Prefetching and caching documents according to probability ranked need S list

[54] PREFETCHING AND CACHING DOCUMENTS ACCORDING TO PROBABILITY RANKED NEED S LIST

[75] Inventors: Peter L. Pirolli, San Francisco; James E. Pitkow, Palo Alto, both ol Calil.

[73] Assignee: Xerox Corporation, Stamford, Conn.

[21] Appl. No.: 09/083,645 [22] Filed: May 22, 1998

[51] Int. CI.7 G06F 17/30

[52] U.S. CI 707/2; 707/5

[58] Field of Search 707/2, 5, 10

[56] References Cited

U.S. PATENT DOCUMENTS

5,442,778 8/1995 Pedersen et al 707/5

5.864,340 1/1999 Bertram et al 345/352

5,991,755 11/1999 Noguchi et al 707/3

6,009,452 12/1999 Horvitz 709/102

OTHER PUBLICATIONS

Anderson, John R. and Lael J. Schooler. "Reflections ol the Environment in Memory," Psychological Science, vol. 2, No. 6, pp. 396-408, Nov., 1991.

Blue Squirrel. "WebWhacker 3.0 Relerence Guide" from URL "http://www.bluesquirrel.com/whacker/." ForeFront Inc., 1995-1996. See in particular pp. 2-2-2-5, 4-2-4-17, 4-29-4-32.

Burell, Quentin, "A Simple Stochastic Model for Library Loans," Journal ol Documentation, vol. 36, No. 2, pp. 115-132, Jun. 1980.

Cao, Pei et al. "Implementation and Performance ol Integrated Application-Controlled File Caching, Preletching, and Disk Scheduling," ACM Transactions on Computer Systems, vol. 14, No. 4, Nov. 1996, pp. 311-343. Pirolli, Peter and Stuart Cad. "The Evolutionary Ecology ol Information Foraging," Palo Alto Research Center Technical Report UIR-R97-01, Palo Alto, CA, 1997.

Pitkow, James E. "Characterizing World Wide Web Ecolo-
gies," Palo Alto Research Center Technical Report
UIR-R97-02, Palo Alto, CA, Jun. 1997.
Schooler, Lael J. and John R. Anderson. "The Role of
Process in the Rational Analysis of Memory," Cognitive
Psychology, vol. 32, No. 3, pp. 219-250, Apr., 1997.
Schiietze, Hinrich. "Dimensions of Meaning," Proceedings
of Supercomputing '92, pp. 787-796, Minneapolis, MN.
U.S. Patent Application No. 08/831,807 entitled "System for
Predicting Documents Relevant to Focus Documents by
Spreading Activation through Network Representations of a
Linked Collection of Documents"to Peter L. Pirolli et al.,
filed April 9, 1997.

U.S. Patent Application No. 09/044,693 entitled "Method and Apparatus for Clustering a Collection of Linked Documents Using Co-Citation Analysis" to James E. Pitkow et al, filed Mar. 18, 1998.

U.S. Patent Application No. 09/053,616 entitled "Method and Apparatus for Pedicting Document Access in a Collection of Linked Documents" to Bernardo A. Huberman et al., filed Apr. 1, 1998.

Primary Examiner—David L. Robertson [57] ABSTRACT

A method is presented for determining whether to prefetch and cache documents on a computer. In one embodiment, documents are prefetched and cached on a client computer from servers located on the Internet in accordance with their computed need probability. Those document with a higher need probability are prefetched and cached before documents with lower need probabilities. The need probability for a document is computed using both a document context factor and a document history factor. The context factor of the need probability of a document is determined by computing the correlation between words in the document and a context Q of the operating environment. The history factor of the need probability of a document is determined by integrating both the recency of document use and the frequency of document use.

20 Claims, 8 Drawing Sheets