[sc34wg3] Re: Public Interest and ISO WAS: [topicmapmail] <mergeMap> questions

Murray Altheim sc34wg3@isotopicmaps.org
Thu, 18 Oct 2001 11:48:26 -0700

"Steven R. Newcomb" wrote:
> Lars Marius indicated that backward compatibility
> with existing implementations was a good reason not to
> adopt the idea of multiple scopes on associations, in
> the standard model.
> I take extremely serious exception to his remark on two
> levels.
> Level 1: The question of whether multiple scopes on
> associations should be supported is not an issue of
> backward compatibility, because:
>   * There is no stated policy in the standard about
>     what to do about equivalent assertions, so there's
>     no previous provision of the standard to be
>     compatible or incompatible with.
>   * Existing topic maps don't have multiple scopes, but
>     again, *allowing* future topic maps to have
>     assertions that have multiple scopes is not the
>     same thing as *requiring* it.  Existing topic maps
>     would not be invalidated by relaxing the constraint
>     that an association must have exactly one scope.
>     By definition, backward compatibility is *always*
>     maintained when constraints are *relaxed*.
>     Backward compatibility problems only occur when new
>     constraints are *added*.  Remember: the ISO 13250
>     standard is a standard for interchangeable topic
>     maps, and what they mean.  Strictly speaking,
>     "backward compatibility" for ISO 13250 has to do
>     with *existing topic maps*, not with *existing
>     implementations.* (Of course, existing
>     implementations are important, too, because it's in
>     the public interest that the public be able to
>     continue to use them.  It's always a balancing act.
>     But if they're broken in a way that causes them,
>     under certain cirumstances, to handle topic maps
>     information unreliably, ambiguously, or
>     inaccurately, it hardly seems fair to the public to
>     encourage the idea that they don't need to be
>     fixed.)

I was not involved in the development of the ISO 13250 standard. You
and Michel encouraged me to take part in a process by which a different
"standard" was developed, namely XML Topic Maps 1.0. I note with no 
irony whatsoever that you fail to mention XTM *once* in describing 
issues surrounding backward compatibility, which I'm certain would be
more in keeping with Lars Marius' remarks. Most of those I know 
developing topic map applications are doing so with XTM in mind, not
ISO 13250. As you know, the reason for XTM's existence was to enable
wider adoption of topic maps than would ever have occurred with 13250.

Your continuing disparagement of XTM as "broken" certainly doesn't 
encourage its widespread adoption, and is likely leading some to 
avoid bothering with it at all. If XTM fails, topic maps will fail.
I note that ISO 13250 is also known to have its own set of problems.
The differences between the December XTM draft that you heartily 
endorsed and the current XTM 1.0 specification are IMO minor. The 
additions you made to the psi1.xtm topic map (such as "role-template"
or "atrole-rpc-template-role-rpc") that were removed in core.xtm 
were because they didn't agree with what the Authoring Group had 
decided (as far back as Swindon [1]) was the scope of activity for
XTM, version 1.0: i.e., we weren't going to support templates. We 
didn't. I note that on your topicmaps.net web site you continue to 
reference psi1.xtm rather than core.xtm. The only essential 
difference between those two topic maps is support for templates.

Apart from this, I don't see that XTM 1.0 is remarkably *different*
from the child you once knew and loved. You seem to either no longer
recognize that child or have grown to dislike it. I don't understand,
and I don't see this as benefitting our community (which is as close
to the "public interest" as I'm willing to go).


[1] Swindon minutes: "Public Subjects To Be Defined in the XTM Spec"
Murray Altheim                         <mailto:murray.altheim&#x40;sun.com>
XML Technology Center, Java and XML Software
Sun Microsystems, Inc., MS MPK17-102, 1601 Willow Rd., Menlo Park, CA 94025

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