The dominance of the Internet in the development ofinformation and communication technology has madeWeb-based distributed solutions increasingly attractive.Apart from providing other services, the World Wide Webis being looked upon as an environment for hostingmodeling and simulation applications. SIMAN is asimulation language that allows users to simulate discreteand continuous systems. In this research, a web-basedinterface or toolkit has been developed for storing andexecuting SIMAN simulation models over the Internet.This toolkit consists of a World Wide Web interface toSIMAN and a web-accessible database for storing usermodels. It provides users an easy-to-use environment fordeveloping text-based simulation models using the SIMANsimulation language. It also allows users to test thefunctionality of a SIMAN model using the SIMANdebugger/run controller

Guru, Ashu

Savory, Paul

Williams, Robert

English

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Industrial and Management Systems Engineering Faculty Publications Industrial and Management Systems Engineering 12-2000 A web-based interface for storing and executing simulation model Ashu Guru University of Nebraska at Lincoln, ashuguru@gmail.com Paul Savory University of Nebraska at Lincoln, psavory2@gmail.com Robert Williams University of Nebraska at Lincoln Follow this and additional works at: https://digitalcommons.unl.edu/imsefacpub  Part of the Industrial Engineering Commons, Operational Research Commons, and the Other Operations Research, Systems Engineering and Industrial Engineering Commons Guru, Ashu; Savory, Paul; and Williams, Robert, "A web-based interface for storing and executing simulation model" (2000). Industrial and Management Systems Engineering Faculty Publications. 25. https://digitalcommons.unl.edu/imsefacpub/25 This Article is brought to you for free and open access by the Industrial and Management Systems Engineering at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Industrial and Management Systems Engineering Faculty Publications by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Proceedings of the 2000 Winter Simulation Conference J. A. Joines, R. R. Barton, K. Kang, and P. A. Fishwick, eds.    A WEB-BASED INTERFACE FOR STORING AND EXECUTING SIMULATION MODELS   Ashu Guru Paul Savory Robert Williams  Department of Industrial and Management Systems Engineering 175 Nebraska Hall University of Nebraska Lincoln, NE  68588-0518, U.S.A.    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.  1 INTRODUCTION  Simulation is an indispensable tool that has proved its capability to help implement better decisions in real-world situations. It provides users the ability to accurately estimate the statistics and efficiency of various solutions and options without physically having to implement them.  Though, in order to use simulation, one needs to have access to powerful computer hardware and software.  Currently, the Internet dominates the development of information and communication technology.  Web-based or distributed solutions and systems are becoming increasingly attractive.  The major aspects of the Internets influence are platform independence, maintenance minimization, reusability, and interoperability. With the exponential growth of Internet communication and advancements in client/server technology, it is now possible to share expensive computational resources over the limitations of geographical distance.  The World Wide Web is being looked upon as an environment for providing modeling and simulation applications.  Improvements in related technologies such as CGI (Common Gateway Interface) and HTML (Hypertext Markup Language) have allowed for the research in Web-based simulation. In this research, a toolkit consisting of a World Wide Web interface to SIMAN is developed (Guru 2000). SIMAN is a simulation language that allows users to simulate discrete and continuous systems.  The developed interface provides users an easy-to-use environment for developing text-based simulation models.  The components of the toolkit are allocated to different servers.  The implementation is essentially a fat server and thin client, where most of the processing is performed at the server.  The clients have access to the server components using a web browser interface.  This implementation is done independent of the SIMAN source code.  By using this approach, the interface acts as a separate shell that interacts with the SIMAN simulation engine over the World Wide Web.  In order to use the system, a user simply requires access to the Internet and an account on the web server.  Apart from the essential features such as compiling, linking and executing simulation models over the World Wide Web, additional toolkit features include:  • Capability to test the functionality of a model through the use of the SIMAN debugger/run controller.   • Capability to store the simulation model in a database so that they can be easily accessed, retrieved, and updated using a user-friendly interface.   1810Guru, Savory, and Williams  All the implementation of the developed software is done in a modular way so that the developed code can be reused for integration with other similar applications.  2 TOOLKIT OVERVIEW  The complete system involves a combination of three hardware and software platforms  an application server, a database server and a SIMAN server.  All these servers are behind a firewall for security purposes.  Figure 1 shows the layout of the three platforms and the interactions between them.  The first server is the Application server.  An Internet user accessing the web address for the site is directed to this server.  The software residing here performs the functions of authenticating the user and providing access to the users models in the database.  It gives the user the capability to edit, add, or delete models in his or her account.   When the user wants to compile, execute or debug a model, this server creates a dynamically-generated HTML document that contains the model frame, experiment frame and model ID as form elements.  The document can then be Posted to the SIMAN server with the instructions of the desired operation.   The second server is the Oracle server. The Application server interacts with the Oracle server in order to provide accessibility to the users models. The models and the user data are stored in a database on this server using a simple two-entity schema.  The first entity is user and has attributes: user ID, user name, email, login and password.  The second entity is model with attributes: model ID, experiment frame and model frame.  The two entities have a relationship of one-to-many (one user can have many models).    All the requests for compiling, linking, executing and debugging the models are posted to the SIMAN server.   The SIMAN simulation software that reside on this server performs the requested operation and returns the results to the user in the form of an HTML document.  This is done by piping the output of the appropriate SIMAN process(es) that are invoked with the CGI script as a dynamically-generated HTML document.  The arguments to these SIMAN processes are ASCII text files containing the SIMAN model and experiment frame.  These files are temporarily created by CGI scripts with the data Posted to them through the HTML forms. To summarize, the developed toolkit allows users to access their simulation models stored in an Oracle database over the Internet.  It gives them the capability to edit, up-date or delete these models through HTML forms.  Once saved to the database, the models can be compiled, linked, executed and debugged on the SIMAN server through the World Wide Web.  The results of the three processes are then sent back to the user in the form of a standard HTML document.   3 SYSTEM ARCHITECTURE  A multi-stage approach was taken to analyze and design the toolkit that will act as an interface between the World Wide Web and the SIMAN simulation engine. The development process involved determining the information requirements of the intended users.  System needs were analyzed and structured decisions were made. These decisions included the conditions, alternatives, actions, and rules under which a model would be developed.  Testing a simulation models validity and reliability to estimate the original system is an important part of the simulation process.  The SIMAN software provides a very effective tool, the SIMAN debugger or run-time controller, to perform this operation.  It was decided to make this run time controller accessible through the Internet.    Internet FirewallSIMAN Server Oracle Server Application Server F all   Figure 1:  Hardware and Software Layout 1811Guru, Savory, and Williams  One of the key features of the toolkit is to give a user the capability to store their models on a remote server and provide accessibility to these models from anywhere through the Internet.  This facility does not require a user to use FTP or TELNET protocols.  To increase the systems functionality, security, and to make the system administrations tasks easier and faster, the simulation models are stored in an online database.  The simulation models can be retrieved, updated or edited by the user.  As users grow, the database will form a repository and a knowledge bank of simulation models.   Based on the evaluated requirements and the decisions made, the complete system was emulated with process and data flow diagram models (Guru 2000). These preliminary models were developed to help make the development process modular and manageable.  Each detail and function to be provided in the system was depicted and explained.  These models formed the skeleton for the system development and implementation cycle.  Even though these models were edited during the complete development cycle, they provided an indispensable aid throughout the development process.  Certain conventions were followed while developing these models and data flow diagrams.  These conventions are based on the recommendations made by Kendall et al. (1999).  The diagramming symbols used for the data flow diagrams are based on work by Gane and Sarson (1979).  Figure 2 depicts the four basic symbols and their representations in the data flow diagrams.  A simplified stepped data flow diagram (Figure 3) shows the global view of the system, its interaction with the users (external entities to the system), as well as inter-process communications.  In this diagram, the processes have been grouped together to simplify the model. To access an account and its associated simulation models, a user must present the proper username and password. Once the user has been authenticated by the system (Figure 3 - Process 1), the user is presented with a screen that contains hyperlinks to models previously stored by the user (Figure 3 - Process 2).  The user has the capability to request an editing screen for a new or a previously stored model.  Once the user has made a request, the appropriate screen is shown.  The user can make the edits or write the new model and save the edits to the database (Figure 3 - Process 3).  After have been saved to the database, the system presents the execution screen to the user. According to the user request, the system either presents the results of compilation, linking or execution (Figure 3 - Process 4) or brings up the debugger screen for the user (Figure 3 - Process 5).  From the debugger interface the user can interactively debug the simulation program. This is accomplished by stopping the SIMAN debugger process and piping the output to the user through a dynamically-generated HTML document.  The state of the debugger is maintained by storing the previous debugger commands of the user as an HTML form element sent back as a part of debugger output. The debugger process is then executed again with the previous commands appended with the new ones posted by the user.  Data FlowExternal Entity1ProcessData Store2Prcs 3Prcs_5External entity: represents anything which is outside the system boundry.  The Siman Users are a typical example of external entities.System Processes: these are essentially the processes whichperform the required operations in the system.  For example to the model input from the user and sane it to a table is a processAs the name depicts this represents a table in the databaseThe transfer of messages between entity and processes, processes and precessesand data stores and processes takes through these data flow arrowsFigure 2: Basic Symbols For Data Flow Diagramsxternal entity: represents anything outside the system boundary.SIMAN users are a typical example of external entitiesSystem processes: these are essentially the processes that perform therequired operation in the system.  For example to read the modelinput from the us r and save i to a table is a processThis represen  a database tableThese flow arrows depict the transfer of information between theprocesses and entities1812Guru, Savory, and Williams  Debugger infoCompiling and execution results infoUsers selectionExecution interface dataModels and experiment infoModels and experimen frames infoUsers Models DataUsers models dataUsers IDLogin infoLogin dataSiman User1Check login & write a cookieUsers DataSiman User2Show the front page of the account with menuUsers Models3update or insert the model & experiment frames and send the execution interface4Perform function as per users requestSiman User5Show Debugger InterfaceSiman UserExecution and compilation selectionDebuggerselection Figure 3: Overall Process Diagram   4 RESEARCH CONTRIBUTIONS  The important contributions of this research are:  (1) The developed toolkit provides the capability of executing SIMAN simulation models on a remote simulation server through the World Wide Web.   (2) All the functionality is implemented by CGI scripting using Perl.  Being written in a scripting language, the system is flexible enough to be ported to various operating platforms.  (3) The developed toolkit offers advantages over classical simulation systems. For example, the modular structure of the toolkit environment allows an exchange of software tools.   (4) The toolkit allows sharing the software and hardware resources over the Internet, independent of the users platform.  A user has access to their 1813Guru, Savory, and Williams  account from anywhere in the world using the Internet.   (5) The system administration is minimized through a user-friendly interface.   (6) The toolkit provides improved security since it does not allow users to telnet into a remote server. This reduces major risks, administration efforts, and security problems. (7) Due to the integration of the database system to store user simulation models, the toolkit has the capability to form a repository of SIMAN models that can be searched.   (8) The implementation of the complete toolkit has been done in a modular manner.  The developed database editor is very flexible. It can be utilized to provide service to any database system that should be connected to the World Wide Web with a minimum of alterations in its configuration files.  5 FUTURE RESEARCH WORK  To improve the functionality of the toolkit, the following additional research is needed:  (1) The toolkit is essentially a fat server and a thin client configuration.  Since Internet technology is improving to allow executables to run on client browsers using Java, the system could be modified to allow graphical model construction.  (2) Other services, such as the input analyzer and the output analyzer of the Arena suite, can be made accessible through the Internet.  (3) The current system is incapable of handling SIMAN simulation models that access external input and output files.  (4) Simulation results are currently not saved. The system can be changed to allow a user to save results into the database.  (5) The effect of using such an environment for learning must be tested. Whether accessibility, user friendly interface and easier availability of such resources make any difference on the learning capability and interests of the users should be investigated.   REFERENCES  Kendall, K., and Kendall, J. 1999.  Systems analysis and design, Fourth Edition, Englewood Cliffs, NJ: Prentice Hall.  Guru, Ashu, 2000.  A modular and integrated simulation management toolkit for storing an executing simulation models over the world wide web.  M.S. Thesis, University of Nebraska-Lincoln. Gane, C., and Sarson T. 1979, Structured systems analysis: tools and techniques, Englewood Cliffs, NJ: Prentice-Hall.   AUTHOR BIOGRAPHIES  ASHU GURU is a Doctoral Student with the Department of Industrial and Management Systems Engineering at the University of Nebraska-Lincoln.  He earned his Bachelors degree in Mechanical Engineering from Delhi College of Engineering, Delhi, India and his M.S. in Manufacturing Systems from the Industrial Engineering department at the University of Nebraska.  His research interests include database management systems and discrete event simulation.  His email address is <ashuguru@ hotmail.com>.  PAUL SAVORY is an Associate Professor in the Industrial and Management Systems Department at University of Nebraska.  Having degrees in industrial engineering, operations research, and computer science, he has taught numerous courses and consulted in the areas of computer simulation, operations research, and statistics, His email address is <psavory@unl.edu>.  ROBERT WILLIAMS is an Associate Professor with the Department of Industrial and Management Systems Engineering and the Center for Nontraditional Manufac-turing Research at the University of Nebraska-Lincoln. Dr. Williams areas of research and teaching interest include traditional and nontraditional manufacturing processes, computer-aided manufacturing, and rapid prototype development.  His email address is <ierpwill@ engunx.unl.edu>.  1814

A web-based interface for storing and executing simulation model

UNL | Libraries

University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
Industrial and Management Systems 
Engineering Faculty Publications 
Industrial and Management Systems 
Engineering 
12-2000 
A web-based interface for storing and executing simulation model 
Ashu Guru 
University of Nebraska at Lincoln, ashuguru@gmail.com 
Paul Savory 
University of Nebraska at Lincoln, psavory2@gmail.com 
Robert Williams 
University of Nebraska at Lincoln 
Follow this and additional works at: https://digitalcommons.unl.edu/imsefacpub 
 Part of the Industrial Engineering Commons, Operational Research Commons, and the Other 
Operations Research, Systems Engineering and Industrial Engineering Commons 
Guru, Ashu; Savory, Paul; and Williams, Robert, "A web-based interface for storing and executing 
simulation model" (2000). Industrial and Management Systems Engineering Faculty Publications. 25. 
https://digitalcommons.unl.edu/imsefacpub/25 
This Article is brought to you for free and open access by the Industrial and Management Systems Engineering at 
DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Industrial and Management 
Systems Engineering Faculty Publications by an authorized administrator of DigitalCommons@University of 
Nebraska - Lincoln. 
Proceedings of the 2000 Winter Simulation Conference 
J. A. Joines, R. R. Barton, K. Kang, and P. A. Fishwick, eds. 
 
 
 
A WEB-BASED INTERFACE FOR STORING AND 
EXECUTING SIMULATION MODELS 
 
 
Ashu Guru 
Paul Savory 
Robert Williams 
 
Department of Industrial and Management Systems Engineering 
175 Nebraska Hall 
University of Nebraska 
Lincoln, NE  68588-0518, U.S.A. 
 
 
 
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. 
 
1 INTRODUCTION 
 
Simulation is an indispensable tool that has proved its 
capability to help implement better decisions in real-world 
situations. It provides users the ability to accurately 
estimate the statistics and efficiency of various solutions 
and options without physically having to implement them.  
Though, in order to use simulation, one needs to have 
access to powerful computer hardware and software.  
Currently, the Internet dominates the development of 
information and communication technology.  Web-based 
or distributed solutions and systems are becoming 
increasingly attractive.  The major aspects of the Internets 
influence are platform independence, maintenance 
minimization, reusability, and interoperability. With the 
exponential growth of Internet communication and 
advancements in client/server technology, it is now 
possible to share expensive computational resources over 
the limitations of geographical distance.  The World Wide 
Web is being looked upon as an environment for providing 
modeling and simulation applications.  Improvements in 
related technologies such as CGI (Common Gateway 
Interface) and HTML (Hypertext Markup Language) have 
allowed for the research in Web-based simulation. 
In this research, a toolkit consisting of a World Wide 
Web interface to SIMAN is developed (Guru 2000). 
SIMAN is a simulation language that allows users to 
simulate discrete and continuous systems.  The developed 
interface provides users an easy-to-use environment for 
developing text-based simulation models.  The components 
of the toolkit are allocated to different servers.  The 
implementation is essentially a fat server and thin 
client, where most of the processing is performed at the 
server.  The clients have access to the server components 
using a web browser interface.  This implementation is 
done independent of the SIMAN source code.  By using 
this approach, the interface acts as a separate shell that 
interacts with the SIMAN simulation engine over the 
World Wide Web.  In order to use the system, a user 
simply requires access to the Internet and an account on the 
web server.  Apart from the essential features such as 
compiling, linking and executing simulation models over 
the World Wide Web, additional toolkit features include: 
 
• Capability to test the functionality of a model 
through the use of the SIMAN debugger/run 
controller.   
• Capability to store the simulation model in a 
database so that they can be easily accessed, 
retrieved, and updated using a user-friendly 
interface.  
 
1810
Guru, Savory, and Williams 
 
All the implementation of the developed software is 
done in a modular way so that the developed code can be 
reused for integration with other similar applications. 
 
2 TOOLKIT OVERVIEW 
 
The complete system involves a combination of three 
hardware and software platforms  an application server, a 
database server and a SIMAN server.  All these servers are 
behind a firewall for security purposes.  Figure 1 shows the 
layout of the three platforms and the interactions between 
them.  
The first server is the Application server.  An Internet 
user accessing the web address for the site is directed to 
this server.  The software residing here performs the 
functions of authenticating the user and providing access to 
the users models in the database.  It gives the user the 
capability to edit, add, or delete models in his or her 
account.   When the user wants to compile, execute or 
debug a model, this server creates a dynamically-generated 
HTML document that contains the model frame, 
experiment frame and model ID as form elements.  The 
document can then be Posted to the SIMAN server with 
the instructions of the desired operation.   
The second server is the Oracle server. The 
Application server interacts with the Oracle server in order 
to provide accessibility to the users models. The models 
and the user data are stored in a database on this server 
using a simple two-entity schema.  The first entity is 
user and has attributes: user ID, user name, email, login 
and password.  The second entity is model with 
attributes: model ID, experiment frame and model frame.  
The two entities have a relationship of one-to-many (one 
user can have many models).    
All the requests for compiling, linking, executing and 
debugging the models are posted to the SIMAN server.  
 The SIMAN simulation software that reside on this 
server performs the requested operation and returns the 
results to the user in the form of an HTML document.  This 
is done by piping the output of the appropriate SIMAN 
process(es) that are invoked with the CGI script as a 
dynamically-generated HTML document.  The arguments 
to these SIMAN processes are ASCII text files containing 
the SIMAN model and experiment frame.  These files are 
temporarily created by CGI scripts with the data Posted 
to them through the HTML forms. 
To summarize, the developed toolkit allows users to 
access their simulation models stored in an Oracle database 
over the Internet.  It gives them the capability to edit, up-
date or delete these models through HTML forms.  Once 
saved to the database, the models can be compiled, linked, 
executed and debugged on the SIMAN server through the 
World Wide Web.  The results of the three processes are 
then sent back to the user in the form of a standard HTML 
document.  
 
3 SYSTEM ARCHITECTURE 
 
A multi-stage approach was taken to analyze and design 
the toolkit that will act as an interface between the World 
Wide Web and the SIMAN simulation engine. The 
development process involved determining the information 
requirements of the intended users.  System needs were 
analyzed and structured decisions were made. These 
decisions included the conditions, alternatives, actions, and 
rules under which a model would be developed.  
Testing a simulation models validity and reliability to 
estimate the original system is an important part of the 
simulation process.  The SIMAN software provides a very 
effective tool, the SIMAN debugger or run-time controller, 
to perform this operation.  It was decided to make this run 
time controller accessible through the Internet. 
 
 
 
Internet 
Firewall
SIMAN Server 
Oracle Server 
Application 
Server 
F all   
Figure 1:  Hardware and Software Layout 
1811
Guru, Savory, and Williams 
 
One of the key features of the toolkit is to give a user 
the capability to store their models on a remote server and 
provide accessibility to these models from anywhere 
through the Internet.  This facility does not require a user 
to use FTP or TELNET protocols.  To increase the 
systems functionality, security, and to make the system 
administrations tasks easier and faster, the simulation 
models are stored in an online database.  The simulation 
models can be retrieved, updated or edited by the user.  As 
users grow, the database will form a repository and a 
knowledge bank of simulation models.   
Based on the evaluated requirements and the decisions 
made, the complete system was emulated with process and 
data flow diagram models (Guru 2000). These preliminary 
models were developed to help make the development 
process modular and manageable.  Each detail and function 
to be provided in the system was depicted and explained.  
These models formed the skeleton for the system 
development and implementation cycle.  Even though 
these models were edited during the complete development 
cycle, they provided an indispensable aid throughout the 
development process.  Certain conventions were followed 
while developing these models and data flow diagrams.  
These conventions are based on the recommendations 
made by Kendall et al. (1999).  The diagramming symbols 
used for the data flow diagrams are based on work by Gane 
and Sarson (1979).  Figure 2 depicts the four basic symbols 
and their representations in the data flow diagrams.  
A simplified stepped data flow diagram (Figure 3) 
shows the global view of the system, its interaction with the 
users (external entities to the system), as well as inter-
process communications.  In this diagram, the processes 
have been grouped together to simplify the model. To access 
an account and its associated simulation models, a user must 
present the proper username and password. Once the user 
has been authenticated by the system (Figure 3 - Process 1), 
the user is presented with a screen that contains hyperlinks to 
models previously stored by the user (Figure 3 - Process 2).  
The user has the capability to request an editing screen for a 
new or a previously stored model.  Once the user has made a 
request, the appropriate screen is shown.  The user can make 
the edits or write the new model and save the edits to the 
database (Figure 3 - Process 3). 
 After have been saved to the database, the system 
presents the execution screen to the user. According to the 
user request, the system either presents the results of 
compilation, linking or execution (Figure 3 - Process 4) or 
brings up the debugger screen for the user (Figure 3 - 
Process 5).  From the debugger interface the user can 
interactively debug the simulation program. This is 
accomplished by stopping the SIMAN debugger process 
and piping the output to the user through a dynamically-
generated HTML document.  The state of the debugger is 
maintained by storing the previous debugger commands of 
the user as an HTML form element sent back as a part of 
debugger output. The debugger process is then executed 
again with the previous commands appended with the new 
ones posted by the user. 
 
Data Flow
External 
Entity
1
Process
Data Store
2Prcs 3Prcs
_5
External entity: represents anything which is outside the system boundry.  
The Siman Users are a typical example of external entities.
System Processes: these are essentially the processes which
perform the required operations in the system.  For example to 
the model input from the user and sane it to a table is a process
As the name depicts this represents a table in the database
The transfer of messages between entity and processes, processes and precesses
and data stores and processes takes through these data flow arrows
Figure 2: Basic Symbols For Data Flow Diagrams
xternal entity: represents anything outside the system boundary.
SIMAN users are a typical example of external entities
System processes: these are essentially the processes that perform the
required operation in the system.  For example to read the model
input from the us r and save i to a table is a process
This represen  a database table
These flow arrows depict the transfer of information between the
processes and entities
1812
Guru, Savory, and Williams 
 
Debugger info
Compiling and execution results info
Users selection
Execution interface data
Models and experiment info
Models and experimen frames info
Users Models Data
Users models data
Users IDLogin info
Login data
Siman 
User
1
Check login & 
write a cookie
Users Data
Siman 
User
2
Show the 
front page of 
the account 
with menu
Users Models
3
update or insert the 
model & experiment 
frames and send the 
execution interface
4
Perform 
function as 
per users 
request
Siman 
User
5
Show 
Debugger 
Interface
Siman 
UserExecution and compilation selection
Debugger
selection
 
Figure 3: Overall Process Diagram 
 
 
4 RESEARCH CONTRIBUTIONS 
 
The important contributions of this research are: 
 
(1) The developed toolkit provides the capability of 
executing SIMAN simulation models on a remote 
simulation server through the World Wide Web.   
(2) All the functionality is implemented by CGI 
scripting using Perl.  Being written in a scripting 
language, the system is flexible enough to be 
ported to various operating platforms.  
(3) The developed toolkit offers advantages over 
classical simulation systems. For example, the 
modular structure of the toolkit environment 
allows an exchange of software tools.   
(4) The toolkit allows sharing the software and 
hardware resources over the Internet, independent 
of the users platform.  A user has access to their 
1813
Guru, Savory, and Williams 
 
account from anywhere in the world using the 
Internet.   
(5) The system administration is minimized through a 
user-friendly interface.   
(6) The toolkit provides improved security since it 
does not allow users to telnet into a remote server. 
This reduces major risks, administration efforts, 
and security problems. 
(7) Due to the integration of the database system to 
store user simulation models, the toolkit has the 
capability to form a repository of SIMAN models 
that can be searched.   
(8) The implementation of the complete toolkit has 
been done in a modular manner.  The developed 
database editor is very flexible. It can be utilized 
to provide service to any database system that 
should be connected to the World Wide Web with 
a minimum of alterations in its configuration files. 
 
5 FUTURE RESEARCH WORK 
 
To improve the functionality of the toolkit, the following 
additional research is needed: 
 
(1) The toolkit is essentially a fat server and a thin 
client configuration.  Since Internet technology is 
improving to allow executables to run on client 
browsers using Java, the system could be 
modified to allow graphical model construction.  
(2) Other services, such as the input analyzer and the 
output analyzer of the Arena suite, can be made 
accessible through the Internet.  
(3) The current system is incapable of handling 
SIMAN simulation models that access external 
input and output files.  
(4) Simulation results are currently not saved. The 
system can be changed to allow a user to save 
results into the database.  
(5) The effect of using such an environment for 
learning must be tested. Whether accessibility, 
user friendly interface and easier availability of 
such resources make any difference on the 
learning capability and interests of the users 
should be investigated.  
 
REFERENCES 
 
Kendall, K., and Kendall, J. 1999.  Systems analysis and 
design, Fourth Edition, Englewood Cliffs, NJ: Prentice 
Hall.  
Guru, Ashu, 2000.  A modular and integrated simulation 
management toolkit for storing an executing 
simulation models over the world wide web.  M.S. 
Thesis, University of Nebraska-Lincoln. 
Gane, C., and Sarson T. 1979, Structured systems analysis: 
tools and techniques, Englewood Cliffs, NJ: Prentice-
Hall.  
 
AUTHOR BIOGRAPHIES 
 
ASHU GURU is a Doctoral Student with the Department 
of Industrial and Management Systems Engineering at the 
University of Nebraska-Lincoln.  He earned his Bachelors 
degree in Mechanical Engineering from Delhi College of 
Engineering, Delhi, India and his M.S. in Manufacturing 
Systems from the Industrial Engineering department at the 
University of Nebraska.  His research interests include 
database management systems and discrete event 
simulation.  His email address is <ashuguru@ 
hotmail.com>. 
 
PAUL SAVORY is an Associate Professor in the 
Industrial and Management Systems Department at 
University of Nebraska.  Having degrees in industrial 
engineering, operations research, and computer science, he 
has taught numerous courses and consulted in the areas of 
computer simulation, operations research, and statistics, 
His email address is <psavory@unl.edu>. 
 
ROBERT WILLIAMS is an Associate Professor with the 
Department of Industrial and Management Systems 
Engineering and the Center for Nontraditional Manufac-
turing Research at the University of Nebraska-Lincoln. Dr. 
Williams areas of research and teaching interest include 
traditional and nontraditional manufacturing processes, 
computer-aided manufacturing, and rapid prototype 
development.  His email address is <ierpwill@ 
engunx.unl.edu>. 
 
1814


https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1021&amp;context=imsefacpub

A web-based interface for storing and executing simulation model

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