xml-dev - Re: xml search engine?

[Dongwook Shin <dwshin@nlm.nih.gov>]

Kay:

As far as I know, there is no clear difference between
the notion of "query engine" and "search engine".

In my understanding, "the query engine" is a broad concept
meaning any procedure that returns "something" against "queries".
On the other hand, search engine is a rather specific
terminology that means any procedure that searches document
space (including WWW) against queries.

There is another concept often called "inference engine" that is
able to infer some conclusion from logical statements.
The inference engine is characterized by that it can deduce
something that is not given in the original statement.

The search engine you mention belongs to "inference engine",
in general sense.

The real issue about the XML search engine that can work across
multiple DTDs is how we can associate "a name" in a DTD with
"another
name" in another DTD. Unfortunately, I cannot find any formal
background to allow this, except the notion of vocabulary matching.
Even in vocabulary matching (or transformation), we need some
mapping in advace, which can not be obtained automatically.
If we can get some mapping, it could be by heuristics, I believe.

Dongwook


Kay Michael wrote:

    > There have been XML search engines back as far as 1991 or
    thereabouts,
    > then operating of course under the rubric of SGML search
    > engines.  ...
    > So there is a considerable body of experience as to what such
    > an API might
    > be like.  For some reason, little of it is reflected in
    > XPath.  W3C held
    > a workshop on the notion of a query language for XML back in
    1998...

    I really think you need to distinguish between a query engine and a
    search
    engine. Query engines answer questions like "find me all documents
    that have
    an <xyz> element as the third grandchild of an <abc> element".
    Search
    engines answer questions like "have you got anything about the
    causes of
    hyperinflation in inter-war Germany?"

    Search engines will use markup tags and namespaces as hints to
    assess the
    relevance of the document to the user's line of enquiry, just as
    they use
    the text. That's quite different from query, which is looking for
    definite
    matches to definite boolean conditions.

    Mike Kay

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--
Dongwook Shin
Visiting Scholar
Lister Hill National Center for Biomedical Communications
National Library of Medicine,
8600 Rockville Pike Bethesda 20894, MD
E-mail: dwshin@nlm.nih.gov
Tel: (301) 435-3257
FAX: (301) 480-3035
URL: http://dlb2.nlm.nih.gov/~dwshin



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