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Re: [Simple] Some thoughts on XCAP's resource architecture

From: Joel M. Halpern <joel@stevecrocker.com>
Date: Wed, 24 Nov 2004 14:58:40 +0000
Message-Id: <>
To: HTTP working group <ietf-http-wg@w3.org>, "simple@ietf.org" <simple@ietf.org>

I am not sure I follow the question here.  Apologies if I am missing the 
point in attempting to answer.

Whether the underlying data is stored in an XML document, an XML document 
plus indexing and related structures, a database, or something else 
entirely is a local implementation choice.  I expect it to be influenced by 
the amount of related data to be handled, and by other product 
issues.  (Similarly, with a web server, the question of whether resources 
are stored as HTML, stored as HTML fragments which are dynmically combined, 
fully dynamically generated, or some other mechanism is a local application 
dependent choice.)

As for extension, it depends upon the problem.  For what we are doing, 
extensions will occur only when the underlying system has new 
capabilities.  And we will then extend the XML Schema.  For some uses, 
being able to store uninterpretted but validated parts of the XML is 
important.  In those cases, the schema provides for extension, and the XCAP 
server ought to be built so it can handle the data.
Adding new features is going to mean adding capabilities to the parts that 
work with the server.  Whether that requires updating the "database" 
probably depends upon the exact underlying implementation.  The degree of 
change required has almost nothing to do with whether XCAP is used to 
communicate the configuration of the new features.


At 09:07 PM 11/23/2004, Cullen Jennings wrote:
> > 2)  Dependencies:  HTTP servers are designed such that static resources
> > are handled independently of each other. Their ETag management is
> > stand-alone, the request and response handling and concurrency are
> > designed for that independence.  By contrast, XCAP contemplates a large
> > number of resources which really map to parts of the same underlying
> > file.  As far as I can tell, that introduces dependencies between
> > resources (for example that a PUT to one URL would require the ETag of
> > another URL to change).
>In thinking about implementing something, it seems that XCAP would more or
>less require me to use a database not a file to manage this stuff. Perhaps
>someone like Joel or the Nokia folks who has actually implemented stuff can
>straighten me out. As the XCAP schemas get extended do I need to extend my
>DB schemas at the same time? Do I also need to extend server code to compute
>new things.
Received on Wednesday, 24 November 2004 15:17:10 UTC

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