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NetSim: A Network-based Environment for Modelling and Simulation
Department of Systems Modelling, Swedish Defence Research Agency (FOI).
Department of Systems Modelling, Swedish Defence Research Agency (FOI).
Department of Systems Modelling, Swedish Defence Research Agency (FOI).
2004 (English)In: Proceedings of SimSafe Conference, 2004Conference paper, Published paper (Refereed)
Abstract [en]

Modelling and Simulation (M&S) is a powerful tool that is used to support training and analysis of military operations, development of military concepts and gradually, it is becoming an integral part of modern C3I systems. As the web has evolved, new ways of carrying out modelling and simulation and realizing C3I systems have emerged. These achievements address some of the research issues considered vital for future development of the M&S/C3I domain. Firstly, web related technologies provide means of overcoming the interoperability barriers, for example through standardized data exchange formats (such as XML), platform independent software (for example Java) and shared knowledge of a domain (semantics). Secondly, networked environments offer ways of setting up virtual organisations, sharing common goals and interests, to efficiently collaborate in problem solving. Finally, computer networks promote efficient sharing of resources, which for example could increase the reuse of existing models or utilize idle processing capacity of computers.

At the Swedish Defence Research Agency (FOI) there is ongoing research, targeting the role of network/web based technologies in M&S, to support defence communities in their work. Our vision comprises an environment supporting the entire M&S-process, including conceptualization, scenario definition, design, development and execution. All these tasks should be maintained by a framework for collaboration, which lets users; developers, analysts, administrators etc, jointly work on a project. During the first phase of this research focus has been on efficient resource sharing and means of collaboration. Through experimental research and implementation of a prototype (NetSim), methods and techniques have been identified to form a framework for collaborative work, resource management and distributed execution.

Following current trends within development of networked applications, decentralized (Peer-to-Peer) solutions were of primary focus when implementing the prototype. Based on the open source Peer-to-Peer platform JXTA, two distinct components of our envisioned system were implemented, namely; a decentralized resource management system deploying a network of workstation for execution of HLA federations and a collaborative environment for joint modelling of federations. Our results show that the utilization of Peer-to-Peer concepts for resource sharing and collaboration are favourable in terms of scalability, robustness and fault tolerance. The technology allows formation of virtual organisations without the need of intermediate resources like centralized and powerful servers. However, some aspects of our implementation temporarily rely on central control, thereby diminishing the benefits of the Peer-to-Peer paradigm. Future research will therefore address distributed algorithms for synchronisation of collaborative work and a more flexible and extendable approach to resource management. Furthermore, as many studies have pointed out before, one of the great challenges of any type of Peer-to-Peer system is discovery and matching of resources. This is an area that deserves great attention when planning for the next generation C3I/M&S tools.

Place, publisher, year, edition, pages
2004.
National Category
Telecommunications
Identifiers
URN: urn:nbn:se:kth:diva-8512OAI: oai:DiVA.org:kth-8512DiVA: diva2:13857
Conference
NATO Modeling and Simulation Group, Symposium on C3I and M&S Interoperability, Antalya, Turkey, October 2003.
Note
QC 20100830Available from: 2008-05-26 Created: 2008-05-26 Last updated: 2010-12-22Bibliographically approved
In thesis
1. A Framework for Component Based Modelling and Simulation using BOMs and Semantic Web Technology
Open this publication in new window or tab >>A Framework for Component Based Modelling and Simulation using BOMs and Semantic Web Technology
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Modelling and Simulation (M&S) is a multi-disciplinary field that is widely used in various domains. It provides a means to study complex systems before actual physical prototyping and helps lowering, amongst others, manufacturing and training costs. However, as M&S gains more popularity, the demand on reducing time and resource costs associated with development and validation of simulation models has also increased. Composing simulation models of reusable and validated simulation components is one approach for addressing the above demand. This approach, which is still an open research issue in M&S, requires a composition process that is able to support a modeller with discovery and identification of components as well as giving feedback on feasibility of a composition. Combining components in order to build new simulations raise the non-trivial issue of composability.

Composability has been defined as the capability to select and assemble reusable simulation components in various combinations into simulation systems to meet user requirements. There are three main types of composability, syntactic, semantic and pragmatic. Syntactic composability is concerned with the compatibility of implementation details, such as parameter passing mechanisms, external data accesses, and timing mechanisms. It is the question of whether a set of components can be combined. Semantic composability, on the other hand, is concerned with the validity of the composition, and whether the composed simulation is meaningful. Pragmatic composability is yet another type which is concerned with the context of the simulation, and whether the composed simulation meets the intended purpose of the modeller. Of these three types syntactic composability is easiest to accomplish and some significant progresses on this issue have been reported in the literature. Semantic and pragmatic composability are much harder to achieve and has inspired many researchers to conduct both theoretical and experimental research.

The Base Object Model (BOM) is a new concept identified within M&S community as a potential facilitator for providing reusable model components for the rapid construction and modification of simulations. Although BOMs exhibit good capabilities for reuse and composability they lack the required semantic information for semantic matching and composition. There is little support for defining concepts and terms in order to avoid ambiguity, and there is no method for matching behaviour of conceptual models (i.e., state machines of the components), which is required for reasoning about the validity of BOM compositions.

In this work we have developed a framework for component-based model development that supports both syntactic and semantic composability of simulation models by extending the BOM concept using ontologies, Semantic Web and Web Services technologies, and developing a rule-based method for reasoning about BOM compositions. The issue of pragmatic composability has not been the focus of this work, and it has only been partly addressed. The framework utilises intelligent agents to perform discovery and composition of components, according to the modeller needs. It includes a collaborative environment, a semantic distributed repository and an execution environment to support model development and execution process.

The basic assumption of this work is that semantic composability should be achieved at conceptual level. Through precise definition and specification of components’ semantic and syntax one can capture the basic requirements for matching and semantically meaningful composition of those components. This requires a common methodology for specification of simulation components. The specification methodology consists of meta-models describing simulation components at different levels. In order to enable automatic matching of meta-models they are formalized and structured using Semantic Web technology in OWL (Web Ontology Language). Hence, the models are based on ontologies to avoid misunderstanding and to provide unambiguous definitions as a basis for reasoning about syntactic and semantic validity of compositions.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. xii, 84 p.
Series
Trita-ICT-ECS AVH, ISSN 1653-6363 ; 08:05
Keyword
Computer science
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-4770 (URN)978-91-7178-957-0 (ISBN)
Public defence
2008-05-23, Sal D, KTH-Forum, Isafjordsgatan 39, Kista, 13:00
Opponent
Supervisors
Note
QC 20100830Available from: 2008-05-26 Created: 2008-05-26 Last updated: 2010-08-30Bibliographically approved
2. Fault-tolerance in HLA-based distributed simulations
Open this publication in new window or tab >>Fault-tolerance in HLA-based distributed simulations
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Successful integration of simulations within the Network-Based Defence (NBD), specifically use of simulations within Command and Control (C2) environments, enforces a number of requirements. Simulations must be reliable and be able to respond in a timely manner. Otherwise the commander will have no confidence in using simulation as a tool. An important aspect of these requirements is the provision of fault-tolerant simulations in which failures are detected and resolved in a consistent manner. Given the distributed nature of many military simulations systems, services for fault-tolerance in distributed simulations are desirable. The main architecture for distributed simulations within the military domain, the High Level Architecture (HLA), does not provide support for development of fault-tolerant simulations.

A common approach for fault-tolerance in distributed systems is check-pointing. In this approach, states of the system are persistently stored through-out its operation. In case a failure occurs, the system is restored using a previously saved state. Given the abovementioned shortcomings of the HLA standard this thesis explores development of fault-tolerant mechanisms in the context of the HLA. More specifically, the design, implementation and evaluation of fault-tolerance mechanisms, based on check-pointing, are described and discussed.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. viii, 40 p.
Series
Trita-ICT-ECS AVH, ISSN 1653-6363 ; 06:03
Keyword
HLA, fault-tolerance, distributed simulations, federate, federation
National Category
Computer Engineering
Identifiers
urn:nbn:se:kth:diva-4063 (URN)
Presentation
2006-06-13, Sal D, KTH-Forum, Isafjordsgatan 39, plan 4, Kista, 14:15
Opponent
Supervisors
Note
QC 20101111Available from: 2006-06-25 Created: 2006-06-25 Last updated: 2010-11-11Bibliographically approved
3. Consistency management in collaborative modelling and simulation
Open this publication in new window or tab >>Consistency management in collaborative modelling and simulation
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

The aim of this thesis is to exploit the technological capabilities of computer supported collaborative work (CSCW) in the field of collaborative Modelling and Simulation (M&S). The thesis focuses on addressing two main problems: (i) providing flexible means of consistency management in collaborative M&S, and (ii) the ability of providing platform and application independent services for collaborative M&S.

In this work, some CSCW technologies and how some of the concepts can be incorporated in a distributed collaborative M&S environment, have been studied. An environment for component based simulation development and visualization, which provides support for collaborative M&S, has been designed. Some consistency policies that can be used in conjunction with distributed simulation and the High Level Architecture (HLA) have been investigated. Furthermore, the efficient utilization of HLA and XML in combination, as the foundation of a CSCW infrastructure has been proved. Two consistency policies were implemented utilizing HLA, a strict and an optimistic, in the distributed collaborative environment. Their performance was compared to the performance of a totally relaxed policy, in various collaboration situations.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 136 p.
Series
Trita-IMIT. LECS, ISSN 1651-4076 ; 2005:11
Keyword
CSCW, collaboration, HLA, distributed simulation, consistency management, CSCW services, modelling and simulation
National Category
Information Science
Identifiers
urn:nbn:se:kth:diva-571 (URN)
Presentation
2005-12-02, sal Gemini, IMIT, Forum, Isafjordsgatan 39, Kist, Stockholm, 13:00
Supervisors
Note
QC 20101222Available from: 2005-12-28 Created: 2005-12-28 Last updated: 2010-12-22Bibliographically approved

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