$Id: multidb,v 1.1 2006-01-17 11:10:30 mike Exp $


YP2 Virtual Databases and Multicast Searching
=============================================

Two of YP2's filters are concerned with multiple-database operations.
Of these, "virt_db" can work alone to control the routing of searches
to one of a number of servers, while "multi" can work with the output
of "virt_db" to perform multicast searching, merging the results into
a unified result-set.  The interaction between these two filters is
necessarily complex, reflecting the real complexity of multicast
searching in a protocol such as Z39.50 that separates initialisation
from searching, with the database to search known only during the
latter operation.

### Much, much more to say!