- From: Harry Halpin <hhalpin@ibiblio.org>
- Date: Tue, 06 Feb 2007 22:05:22 -0500
- To: jacek@jacek.cz, public-grddl-wg <public-grddl-wg@w3.org>, carine@w3.org, eric@w3.org
Congrats on getting SAWSDL to Candidate Recommendation. I'm Harry Halpin, Chair of the GRDDL WG [1] which links XML and XHTML (including "microformats") to the Semantic Web in order to facilitate the deployment of the Semantic Web. I have a news posting and a few comments. There was an action for WG member Fabien to determine the relationship between GRDDL and SAWSDL these to you earlier, but due to his travelling I will attempt to articulate these. In order to prevent a "surprise" Last Call, I'd like for your WG to know that we are going to go, barring any final comments or problems, to request move to Last Call on or shortly after Feb 15th for the following three documents: 1) GRDDL Specification [2] 2) GRDDL Primer [3] 3) GRDDL Use Cases [4] We believe this technology is related to the SAWSDL WG as a GRDDL can be considered a type of function or "process" from XML to RDF, and after reading the latest version of SAWSDL I believe there is a definite and interesting relationship to SAWSDL [5]. First, according to my reading of [5], ""liftingSchemaMapping and loweringSchemaMapping, that are added to XML Schema element declarations, complex type definitions and simple type definitions for specifying mappings between semantic data and XML." In essence, a GRDDL is a way for a "lifting". However, there are three differences: 1) "lifting" as you define it maps to a "semantic model", which "does not rely on any particular semantic modeling language. It only requires that the semantic concepts defined in it be identifiable via URI references." In this regard, GRDDL is a subset of "lifting," as it defines its output to a RDF graph, a subset of all "semantic models". 2) GRDDL applies to XML documents in general, including XHTML and XML Schema. Insofar as "lifting" as defined in SAWSDL by "liftingSchemaMapping" refers to XML Schema, GRDDL is a superset of "lifting". 3) Lastly and most importantly, SAWSDL specifIes a way of specifying the mapping that is componentized to the types of the XML Schema, while GRDDL currently only operates over the whole XML document, and so cannot at this time specify transformations at the level of simple and complex XML Schema types. I think these observatons require no changes to SAWSDL as the spec stands. However, it would be nice to put in a reference to GRDDL, such as after the sentence: "Other languages, such as XQuery can also be used." "GRDDL (Gleaning Resource Descriptions from Dialects of Language) is a way of "lifting" XML documents, including XML Schema, to RDF. Transformations created for use by GRDDL can be used as lifting mappings for SAWSDL if appropriate." In other words, nothing new should be implemented, and the note merely notices the relationship and that if someone makes a GRDDL transform for an XML Schema to RDF someone can save effort and use the same transform if wanted in a SAWSDL. I would also like to add a note about the relationship to SAWSDL one of the GRDDL documents. thanks! [1] http://www.w3.org/2001/sw/grddl-wg/ [2] http://www.w3.org/2004/01/rdxh/spec [3] http://www.w3.org/2001/sw/grddl-wg/doc29/primer.html [4] http://www.w3.org/2001/sw/grddl-wg/doc43/scenario-gallery.htm [6] http://www.w3.org/TR/sawsdl/ -- -harry Harry Halpin, University of Edinburgh http://www.ibiblio.org/hhalpin 6B522426
Received on Wednesday, 7 February 2007 03:05:28 UTC