Semantic web service architecture for simulation model reuse

COTS simulation packages (CSPs) have proved popular in an industrial setting with a number of software vendors. In contrast, options for re-using existing models seem more limited. Re-use of simulation component models by collaborating organizations is restricted by the same semantic issues however that restrict the inter-organization use of web services. The current representations of web components are predominantly syntactic in nature lacking the fundamental semantic underpinning required to support discovery on the emerging semantic web. Semantic models, in the form of ontology, utilized by web service discovery and deployment architecture provide one approach to support simulation model reuse. Semantic interoperation is achieved through the use of simulation component ontology to identify required components at varying levels of granularity (including both abstract and specialized components). Selected simulation components are loaded into a CSP, modified according to the requirements of the new model and executed. The paper presents the development of ontology, connector software and web service discovery architecture in order to understand how such ontology are created, maintained and subsequently used for simulation model reuse. The ontology is extracted from health service simulation - comprising hospitals and the National Blood Service. The ontology engineering framework and discovery architecture provide a novel approach to inter- organization simulation, uncovering domain semantics and adopting a less intrusive interface between participants. Although specific to CSPs the work has wider implications for the simulation community

A distributed simulation methodology for large-scale hybrid modelling and simulation of emergency medical services

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonHealthcare systems are traditionally characterised by complexity and heterogeneity. With the continuous increase in size and shrinkage of available resources, the healthcare sector faces the challenge of delivering high quality services with fewer resources. Healthcare organisations cannot be seen in isolation since the services of one such affects the performance of other healthcare organisations. Efficient management and forward planning, not only locally but rather across the whole system, could support healthcare sector to overcome the challenges. An example of closely interwoven organisations within the healthcare sector is the emergency medical services (EMS). EMS operate in a region and usually consist of one ambulance service and the available accident and emergency (A&E) departments within the coverage area. EMS provide, mainly, pre-hospital treatment and transport to the appropriate A&E units. The life-critical nature of EMS demands continuous systems improvement practices. Modelling and Simulation (M&S) has been used to analyse either the ambulance services or the A&E departments. However, the size and complexity of EMS systems constitute the conventional M&S techniques inadequate to model the system as a whole. This research adopts the approach of distributed simulation to model all the EMS components as individual and composable simulations that are able to run as standalone simulation, as well as federates in a distributed simulation (DS) model. Moreover, the hybrid approach connects agent-based simulation (ABS) and discrete event simulation (DES) models in order to accommodate the heterogeneity of the EMS components. The proposed FIELDS Framework for Integrated EMS Large-scale Distributed Simulation supports the re-use of existing, heterogeneous models that can be linked with the High Level Architecture (HLA) protocol for distributed simulation in order to compose large-scale simulation models. Based on FIELDS, a prototype ABS-DES distributed simulation EMS model was developed based on the London EMS. Experiments were conducted with the model and the system was tested in terms of performance and scalability measures to assess the feasibility of the proposed approach. The yielded results indicate that it is feasible to develop hybrid DS models of EMS that enables holistic analysis of the system and support model re-use. The main contributions of this thesis is a distributed simulation methodology that derived along the process of conducting this project, the FIELDS framework for hybrid EMS distributed simulation studies that support re-use of existing simulation models, and a prototype distributed simulation model that can be potentially used as a tool for EMS analysis and improvement.MATCH Programm

On the Role of Assertions for Conceptual Modeling as Enablers of Composable Simulation Solutions

This research provides a much needed systematic review of the roles that assertions play in model composability and simulation interoperability. In doing so, this research contributes a partial solution to one of the problems of model composability and simulation interoperability—namely, why do simulation systems fail to achieve the maximum level of interoperability possible? It demonstrates the importance of the assertions that are made during model development and simulation implementation, particularly as they reflect the unique viewpoint of each developer or user. It hypothesizes that it is possible to detect composability conflicts by means of a four-step process developed by the author for capturing and comparing assertions. It demonstrates the process using a well understood example problem—the Falling Body Problem—developing a formal model of assertion, a strategy for assertion comparison, an inventory of forces, and a catalog of significant assertions that might be made for each term in the solution to the problem. Finally, it develops a software application to implement the strategy for comparing sets of assertions. The software successfully detects potential conflicts between ontologies that were otherwise determined to be ontologically consistent, thus proving the hypothesis

Semantic Virtual Factory supporting interoperable modelling and evaluation of production systems

Modelling, simulation and evaluation of manufacturing systems are relevant activities that may strongly impact on the competitiveness of production enterprises both during the design and the operational phases. This paper addresses the application of a semantic data model for virtual factories to support the design and the performance evaluation of manufacturing systems, while exploiting the interoperability between various Digital Enterprise Technology tools. The paper shows how a shared ontology-based framework can be used to generate consistent 3D virtual environments and discrete event simulation models, demonstrating this way how the proposed solution can provide an interoperable backbone for heterogeneous software tools

Simulation Software as a Service and Service-Oriented Simulation Experiment

Simulation software is being increasingly used in various domains for system analysis and/or behavior prediction. Traditionally, researchers and field experts need to have access to the computers that host the simulation software to do simulation experiments. With recent advances in cloud computing and Software as a Service (SaaS), a new paradigm is emerging where simulation software is used as services that are composed with others and dynamically influence each other for service-oriented simulation experiment on the Internet. The new service-oriented paradigm brings new research challenges in composing multiple simulation services in a meaningful and correct way for simulation experiments. To systematically support simulation software as a service (SimSaaS) and service-oriented simulation experiment, we propose a layered framework that includes five layers: an infrastructure layer, a simulation execution engine layer, a simulation service layer, a simulation experiment layer and finally a graphical user interface layer. Within this layered framework, we provide a specification for both simulation experiment and the involved individual simulation services. Such a formal specification is useful in order to support systematic compositions of simulation services as well as automatic deployment of composed services for carrying out simulation experiments. Built on this specification, we identify the issue of mismatch of time granularity and event granularity in composing simulation services at the pragmatic level, and develop four types of granularity handling agents to be associated with the couplings between services. The ultimate goal is to achieve standard and automated approaches for simulation service composition in the emerging service-oriented computing environment. Finally, to achieve more efficient service-oriented simulation, we develop a profile-based partitioning method that exploits a system’s dynamic behavior and uses it as a profile to guide the spatial partitioning for more efficient parallel simulation. We develop the work in this dissertation within the application context of wildfire spread simulation, and demonstrate the effectiveness of our work based on this application

An Agile Roadmap for Live, Virtual and Constructive-Integrating Training Architecture (LVC-ITA): A Case Study Using a Component based Integrated Simulation Engine

Conducting seamless Live Virtual Constructive (LVC) simulation remains the most challenging issue of Modeling and Simulation (M&S). There is a lack of interoperability, limited reuse and loose integration between the Live, Virtual and/or Constructive assets across multiple Standard Simulation Architectures (SSAs). There have been various theoretical research endeavors about solving these problems but their solutions resulted in complex and inflexible integration, long user-usage time and high cost for LVC simulation. The goal of this research is to provide an Agile Roadmap for the Live Virtual Constructive-Integrating Training Architecture (LVC-ITA) that will address the above problems and introduce interoperable LVC simulation. Therefore, this research describes how the newest M&S technologies can be utilized for LVC simulation interoperability and integration. Then, we will examine the optimal procedure to develop an agile roadmap for the LVC-ITA. In addition, this research illustrated a case study using an Adaptive distributed parallel Simulation environment for Interoperable and reusable Model (AddSIM) that is a component based integrated simulation engine. The agile roadmap of the LVC-ITA that reflects the lessons learned from the case study will contribute to guide M&S communities to an efficient path to increase interaction of M&S simulation across systems

Software Frameworks for Model Composition

A software framework is an architecture or infrastructure intended to enable the integration and interoperation of software components. Specialized types of software frameworks are those specifically intended to support the composition of models or other components within a simulation system. Such frameworks are intended to simplify the process of assembling a complex model or simulation system from simpler component models as well as to promote the reuse of the component models. Several different types of software frameworks for model composition have been designed and implemented; those types include common library, product line architecture, interoperability protocol, object model, formal, and integrative environment. The various framework types have different components, processes for composing models, and intended applications. In this survey the fundamental terms and concepts of software frameworks for model composition are presented, the different types of such frameworks are explained and compared, and important examples of each type are described

Composable simulation models and their formal validation

Ph.DDOCTOR OF PHILOSOPH

Modularization Approaches in the Context of Monolithic Simulations

Qualitätsmerkmale eines Software-Systems wie Zuverlässigkeit oder Performanz können über dessen Erfolg oder Scheitern entscheiden. Diese Qualitätsmerkmale können im klassischen Software-Ingenieurswesen erst bestimmt werden, wenn der Entwurfsprozess bereits vollendet ist und Teile des Software-Systems implementiert sind. Computer-Simulationen erlauben es jedoch Schätzungen dieser Werte schon während des Software-Entwurfs zu bestimmen. Simulationen werden erstellt um bestimmte Aspekte eines Systems zu analysieren. Die Repräsentation des Systems ist auf diese Analyse spezialisiert. Diese Spezialisierung resultiert oft in einer monolithischen Struktur der Simulation. Solch eine Struktur kann jedoch die Wartbarkeit der Simulation negativ beeinflussen und das Verständnis und die Wiederverwendbarkeit der Repräsentation des Systems verschlechtern. Die Nachteile einer monolithischen Struktur können durch das Konzept der Modularisierung reduziert werden. In diesem Ansatz wird ein Problem in kleinere Teilprobleme zerlegt. Diese Zerlegung ermöglicht ein besseres Veständnis und eine bessere Handhabung der Teilprobleme. In dieser Arbeit wird ein Ansatz präsentiert, um die Kopplung von neu entwickelten oder bereits existierenden Simulationen zu einer modularen Simulation zu beschreiben. Dieser Ansatz besteht aus einer Domänenspezifischen Sprache (DSL), die mit modellgetriebenen Technologien entwickelt wird. Die DSL wird in einer Fallstudie angewendet, um die Kopplung von zwei Simulationen zu beschreiben. Weiterhin wird die Kopplung dieser Simulationen mit einem existierenden Kopplungsansatz gemäß der erzeugten Beschreibung manuell implementiert. In dieser Fallstudie wird die Vollständigkeit der Fähigkeit der DSL untersucht, die Kopplung von mehreren Simulation zu einer modularen Simulation zu beschreiben. Weiterhin wird die Genauigkeit des Modularisierungsansatzes bezüglich der Verhaltensbewahrung der modularen Simulation gegenüber der monolithischen Version evaluiert. Hierfür werden die Resultate der modularen Simulation mit denen der monolithischen Version verglichen. Zudem wird die Skalierbarkeit des Ansatzes durch die Betrachtung der Ausführungszeiten untersucht, wenn mehrere Simulationen gekoppelt werden. Außerdem wird der Effekt der Modularisierung auf die Ausführungszeit in Relation zur monolithischen Simulation betrachtet. Die erhaltenen Resultate zeigen, dass die Kopplung der beiden Simulationen der Fallstudie, mit der DSL beschrieben werden kann. Die Resultate bezüglich der Evaluation der Genauigkeit weisen Probleme bei der Interaktion der Simulationen mit dem Kopplungsansatz auf. Nichts desto trotz bleibt das Verhalten der monolithischen Simulation in der modularen Version insgesamt erhalten. Die Evaluation zeigt, dass die modulare Simulation eine Erhöhung der Ausführungszeit im Vergleich zur monolithischen Version erfährt. Zudem deutet die Analyse der Skalierbarkeit darauf hin, dass die Ausführungszeit der modularen Simulation nicht exponentiell mit der Anzahl der gekoppelten Simulationen wächst

Needs of Service Identification for Service-Oriented Business Process Management

Since the trend of adopting SOA into enterprise applications, the needs for definition and identification of services have been recognized. There is a growing body of research carried out on the identification of different types of services. Identifying right granularity services is important: if the service is of large size, it goes against the reusability principle of SOA, whereas if the service is of small size, then it causes unnecessary computing power for implementing any business functions. Without a formal (semi)- automatic approach to identify services, it is difficult in migrating existing systems into service-oriented systems. This paper explores the need for service identification for service-oriented business process management systems. The current approaches, techniques and methods of service identification are reviewed, and limitations of the each approach is analysed. New requirements and techniques are demonstrated in creating improved dynamic services with consideration for interoperability, modularity, reusability within information environment