>>>> [log in to unmask] 14-05-02 17:05 >>>
>Another example of the same term being completely different in two domains
>is 'subject'. What is the subject of this email? It's "Re: Betr. Ralph's
>Premises". If this were a book, then it might be "Information Retrieval
>Protocols -- SRW"
You asked me "What is the subject of this email?" and not "What is the dc.subject of this email?" or
"What is the bath.subject of this email?" If you did, I had to ignore the prefix, because I have no way to establish whether the subject is a dc.subject or a bath.subject.
On Tue, 14 May 2002, LeVan,Ralph wrote:
> > -----Original Message-----
> > From: Theo van Veen [mailto:[log in to unmask]]
> > Sent: Tuesday, May 14, 2002 10:13 AM
> > I do NOT support these 2 premises.
> > In relation with prefixes like "dc" and "bath" Explain can
> > provide information on index sets but it should not be a
> > prerequisite for doing a search. Explain should only explain
> > that for example searching for "title" in CQL actually means
> > searching for "dc.title" or "batch.title". I would suggest to
> > use Explain to PREVENT the need for prefixes in CQL. In that
> > case one can always do a distributed search for "title" and
> > only those folks, who want to distinct between "dc.title" and
> > "bath.title", ask (before or after) for Explain to see which
> > "kind of title" is being used by a specific server.
> So, if I support both dc.title and bath.title and you send me unqualified
> title, what do you expect me to do? It just so happens that I specified in
> my explain record that the default index set was bath, but what if you were
> expecting it to be dc? Or worse yet, what if my default index set was ach
> (American College of Heraldry) and you were inadvertently searching
> heraldric titles which would be equivalent to dc names?
> Broadcast unqualified searches are doomed to failure. We can probably come
> to a gentlemens agreement that we'll support the dc index set when it is
> defined, so dc.title searches have a better chance of succeeding, but there
> are no guarantees.
> > Can anyone explain to me the added value of distinction
> > between dc.title and bath.title in CQL.
> Because those indexes map to completely different combinations of z39.50
> attributes. They are different things. They will have different searching
> > I understand that due
> > to the abstraction in Z39.50 you need to know the
> > attributeset to know what an attribute means. But in CQL you
> > do not need this because of the use of indexes with
> > user-understandable name and so there is also no need to know
> > a prefix. The prefix does not modify the meaning of an index
> > name (I hope) and does not add any information that is
> > meaningfull to the user or the server.
> Sorry, but that's just plain wrong. Bath titles and DC titles will be
> different. You will see the difference in the attributes that they map to.
> The prefix will be critical in distinguishing between them.
> > The disadvantage of using prefixes in CQL is that it is not
> > possible to do a search in previously unknown databases with
> > usual indexes like title, author and subject. This prevents
> > the concept of "EasyLink" (links, being automatically
> > generated SRU-queries). I can now use a few lines of code to
> > translate OpenURL's to SRU-queries. With previously unknown
> > prefixes this becomes very hard.
> Stick a dc prefix on them and maybe they'll work.
,'/:. Rob Sanderson ([log in to unmask])
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