[topicmapmail] PSIs - alternatives

[Murray Altheim]

Quoting Alexander Johannesen <alexander.johannesen at gmail.com>:
> On 6/20/06, Steve Pepper <pepper at ontopia.net> wrote:
[...]
>> In fact, I think Simon raises very important points. The PSI
>> mechanism is fundamentally sound but it is not being used as
>> widely as it should, mostly because of the lack of a discovery
>> mechanism.
>
> I remember when I was but a wee lad on this very mailing-list, raising
> the exact issues. :) There were no drive towards centralised resolvers
> then, I haven't seen any drive towards that of late, some think it's
> the wrong idea (centralised anything being bad), while others are
> waiting for someone else to just go ahead and do it.
>
> As to PSI's being sound; well, if it *was* sound, then we would all
> use it. Perhaps it's a marketing problem, though, but to me the notion
> that the PSI itself is really without meaning until you attach some to
> it I think is hard for a lot of people to grok. I only see aggregated
> and federated PSI's as the way to truly solve this (who knows; a
> metamodel of PSI resolving?), but that would be a centralised resolver
> service, and who's willing to host, service and maintain such a thing?
> How do you do this decentralised? SemWeb people tends to solve this by
> ... uh, not solving it, so what are our options?

I don't think use or lack of use of a given technology is really any
statement about its inherent viability, or even about its marketing.
I agree with Steve -- PSIs are fine. I think any lack of visibility
is simply about a lack of visibility:  i.e., publication of PSIs and
about knowledge of publication. For all we know there may be a great
deal more PSI use than we know about, as it may be two-party usage,
or it simply may not be surfacing here.

> ...
>>> And since your PSI doesn't actually have to
>>> point to anything that exsists, it doesn't matter that the PSI as a
>>> URI works, and that means that people not only can but *will* break
>>> them over time.

"Breaking" over time is not necessarily a bad thing. But I'd question
the meaning of "breaking", i.e., the URI is still viable as an identifier
in 1000 years, even if the domain doesn't resolve. The responsibility
for resolution (semantically, not network-wise) is that of the parties
participating in the communication. If their needs are met, outside
users of the products of their communication (i.e., interlopers) may
very well be using that communication outside of the context of its
original intention and hence it could be considered "broken" even if
there is continued network resolution. But these kinds of issues aren't
discernable from the network/computer side of things anyway, so they're
likely out of scope for this discussion. Not that they're unimportant.

>> Actually, to be considered a PSI (i.e., a Published Subject Identifier),
>> according to the OASIS recommendations, a PSI must resolve to a subject
>> indicator. That's the whole point. Why publish an identifier if there's no
>> way for potential users to figure out what it is supposed to identify?
>
> And you have never used a PSI that didn't resolve to something? :) I
> think there is a difference between reality and practice here; we
> would *love* our PSI's to resolve to something we could use straight
> away, but at most you get HTML page with some text on it which isn't
> useful for machine parsing. So whether the PSI is real or imaginary
> doesn't really matter as long as the meaning of it still relies on
> human interaction and for this human to model it in their respective
> topic maps.

I agree. Stating that something *must* resolve to a subject identifier
is fine, but in practice it's simply the usage of the common identifier
between two or more parties that's important. The documentation may be
found online, but where online might not be patently obvious to those
outside of the intended communication. Having no central registry (not
that I believe that is either necessary or possible) simply means that
PSIs are (as any term of art) used within their communities of use.

Tautological, yes.

>> As I said, I think the PSI approach is fundamentally sound and I have been
>> pushing it in the W3C recently, albeit under a name that relates more
>> immediately to what people in the W3C know and understand. [1] The response
>> so far has been very positive and I am hoping to initiate an activity that
>> involves W3C, SC34 and OASIS in the near future.
>
> And this is good progress indeed; glad to hear of it.

Yes, I agree.

One thing I might suggest (and will likely be something I tackle at
some point myself) is to piggyback the publication and availability
of individual PSIs and PSI sets through digital library means, i.e.,
the typical discovery and distribution channels of DL registry
information, such as OAI-PMH. For example, one web service could
query another via OAI-PMH and receive any available PSIs or PSI sets
matching a query. There's a ton of work being done on federated
searching within digital libraries.

If I haven't said it before here explicitly, I believe digital
libraries are going to be the Next Big Thing. They might not end
up being called that, but there's an great deal of both research
and development being done within the library community, and almost
all of the issues being tackled here (such as subject identity,
identification schemes, federation of identity, classification,
classification systems, etc.) and in related areas by the W3C
have been under consideration for many years within the library
community. There's little point in reinventing the wheel here.

----

Just for the record: since I didn't see the original message from
Steve Pepper, portions of which Alexander included previously in
this thread, I'm assuming "[1]" was a reference to Steve Pepper's
paper, so I'm including the information on it here:

    Towards the Semantic Superhighway: A Manifesto for Published
    Subjects, Steve Pepper, Ontopia, 2006.
    http://www.ibiblio.org/hhalpin/irw2006/spepper.html

Murray

...........................................................................
Murray Altheim <murray06 at altheim.com>                              ===  = =
http://www.altheim.com/murray/                                     = =  ===
SGML Grease Monkey, Banjo Player, Wantanabe Zen Monk               = =  = =

       In the evening
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