Common search and retrieval protocols and formats are desirable for interoperability - consider the problems of maintaining MetaCrawler . It is possible to support a variety of protocols and formats, but only up to a point. Expect some loss of information if deriving everything from one database. Introducing centroids Provide an abstract characterization of the database in a standard format. Can export this to any number of index servers by pushing or pulling.
Index servers act as brokers between client and potentially multiple servers.
Obvious application of this technology would be for subject specific brokers. Conclusions Much interest in centroid approach as a scaleable way of doing whole-Web indexing and searching. No clear winner in the lowest common denominator search and retrieval protocol and data format stakes. More work needed. Fundamentally incompatible with advertising based revenue model.