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Re: [SE] Suggestion of new note

From: Holger Knublauch <holgi@stanford.edu>
Date: Tue, 04 Oct 2005 17:58:14 +0100
Message-ID: <4342B4A6.6020303@stanford.edu>
To: public-swbp-wg@w3.org

Hi John,

thanks a lot for your comments - I will try to address them where 
appropriate.  Responses below.


John McClure wrote:
> A few scattered thoughts....
> Perhaps under the title "Worldliness" (!):
> 1. OWL ontologies define simultaneously an external XML representation for
> resources that can be exchanged via text messages, files, or columns in a
> database -- OO implies (proprietary) binary protocols for object persistence to
> a binary file or an object database.

I don't think OO necessarily emplies binary formats.  There are many XML 
data binding schema for Java out there, for example.  But you are right 
that one of the advantages of OWL/RDF is that developers get the 
standard XML syntax (with parsers etc) for free.  This has already been 
pointed out in the note: "RDF and OWL objects have a standard 
serialization based on XML, with unique URIs for each resource inside 
the file."  Please let me know if you still don't see this point 
adequatly addressed.

> 2. OWL/RDF defines conventions for naming and referencing objects; OO does not
> address such issues at all. OWL thus distinguishes between 'first-class' and
> 'anonymous' resources, while for OO, all objects are anonymous.

This is a good point and I have added a corresponding row to the table. 
  As far as I know, the only "standardized" way of addressing a certain 
instance in OO would be using a kind of a path expression, perhaps in 
OCL.  But the fact that OO systems are usually not internet aware and 
closed (as you point out) explains why this hasn't been a focus of OO 
language designers.

> 3. OWL defines a root instance class -- Thing -- while OO advocates can still be
> heard to discuss whether a 'sky-level' class should exist or not (maybe that was
> settled, and I just missed it?).

That is true, but at least in Java such a top-level java.lang.Object 
also exists.  Anyway, perhaps you could clarify why this is an issue 
worth pointing out - is there an important argument in favor of a common 
root class?

> 4. OWL schemas are open -- anyone can make statements about another's schema or
> any (named) part of that schema.

I think this is already addressed in the table "All parts of an OWL/RDF 
file are public and can be linked to from anywhere else."

> I think it's important to communicate the THEME that "OWL is Internet-ready OO,
> addressing certain issues that OO does not or cannot" rather than the theme that
> "OWL is great and OO is deficient" -- a turnoff for sure for certain audiences.

We will discuss this in our task force's next telecon.  You are right 
that we shouldn't put off OO developers.  Their languages were designed 
with different goals in mind.  I need to walk through the article to see 
where we give a wrong impression to the OO folks.

> Being "Internet-ready" means providing solutions for issues that simply did not
> apply to local and closed binary stovepipes. People like and easily grasp the
> notion of being "Internet-ready"... Show historical perspective by tracing the
> development of and problems with developing wire protocols for binary objects --
> that is, CORBA and the IDL, which was but a standardized OLE (remember those
> days?) ...

I would be pleased to add such a paragraph on the evolution of Corba 
etc.  I am unfortunately not an expert in this area.  So I would welcome 
contributions from others.

> I suggest a section about the smilarities between OO and OWL, primarily focusing
> on the notion that BOTH result in an INFORMATION SCHEMA. So, a section about
> "Designing Ontologies vs Designing Object Class Hierarchies" would be amazingly
> eye-catching and which could be an opportunity to hark some best practices for
> OWL schema development but perhaps more importantly, would be the place to
> discuss the degree to which an OO schema can be drawn directly from an OWL
> schema and vice-versa.

One of our design goals of this note (which probably isn't documented 
anywhere) is to keep the paper *short*.  While I fully agree that these 
aspect would be great to include, we may end up writing a book, which is 
beyond the goals of our group.  Having said this, I would welcome 
contributions from others to add such content in.

> I also suggest that it be prominently said that OWL (schemas and data) files are
> normally processed by an OO-based system, ie fully highlighting the fact that
> OWL is not an application language, while OO is, to a degree. This is necessary
> I think because the AUDIENCE for this note would be systems architects and
> development folks; one area these folks most care about is interfacing OWL files
> to their installed base of OO applications and application-building tools, so it
> would be on-point to address how an OWL schema can relate to an OO schema. In
> other words, it would be good to explain how OO remains, indeed, a key part of
> the solution stack for development organizations, with OWL now in the picture.

Absolutely, this is one of the items that I will try to strengthen in 
future versions.  In fact the embedding of OWL/RDF into OO systems 
should be one of the outcomes of the (yet incomplete) section 4 of the 
note ("Programming with RDF Schema and OWL").

> Finally, I think that a discussion about the impact of OWL on information
> querying is quite important, that is, contrast object databases to XML/OWL
> databases and contrast the query languages that are being used/developed for
> each.

The note mentions at various places that RDF/OWL models supported by 
reasoners can be used as a rich query engine.  Again, if we want to dig 
deeper into this comparison, I may need to forward to other, more 
knowledgeable members of the community.
Received on Tuesday, 4 October 2005 16:59:46 UTC

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