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Sterling work, Sean.
Your schema also happens to be the first I've seen that not only covers
RDF/XML's various syntax forms but also adequately represents the OPML
format [1], which is particularly difficult to validate because it has
allows [attribute*]. A marvellous piece of unification.
Cheers,
Danny.
[1] http://www.opml.org/spec
Sean McGrath wrote:
> All,
>
> It seems to me that modern schema languages such as RelaxNG and W3C
> XML schema, have a significant role to play in simplifying data
> inter-operability and helping us move away from incessant disagreements
> about data models that plagued the DTD years.
>
> As an example of what can be achieved, and as a discussion piece, I
> have created a schema that allows *all* versions of RSS and the
> newer Atom notation to all conform to a single, simple schema. I'm
> convinced
> that this harmonization will make life a lot easier for syndication tool
> creators and feed creators alike.
>
> I have included Relax NG compact syntax, Relax NG and W3C XML Schema
> versions.
>
> (The is no DTD version because DTDs lack the all important attribute
> wild carding capability
> of modern schema languages. A capability that is vital to the power of
> this technique - especially
> in the namespace-centric world we live in.)
>
> Here is a fragment of RSS 1.0 for example:
> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";>
> <items>
> <rdf:Seq><rdf:li
> rdf:resource="http://localhost:8080/DrRoryOHanlon/000013.html"; />
> <rdf:li
> rdf:resource="http://localhost:8080/DrRoryOHanlon/000012.html"; />
> <rdf:li
> rdf:resource="http://localhost:8080/DrRoryOHanlon/000004.html"; />
> <rdf:li
> rdf:resource="http://localhost:8080/DrRoryOHanlon/000003.html"; />
> </rdf:Seq>
> </items>
> </rdf:RDF>
>
> and here is the same document, cross-translated to my interoperability
> schema:
> <tag type="rdf:RDF"
> xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";>
> <tag type="items">
> <tag type="rdf:Seq"><tag type="rdf:li"
> rdf:resource="http://localhost:8080/foo/000013.html"; />
> <tag type="rdf:li"
> rdf:resource="http://localhost:8080/foo/000012.html"; />
> <tag type="rdf:li"
> rdf:resource="http://localhost:8080/foo/000004.html"; />
> <tag type="rdf:li"
> rdf:resource="http://localhost:8080/foo/000003.html"; />
> </tag>
> </tag>
> </tag>
>
> Here is the schema. Comments welcome.
>
> -- W3C XML schema --
> <?xml version="1.0" encoding="UTF-8"?>
> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema";
> elementFormDefault="qualified">
> <xs:element name="tag">
> <xs:complexType>
> <xs:sequence>
> <xs:element minOccurs="0" maxOccurs="unbounded" ref="tag"/>
> </xs:sequence>
> <xs:anyAttribute processContents="skip"/>
> </xs:complexType>
> </xs:element>
> </xs:schema>
>
> -- Relax NG --
> <?xml version="1.0" encoding="UTF-8"?>
> <grammar xmlns="http://relaxng.org/ns/structure/1.0";>
> <start>
> <ref name="TAG"/>
> </start>
> <define name="TAG">
> <element name="tag">
> <zeroOrMore>
> <attribute>
> <anyName/>
> </attribute>
> </zeroOrMore>
> <zeroOrMore>
> <ref name="TAG"/>
> </zeroOrMore>
> </element>
> </define>
> </grammar>
>
> -- Relax NG Compact Syntax --
> start = TAG
>
> TAG = element tag {
> attribute * { text }*,
> TAG *
> }
>
> Sean
>
>
> Sean McGrath
> http://seanmcgrath.blogspot.com
>
>
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--
----
Raw
http://dannyayers.com
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