Modeling and Simulation as a Service.
ABSTRACT
DEVS Modeling & Simulation separates a model from its simulator. A DEVS model describes the structure and the behavior of a system, while a DEVS simulator generates the trajectories of these descriptions through execution threads. The goal of a DEVS standard is to provide a simple and mostly automated way of executing simulations that involve remote and/or heterogeneous DEVS models.
This can be achieved by taking two different approaches, which are simulator-based interoperability and model-based interoperability:
- In model-based interoperability, models themselves are deployed as services instead of simulators. Using this model driven approach, the operations invoked through the network are no longer simulation mechanisms, but model functions.
- In simulator-based interoperability, the main idea is to have a collection of simulation services distributed over the Internet.
These services provide several operations for simulating DEVS models in a unified manner. In this work,we propose a Web Services-based modeling and simulation which can be used to solve the above-mentioned problem of interoperability of DEVS-based models and DEVS-based simulator. We thendeployed an example of Web Services-based modeling and simulation using the DEVS toolkit SimStudio_1.1and Apache Axis2.
TABLE OF CONTENT
Chapter 1: Introduction…………………………………………………………………………………….10
I.1 Research Context…………………………………………………………………………………….10
I.2 Problem Statement…………………………………………………………………………………..10
I.3Research Objectives………………………………………………………………………………….10
I.4 Research methodology……………………………………………………………………………..10
I.5 Organization of the document……………………………………………………………………11
Chapter 2: Related work…………………………………………………………………………………..12
2.1 Standardizing DEVS Model Representation…………………………………………………12
2.2 DEVS/SOA………………………………………………………………………………………………12
2.3 DEVS Modeling Language (DEVSML)………………………………………………………….13
Chapter 3: DEVS and Web services State of Art…………………………………………………..14
3.1 DEVS…………………………………………………………………………………………………….14
3.1.1 DEVS modeling formalism…………………………………………………………………..15
3.1.1.1 Classic DEVS atomic model……………………………………………………………15
3.1.1.2 Classic DEVS coupled model………………………………………………………….16
3.1.1.3 PDEVS atomic model…………………………………………………………………….17
3.1.1.4 PDEVS coupledmodel……………………………………………………………………18
3.1.2. DEVS toolkits……………………………………………………………………………………18
3.2Web services…………………………………………………………………………………………..19
3.2.1 Service-Oriented Architectures (SOA)…………………………………………………..19
3.2.2 Existent technologies-based SOA…………………………………………………………21
3.2.2.1 CORBA………………………………………………………………………………………..21
3.2.2.2 JAVA RMI……………………………………………………………………………………..21
3.2.2.3 DCOM…………………………………………………………………………………………22
3.2.3Web Services……………………………………………………………………………………..23
3.2.3.1 Web Services components…………………………………………………………….24
3.2.3.2 Service Description: WSDL…………………………………………………………….25
3.2.3.3 Service Discovery (UDDI)………………………………………………………………25
3.2.3.4 Why Web Services………………………………………………………………………..26
3.2.3.5 Web services Tools and Vendors……………………………………………………..27
3.2.3.6 Example of services……………………………………………………………………..27
Chapter 4: DEVS modeling and simulation as a service………………………………………..29
4.1 Overview……………………………………………………………………………………………….29
4.2 DEVS modeling and simulation as a service………………………………………………..29
4.2.1 Example of DEVS modeling and simulation as a service using the
SimStudio_1.1…………………………………………………………………………………………..29
4.2.1.1 Axis2 Web Services deployment of the SimStudio_1.1……………………….30
4.2.1.1.1 Configuration of Eclipse for Web Services with Axis2……………………30
4.2.1.1.2 Configuration of services.xml……………………………………………………31
4.2.1.1.3 Creation and deployment of Service archive………………………………34
4.2.1.2Consuming the Axis2 Web Services…………………………………………………35
Chapter 5 Conclusion………………………………………………………………………………………36
5.1 Result……………………………………………………………………………………………………36
5.2Challenges………………………………………………………………………………………………36
5.3 Perspectives…………………………………………………………………………………………..36
References……………………………………………………………………………………………………..38
RESEARCH CONTEXT
During the last years, the DEVS community provides many contributions towards the realization of a world-wide platform for collaborative Modeling & Simulation. The goal of such a platform would be to enable the sharing and reuse of models between scientists, as well as the seamless simulation of distributed and heterogeneous models.
Therefore, one of the major research fields is the definition of architectures for integrating heterogeneous DEVS components, meaning simulators and/or models written in different frameworks and programming languages. In this thesis, we present Web services, one strategy for providing such interoperability between DEVS components.
Web services are concerned with the problems of enabling systematic applicationto-application interactions over the Web, and the integration of the existing network computer infrastructure into the Web. The goal of Web services is to provide a flexible frameworkbased on sending XML messages in a specific SOAP format.
SOAP is a specification that defines an XML grammar for both sending messages and responding to messages that you receive from other parties. The goal of SOAP is to describe a message format that is not bound to any hardware or software architecture, but one that carries a message from any platform to any other platform in an unambiguous fashion.
REFERENCES
T. Wutzler and H. S. Sarjoughian, “Interoperability among parallel DEVS simulators and
models implemented in multiple programming languages,” Simulation, vol. 83, no. 6, pp.
473–490, 2007.C. Seo and B. P. Zeigler, “Interoperability between DEVS simulators using service oriented
architecture and DEVS namespace,” in Proceedings of the 2009 Spring Simulation
Multiconference, 2009, p. 157.G. A. Wainer, K. Al-Zoubi, O. Dalle, D. R. Hill, S. Mittal, J. L. R. Martín, H. Sarjoughian,
L. Touraille, M. K. Traoré, and B. P. Zeigler, “15 DEVS Standardization: Foundations and
Trends,” Discrete-Event Model. Simul. Theory Appl., p. 389, 2010.S. Mittal, J. L. Risco-Martín, and B. P. Zeigler, “DEVSML: automating DEVS execution
over SOA towards transparent simulators,” in Proceedings of the 2007 spring simulation
multiconference-Volume 2, 2007, pp. 287–295.G. A. Wainer, K. Al-Zoubi, D. R. Hill, S. Mittal, J. L. Risco, H. S. Martín, L. Touraille, M.
K. Traoré, and B. P. Zeigler, “16 An Introduction to DEVS Standardization,” DiscreteEvent Model. Simul. Theory Appl., p. 393, 2010.G. A. Wainer and P. J. Mosterman, Discrete-event modeling and simulation: theory and
applications. CRC Press, 2010.A. Moreno, J. L. Risco-Martín, E. Besada, S. Mittal, and J. Aranda, “DEVS/SOA: Towards
DEVS Interoperability in Distributed M&S,” in Distributed Simulation and Real Time
Applications, 2009. DS-RT’09. 13th IEEE/ACM International Symposium on, 2009, pp.
144–153.G. A. Wainer, K. Al-Zoubi, D. R. Hill, S. Mittal, J. L. Risco, H. S. Martín, L. Touraille, M.
K. Traoré, and B. P. Zeigler, “17 Standardizing DEVS Model Representation,” DiscreteEvent Model. Simul. Theory Appl., p. 427, 2010.
StudentsandScholarship Team.