I'm pretty sure any typical Fidonet BBS system did this sort of thing back in the 1980s. They used a Nodelist which categorized other Fideonet nodes geographically and including a topical index of store-and-forward discussion areas called Echoes. There was definitely "a plurality of computers" on Fidonet. The echo tossers and netmail handlers could be considered as agents handling "search requests" from other systems. The nodelist was divided into zones which represented major geographical areas and some file and message transfer functions limited searches to a single zone ("elect one of said hierarchy of geographical areas") before providing results. It's been years since I used Fidonet but I think you could argue that it embodied many of the principles described in this patent. You might find similar functionality in Usenet systems back in UUCP days too.