Roy J Levin

7849354, Dec 7, 2010

Jun 12, 2007

11/811780

Vijayan Prabhakaran - Sunnyvale CA, US
Venugopalan Ramasubramanian - Mountain View CA, US
Lidong Zhou - Sunnyvale CA, US
Roy Levin - Palo Alto CA, US
Chandramohan A. Thekkath - Palo Alto CA, US

Microsoft Corporation - Redmond WA

G06F 11/00

714 6, 714 15, 707695, 717170

Multiple versions of data on different sets of machines allow a system to degrade gracefully even when experiencing excessive failures. When excessive failures cause the latest versions to be unavailable, the system becomes degraded, but still offers an old version if available. A most recent coherent set of the available older versions is found and provided. The degree of degradation increases gradually as the system experiences more and more failures. Graceful degradation is desirably complementary to fault tolerance.

59406194, Aug 17, 1999

Oct 25, 1996

8/738150

Martin Abadi - Palo Alto CA
James J. Horning - Palo Alto CA
Butler W. Lampson - Cambridge MA
Roy Levin - Palo Alto CA
Jean-Jacques Levy - Paris, FR
Yuan Yu - Santa Clara CA

Digital Equipment Corporation - Maynard MA

G06F 945

395705

In a computerized method, a computer program is analyzed while the program is interpreted. The program is expressed in a first memory as input values and functions. Some of the input values are complex values which can have a plurality of component values. Each function operates on combinations of the input values and the functions of the program. The program is interpreted in a processor connected to the first memory. The processor is also connected to a second memory to store result values produced during the interpretation. Selected input values, components of the complex values, and functions are named only if the selected values, components, and functions are necessary to produce a selected result value. For each function of the program, the function which is interpreted, the input values on which the function depends, and the result value produced by the function during interpretation, are recorded in the second memory to dynamically perform a precise dependency analysis of the program.

57489610, May 5, 1998

Aug 30, 1996

8/706382

Christine Beth Hanna - Woodside CA
Roy Levin - Palo Alto CA

Digital Equipment Corporation - Maynard MA

G06F 1730

395701

A software system is defined by a tree of system models which are written in a functional language. During a build of the software system, the functions are interpreted and the results of the expensive expressions are cached. Each function is examined before interpretation to see if it has been evaluated before. If a function has already been evaluated, the cached result is retrieved by the evaluator and the time which would have been spent re-evaluating the function is saved.

55008810, Mar 19, 1996

Jul 12, 1993

8/090844

Roy Levin - Palo Alto CA
Christine B. Hanna - Woodside CA

Digital Equipment Corporation - Maynard MA

G06F 944

395700

The problems of efficiently building a large software system are solved by the present invention of language scoping for effective configuration descriptions. A software system is defined by a tree of system models which are written in a functional language. The functional language provides a unique combination of static and dynamic scoping. This combination is required to write modular, flexible, and concise, yet complete, configuration descriptions.