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RE: use of IRIs in WS-Addressing

From: Jonathan Marsh <jmarsh@microsoft.com>
Date: Tue, 24 May 2005 10:19:52 -0700
Message-ID: <7DA77BF2392448449D094BCEF67569A507A595A2@RED-MSG-30.redmond.corp.microsoft.com>
To: "Jacek Kopecky" <jacek.kopecky@deri.org>
Cc: <public-ws-addressing-comments@w3.org>

Thanks for the comment, which the WG tracked as lc65 [1].  The WG closed
the issue without action further to accepting other issues
distinguishing between IRIs and URIs more accurately (see lc8 and lc23).
See our specific response below.

> -----Original Message-----
> From: public-ws-addressing-comments-request@w3.org [mailto:public-ws-
> addressing-comments-request@w3.org] On Behalf Of Jacek Kopecky
> Sent: Tuesday, May 03, 2005 6:37 AM
> To: public-ws-addressing-comments@w3.org
> Subject: use of IRIs in WS-Addressing
> Hi,
> as an LC comment for WS-Addressing, I'm unclear about why the working
> group chose to use IRIs instead of URIs. All the schemas specify
> anyURI
> which would imply the values are URIs.

As you know, IRIs allow non-ascii characters, while URIs are strictly
limited to a subset of ascii.  In practice, many people have used
non-ascii characters in their XML attributes and elements outside the
ascii range, relying on the infrastructure to escape the offending
characters before using the URI as such.  We view codifying this
practice as has been done in other specs (including XML itself) as
assisting in interoperability.

> I'm aware that URIs and IRIs are interchangeable, in other words that
> all IRIs can be represented as URIs. I'm unsure if the there is an
> unambiguous transformation from URI to IRI.

There is - every URI is by definition a valid IRI.  The identity
transformation is sufficient.

> Therefore I'd prefer the WS-Addressing specification to use the term
> URI, perhaps stating that IRIs can be used (transformed into URIs as
> described in the IRI spec). 

By using the more general term, users still can use URIs as they did
before, but the spec will also be fully useable with IRIs without
manually performing the escaping.

> In any case, the distinction between URI
> and
> IRI is mostly for presentation to a human operator, and IRIs do not
> directly validate as xs:anyURI so the XML will carry URIs.

IRIs will directly validate as xs:anyURI.  See the second paragraph of
[2] which defines the mapping from lexical to value spaces including
%-escaping.  Rather than include similar tortuous prose in our spec, we
refer to IRI which codifies such escaping more clearly.  It helps, for
instance, in defining a comparison operation between two values which we
believe will help interoperability.

In sum, although IRIs have a small impact on the readability of the spec
to those not familiar with IRIs, they also provide immediate clarity,
precision, and interoperability benefits in addition to future-proofing
our spec against IRI deployment.

[1] http://www.w3.org/2002/ws/addr/lc-issues/#lc65
[2] http://www.w3.org/TR/xmlschema-2/#anyURI

> Best regards,
>                    Jacek Kopecky
>                    Ph.D. student researcher
>                    Digital Enterprise Research Institute
>                    University of Innsbruck
>                    http://www.deri.org/
Received on Tuesday, 24 May 2005 17:19:58 UTC

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