막연히, RDF 가 더 간단하고, 머신 친화적(?) 이라고 알고 있다가,
문득 생각나 찾아봤다.
비슷한 질문을 수없이 들었다는 Tim 이 꽤 간단 명료하게 해설을 해놓았다.
관심이 있다면 꼭 읽어보기 바란다.
XML 는 구조가 다변적이고 의미가 애매해서 문제가 된단다. 원문에 예제들이 있다.
물론, 이것이 장점이 될수도 있겠지만  의미를 해석하는데는  한계가 있다.

Things you can do with RDF which you can't do with XML include

  • You can parse the semantic tree, which end up giving you a set of (possibly mutually referential) triples and then you can use the ones you want ignoring the ones you don't understand.

Problems with basing you understanding on the structure include

  • Without having gone to the trouble of getting the schema, or having an application hand-programmed to recognise a particular document type, you can't pick up any semantic information from a document;
  • When an XML schema changes, it could typically introduce new intermediate elements (like "details" in the tree above or "div" is HTML). These may or may or may not invalidate any query which has been based on the structure of the document.
  • If you haven't gone to the trouble of making a semantic model, then you may not have a well defined one. ( Look at a label on the jam jar which says: "Expires 1999". What expires: the label, or the jam? Here the ambiguity is between a statement about a statement about a document, and a statement about a document. )

Why RDF model is different from the XML model - Tim Berners-Lee


Posted by ukmie
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http://www.idealliance.org/proceedings/xtech05/papers/03-06-01/

This paper describes GRDDL, standing for "Gleaning Resource Descriptions from Dialects of Languages", a technology under development in W3C designed to fill part of this gap, allowing document authors to associate automatically formalized RDF statements with XHTML and XML-based formats.


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Abstract

While SGML and XML languages have had for a long time the possibility to describe syntactic constraints of their vocabularies using DTD and other schema languages, no specific mechanism exists to allow for the mapping between these syntactic constraints and their semantic implications.

GRDDL, a technology in development in W3C, allows to incorporate semantics from XML vocabularies and XHTML conventions into the Semantic Web by re-using existing extensibility hooks of the Web. This paper explains the basic principles of its mechanisms, and explore how it can be applied for various communities.


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Posted by ukmie
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