In the Service Oriented Architecture (SOA) services are computational elements that are published, discovered, consumed and aggregated across platform and organizational borders. The most commonly used technology to achieve SOA are Web Services (WSs). This is due to standardization process (WSDL, SOAP, UDDI standards) and a wide range of available infrastructure and tools. A very interesting aspect of WSs is their composeability. WSs can be easily aggregated into complex workflows, called Composite Web Services (CWSs). These compositions of services enable further reuse and in this way new, even more complex, systems are built.<p>Although there are many languages to specify or implement workflows, in the service-oriented systems BPEL (Business Process Execution Language) is widely accepted. With this language WSs are orchestrated and then executed with specialized engines (like ActiveBPEL). While being very popular, BPEL has certain limitations in monitoring and optimizing executions of CWSs. It is very hard with this language to adapt CWSs to changes in the performance of used WSs, and also to select the optimal way to execute a CWS. <p>To overcome the limitations of BPEL, I present a model-aware approach to execute CWSs. To achieve the model awareness the Coloured Petri Nets (CPN) formalism is considered as the basis of the execution of CWSs. This is different than other works in using formal methods in CWSs, which are restricted to purposes like verification or checking of correctness. Here the formal and unambiguous notation of the CPN is used to model, analyze, execute and monitor CWSs. Furthermore this approach to execute CWSs, which is based on the CPN formalism, is implemented in the model-aware middleware. It is also demonstrated how the middleware improves the performance and reliability of CWSs.

In the Service Oriented Architecture (SOA) services are computational elements that are published, discovered, consumed and aggregated across platform and organizational borders. The most commonly used technology to achieve SOA are Web Services (WSs). This is due to standardization process (WSDL, SOAP, UDDI standards) and a wide range of available infrastructure and tools. A very interesting aspect of WSs is their composeability. WSs can be easily aggregated into complex workflows, called Composite Web Services (CWSs). These compositions of services enable further reuse and in this way new, even more complex, systems are built.<p>Although there are many languages to specify or implement workflows, in the service-oriented systems BPEL (Business Process Execution Language) is widely accepted. With this language WSs are orchestrated and then executed with specialized engines (like ActiveBPEL). While being very popular, BPEL has certain limitations in monitoring and optimizing executions of CWSs. It is very hard with this language to adapt CWSs to changes in the performance of used WSs, and also to select the optimal way to execute a CWS. <p>To overcome the limitations of BPEL, I present a model-aware approach to execute CWSs. To achieve the model awareness the Coloured Petri Nets (CPN) formalism is considered as the basis of the execution of CWSs. This is different than other works in using formal methods in CWSs, which are restricted to purposes like verification or checking of correctness. Here the formal and unambiguous notation of the CPN is used to model, analyze, execute and monitor CWSs. Furthermore this approach to execute CWSs, which is based on the CPN formalism, is implemented in the model-aware middleware. It is also demonstrated how the middleware improves the performance and reliability of CWSs.

Reducing the complexity in information systems is a main concern on which researchers work. Separation of concerns, also known as the principle of ‘divide and conquer’, has long time been a strategy for dealing with complexity. Two examples of the application of this principle in the area of information system design are the break out the data management into Database Management Systems(DBMSs) and the separation of the business logic from the application logic into Business Process Management Systems (BPMSs). However, separation of cross-cutting concerns from the core-concern of a business process is not yet supported in the Business Process Management (BPM) area. Aspect Oriented principle recommends such a separation. When looking into the business process, several concerns, such as security and privacy, can be identified. Therefore, a formal model that provides a foundation for enabling BPMSs to support separation of concerns in BPM area is needed. This thesis provides a formal model for dealing with separation of concerns in the BPM area. Implementing this model in BPMSs would facilitate the design and implementation of business processes with a lower level of complexity, which in turn would reduce the costs associated with BPM projects. The thesis starts with a literature review on aspect orientation both in programming and in the BPM areas. Based on this study, a list of requirements for an Aspect Oriented Service for BPMSs is compiled. Then a formal model for such a service, fulfilling a set of these requirements, is designed using Coloured Petri Nets and implemented in CPN Tools. The model is evaluated through the execution of a number of scenarios. The solution is also validated through an industrial case study. The results of the case study are presented the direction for future work outlined. The case study demonstrates that separation of concerns through aspect orientation does indeed reduce the complexity of business process models.

A fairly general model of the elevator system is presented. Coloured Petri Nets (CPN) and CPN tools are adopted as modeling tools. The model, which is independent of the number of floors and elevators, covers different stages of the elevator system in substantial detail. The model assists simulation-based analysis of different algorithms and rules which govern real elevator systems. The results prove the compatibility and applicability of this model in various situations and demonstrate the expressive power and convenience of CPN. / Thesis / Master of Applied Science (MASc)

Systems biology aims to describe and understand biology at a global scale where biological systems function as a result of complex mechanisms that happen at several scales. Modelling and simulation are computational tools that are invaluable for description, understanding and prediction these mechanisms in a quantitative and integrative way. Thus multi-scale methods that couple the design, simulation and analysis of models spanning several spatial and temporal scales is becoming a new emerging focus of systems biology. This thesis uses an exemplar – Planar cell polarity (PCP) signalling – to illustrate a generic approach to model biological systems at different spatial scales, using the new concept of Hierarchically Coloured Petri Nets (HCPN). PCP signalling refers to the coordinated polarisation of cells within the plane of various epithelial tissues to generate sub-cellular asymmetry along an axis orthogonal to their apical-basal axes. This polarisation is required for many developmental events in both vertebrates and non-vertebrates. Defects in PCP in vertebrates are responsible for developmental abnormalities in multiple tissues including the neural tube, the kidney and the inner ear. In Drosophila wing, PCP is seen in the parallel orientation of hairs that protrude from each of the approximately 30,000 epithelial cells to robustly point toward the wing tip. This work applies HCPN to model a tissue comprising multiple cells hexagonally packed in a honeycomb formation in order to describe the phenomenon of Planar Cell Polarity (PCP) in Drosophila wing. HCPN facilitate the construction of mathematically tractable, compact and parameterised large-scale models. Different levels of abstraction that can be used in order to simplify such a complex system are first illustrated. The PCP system is first represented at an abstract level without modelling details of the cell. Each cell is then sub-divided into seven virtual compartments with adjacent cells being coupled via the formation of intercellular complexes. A more detailed model is later developed, describing the intra- and inter-cellular signalling mechanisms involved in PCP signalling. The initial model is for a wild-type organism, and then a family of related models, permitting different hypotheses to be explored regarding the mechanisms underlying PCP, are constructed. Among them, the largest model consists of 800 cells which when unfolded yields 164,000 places (each of which is described by an ordinary differential equation). This thesis illustrates the power and validity of the approach by showing how the models can be easily adapted to describe well-documented genetic mutations in the Drosophila wing using the proposed approach including clustering and model checking over time series of primary and secondary data, which can be employed to analyse and check such multi-scale models similar to the case of PCP. The HCPN models support the interpretation of biological observations reported in literature and are able to make sensible predictions. As HCPN model multi-scale systems in a compact, parameterised and scalable way, this modelling approach can be applied to other large-scale or multi-scale systems.

Coloured Petri nets (CPN) are an extension of a standard place-transition Petri nets (P/T PN). Every token and place have its type (and eventually a value) and various inscriptions can be inserted into the net. CPN excel with great readibility and expresivity. At the same time, they carry a well-defined formal basis, which eases its computer simulation and allows limited verification of certain attributes to be performed. Motivation for doing this project is the simple fact that currently only one public software tool is available for CPN creation and simulation - CPNTools developed on the Aarhus university. The program, however, is quite complicated and hard to handle for an unexperienced user. The goal is to research capabilities and properties of both CPNs and CPNTools and on this basis design and implement a didactic application with swift and intuitive interface that helps users without deeper theoretical insight to get a grasp of the problematics.

<p> This thesis presents a new modelling technique for the complex current system. It integrates object-oriented methodology into Petri Nets formalism.</p> <p> Petri Nets are used for modelling concurrent systems. They have natural graphical representation as well as formal specifications. They have been successfully used in various industrial applications. But with the development of distributed and network systems, their traditional weakness, namely their inadequate support for compositionality, is a big obstacle to their practical use for large, complex systems. To address this problem, we introduce the Object-Oriented Coloured Petri Nets (OO-CPN), which integrates the powerful modularity of an object-oriented paradigm into Petri Nets formalism. OO-CPN is based on Coloured Petri Nets and supports the concepts of object, class, inheritance and polymorphism.</p> / Thesis / Master of Science (MSc)

Nous présentons dans ce travail de thèse des approches pour la spécification et la vérificationdes systèmes temporisés. La première partie concerne une méthode de spécification enutilisant les diagrammes états-transitions pour modéliser un système donné en partant d’unedescription textuelle. Cette méthode guide l’utilisateur pour le développement de la modélisation.Elle comporte plusieurs étapes et utilise des observateurs d’états et des événements afind’engendrer le diagramme états-transitions. Un outil qui implémente les différentes étapes de laméthode de spécification pour une application semi-automatique est présenté. La seconde partieconcerne une traduction des diagrammes états-transitions vers les réseaux de Petri colorés, cequi permet d’utiliser les méthodes de vérification. Nous prenons en considération dans cette traductionun ensemble important des éléments syntaxiques des diagrammes états-transitions, telsque la concurrence, la hiérarchie, etc. Un outil qui implémente la traduction pour un passageautomatique des diagrammes états-transitions vers les réseaux de Petri colorés est en cours de développement.La dernière partie concerne l’intégration des contraintes temporelles dans les deuxapproches précédentes. Nous définissons des annotations pour les diagrammes états-transitionsdont nous fournissons la syntaxe et la sémantique. Ces annotations seront ensuite utilisées dansla méthode de spécification et la traduction. Le but est de proposer des annotations faciles àcomprendre et à utiliser avec une syntaxe qui prend en compte des contraintes parmi les plusutilisées. / In order to specify and verify timed systems, we present in this thesis approaches using UMLstate machines and coloured Petri nets. Our first approach is a specification method that takesinto account a textual description of the system and generates the corresponding state machinediagram. This method helps a non-expert user to model a system in a structural way. We presenta tool that implements the specification method. Our second approach is the translation of UMLstate machine diagrams to coloured Petri nets diagrams. In this approach we take into account animportant set of UML state machine elements that allows the modelling of concurrent systems,etc. A tool that implements the approach and allows us to automate the translation is beingdeveloped. Finally, the last approach is the integration of time constraints in our specificationmethod and in our translation. We propose a set of annotations to model time in state machinediagrams, and we define the corresponding syntax and semantics.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / The demand for electricity grows in the same way as the consumers requirement for an uninterrupted supply. Many reliability indices are applied by regulatory agencies, utilities and consumers for measuring the power systems reliability. The improvement of such indices has been required by regulatory agencies and pursued by energy distributors. Therefore, the application of automatic restauration systems has gained relevance as a support tool for control center operators for a quick and secure restauration of faulty electric networks. This work proposes two contributions to the restoration process of radial power system networks. The former is a multiobjective algorithm for effective switch placement in distribution networks. Multiobjective optimization techniques are applied to achieve a set of non-dominated solutions rather than an unique one. Therefore, the decision making for switch placement is eased by the flexibility given from the multiple solutions. The latter contribution is a model for automatic restoration of power distribution networks adaptable to the network topology changes and able to ensure the operational security of the power system network. The proposed model is based on coloured Petri nets as the modelling tool. Reusability and extensibility features have been pursued and implemented on the proposed model. As a result, the needed time to restore faulty power system networks is reduced without compromising its operational security. Case studies are presented demonstrating the benefits to the power system distribution utilities obtained with the deployment of the proposed tools to improve the reliability of the power system networks. / A demanda por energia elÃtrica cresce e de igual modo a exigÃncia dos consumidores pela continuidade do seu fornecimento. Diversos Ãndices de confiabilidade sÃo utilizados por agÃncias reguladoras, concessionÃrias e consumidores para aferir a continuidade dos sistemas elÃtricos de potÃncia. A melhoria de tais Ãndices vem sendo requisitada por agÃncias reguladoras e perseguida pelas concessionÃrias de energia. Para tanto, o uso de sistemas de restauraÃÃo automÃtica vem ganhando destaque como uma ferramenta de apoio a operadores de centros de controle para a restauraÃÃo rÃpida e segura de redes elÃtricas em situaÃÃes de falta. Este trabalho apresenta duas contribuiÃÃes para a restauraÃÃo automÃtica de redes radiais de distribuiÃÃo de energia. A primeira consiste em um algoritmo para o posicionamento eficiente de chaves telecontroladas em redes de distribuiÃÃo. TÃcnicas de otimizaÃÃo multiobjetivo sÃo aplicadas para obter-se como resultado um conjunto de soluÃÃes nÃo-dominadas ao invÃs de uma Ãnica soluÃÃo. Com isso, a tomada de decisÃo para o posicionamento eficiente de chaves na rede elÃtrica à facilitado pela flexibilidade das mÃltiplas soluÃÃes oferecidas pelo algoritmo proposto. A segunda contribuiÃÃo do trabalho consiste em um modelo para restauraÃÃo automÃtica da rede de distribuiÃÃo de energia adaptÃvel Ãs mudanÃas de topologia e que garante a seguranÃa operacional da rede elÃtrica. O modelo proposto fundamentou-se em Redes de Petri Coloridas como ferramenta de modelagem. CaracterÃsticas de reusabilidade e extensibilidade foram buscadas e implementadas no modelo proposto. Como resultado, o tempo necessÃrio para restaurar redes elÃtricas em condiÃÃo de falta à reduzido sem comprometer a seguranÃa do sistema elÃtrico. Estudos de caso sÃo apresentados evidenciando os benefÃcios para concessionÃrias de distribuiÃÃo de energia com a implementaÃÃo das ferramentas propostas para melhoria da confiabilidade da rede elÃtrica.

A arquitetura IP Multimedia Subsystem, proposta pelo consórcio 3rd Generation Partnership Project como base para o suporte à convergência entre telefonia móvel e a Internet, define uma série de elementos arquiteturais, entre os quais, o componente Call Session Control Function e o protocolo Session Initiation Protocol. Session Initiation Protocol é um protocolo da camada de aplicação utilizado para estabelecer, modificar e terminar sessões multimídia entre dispositivos. Em redes baseadas na arquitetura IP Multimedia Subsystem, o Session Initiation Protocol é o responsável pela comunicação entre dispositivos e a rede, e entre os componentes responsáveis pelo gerenciamento de sessão. Nos últimos anos, estudos detectaram degradação de desempenho em redes baseadas na arquitetura IP Multimedia Subsystem em função das características centralizadas do Session Initiation Protocol e dos componentes de gerenciamento de sessão. Este trabalho apresenta uma arquitetura distribuída para redes baseadas em IP Multimedia Subsystem, tendo como fundamento o paradigma de computação paralela baseado em espaço de tuplas onde os servidores são organizados em uma rede P2P, com objetivo de prover uma infraestrutura escalável e tolerante a falhas. A validação da arquitetura em termos de desempenho e escalabilidade se deu através de modelagem formal e simulação com Redes de Petri Coloridas. / The IP Multimedia Subsystem architecture, proposed by the 3rd Generation Partnership Project consortium as basis to support the convergence between mobile networks and the Internet, defines a set of architectural elements, among them, the Call Session Control Function and the Session Initiation Protocol. The Session Initiation Protocol is an application layer protocol used to establish, modify and terminate sessions between devices. On the IP multimedia subsystem based network, the Session Initiation Protocol play a key role on the communication between devices and the network, and between session management components. In the last years, studies have detected a performance bottleneck on IP multimedia subsystem networks due to centralized characteristic of the Session Initiation Protocol and in Session Control components. This work shows a distributed architecture for IP Multimedia Subsystem networks based on the tuple space paradigm, and the servers structured in a P2P network, aiming to achieve a scalable and fault-tolerant infrastructure. The validation of the architecture on the performance and scalability took place through the Coloured Petri Net formal modeling and simulation.