Actually, it clarifies it in my mind. I think what you described is 
exactly what I was thinking. I like the name catalog as well.

I think that for a database implementation (which the GDM itself is not) 
and also for this xml implementation (although not strictly necessary) I 
will go with that model. In any case, it can be recomposed into the 
original GDM so I'll go that route.


Beau Sharbrough wrote:
> Hans,
> This has been a fruitful discussion, I think. If I could offer a few
> thoughts from a LWG perspective (even though Velke and Anderson know a great
> deal more than I do about it)....
> * The GDM was never mean to be a database design. I know that you've said
> that many times but it bears repeating. In this case it's useful to repeat
> because you are concerned about redundant storage and the LWG was not
> thinking about storage. At the same time, they were thinking about the
> relationships between entities and perhaps this one is one that can be
> decomposed.
> If we oversimplify (because that helps me understand), let's instantiate
> some of these classes.
> Repository - Library.
> Source - Book.
> In theory, if I associate a book with a library I am describing their
> collection. I could associate a lot of sources with a repository, including
> call numbers and their condition, without being involved in a genealogical
> search. I'm not certain, but I think that this association might best be
> referred to as a CATALOG, which is a well-established model for that
> association.
> I think that the LWG may have thought that all linking of sources to
> repositories would take place as the result of a research activity, hence
> the association of activity to this association of sources and repositories.
> On reflection, it seems reasonable to have two separate associations - one
> of SOURCE to REPOSITORY (called CATALOG?), and another of ACTIVITY to
> I don't think that the LWG ever imagined that the Allen County Public
> Library might ever publish an electronic catalog that was compatible with a
> GDM compatible client. Hey, it was 1996.
> Now it doesn't seem so far-fetched that a GDM compatible client could
> contain links to online catalogs - assuming that they aren't being revised
> in ways that break the links.
> Does that complicate the issue sufficiently?
> Beau
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
> Hans Fugal
> Sent: Wednesday, July 10, 2002 11:08 PM
> Subject: Re: [gdmxml] more thoughts on entering a source
> I spent a while wrestling this out with my brother Jacob today. There
> are situations where one would need to know more than just
> repository-id and source-id. For instance, if a particular repository
> had more than one copy of source and you wanted to indicate which one
> you had searched, repository-id and source-id are not sufficient - you
> would also need to know the call-number.  But the call-number itself is
> not unique so can't be used as the primary key in repository-source.
> Using activity-id as the third key doesn't seem to work though, because
> of the extreme redundancy I pointed out. I think repository-source needs
> an id field as a primary key, then search can reference that
> repository-source-id instead of having repository-id and source-id, and
> we take activity-id out of repository-source.
> Jacob also helped me see the light on these associative tables (like
> repository-source and source-group-source). While I understood their
> importance in a database context, I was tempted to collapse them a bit
> in xml context. While that's possible to do while still keeping data
> integrity, it is better to keep it separate.
> As always, I welcome your feedback...
> <hans/>
> * Stan Mitchell [Tue,  9 Jul 2002 at 23:12 -0700]
> <quote>
>>Yes, it does seem that your suggestion reduces redundancy
>>without sacrificing search capability.
>>Hans Fugal wrote:
>>>But then you have to store call-numbers possibly many times. For
>>>example, a professional researcher would doubtless perform many searches
>>>in any particular US Census. For that Census the repository, source, call
>>>number and description would all be the same for every repository-source
>>>record. The only unique information in each record would be the
>>>activity-id. Yet if we take out the activity-id from repository-source
>>>we get rid of that redundancy. AFAICS there is no loss of querying power
>>>when we do so - search has all three keys, so if you want to know which
>>>searches you did on a particular call-number, you only have to query the
>>>search table with the repository-id and source-id.  Or am I still
>>>missing something?
>>gdmxml mailing list
> </quote>
> --
> "Everybody is talking about the weather but nobody does anything about it."
>         -- Mark Twain
> _______________________________________________
> gdmxml mailing list
> _______________________________________________
> gdmxml mailing list

gdmxml mailing list

Reply via email to