RE: relative uri references

Hello,

 

In the RDF syntax, the resolution of URI references is governed fully by the underlying RDF format. For example, if you are working
with RDF/XML, then the RDF parser should use xml:base. In addition, the XML parser will expand any XML entities as well. There is no
equivalent of the Namespace declaration in the RDF syntax.

 

In the XML Syntax, there are no Namespace declarations either. Again, you have is xsd:base for relative URIs, and this is explicitly
mentioned in the document. Furthermore, we don't need a specific URI abbreviation mechanism is because XML Syntax ontology documents
can use XML entities for abbreviation of long URIs.

 

The functional-style syntax and the Manchester syntax, in contrast, cannot rely on other specifications (such as RDF of XML) for
abbreviation and expansion of URI references, so they need their own URI resolution mechanisms. In the functional-style syntax
ontology documents, only namespace declarations are expanded, and relative URIs are not expanded. I think this is correct: we never
say that the URIs of ontology entities must be absolute. Thus, if someone actually creates ontology entities with relative URIs, the
functional-style syntax will correctly capture this.

 

Note that URIs have a well-defined identity. Therefore, a relative URI provides a perfect way of identifying some ontology entity -
that is, it is a URI just like any other.

 

Hence, it seems to me that we don't really need to say anything more than what we've already said. We might only introduce
additional clarification into the XML Syntax document about relative URIs: we might say that if you want to store such URIs, then
you should explicitly turn xml:base off on the element whether you are doing so; otherwise, your relative URIs will accidentally be
resolved against the xml:base and that wopuld lead to problems. You can turn this resolution off by placing on the element an
xml:base with some opaque URI.

 

Regards,

 

            Boris

 

  _____  

From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org] On Behalf Of Alan Ruttenberg
Sent: 24 November 2008 06:05
To: W3C OWL Working Group
Subject: relative uri references

 

Do we not  have to say how these are resolved in the functional and manchester syntax, and might it not be best to explicitly say so
for all syntaxes? 

 

-Alan