Accession Number : ADA186967

Title :   Replication and Reconfiguration in a Distributed Mail Repository.

Descriptive Note : Technical rept.,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR COMPUTER SCIENCE

Personal Author(s) : Day, Mark S

PDF Url : ADA186967

Report Date : Apr 1987

Pagination or Media Count : 116

Abstract : Conventional approaches to programming produce centralized programs that run on a single computer. However, an unconventional approach can take advantage of low-cost communication and small, inexpensive computers. A distributed program provides service through programs executing at several nodes of a distributed system. Distributed programs can offer two important advantages over centralized programs: high availability and scalability. In a highly-available system, it is very likely that a randomly-chosen transaction will complete successfully. A scalable system's capacity can be increased or decreased to match changes in the demands placed on the system. When a node unavailable because of maintenance or a crash, transactions may fail unless copies of the node's information are stored at other nodes. Thus, high availability requires replication of data. Both the maintenance of a highly-available system and scalability require the ability to modify and extend a system while it is running, called dynamic reconfiguration or simply reconfiguration. This thesis considers the problem of building scalable and highly-available distributed programs without using special processors with redundant hardware and software. It describes a design and implementation of an example distributed program, an electronic mail repository. The thesis focuses on how to design and implement replication and reconfiguration for the distributed mail repository, considering these questions in the context of the programming language Argus, which was designed to support distributed programming.

Descriptors :   *COMMUNICATION AND RADIO SYSTEMS, *COMPUTER PROGRAMS, *COMPUTERS, *DISTRIBUTION, CENTRALIZED, COMPUTER PROGRAMMING, LOGISTICS SUPPORT, LOW COSTS, NODES, REDUNDANCY

Subject Categories : Non-radio Communications
      Computer Programming and Software
      Computer Hardware

Distribution Statement : APPROVED FOR PUBLIC RELEASE