> -----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.