From: jean@cse.ucsc.edu (Jean McKnight)
Newsgroups: comp.doc.techreports
Subject: UCSC TR: WEAK-CONSISTENCY GROUP COMMUNICATION AND MEMBERSHIP
Date: 11 Dec 1992 23:18:28 GMT
Organization: University of California, Santa Cruz (CE/CIS Boards)
NNTP-Posting-Host: oak.ucsc.edu
Originator: golding@oak

          University of California at Santa Cruz
Baskin Center for Computer Engineering and Information Sciences 

The following technical report is available electronically.
Instructions for getting it follow the abstract.

UCSC-CRL-92-52  (ONLY available electronically, as ucsc-crl-92-52.ps.Z)
WEAK-CONSISTENCY GROUP COMMUNICATION AND MEMBERSHIP
Richard Andrew Golding (Ph.D. dissertation)
December 1992

Abstract: Many distributed systems for wide-area networks can be built
conveniently, and operate efficiently and correctly, using a *weak
consistency group communication* mechanism. This mechanism organizes a
set of *principals* into a single logical entity, and provides methods
to multicast messages to the members.  A weak consistency distributed
system allows the principals in the group to differ on the value of
shared state at any given instant, as long as they will eventually
converge to a single, consistent value.  A group containing many
principals and using weak consistency can provide the reliability,
performance, and scalability necessary for wide-area systems.
     I have developed a framework for constructing group communication
systems, for classifying existing distributed system tools, and for
constructing and reasoning about a particular group communication model.
It has four components: message delivery, message ordering, group
membership, and the application.  Each component may have a different
implementation, so that the group mechanism can be tailored to
application requirements.
     The framework supports a new message delivery protocol, called
*timestamped anti-entropy*, which provides reliable, eventual message
delivery; is efficient; and tolerates most transient processor and
network failures.  It can be combined with message ordering
implementations that provide ordering guarantees ranging from
unordered to total, causal delivery.  A new group membership protocol
completes the set, providing temporarily inconsistent membership views
resilient to up to  k  simultaneous principal failures.
     The Refdbms distributed bibliographic database system, which has
been constructed using this framework, is used as an example.  Refdbms
databases can be replicated on many different sites, using the group
communication system described here.
     Keywords:  replicated data, wide-area networks, anti-entropy,
epidemic replication, frameworks.

This technical report is available electronically through either 
of the following methods:
1.  through anonymous ftp from ftp.cse.ucsc.edu, in /pub/tr. Log in 
    as "anonymous", use your email address as your password, specify 
    "binary" before getting the file.  Uncompress before printing.
2.  by mail to automatic mail server rnalib@ftp.cse.ucsc.edu.
    Put this command on the subject line or in the body of the message:
	@@ send ucsc-crl-92-52.ps.Z from tr
    To get the index or abstract list:
	@@ send INDEX from tr
	@@ send ABSTRACTS.1992 from tr
    To get the list of the tr directory:
	@@ list tr
    To get the list of commands and their syntax:
	@@ help commands

Questions:  jean@cse.ucsc.edu

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