Mark A. Sheldon
MIT, PhD Thesis, 1995

This thesis presents a new architecture for information discovery based on a hierarchy of content routers that provide both browsing and search services to end users. Content routers catalog information servers, which may in turn be other content routers. The resulting hierarchy of content routers and leaf servers provides a rich set of services to end users for locating information, including query refinement and query routing. Query refinement helps a user improve a query fragment to describe the user's interests more precisely. Once a query has been refined and describes a manageable result set, query routing automatically forwards the query to relevant servers. These services make use of succinct descriptions of server contents called content labels. A unique contribution of this research is the demonstration of a scalable discovery architecture based on a hierarchical approach to routing.

Results from four prototype content routing systems, based on both file system (NFS) and information system (HTTP) protocols, illustrate the practicality and utility of the content routing architecture. The experimental systems built using these prototypes provide access to local databases and file systems as well as over 500 Internet WAIS servers.

Experimental work shows that system supported query refinement services provide users with an essential tool to manage the large number of matches that naive queries routinely generate in a large information system. Experience with the prototype systems suggests that the content routing architecture may scale to very large networks.

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