[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Do we need link-catalogs for schemas? (was Re: More namespaces perve
Real simple question: What is a GI? Bill -----Original Message----- From: Rick Jelliffe <ricko@a...> To: xml-dev@i... <xml-dev@i...> Date: Sunday, October 11, 1998 12:01 PM Subject: Do we need link-catalogs for schemas? (was Re: More namespaces perversion) > Charles Frankston ¼g¹D¡G > >> Is there one "link-catalog" per document, or can I nest and scope >them? >> I.e. how do you deal with the fragment composition issue? > >At its simplest, the link-catalog is just aweb of XLL extended pointers, >with >roles given using some nice FPI/URN mechanism. I dont see that it >should matter >if all the links were put in the same entry in the same resource: ><XML-DEV:link-catalog> > <entry id="lc1" GI="p" namespace="urn:www.w3.org/html4#p" > > <description>Links for HTMLs P element type</description> > <!-- links to schemas --> > <a href="www.w3.org/html4.dtd#p" > role="-//www.w3.org//NOTATION XML DTD//EN" /> > <a href="www.schema.net/Xschema/html4.xml#p" > role="-//www.w3.org//NOTATION XSchema//EN" /> > </entry></XML-DEV:link-catalog> >or inn different entries in the same resource ><XML-DEV:link-catalog> > <entry id="lc1" GI="p" namespace="urn:www.w3.org/html4#p" > > <description>Links for HTMLs P element type</description> > <!-- links to schemas --> > <a href="www.w3.org/html4.dtd#p" > role="-//www.w3.org//NOTATION XML DTD//EN" /> > </entry> > <entry id="lc2" GI="p" namespace="urn:www.w3.org/html4#p" > > <description>Links for HTMLs P element type</description> > <a href="www.schema.net/Xschema/html4.xml#p" > role="-//www.w3.org//NOTATION XSchema//EN" /> > </entry></XML-DEV:link-catalog> > >or even in different resources ><XML-DEV:link-catalog> > <entry id="lc1" GI="p" namespace="urn:www.w3.org/html4#p" > > <description>Links for HTMLs P element type</description> > <!-- links to schemas --> > <a href="www.w3.org/html4.dtd#p" > role="-//www.w3.org//NOTATION XML DTD//EN" /> > </entry></XML-DEV:link-catalog> > > ><XML-DEV:link-catalog> > <entry id="lc1" GI="p" namespace="urn:www.w3.org/html4#p" > > <description>Links for HTMLs P element type</description> > <a href="www.schema.net/Xschema/html4.xml#p" > role="-//www.w3.org//NOTATION XSchema//EN" /> > </entry></XML-DEV:link-catalog> > >I leave out other examples where one link in an entry merely points to >another >link in another entry, or points to another link-catalog in another >resource. >The link-catalog does nto need to be part of a document: it can be part >of an >application--an XML editor from Microsoft would presumably infer a >link-catalog >linking to Microsoft schema data (using Microsoft schema notations) in >augmentation to whatever link-catalogs were present in the particular >document >instance (or #FIXED linked from its DTD). > >For nesting and scoping, a link-catalog link for the doctype element >(i.e. the >root) is enough to locate a whole schema. Minimally, all that is needed >is an >entry for every unique namespace. But individual entries can be used to >annotate >and extend schemas for particular purposes, in particular by adding >sub-schemas >and documentation. This is how people would expect such a link-catalog >to work. > >Delegation is fine to provide, if users expect it. > >The use of such a mechanism allows registration of various subclassing >mechanisms >too so that local poicy can be implemented: ><XML-DEV:link-catalog> > <entry id="lc1" GI="p" namespace="urn:www.w3.org/html4#p" > > <description>Links for HTMLs P element type</description> > <a href="html4/p/id-check.jar/" > role="-//Rick Jelliffe//NONSGML Java program to check a DOM >that > paragraph IDs start with small letter p//EN" /> > </entry></XML-DEV:link-catalog> > >In that case, the link invokes a validation program. My kindly browser >manufacturer might even define callbacks into which I can put data entry > >programs: ><XML-DEV:link-catalog> > <entry id="lc1" GI="table" namespace="urn:www.w3.org/html4#p" > > <description>Links for HTMLs P element type</description> > <a href="html4/table-entry.jar/" > role="-//IDN ms.com//NONSGML IE6 Data Entry Program//EN" /> > </entry></XML-DEV:link-catalog> >I >As far as nesting and scoping, I would tend not to want to provide any >mechanism. >The idea is to create a web of type-links which augment each other >rather than >replace. But I cannot see why any vendors could not implement their own >policy: >to ignore (but not delete) links using other vendor's schema or to >automatically >add or infer links to schemas at their own site. Or to prefer "close" >entries in >preference to "far" entries. I want to allow Microsoft to come up with >their own >schema system and to compete on that, but not exclude another vendor >from also >having their own system. > >For new readers, the "composing of fragments issue" is this: if we cut >out a WF >fragment of one document and paste it into another, how can we cart >along all the >other information (catalogs, schema data, type links, etc). The >important thing >is that the link catalog entries are organized to GIs (other things may >be >possible, but I want to get GIs right first): these entries can be cut >up into >fragments just as simply as a document can be. > >In a link-catalog system, the schemas themselves (or CSS, or whatever) >are not >cut up with the document. The same code which corrects the namespace >declarations during such cut and pasting also has enough information to >correct >link-catalogs. (Whether the link-catalog can stay the same (in which >case a >fragment carts around some of its orinigating context, which may be an >OK thing), >or just have the GI changed to the GI of the fragment, is not clear to >me. ) > >In a sense, there are already many kinds of data which are crying out >for this >kind of link: >MIME catalogs, CSS/XSL, Web schemas, all of these are based on linking >from type >information. (Actually, I suppose that with the namespace proposal, >even OASIS >SOCATs fall into class of inforamtion, to a certain extent. In the case >of MIME >catalogs, the grain is kept at the highest level, in the case of >CSS/XSL, the >grain is quite detailed structured information. We see on XML-DEV at the >moment >several discussions on how to create objects by linking methods to GIs. > >The web would be richer, and many kinds of systems simpler, if there >were a nice >simple mechanism for doing this, such as this kind of link-catalog. As >I have >mentioned, I am not sure that there is a great need for a Web-Schema >system, such >as is being proposed. I think it would be much better fro W3C to agree >on simple >datatyping, and then agree on some link-catalog system with some >predetermined >FPIS so that basic standard schemas can be invoked (and also CSS, XSL, >DTDs, RDF, >SOCATs, MIME catalogs, etc). That leaves vendors free to develop >schemas which >are optimized for their constituency in whatever ad hoc consortia are >commercially appropriate. > >In ISO I noticed a very strong feeling that when a standard moved to far >from >"infrastrucutre" to "application" it all got too political and >unsatisfactory, >and even perhaps anti-competitive and futile. One might think that a >schema >definition language is "infrastructure", but I rather fancy that it >might be >closer to "application", in that it undoubtedly will reflect the >capabilities of >the commercial products of its developers. > > > Rick Jelliffe > > > xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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