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Re: XLink embedding (was Re: W3C XML Schema best practice: inclusions)

• From: uche.ogbuji@f...
• To: martind@n...
• Date: Wed, 13 Dec 2000 08:58:04 -0700 (MST)

> In fact, links and inclusion are strange beast. We have  experimented a
lot
> with the Xinclude and the xlink constructs and found certain limitations
> like:
>
> caching: it is very rare that document providers set the caching
property in
> the right manner. It is a lot useful to be able to override a cache
> document's time to live.

Eh what?  I don't think it's a good idea to override the server's
specified
TTL.  If the provider doesn't know how to use HTTP, it's a problem you
should
take up with them.  Any service provider that set their TTL to 0 in a
misguided attemp to improve hit count, or any other such trickery would
probably eventually get yelled at by users.

Even if this is something you _absolutely_ have to have this override in
the
consumer, I think that is a highly application-specific matter that should
not
be addressed by the XInclude or XLink.

> styling: If a document contains more than one fragment to include, to be
> able to process each fragment before any inclusion can accelerate the
> overall processing if we can perform the transformations and the
inclusions
> in parallel.

Is this realistic to expect?  It's certainly hard to imagine this scenario
with XSLT stylesheets, since XSLT processing tends to be highy non-linear.
It's certainly possible with CSS, but are the saving worth the processing
complexity in the user agent?

> device-profiling: to be able to include XML fragments for certain kind
of
> devices but not for others - kind of conditional inclusion

Sounds as if this could be at least partly handled by content-negotiation
at  the transport layer.  Maybe it would be nice to have an extension
mechanism  for transport-level parameters in inclusions and linking.  Then
my implementation could extend the spec to support a set of http-header
attributes in the origin element that are tacked on the the HTTP request
headers.


-- 
Uche Ogbuji                               Principal Consultant
uche.ogbuji@f...               +1 303 583 9900 x 101
Fourthought, Inc.                         http://Fourthought.com
4735 East Walnut St, Ste. C, Boulder, CO 80301-2537, USA
Software-engineering, knowledge-management, XML, CORBA, Linux, Python

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