:type="simple" xlink:show="embed" > > xlink:actuate="onLoad" /> > > > > 2) Suppose we have another integration language "XML Security" that > requires > > adding references to security preference files via a URL > > xsecurity:preferences="..." > > > > <myElement xsecurity:preferences="/security/pref1.xsp"> > > ... > > </myElement> > > > > Someone says they should make this XLink compatible, so they instead > > just define a new xlink:role "http://example.org/security": > > > > <myElement xlink:href="/security/pref1.xsp" xlink:type="simple" > > xlink:show="embed" > > xlink:actuate="onLoad" xlink:role="http://example.org/security" /> > > > > Well, now when we want to integrate XML Handlers with XML Security, we > can't > > put a security preferences URI on the <script> element because it already > > has a URI. So we can't integrate the two: we have to redesign one of them; > > integration is impossible. > > > > We can't redesign XML Security because it doesn't have any elements, so we > > have to redesign XML Handlers. > > > > Well, we can't make the security preferences a child of <script> > > > > <script ...> > > <security ...> > > ... > > </script> > > > > because that would clash with the intended semantics of 'embed' on the URI > > on the <script> element. So how about making it a parent of <script>: > > > > <security xlink:href="/security/pref1.xsp" xlink:type="simple" > > xlink:show="embed" > > xlink:actuate="onLoad" xlink:role="http://example.org/security"> > > <script xlink:href="/scripts/pop" xlink:type="simple" > > xlink:show="embed" > > xlink:actuate="onLoad" /> > > </security> > > > > Oh no. That contradicts the embed property too. Oh well, then we have to > > create a brand new extended link element: > > > > <secureScript xmlns:xlink="http://www.w3.org/1999/xlink" > > xlink:type="extended"> > > <resource xlink:href="/security/pref1.xsp" > > xlink:type="locator" xlink:label="security" > > xlink:role="http://example.org/security"> > > <resource xlink:href="/scripts/pop" > > xlink:type="locator" xlink:label="script" > > xlink:role="whatever" /> > > <resource xlink:type="resource" xlink:label="here"/> > > <arc xlink:type="arc" xlink:from="here" xlink:to="script" > > xlink:show="embed" xlink:actuate="onLoad" /> > > <arc xlink:type="arc" xlink:from="here" xlink:to="security" > > xlink:show="embed" xlink:actuate="onLoad" /> > > </secureScript> > > > > though I'm not sure where I'm going to put my inline script in this anymore > > (and I left a few things off, to simplify it and save my wrists). > > > > 3) And then along comes the XML Privacy group that introduces the XML > > Privacy specification that says that in order to reference a privacy > > preference file from XML, you have to put a URL ... no let's not do that > > today. > > > > All we wanted to say was > > > > <script src="/scripts/pop" > > xsecurity:preferences="/security/prefs1.xsp"/> > > > > HLink, just released, allows you to define this. > > http://www.w3.org/TR/hlink/ > > > > Steven Pemberton > > Chair W3C HTML Working Group, co-chair W3C Forms Working Group.
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