[sc34wg3] TM Data Model issue: prop-subj-address-values

Geir Ove Grønmo sc34wg3@isotopicmaps.org
30 Oct 2003 22:54:55 +0100

* Kal Ahmed
| My opinion is that [subject locator] has to be a single resource if the
| concept of a subject-constituting resource is to have any real meaning
| in a topic map.

Here we agree 100%.

| What would it mean for a topic to have two different subject
| constituting resource locators ? If the two locators resolve to
| the same resource representation (e.g. mirror sites), then they are
| *not* the same resource so you have a topic that represents two
| different subjects and that is not allowed. If you want to assert that
| the two resources provide representations of the same subject, then
| you should be using subject indicators.

I agree. It has to be the exact same resource byte-by-byte. 

I think there is a balance here being able, in the topic map data model,
to hold alternative [subject] locators to the same resource without
forcing all topic map processors to enforce the heuristics of
identifying them. Either you have to store the equivalent locators in
the topic map or leave proving-they-are-different-resources to the topic
map processors. This is the essence I think.

| More tricky is the case where two locators return the same resource
| (e.g because of server-side settings that turn
| http://www.techquila.com/ into http://www.techquila.com/index.html),
| but in a heuristic (which is what this is), you have to sometimes
| accept that you need to be inexact to produce something workable.

I _might_ consider http://example.org/, http://example.org/.,
http://example.org/foobar/../, http://example.org/nodes.py?id=root,
http://example.org/index.htm, http://example.org/index.jsp and
http://example.org/index.html all to reference the same resource even
though they are different locators. Not sure, but this issue may boil
down to whether or not the same _resource_ can be referenced by more
than _one_ URI. This depends on our definition of what a _resource_

| If you were to allow multiple subject locators, you would not only
| allow the arguably correct case of two locators which return the same
| resource, but also a whole raft of incorrect cases where the two
| locators return different resources. [subject locator] is the lesser
| of these two evils.

If it is incorrect -- then it is the _authors_ fault. No more no
less. If it is incorrect - that's a human being's fault. Shit in - shit
out etc. That's life.

Why would we not want to trust topic maps authors?

Geir O.