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USE OF ABSTRACT OBJECTS AND CONCRETE INSTANCES TO DEAL WITH PROBLEMS OF SYNCHRONIZATION AND REPLICATION

IP.com Disclosure Number: IPCOM000027734D
Original Publication Date: 1999-Apr-30
Included in the Prior Art Database: 2004-Apr-09

Publishing Venue

Xerox Disclosure Journal

Abstract

A new architecture is proposed for synchronizing multiple replicated copies of information. This problem is acute when reliable, instantaneous communication among sites cannot be guaranteed (as in cases of mobile computing and distributed data bases).

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XEROX DISCLOSURE JOURNAL

USE OF ABSTRACT OBJECTS AND CONCRETE INSTANCES TO DEAL WITH PROBLEMS OF SYNCHRONIZATION AND REPLICATION
Brian C. Smith
Paul Dourish
Annette M. Adler

Proposed Classification
U. S. C1. 395/619 Int. C1. G06f OO/OO

Summary

A new architecture is proposed for synchronizing multiple replicated copies of information. This problem is acute when reliable, instantaneous communication among sites cannot be guaranteed (as in cases of mobile computing and distributed data bases).

Traditional approaches treat the problem as one of synchronizing a set of approximately identical entities. In contrast, the proposed architecture defines all the (multiple) concrete copies as instances of a single governing "abstract" object, one that exists at no specific site. The model of this architecture has two prime benefits. First, it facilitates the solution of problems of failure, divergence, and context-dependence. Second, because it is based on the user's model of what they are trying to do (i.e., the user's model of their work) rather than the designer's model of the enabling technology, it radically increases system comprehensibility and hence utility.

Background

In an increasingly decentralized world of distributed networks, client-server architectures, mobile computing, telecommuting, and the like, end-users and managers confront (well recognized) problems of synchronizing multiple replicated copies of information: data bases, software repositories, shared mailboxes, etc. The problem is particularly acute when reliable, instantaneous communication among sites cannot always be guaranteed (such as in cases of distributed data bases and mobile computing). The possibility of "disconnection" among copies in such situations, opens up the possibility that different copies will be changed incompatibly, leading to irresolvable conflicts among different copies.

XEROX DISCLOSURE JOURNAL - Vol. 24, No. 2 MarcWApril 1999 49

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USE OF ABSTRACT OBJECTS AND CONCRETE INSTANCES TO DEAL WITH PROBLEMS OF SYNCHRONIZATION AND REPLICATION (Cont'd)

Such synchronization problems arise in many settings, ranging from relatively simple
(e.g., a single user trying to work both home and at the office) to quite complex (e.g., multiple users on distributed sites working on a single document or software project).

Problem

Traditional approaches treat the synchronization problem as one of copying back-and- forth approximately identical "replicated" entities, of which one or more are taken to be (possibly duplicates) of "the real thing."

Although this model often works in simple cases, it provides no help with a number of issues that come up in the following complex settings:

a. What to do when different concrete instances are both changed, possibly incompatibly (e.g., much commercial replication software, such as that built into Lotus Notes@, simply prohibits such cases from arising, by dubbing o...