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WSC'00 |
Distributed Web-Based Simulation
Optimization
Yuh-Chyun Luo (Chung-Cheng Institute of Technology),
Chun-Hung Chen (George Mason University), Enver Yücesan (INSEAD) and Insup Lee
(University of Pennsylvania)
Abstract:
Web technology is having a significant impact on
computer simulation. Most of the effort in web-based simulation is aimed at
modeling, particularly at building simulation languages and at creating model
libraries that can be assembled and executed over the web. We focus on the
efficiency of simulation experimentation for optimization. We introduce a
framework for combining the statistical efficiency of simulation optimization
techniques with the effectiveness of parallel execution algorithms. In
particular, the Optimal Computing Budget Allocation (OCBA) algorithm is
implemented in a web-based environment for low-cost parallel and distributed
simulation experimentation. A prototype implementation with some experimental
results is presented.
The Monarc Toolset for Simulating Large
Network-Distributed Processing Systems
Iosif C. Legrand and Harvey
B. Newman (California Institute of Technology)
Abstract:
The next generation of High Energy Physics experiments
have envisaged the use of network-distributed Petabyte-scale data handling and
computing systems of unprecedented complexity. The general concept is that of
a "Data Grid Hierarchy" in which the central facility at the European
Laboratory for Particle Physics (CERN) in Geneva will interact and coherently
manage tasks shared by and distributed amongst national "Tier1 (National)
Regional Centres" situated in the US, Europe, and Asia. CERN and the Tier1
Centers will further communicate and task-share with the Tier2 Regional
Centers, Tier3 centers serving individual universities or research groups, and
thousands of "Tier4" desktops and small servers. The design and optimization
of systems with this level of complexity requires a realistic description and
modeling of the data access patterns, the data flow across the local and wide
area networks, and the scheduling and workload presented by hundreds of jobs
running concurrently on large scale distributed systems exchanging very large
amounts of data. The simulation toolset developed within the "Models Of
Networked Analysis at Regional Centers" - MONARC project provides a code and
execution time-efficient design and optimisation framework for large scale
distributed systems. A process-oriented approach for discrete event simulation
has been adopted because it is well suited to describe various activities
running concurrently, as well the stochastic arrival patterns typical of this
class of simulations. Threaded objects or "Active Objects" provide a natural
way to map the specific behaviour of distributed data processing (and the
required flows of data across the networks) into the simulation program.
Object-Oriented Simulation of Distributed Systems
Using Java® and Silk®
Richard A. Kilgore (ThreadTec, Inc.) and
Emmett Burke (Symbi Systems, Inc.)
Abstract:
An object-oriented modeling infrastructure using the
Java-based, Silk simulation classes is defined that enables the simulation of
multitasking, distributed systems using symmetric multiprocessors. The
simulation infrastructure is being used to evaluate alternative architectures
for embedded, distributed systems. We show how the underlying structure is
adapted to several different applications, including various Internet
applications. The paper describes the infrastructure, its robustness, and the
application of the model to produce insights for a system under design. The
simulation infrastructure enables a high fidelity representation of the
internal complexity of the application on each processing node, the operating
system behavior, and the disks and network. The simple yet powerful
representation leverages the use of the Silk entity-thread architecture to
achieve a simulation architecture that maps to the actual system architecture
in both conceptual design and processing sequence. The model has been
validated through instrumentation of the evolving target system.
A Web-Based Interface for Storing and Executing
Simulation Models
Ashu Guru, Paul Savory, and Robert Williams
(University of Nebraska)
Abstract:
The dominance of the Internet in the development of
information and communication technology has made Web-based distributed
solutions increasingly attractive. Apart from providing other services, the
World Wide Web is being looked upon as an environment for hosting modeling and
simulation applications. SIMAN is a simulation language that allows users to
simulate discrete and continuous systems. In this research, a web-based
interface or toolkit has been developed for storing and executing SIMAN
simulation models over the Internet. This toolkit consists of a World Wide Web
interface to SIMAN and a web-accessible database for storing user models. It
provides users an easy-to-use environment for developing text-based simulation
models using the SIMAN simulation language. It also allows users to test the
functionality of a SIMAN model using the SIMAN debugger/run controller.
A Java-Based Simulation Manager for Web-Based
Simulation
Charles Marr and Christopher Storey (US Army), William
E. Biles (University of Louisville) and Jack P.C. Kleijnen (Tilburg
University)
Abstract:
This paper discusses a Web-based simulation manager
program that executes an Application Service Provider (ASP) event for a
customer who does not possess the in-house capability to program complex
simulations. The utility in using this simulation manager is that the customer
needs results in near real-time; that is, approximately the time to run one
complete replication of the simulation model plus some overhead time to send
the commands necessary to execute the simulation and to process the results.
The simulation manager executes simulation studies in a parallel replications
format, using either designed experiments or optimization methodologies, by
sending the appropriate messages to a set of engine processors to cause the
execution of the prescribed simulation trials. It then receives and analyzes
the simulation results produced by the simulation engines, and sends a project
report to the human customer.
An Interactive Land Use VRML Application (ILUVA) with
Servlet Assist
Lee A. Belfore, II and Suresh Chitithoti (Old
Dominion University)
Abstract:
We summarize progress achieved on an interactive land
use VRML application (ILUVA) with servlet assist. The purpose of this
application is to enable one to take a virtual land area and add buildings,
roadways, landscaping and other features. The application is implemented
entirely using standard web based technologies to allow fairly universal
accessibility. The Virtual Reality Modeling Language (VRML) is a programming
language that describes three dimensional objects and defines interactions
associated with these objects. In this work, we show how the interactive
capabilities can be expanded by employing Java servlets for recording user
actions and for restoring prior sessions. The Java servlets offer several
powerful capabilities including enabling logging permanent records of user
sessions, retrieval of prior sessions, and dynamically generated VRML.
A Model-Based Approach for Component Simulation
Development
Perakath Benjamin, Dursun Delen, and Richard Mayer
(Knowledge Based Systems, Inc.) and Timothy O’Brien (John F. Kennedy Space
Center, NASA)
Abstract:
The increasing complexity of systems has enhanced the
use of simulation as a decision-support tool. Often, simulation is the only
scientific methodology available to practitioners for the analysis of complex
systems. However, only a small fraction of the practical benefits of
simulation modeling and analysis have reached the potentially large user
community because of the relatively high requirement of time, effort, and cost
needed to build and successfully use simulation models. In this paper we
describe a model-based approach that seeks to address these problems via the
implementation of MODELSIM––a comprehensive modeling and analysis architecture
that includes (i) application of the IDEF3 and IDEF5 methods for simulation
modeling and analysis specification, (ii) automatic generation of executable
component-based simulations from IDEF-based descriptive models, and (iii)
reusable libraries of modeling components to facilitate rapid configuration of
models as needed over extended periods of time.
Dynamic Component Substitution in Web-Based
Simulation
Dhananjai Madhava Rao and Philip A. Wilsey (University
of Cincinnati)
Abstract:
Recent breakthroughs in communication and software
engineering has resulted in significant growth of web-based computing.
Web-based techniques have been employed for modeling, simulation, and analysis
of systems. The models are commonly developed using component based techniques
where a system is represented as a set of interconnected components. A
component is a well-defined software module that is viewed as a ``black box''
element. However, the behavior of a component, which is necessary for
simulation, can be implemented by different modelers including third party
manufacturers. Web-based simulation environments enable effective sharing and
reuse of components thereby minimizing model development overheads. In
component based simulations, one or more components can be substituted during
simulation with a functionally equivalent set of components. Such Dynamic
Component Substitutions(DCS) provide an effective technique for selectively
changing the level of abstraction of a model during simulation. It provides a
tradeoff between simulation overheads and model details. It can be used to
effectively study large systems and accelerate rare event simulations to
desired scenarios of interest. DCS may also be used to achieve fault-tolerance
in Web-based simulations. This paper presents the ongoing research to design
and implement support for DCS in A Web-based Environment for Systems
Engineering (\wese).
Finding a Substrate for Federated Components on the
Web
John A. Miller, Andrew F. Seila, and Junxiu Tao (University of
Georgia)
Abstract:
Recent developments in software component technology
have renewed the promise of reusable software. Combining this with the
possibilities of sharing simulation results and models using the Internet
makes these new developments all the more important, particularly for
Web-Based Simulation. Interoperability standards and data interchanges
standards (e.g., XML) help facilitate having simulation models interact with
other simulation models as well as other information technology components.
This paper examines newer component technologies such as Enterprise Java Beans
(EJB) and Jini in a search for an ideal substrate for Web-Based Simulation.
Components will need distributed capabilities as well as the ability to
flexibly and dynamically join an existing group of interacting components
(referred to as a federation).
SIMFONE´: An Object-Oriented Simulation
Framework
Manuel D. Rossetti (University of Arkansas) and Ben
Aylor, Ryan Jacoby, Alyson Prorock, and Antoine White (University of Virginia)
Abstract:
This paper presents an overview of a software design
framework for the development of object-oriented simula-tions. The framework
is documented using the Unified Modeling Language (UML) and is divided into
packages to organize the collection of classes into important functional
areas. The purpose of the framework is two-fold. First, the framework is
useful in understanding the concepts and abstractions within simulation
modeling and languages. Secondly, the framework can serve as the basis for the
de-velopment of object-oriented simulation libraries. We illustrate the latter
through a Java implementation.
VisualSLX - An Open User Shell for High-Performance
Modeling and Simulation
Thomas Wiedemann (Technical University of
Berlin)
Abstract:
SLX by Wolverine software is actually one of the
fastest simulation languages. Besides the high performance the SLX-compiler
can be extended very easily by user specific syntax rules and new basic
functions. This "pyramid power" of SLX is used to build a new system for
modeling and simulation - VisualSLX. This system is a shell atop the standard
SLX-compiler and the runtime system. All model and simulation data are stored
in a universal data-base. VisualSLX could be used for a comfortable, rapid
visual modeling and for remote modeling and simulation through the internet
without any knowledge of the SLX-syntax and modeling paradigms. This paper
reveals the architecture and the underlying data structures of the system.
Additional requirements and interfaces are caused by the application of
VisalSLX as a web-based modeling and simulation system.
A Review of Web Based Simulation: Whither We
Wander?
Jasna Kuljis and Ray J. Paul (Brunel University)
Abstract:
This paper considers a variety of new technologies for
discrete-event simulation software development. Environments and languages for
web based simulation are reviewed. Web based applications are discussed. After
proposing a summary of the review, ways of working that will have an
unpredictable effect on the future of simulation modeling are proposed.
Issues in Java-Based Continuous Time Step Physical
Modelling
Lisa A. Schaefer (The MITRE Corporation) and Philip M.
Wolfe (Arizona State University)
Abstract:
This paper discusses the problems involved in
developing a Java based simulation model of autonomous entities that can
navigate themselves in 2-dimensional space. We develop some ideas for solving
those problems. The ideas mentioned in this paper can be applied to
simulations that have fuzzy logic for navigation, encapsulation for
object-oriented simulation, many instances of objects, or statistically
complex results. We cite reasons for distributing a simulation among several
computers and propose several topics for future research.
Java Engine for UML Based Hybrid State
Machines
Andrei V. Borshchev, Yuri B. Kolesov, and Yuri B.
Senichenkov (St. Petersburg Technical University)
Abstract:
One of the approaches to modeling hybrid systems is to
assign algebraic-differential equations describing the continuous behavior to
states of state machines that represent discrete logic. The resulting hybrid
state machine is a powerful concept to specify complex interdependencies
between discrete and continuous time behaviors. It, however, exposes the
simulation engine to a number of problems, which we discuss. The hybrid state
machine based approach presented in this paper is fully supported by
UML-RT/Java tool developed at Experimental Object Technologies.