W3C home > Mailing lists > Public > public-xml-core-wg@w3.org > December 2004

FW: XInclude use case for Device Independence

From: Paul Grosso <pgrosso@arbortext.com>
Date: Wed, 8 Dec 2004 12:39:45 -0500
Message-ID: <F13E1BF26B19BA40AF3C0DE7D4DA0C0301FD1BC3@ati-mail01.arbortext.local>
To: <public-xml-core-wg@w3.org>
Cc: "Rotan Hanrahan" <Rotan.Hanrahan@MobileAware.com>

With permission, I am forwarding this to the XML Core WG
mailing list.  Please include Rotan Hanrahan on the cc line
in any replies.

paul

-----Original Message-----
From: Rotan Hanrahan [mailto:Rotan.Hanrahan@MobileAware.com] 
Sent: Wednesday, 08 December, 2004 4:30
To: Paul Grosso; Norman.Walsh@east.sun.com; ht@w3.org
Subject: XInclude use case for Device Independence

Greetings,

I'm reporting on an idea and a "difficulty" related to XInclude from the
DIWG, and I'm seeking some comments from people more familiar with the
use and direction of XInclude, which I will subsequently report to DIWG.

At a DIWG face-to-face some weeks ago, the possibility of using XInclude
with DISelect [1] was discussed. This presents an interesting use case
whereby DISelect provides a content negotiation function, and XInclude
acquires the content selected via DISelect.

Among the many illustrative cases, we considered the following:

<?xml version='1.0'?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html
 xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"
 xmlns:xi="http://www.w3.org/2001/XInclude">
 xmlns:sel="http://www.w3.org/2004/CSelection">
  <head><title>News</title></head>
  <body>
    <h1>Top Story</h1>
    <sel:select>
      <sel:when sel:expr="dc:cssmq-width('px') &gt; 200">
        <xi:include href="/full_story.xyz?date=EXPRESSION_GOES_HERE"/>
      </sel:when>
      <sel:otherwise>
        <xi:include href="/small_story.xyz?date=EXPRESSION_GOES_HERE"/>
      </sel:otherwise>
    </sel:select>
  </body>
</html>


In this case we used DISelect to choose a suitable version of a news
story. The selection is based on the pixel width of the screen similar
to the approach used in CSS Media Queries. This is a simple template
mechanism. However, the href of the XInclude requires a parameter to be
passed to the process. We have illustrated this as a "date" value
determined by an expression. We have considered the possibility of using
XPath expressions within the href attribute, but currently the XInclude
proposal only supports escaping of characters. It does not support any
form of "evaluation" of the href.

Can you advise on any alternative strategy that might be adopted to
facilitate the passing of evaluated parameters to URLs referenced by
XInclude markup?

One alternative proposed at the meeting was an extension to DISelect
that would mimic (or map to) XInclude but would permit XPath expressions
to create the href attribute value. This would, however, create a new DI
variant of XInclude and we would need to keep the DI version of XInclude
in step with the official version of XInclude. This idea does not
attract much support, so we are seeking advice on how to proceed.

Any advice or guidance you can offer us would be most welcome, and feel
free to share this request with whoever you deem may be best suited to
offer support.

Regards,
---Rotan Hanrahan (DIWG and AC Rep for MobileAware)

[1] http://www.w3.org/TR/cselection/
Received on Wednesday, 8 December 2004 17:40:01 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 21:16:34 UTC