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[ejw@cse.ucsc.edu: FW: Rohit Khare CS seminar Fri Oct 24]

From: Mark Baker <distobj@acm.org>
Date: Fri, 17 Oct 2003 16:11:30 -0400
To: www-ws-arch@w3.org
Message-ID: <20031017161130.A921@www.markbaker.ca>


----- Forwarded message from Jim Whitehead <ejw@cse.ucsc.edu> -----

From: "Jim Whitehead" <ejw@cse.ucsc.edu>
To: "FoRK" <FoRK@xent.com>
Subject: FW: Rohit Khare CS seminar Fri Oct 24
Date: Fri, 17 Oct 2003 12:51:06 -0700
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Bay Area FoRKs might be interested.

- Jim

-----Original Message-----
From: Ma Xiong [mailto:maxiong@soe.ucsc.edu]
Sent: Friday, October 17, 2003 12:32 PM
To: soe-seminars@soe.ucsc.edu
Subject: Rohit Khare CS seminar Fri Oct 24

"Extending the REpresentational State Transfer (REST) Architectural
Style for Decentralized Systems"

Rohit Khare
Univ. of California, Irvine

Friday, October 24, 2003
Baskin Engineering #330
2:00pm - 3:30pm

Because it takes time and trust to establish agreement, traditional
consensus-based architectural styles cannot safely accommodate
resources that change faster than it takes to transmit notification of
that change, nor resources that must be shared across independent
agencies. There are physical and logical limits that make simultaneous
agreement (a strong form of consensus for read/write variables)
expensive and ultimately, impossible. In practice, software architects
resolve this contradiction by assuming that network latency is
negligible and that computers operated by independent agencies are
reliable - two increasingly shaky assumptions about integrating
services across the Internet.

Our approach to this challenge is architectural: proposing constraints
on the configuration of components and connectors that induce desired
properties of the whole application. Specifically, we present,
variations of the World Wide Web's REpresentational State Transfer
(REST) architectural style that are optimized for centralized,
distributed, estimated, and decentralized systems.

For centralized resources, we enforce simultaneous agreement by
extending REST into an event-based architectural style by adding
Asynchronous event notification and Routing through active proxies
(ARREST). For distributed control of shared resources, we enforce ACID
transactions by further extending REST with end-to-end Decision
functions that enable each component to serialize all updates

The alternative to simultaneous agreement is decentralization:
permitting independent agents to make their own decisions. This
requires accommodating four intrinsic sources of uncertainty that arise
when communicating with remote agencies: loss, congestion, delay, and
disagreement. Their corresponding constraints are Best-effort data
transfer, Efficient summarization of data to be sent, Approximate
estimates of current values from data already received, and
Self-centered trust management.

These so-called 'BASE' properties can be enforced by replacing
references to shared resources with end-to-end Estimator functions.
Such extensions to REST can increase precision of measurements of a
single remote resource (ARREST+E); as well as increase accuracy by
assessing the opinions of several different agencies (ARRESTED).
The contributions of this work include: a formal definition of
decentralization; an analysis of the limitations of consensus-based
software architectural styles; derivation of new architectural styles
that can enforce the required properties; and implementations that
demonstrate the feasibility of those styles and sample applications.

Rohit Khare founded KnowNow in 2000 based on his doctoral research at
the Information and Computer Science department at the University of
California, Irvine, focusing on next-generation protocols for HTTP and
proactive event notification services with Prof. Richard N. Taylor.
Rohit's participation in Internet standards development with world
renowned technical teams at MCI's Internet Architecture group and the
World Wide Web Consortium at the MIT Laboratory for Computer Science,
where he focused on security and eCommerce issues, led him to found 4K
Associates as well as editing the World Wide Web Journal for O'Reilly &
Associates. Rohit received a B.S. in Economics and in Engineering and
Applied Science with honors from Caltech in 1995 and a Master's degree
in Software Engineering from UC Irvine in 2000.

Host: Professor Jim Whitehead

Anyone needing special arrangements to accommodate a disability is
encouraged to call Ma Xiong, at Baskin School of Engineering,
(831) 459-5745.

FoRK mailing list

----- End forwarded message -----

Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca
Received on Friday, 17 October 2003 20:38:00 UTC

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