xml-dev - Re: Hierarchical namespaces?

["Frank Boumphrey" <bckman@ix.netcom.com>]

I think that we need to remember that a namespace is just a unique name, it
is not an URI. URI's are used because they happen to be unique names
presumably under the control of the namespace author. There is nothing to
stop me from using 'superfragilisticexpialidocious' as a name space.

thus
xmlns='www.parts.com/computer/memory/sram'

and

xmlns= 'www.nextguy.com/computer-memory-sram'

may be technically the same URI, but they are different namespaces!

Frank

----- Original Message -----
From: Joe Lapp <jlapp@webMethods.com>
To: <xml-dev@ic.ac.uk>
Sent: Wednesday, December 29, 1999 8:44 PM
Subject: Hierarchical namespaces?


> I've been thinking about the utility of naming all elements and most
> attributes using a namespace-URI/local-name pair.  Let's denote such a
> name as (namespace, local-name).  (I say "most" attributes because it
> won't name anything in the per-element-type partition.)  Seems to me
> that filtering operations would commonly extract names belonging to a
> particular namespace, so requests for (namespace, *) might be pretty
> common.  Let's look at this more closely...
>
> Suppose I'm defining elements that describe electronics parts.  I'm
> going to want to organize them hierarchically.  For example:
>
>   www.parts.com/computer/memory/sram
>   www.parts.com/computer/memory/dram
>   www.parts.com/computer/cpus/intel
>   www.parts.com/computer/cpus/amd
>   www.parts.com/stereo/speaker/surround
>   www.parts.com/stereo/speaker/subwoofer
>
> etc.
>
> It may make sense for one application to examine all computer parts,
> another to examine all computer memory parts, and so on.  If I want all
> memory parts I have to know all the pertinent namespace URIs.  If I
> know that the URIs are structured hierarchically, I could do a wildcard
> search on the URI itself -- assuming I had a tool that let me do so (do
> any yet?).
>
> But because URIs allow this, the next guy organizes his namespaces
> differently:
>
>   www.nextguy.com/computer-memory-sram
>   www.nextguy.com/computer-memory-dram
>   www.nextguy.com/computer-cpus-intel
>   www.nextguy.com/computer-cpus-amd
>   www.nextguy.com/stereo-speaker-surround
>   www.nextguy.com/stereo-speaker-subwoofer
>
> And the next next guy does so as follows:
>
>   www.nextnextguy.com/computer?memory=true+type=sram
>   www.nextnextguy.com/computer?memory=true+type=dram
>   www.nextnextguy.com/computer?cputype=intel
>   www.nextnextguy.com/computer?cputype=amd
>   www.nextnextguy.com/stereo/speaker?surround
>   www.nextnextguy.com/stereo/speaker?subwoofer
>
> To make namespace filtering work for the general case requires
> regex-like matching capabilities.  And regex matching isn't very easy
> to optimize for performance (such as via indexing).  It also isn't the
> kind of thing we want the average XML user to have to learn -- seems to
> me that it would have to bubble up to the user interface, at least on
> generic XML tools.
>
> So I'm thinking that we need a *standard* way to organize namespaces
> hierarchically, and that we need one before namespace usage is so
> widespread that we absolutely have to provide regex support.
>
> But maybe I'm jumping the gun.  I haven't yet heard anyone scream out
> in pain, though I'm not sure we should be waiting for pain to come.
>
> --
> Joe Lapp              (Looking for some good people to help design
> Principal Architect    and build the Internet's business-to-business
> webMethods, Inc.       XML infrastructure.  We are 100% Java.)
> jlapp@webMethods.com           http://www.webMethods.com
>
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