I thought the requirement was to send the *same* query to multiple databases
(at the same server). Sending *different* queries would be complex, but I
don't understand that to be a firm requirement. Is is?

And if not, wouldn't sending the *same* query be significantly simpler --
all we need to do is allow specification of multiple destinations (and there
are a number of ways to do that).

And on the response: is it necessary to bundle responses together or is
multiple responses ok?

--Ray

----- Original Message -----
From: "Sebastian Hammer" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, September 17, 2003 1:46 PM
Subject: Agenda Item: Metasearching - Multi-database search


> Hi All,
>
> Ray asked Brad Buckley of Gale to provide his input on Metasearch-specific
> requirements. His response to Ray echoes discussion from the Metasearch
> workshop in Denver earlier this year and I think it's a good point to
raise.
>
> Content-providers like Gale, who hosts large numbers of databases, are
> faced with a peculiar challenge from metasearch engines. Specifically it
> involves metasearchers automatically launching parallel searches against
> several Gale-owned databases at once. This is perceived as a useful
service
> by the developers and operators of metasearch engines, but it creates
> issues related to performance for the operator of the databases. Picture a
> situation where a single user fires off a search in a metasearch portal
> which is automatically turned into 10, 20, or 100 parallel search
> operations against the server.. imagine this kind of activity from a
> popular metasearch portal, and things might start to get pretty hot in the
> server pit at Gale (for example).
>
> In a nutshell, the proposal is for a mechanism that allows a metasearch
> engine to 'bundle' these searches into a single request, and similarly to
> allow the server to bundle the responses into a single package.
>
> We're talking about something that goes beyond mere multi-database
> searching in the original Z39.50 sense of the word.. we need individual
> hit-counts (and result sets) back from the server, and we will probably in
> some cases wish to send different query expressions to different
> databases... it comes much more close to the idea of a compound PDU model
> which was discussed for Z39.50 a while back. A way to implement this would
> be to introduce a "wrapper" element to allow multiple SRW requests to go
in
> the same SOAP package. Another benefit for the content provider would be
> the ability to manage resources by refusing individual component requests
> (eg. during peak loads) without having to fail all requests. Presumably
> this would allow greater "fairness" in managing scant resources.
>
> I am personally ambivalent about this, and even as a metasearch engine
> developer, I feel that there are some thorny issues here. But this is an
> attempt to honestly represent a requirement that was put on the table by
> representatives of the content providers in Denver.
>
> --Sebastian
> --
> Sebastian Hammer, Index Data <http://www.indexdata.dk/>
> Ph: +45 3341 0100, Fax: +45 3341 0101