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Re: ENCODE_FOR_LOCAL_NAME

From: Axel Polleres <axel.polleres@deri.org>
Date: Wed, 14 Dec 2011 18:50:50 +0100
Cc: "public-rdf-dawg-comments" <public-rdf-dawg-comments@w3.org>
Message-Id: <D4505223-714B-454E-8479-4327CF3389F5@deri.org>
To: David Booth <david@dbooth.org>
Hi David,

In response to http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2011Nov/0017.html

 > It would be helpful if SPARQL would define an ENCODE_FOR_LOCAL_NAME
 > function.
 > 
 > At present, SPARQL provides the ENCODE_FOR_URI function to facilitate
 > the generation of new URIs within SPARQL queries or updates.  This is
 > helpful, however often one needs to generate a new URI with a fixed
 > prefix and variable local name part, so that the generated URIs can be
 > used conveniently in subsequent SPARQL, Turtle and RDF/XML contexts.
 > But because the syntactic restrictions for local names (in SPARQL,
 > Turtle and XML) are more stringent than for URIs in general, additional
 > encoding is required.

The working group is capturing points as input for any future chartering process at

http://www.w3.org/2009/sparql/wiki/Future_Work_Items

where we have added this suggestion.

We would be grateful if you would acknowledge that your comment has been answered by sending a reply to this mailing list.

Axel, On behalf of the SPARQL WG

On 8 Nov 2011, at 03:33, David Booth wrote:

> It would be helpful if SPARQL would define an ENCODE_FOR_LOCAL_NAME
> function.
> 
> At present, SPARQL provides the ENCODE_FOR_URI function to facilitate
> the generation of new URIs within SPARQL queries or updates.  This is
> helpful, however often one needs to generate a new URI with a fixed
> prefix and variable local name part, so that the generated URIs can be
> used conveniently in subsequent SPARQL, Turtle and RDF/XML contexts.
> But because the syntactic restrictions for local names (in SPARQL,
> Turtle and XML) are more stringent than for URIs in general, additional
> encoding is required.
> 
> For example, in
> 
>   PREFIX ex: <http://example/>
>   . . .
>   BIND(uri(concat(str(ex:), encode_for_uri("Frankfurt"))) AS ?city)
> 
> ?city becomes <http://example/Frankfurt>, which can be conveniently
> written as:
> 
>   ex:Frankfurt
> 
> But if instead we have
> 
>   BIND(uri(concat(str(ex:), encode_for_uri("Los Angeles"))) AS ?city)
> 
> then encode_for_uri returns "Los%20Angeles", so ?city becomes
> 
>   <http://example/Los%20Angeles>
> 
> which cannot be written as
> 
>   ex:Los%20Angeles
> 
> because "%" is forbidden in a local name.  However,
> 
>   encode_for_local_name("Los Angeles")
> 
> would instead return a more stringently escaped string that would be
> guaranteed legal in a local name.  For example, it could return
> "Los_P20Angeles" (having "%" further encoded as "_P").  There are many
> ways this encoding could be done; this is just one example.  Ideally the
> SPARQL spec should pick one particular way as the standard (or the
> default).
> 
> I do not expect the working group to be able to address this for the
> current release of SPARQL, but I would be grateful if it could be placed
> on a wish list for the next version.
> 
> Thanks!
> 
> --
> David Booth, Ph.D.
> http://dbooth.org/
> 
> Opinions expressed herein are those of the author and do not necessarily
> reflect those of his employer.
> 
> 
> 
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Received on Wednesday, 14 December 2011 17:51:51 GMT

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