> Date: Fri, 4 Jun 2004 09:33:17 +0200
> From: Marc Cromme <[log in to unmask]>
>
> What is really needed for federated search and merging of hit sets is:
>
> 1) an by the appropriate relevance ranking algorithm ordered response
> set from any of the SRW servers - that's what you are adressing

Yes.

> 2) an indication of the actual relevance value of every record in
> the hit set (this needs a new SOAP tag in SRW)

No SRW changes are needed for this: there are already two mechanisms
for including this information.  One is just to add it to the returned
record, so instead of a DC record you get a DC-with-relevance-score
record.  The other, which was invented specifically for this kind of
thing, is an extraRecordData packet (which would need to be requested
with an extraRequestData packet in the search request.)

> 3) an indication of the possible range of relevance values for each
> server implementation - I can not meaningful merge ranked hit sets
> of two servers if the one assigns ranking values [0, 10.000] and the
> other [-inf, +inf]. So the servers have to tell me in what range
> relevance values will be.

This is best transferred as an extraResponseData packet.

> Obivously, ther must ne made place for 2) and 3) in the  SRW
> protocol.

Already done :-)

 _/|_    _______________________________________________________________
/o ) \/  Mike Taylor  <[log in to unmask]>  http://www.miketaylor.org.uk
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