Altova Mailing List Archives


Re: [xml-dev] Motivations for namespaces (sorry)

From: "Eric van der Vlist" <vdv@--------.--->
To: <xml-dev@-----.---.--->
Date: 7/10/2003 3:02:00 PM
Thomas B. Passin said:
> [Eric van der Vlist]
>>
>> Chiusano Joseph said:
>> > Eric,
>> >
>
>> I would argue that in this case, what's identifying your "document
>> type" is the xsi:schemaLocation more than the namespaces!
>> My point was rather that namespaces alone are not enough to guess
>> what's the document as a whole is about.
>
> In the task I described a post ago, it is exactly the namespace URI -
> OK, in practice it really is the prefix,  so there! - that is so
> helpful.
.../...
> That's important.  That's why virtually all xslt stylesheets use xsl:.
> That's why virtually all XML Schemas use xs: or xsd:.  That's why xhtml
> documents almost always use html: or xhtml:.  It is why we name
> variables with mnemonic names rather that "dhf340cksdfnmg".  It is
> mostly why we use readable URLs instead of GUIDs.

Thomas,

This sounds like a really innovative use of namespace prefixes! What about
languages such as Schematron and Relax NG (not to mention Examplotron
which is worse) which use to use a default namespace?
Also, let's take a RSS 1.0 document:

<?xml version="1.0" encoding="utf-8"?>
 <rdf:RDF
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:dc="http://purl.org/dc/elements/1.1/"
  xmlns:sy="http://purl.org/rss/1.0/modules/syndication/"
  xmlns:co="http://purl.org/rss/1.0/modules/company/"
  xmlns:ti="http://purl.org/rss/1.0/modules/textinput/"
  xmlns="http://purl.org/rss/1.0/"
>
   <channel rdf:about="http://meerkat.oreillynet.com/?_fl=rss1.0">
    <title>Meerkat</title>
    <link>http://meerkat.oreillynet.com</link>
    <description>Meerkat: An Open Wire Service</description>
    <dc:publisher>The O'Reilly Network</dc:publisher>
    <dc:creator>Rael Dornfest (mailto:rael@o...)</dc:creator>
    <dc:rights>Copyright &#169; 2000 O'Reilly &amp; Associates,
    Inc.</dc:rights>    <dc:date>2000-01-01T12:00+00:00</dc:date>
    <sy:updatePeriod>hourly</sy:updatePeriod>
    <sy:updateFrequency>2</sy:updateFrequency>
    <sy:updateBase>2000-01-01T12:00+00:00</sy:updateBase>
    ...

How do you say that's its a RSS document? If we had to use a "rss" prefix
for the document element, that would give:
<?xml version="1.0" encoding="utf-8"?>
 <rss:RDF
  xmlns:rss="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:dc="http://purl.org/dc/elements/1.1/"
  xmlns:sy="http://purl.org/rss/1.0/modules/syndication/"
  xmlns:co="http://purl.org/rss/1.0/modules/company/"
  xmlns:ti="http://purl.org/rss/1.0/modules/textinput/"
  xmlns="http://purl.org/rss/1.0/"
>

That's technically valid, but isn't it most confusing?

Eric
-- 
Freelance consulting and training.
                                            http://dyomedea.com/english/
------------------------------------------------------------------------
Eric van der Vlist       http://xmlfr.org            http://dyomedea.com
(W3C) XML Schema ISBN:0-596-00252-1 http://oreilly.com/catalog/xmlschema
------------------------------------------------------------------------

Disclaimer

These Archives are provided for informational purposes only and have been generated directly from the Altova mailing list archive system and are comprised of the lists set forth on www.altova.com/list/index.html. Therefore, Altova does not warrant or guarantee the accuracy, reliability, completeness, usefulness, non-infringement of intellectual property rights, or quality of any content on the Altova Mailing List Archive(s), regardless of who originates that content. You expressly understand and agree that you bear all risks associated with using or relying on that content. Altova will not be liable or responsible in any way for any content posted including, but not limited to, any errors or omissions in content, or for any losses or damage of any kind incurred as a result of the use of or reliance on any content. This disclaimer and limitation on liability is in addition to the disclaimers and limitations contained in the Website Terms of Use and elsewhere on the site.