Consistency Maintenance and Group Undo in Real-Time Group Editors
ACM Group'99
Workshop
November 14, 1999.
Embassy Suites Hotel,
Phoenix, Arizona, USA
Final Program (with Photos)
Clarence (Skip) Ellis ,
Chengzheng Sun ,
and
Matthias Ressel ,
Contents
Real-time group editing systems allow a group of users to view and edit
a shared document at the same time. They can be used in a wide range of
advanced computing application areas, including collaborative documentation,
collaborative CAD/CASE, electronic meeting/conferencing, and distance education.
Benefits include synergetic effects, awareness of what others are doing,
reduced redundancy, enhanced group feeling, reduced editing cycles, availability
of the latest version, and not being locked out. In short, less cost and
more value.
They also bring in new challenges, which were not met in traditional
distributed and/or single-user interactive applications. High responsiveness,
high concurrency, high awareness, and independence of network latency (especially
for geographically dispersed users in the Internet environment) have been
identified as the key requirements to these types of systems.
These requirements lead to some major problems in designing such kind
of collaborative systems. Under the assumption of not negligible network
latency, high responsiveness can only be achieved if the application state
(e.g., a text document) is replicated and user commands are executed on
the local state immediately. The so-called optimistic algorithms follow
this approach.
Optimistic algorithms have to make sure, however that several required
properties are not violated:
-
Convergence - Final document states have to be the same on all sites.
-
Causality Preservation - Execution order has to follow the cause-effect
order.
-
Intention Preservation - The actual effect of an executed command
has to equal the intended effect.
These three subproblems can be summarized as the consistency maintenance
problem. Some of the most promising research has focused on algorithms
based on operational transformation (OT), which ensures convergence and
intention preservation while allowing concurrent operations
to be executed in any order (for good responsiveness)
by properly transforming operations according to their execution context.
There has been some evidence in the meantime that the problems of consistency
maintenance and group undo are closely related. Therefore any research
on group undo, especially if it is OT-based, will be of interest to this
workshop, too.
Other topics of interest include the generalization and application
of the OT-technology to other groupware and distributed systems, e.g:
-
collaborative hypertext/graphics/image/multimedia editors,
-
collaborative CAD, CASE, and database applications,
-
internet-based multi-player games.
Objectives
-
Get to know and analyze different approaches for consistency maintenance.
-
Compare OT-based approaches against each other as well as against traditional
approaches like turn-taking, locking, serialization, causal ordering.
-
Gain a better understanding of similarities and differences of the known
approaches.
-
Define a common nomenclature.
-
Specify a standard set of examples (like the dOPT puzzle) for testing existing
and future approaches.
-
Support the formalization, verification, and optimization of OT-based systems.
-
Evaluate OT-based systems from the end-users' point of view.
Organizers
Dr. Clarence (Skip) A. Ellis is
Professor of Computer Science and Co-Director of the Collaboration Technology
Research Group at the University of Colorado. At Colorado, he is a member
of the Systems Software Lab, and the Institute for Cognitive Science. He
is involved in research and teaching of groupware, coordination theory,
and operating systems. Dr. Ellis has worked as a researcher and developer
at MCC, Xerox PARC, Bull Corp, Bell Telephone Labs, IBM, Los Alamos Scienti
c Labs, and Argonne National Lab. His academic experience includes teaching
at Stanford University, MIT, University of Texas, Stevens Institute of
Technology, and at Chiaotung University in China under an AFIPS overseas
teaching fellowship.
Dr. Chengzheng Sun is a
Professor in the School of Computing & Information Technology, Griffith
University, Brisbane, Australia. Before joining Griffith University in 1993,
he had worked in Changsha Institute of Technology, University of Amsterdam,
Philipes Research Labs Eindhoven, and ACE in Amsterdam, for over 15
years in the areas of distributed and parallel computing systems. His areas of expertise
and current research interests include Internet and Web computing
technologies and applications; real-time groupware systems and CSCW (Computer-Supported
Cooperative Work); distributed operating systems and computer networks; and parallel
logic and object-oriented programming systems.
Dr. Matthias Ressel
is a Senior Developer at the Advanced Engineering Center in the IT section
of the UBS AG, Basel, Switzerland. In the framework of a cooperation he
is currently located at the Institute for Computer Science of the University
of Stuttgart, Germany. Developping algorithms for consistency maintenance
and group undo have been part of his doctoral thesis which he finished
in 1997 at the University of Stuttgart. Before he had worked for several
national and international research projects in the areas of workflow and
collaborative multimedia authoring. His areas of expertise and interest
include object-oriented programming, human-computer as well as human-computer-human
interaction, and distributed collaborative real-time groupware. He teaches
CSCW and software ergonomy.
Participants
We invite researchers and practicioners from different areas like distributed
computing, interactive systems (human-computer interaction), and CSCW (human-human
interaction) in general. Researchers with experience in designing or implementing
real-time group editors or undo for groupware as well as people experienced
in the use of different kinds of group editors are especially encouraged
to participate. The number of participants should not exceed 20.
Submissions
The workshop will be of one day duration. Potential participants should
submit a position paper (2-4 pages). We encourage submissions appropriate
to the issues identified, but we also welcome new insights or topics.
Submissions should be sent in electronic Word95, PDF, Postscript, or plain text format
to:
Chengzheng Sun, Griffith University,
Australia, scz@cit.gu.edu.au
or
Matthias Ressel,
University of Stuttgart, Germany, ressel@informatik.uni-stuttgart.de
Non electronic materials can be sent to:
Chengzheng Sun
School of Computing and InfoTech
Griffith University
Qld 4111, Australia
or (especially from Europe) to:
Matthias Ressel
University of Stuttgart
Breitwiesenstr. 20-22
D-70565 Stuttgart
Germany
Important dates:
Submission - October 10, 1999
Notification of acceptance - October 20, 1999
URLs
SIGCE: An International
Special Interest Group on Collaborative Editing