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Re: Question on xml namespace

• To: "XML Developers List" <xml-dev@l...>
• Subject: Re: Question on xml namespace
• From: "G. Ken Holman" <gkholman@C...>
• Date: Tue, 19 Apr 2005 11:02:37 -0400
• In-reply-to: <20050419134908.16240.qmail@m...>
• References: <20050419134908.16240.qmail@m...>

At 2005-04-19 09:48 -0400, Saha Rabindra N wrote:
>  Can somebody tell me the real use of xml namespace in xml domain only.
>I know that xml namespace is useful in xsl.

The use of XML in any XML document is the same use as is used in an XSL 
document: global vocabulary distinction and identification.

>But is there any real use of namespace to represent one xml document.

Because all XML is is a labelled hierarchy of information and nothing more, 
using namespaces provides a rich method of writing the labels.  This method 
distinguishes labels as being from different "owners" and, for each 
"owner", distinguishes labels from each other in a collection of labels.

I put the word owner in quotes because depending on the URI method you use 
for the namespace URI it may actually be owned through public registration 
(such as domain names in a URI) or it may not actually be owned but just 
private use (such as private-use conventions allow in a URN).

>Can somebody provide some example ?

I published a new formatting semantic called the Page Sequence Master 
Interleave (PSMI) and I labelled it as a one-element vocabulary using a URI 
that I "own" as "http://www.CraneSoftwrights.com/resources/psmi".  I also 
published a stylesheet that reads any instance of XSL-FO+PSMI and 
transforms it into a pure XSL-FO instance for use with any XSL-FO engine 
(since the engines don't recognize my label as representing my semantic).

Users add the element from this vocabulary to their XSL-FO whenever they 
want to take advantage of this new formatting concept.  Because the element 
is labeled with a globally-unique label, no other stylesheet could 
mistakenly process the information labelled this way as some other semantic 
(though of course they could deliberately choose to process the information 
labelled this way as some other semantic).

For one of my customers working with a published vocabulary deployed across 
many (many!) installations, each installation can mix into instances of the 
published vocabulary their own labels in their own namespaces that 
represent their own semantic interpretations of the information they label 
that way.  Which is all that I did when I added my own information with my 
own labels to an instance using the standard labels to represent the 
standardized semantics for the labelled information.

I hope this helps.

. . . . . . . . . Ken

--
World-wide on-site corporate, govt. & user group XML/XSL training.
G. Ken Holman                 mailto:gkholman@C...
Crane Softwrights Ltd.          http://www.CraneSoftwrights.com/x/
Box 266, Kars, Ontario CANADA K0A-2E0    +1(613)489-0999 (F:-0995)
Male Breast Cancer Awareness  http://www.CraneSoftwrights.com/x/bc
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• References:
  • Question on xml namespace
    • From: "Saha Rabindra N" <saha.rn@m...>

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