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RE: DAML-ONT: RDF syntax

From: Holmes III, William S <william.s.holmes.iii@lmco.com>
Date: Wed, 25 Oct 2000 10:50:25 -0400
To: "'Dan Connolly'" <connolly@w3.org>, Sergey Melnik <melnik@db.stanford.edu>
Cc: www-rdf-logic@w3.org
Message-id: <079B626B05A0D3118B1000508B0EA5E9048B8D69@emss04m05.ems.lmco.com>
I hope I'm not being impertinent, but I believe from a user perspective 
there would be value and flexibility added by supporting XML entities in 
attribute values.  They probably wouldn't be used extensively, and might 
not be a topic covered by an introductory DAML tutorial; however, 
there are a few reasons I could see them as being useful.

1) We can't assume everyone is going to be using a graphical editor for 
   annotating their content. Quite a few developers still prefer to edit 
   their HTML with a text editor rather then use a WYSIWYG editor. In this
   case, I'm sure an error would be easier to spot if a URL is only used once
   at the top of a page instead of multiple times throughout a page.

2) XML Entities would allow for local development and testing without having 
   to play with network host files or caching software (which unfortunately 
   in some cases isn't necessarily feasible or practical).

So I don't think XML entities should be so readily dismissed.

However, I don't agree that URI-references should be fully qualified.  
Section 4.2 of RFC 2396 (http://www.isi.edu/in-notes/rfc2396.txt) specifically
addresses local references, and as Dan stated, local references have 
been in use and an accepted practice for some time in the web community. 

Regards,
 Bill H.


> -----Original Message-----
> From:	Dan Connolly [SMTP:connolly@w3.org]
> Sent:	Tuesday, October 24, 2000 6:46 PM
> To:	Sergey Melnik
> Cc:	www-rdf-logic@w3.org
> Subject:	Re: DAML-ONT: RDF syntax
> 
> Sergey Melnik wrote:
> > 
> > (The information provided below reflects the opinion of the Stanford
> > DAML team.)
> > 
> > The DAML-ONT specification posted on daml.org has several deficiences
> > with respect to the RDF syntax.
> > 
> > I made several minor syntactic changes to the specification to ensure
> > that available RDF tools (like [1]) can process it correctly. Both the
> > new version of the spec and the SED script I used are appended.
> > 
> > I'd recommend to DAML participants to consider the following syntactic
> > issues while working on the "homework" assignments and using DAML-ONT.
> > Example:
> > 
> > Original definition:
> > 
> >         <Property ID="subClassOf">
> >           <equivalentTo
> > resource="http://www.w3.org/2000/01/rdf-schema#subClassOf"/>
> >         </Property>
> > 
> >         Deficiencies:
> >           - invalid RDF syntax: attributes "ID" and "resource" are not
> > qualified and
> >             won't be recognized by all RDF parsers.
> 
> The spec doesn't require ID and resource to be qualified;
> in fact, as written, it doesn't allow them to be qualified:
> 
>   [6.6] idAttr         ::= ' ID="' IDsymbol '"'
>  [6.18] resourceAttr   ::= ' resource="' URI-reference '"'
> http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#grammar
> 
> So it looks to me like the bug is in your tools[1],
> not in the DAML schema.
> 
> >           - the definition is location-dependent. If the DAML/RDF file is moved
> > to another location
> >             (e.g. stored on a local disk), it will break.
> 
> How so? Ah... you elaborate below...
> 
> In general, if you take a document from one
> part of the web and copy its contents to some other
> part of the web, you've created another document.
> If the resulting document doesn't do what you expect,
> it doesn't mean there's something broken/wrong with the original
> document.
> 
> >           - including full resource URIs is time consuming and error-prone.
> 
> Er... this "time consuming and error-prone" job is done.
> I don't see why it matters how it was done.
> 
> > Better definition:
> > 
> >         <Property rdf:ID="&daml-o;subClassOf">
> >           <equivalentTo rdf:resource="&rdfs;subClassOf"/>
> >         </Property>
> > 
> >         This definition requires declaration of corresponding XML entities on
> > the top of the document
> >         (see appended daml-o.rdf specification).> 
> 
> I prefer not to rely on XML entity declaration syntax.
> In relying only on elements and attributes, the
> amount of XML knowledge required of DAML users is
> limited to the material covered in:
> 
> XML Tutorial 1: Well-Formed XML Documents
>             by Bonnie SooHoo Aug. 4, 2000 in webreview.com 
> http://www.daml.org/2000/10/daml-walkthru
> 
> The specification of XML entities, on the other hand,
> is a mess. It comes up at least 82 times in the XML 1.0
> errata.
> http://www.w3.org/XML/xml-19980210-errata
> 
> > When in question, please always use fully-qualified tag names and
> > attributes in your DAML/RDF files. Similarly, try to avoid relative
> > references to locally defined resources. For example,
> > 
> >         <complementOf rdf:resource="&daml-o;Thing"/>
> > 
> > is superior to
> > 
> >         <complementOf resource="#Thing"/>
> 
> I disagree; "#Thing" is syntax that has been common
> to the web community since 1990 or so, and I don't
> see any reason to avoid it.
> 
> I don't see any reason to support re-publishing
> this schema at a different address (e.g. saving
> it locally to a file). If you want to use it
> off-line, then set up a cache; i.e. teach
> your software that it can dereference
> http://www.w3.org/2000/01/rdf-schema by
> looking at a file on local disk.
> 
> 
> > The amended spec is also available as
> > http://www-db.stanford.edu/~melnik/daml/daml-o.rdf
> > 
> > Sergey Melnik & Stanford DAML team
> > 
> > [1] http://www-db.stanford.edu/~melnik/rdf/api.html
> 
> 
> -- 
> bind default <http://www.w3.org/People/Connolly/kb>
> <mailto:connolly@w3.org> is mailbox of 
>   [a Person; called "Dan Connolly";
>   affiliation [ a Consortium; called "W3C";
> 	     homePage <http://www.w3.org> ];
>   homePage <http://www.w3.org/People/Connolly/>;
>  ]
Received on Wednesday, 25 October 2000 10:52:44 GMT

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