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\begin{document}

\title {\vspace{-0.75in}\Large\bf Design Architectures and Performance Evaluation of
Publisher/\-Subscriber Services in QoS-enabled Component
Middleware\thanks{This work was sponsored in part by grants from NSF
ITR CCR-0312859, Siemens, and DARPA/AFRL contract \#F33615-03-C-4112}}

\author{George Edwards, Gan Deng and Aniruddha Gokhale \\ 
\normalsize{\{george.t.edwards,gan.deng,a.gokhale\}@vanderbilt.edu} \\
\normalsize{Department of Electrical Engineering and Computer Science,
Vanderbilt University} \\ 
\normalsize{Nashville, TN 37235, USA}}
\date{}

\maketitle
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\subsection*{\centering Abstract}
{\em The publisher/\-subscriber communication paradigm, such as the one 
provided by event-based communication services, is inherently
well-suited to support large-scale distributed real-time and embedded
(DRE) systems, such as avionics mission computing or distributed
audio/video processing. Recent trends indicate that DRE systems are
increasingly being developed by means of the component-based software
development paradigm, in particular, using quality of service (QoS)-enabled
implementations of the CORBA Component Model. However, these platforms
do not yet provide any standard support for incorporating real-time
event-based communication services and optimizations that have
previously been developed and tested for object-oriented middleware
like CORBA. The result is that developers of these large and complex
DRE systems must custom-build publisher/\-subscriber solutions within
component middleware. Applications that are developed in this ad hoc,
tedious, and error-prone way are costly to design, implement and
maintain, and more importantly, may not satisfy real-time requirements
of DRE systems scalably. Therefore, DRE system developers urgently
require real-time event services that support component-based
applications while simultaneously preserve the performance
optimizations required by DRE applications.  

This paper makes three contributions to the R\&D on supporting
component-based real-time event services scalably for DRE
systems. First, we outline three different design choices for
incorporating publisher/\-subscriber services within QoS-enabled
component middleware. Second, we describe our novel approach that
%draws on the combined strengths of using a model-driven and
%are we using model-based solutions? - so I commented it out - Andy
draws on the strengths of using a 
patterns-driven solution to integrating, configuring and deploying
real-time event services scalably in QoS-enabled component middleware. 
Third, we illustrate via empirical benchmarking results how component-based
real-time event services satisfy the QoS and scalability requirements
of DRE applications. 
%Our results with ... indicate ...
% we should add the last line if there is a number to be mentioned
}   

\noindent{\bf Keywords:} Real-time Publisher/\-Subscriber Service,
Component Middleware, CORBA Component Model, Model-based Systems, Patterns.

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\end{document}

