http:^^www.cs.unc.edu^research^cb.html

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Date: Wed, 20 Nov 1996 20:04:05 GMT
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Last-modified: Mon, 11 Nov 1996 22:38:29 GMT
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<TITLE> Collaboration Bus </TITLE>

<H1> Collaboration Bus</H1>
<p>
<STRONG> Sponsors: </STRONG>
<!WA0><A HREF = "http://www.ito.arpa.mil/">
DARPA Information Technology Office
</A>
</p>
<STRONG> Faculty </STRONG>:
<!WA1><A HREF = "http://www.cs.unc.edu/~dewan"> Prasun Dewan, </A>
<!WA2><A HREF = "http://www.cs.unc.edu/~wahab"> Hussein Abdel-Wahab, </A>
<!WA3><A HREF = "http://www.cs.unc.edu/~sc"> Siddhartha Chatterjee, </A>
<!WA4><A HREF = "http://www.cs.unc.edu/~jeffay"> Kevin Jeffay, </A>
<!WA5><A HREF = "http://www.cs.pdx.edu/~mchugh"> John McHugh, </A>
<!WA6><A HREF = "http://www.cs.unc.edu/~nyland"> Lars Nyland, </A>
<!WA7><A HREF = "http://www.cs.unc.edu/~prins"> Jan Prins, </A>
<!WA8><A HREF = "http://www.cs.unc.edu/~jbs"> John Smith, </A>
<!WA9><A HREF = "http://www.cs.unc.edu/~stotts"> Dave Stotts </A>

</p>

<STRONG> Students </STRONG>:
<!WA10><A HREF = "http://www.cs.unc.edu/~clark"> Michele Clark, </A>
<!WA11><A HREF = "http://www.cs.unc.edu/~meehan"> Mike Meehan, </A>
<!WA12><A HREF = "http://www.cs.odu.edu/~mohamed"> Emad Eldin Mohamed, </A>
<!WA13><A HREF = "http://www.cs.unc.edu/~munson"> Jon Munson, </A>
<!WA14><A HREF = "http://www.cs.unc.edu/~nee"> Peter Nee, </A>
<!WA15><A HREF = "http://www.cs.unc.edu/~rusev"> Vassil Roussev, </A>
<!WA16><A HREF = "http://www.cs.unc.edu/~sharma"> Anshu Sharma </A>
</p>
<STRONG> Description </STRONG>:

In this project,
we will address the problem of composing new collaborative
systems from existing single-user and collaborative systems.
We propose to develop a new software abstraction,
called the collaboration bus,
that makes it easy to compose collaborative systems.
The collaboration bus will be an extensible infrastructure that provides
general definitions of collaboration services,
default implementations of these services,
rules for interconnecting these services,
and mechanisms for extending the set of supported services.
<p>
The set of generic services supported by the bus will include
(a) a data model for defining shared workspaces consisting of structured objects;
(b) a user interface model
that allows shared objects to be manipulated using
user interfaces that support
text, graphics, audio, video, and virtual reality;
(c) a coupling model that
enables users in a joint session to share data and user-interface
objects and controls their interactions to ensure security and
consistency contraints are not violated;
(d) migration and replication mechanisms that ensure that
the bus does not become a bottleneck; 
and
(e) real-time services, consisting of scheduling algorithms and network protocols,
for ensuring real-time coupling among the collaborators.
collaborative session and making users in a session aware of the
Previous work has addressed the heterogeneity problem in other domains such
as software engineering, operating systems, and database systems.
Our project will extend this research by providing
an interconnection technology for the collaboration domain.
It will offer two forms of interoperability:
(1) inter-service interoperability,
which will allow existing implementations of different collaboration
services,
such as user-interface and real-time services,
to be combined in new collaborative systems;
and
(2) intra-service interoperability,
which will resolve inconsistencies among different, competing instances
of the same service,
such as explicit and implicit schemes for creating joint sessions,
provided by different existing systems that need to interoperate with each other.
The following diagram illustrates the capabilities of the collaboration bus.

<p>

<center>
Click on the picture to see a bigger version.
</center>
<center>
<!WA17><A HREF="http://www.cs.unc.edu/Research/cb/proj_fig_large.gif"><!WA18><IMG SRC="http://www.cs.unc.edu/Research/cb/proj_fig.gif"></A>
</center>

<p>

The concept of a collaboration bus requires a general abstraction
that covers the functionality of existing collaborative systems.
In particular, the bus must define a reference model that
captures similarities and differences among multiple solutions
to a problem.
In addition, it must provide,
when possible, semantic translation to allow dissimilar
solutions to the same problem to coexist.
It must also define composition functions that allow a service
to be composed with other collaboration services.
Finally,
the bus must not become a bottleneck that significantly
increases the response times of users.

<p>

The following approach will be used in designing, implementing and
evaluating the bus:
(a) Identify the services that a collaborative application requires.
(b) Identify a reference model for each of these services.
(c) Identify semantics translations and composition functions for
each of these services.
(d) Incorporate, into the bus, a default implementation of the service
and the associated semantic translations and composition functions.
(e) Develop mechanisms and policies for replicating and migrating
parts of the bus.
(f) Develop mechanisms for protecting the operations on the bus.
(g) Carry out interoperability experiments involving each of these
services using state-of-the-art existing software.

<p>

Our plans for the next year are to:
(a) Identify potential clients of the collaboration bus
and scenarios of how these clients would interoperate with each
other.
(b) Characterize real-time requirements of collaborative virtual
environments based on initial experiments.
(c) Design version 1 of the
collaboration bus,
which will include reference models, semantic translations, and
composition functions for
session management,
coupling,
and
virtual environments.
(d) Start a Java-based implementation of version 1 of the bus.

<H2> Other Project Information </H2>

<!WA19><A HREF = "http://www.cs.unc.edu/Research/cb/icv.ps"> IC & V Meeting Talk Postscript </A> -- one slide per page, works
with gv. 

<p>

<!WA20><A HREF = "http://www.cs.unc.edu/Research/cb/icv-small.ps"> IC & V Meeting Talk Postscript </A> - 4 slides on one page - does not
work with gv, use gs or print it.

<p>

<!WA21><A HREF = "ftp://ftp.cs.unc.edu/pub/users/dewan/cb/quad.ps">
Quad Chart Postscript </A>

<p>

<!WA22><A HREF = "http://www.cs.unc.edu/Research/cb/prog96.html"> Project Summary </A>

<H2> Related Links </H2>

<!WA23><A HREF = "http://www.cs.unc.edu/~dewan/colab.html"> UNC Collaboration Projects

<p>

<!WA24><A HREF = "http://www.ito.arpa.mil/icv/projects.html"> DARPA Intelligent Visualization and
Collaboration (IC&V) Projects </A>

<P>
<ADDRESS>
- Last revised:
Mon Nov 11 17:36:55 EST 1996
by <!WA25><a
href="http://www.cs.unc.edu/~dewan">[e-mail]</a>
</ADDRESS>
<P>