Towards semantics-driven modelling and simulation of context-aware manufacturing systems

Systems modelling and simulation are two important facets for thoroughly and effectively analysing manufacturing processes. The ever-growing complexity of the latter, the increasing amount of knowledge, and the use of Semantic Web techniques adhering meaning to data have led researchers to explore and combine together methodologies by exploiting their best features with the purpose of supporting manufacturing system's modelling and simulation applications. In the past two decades, the use of ontologies has proven to be highly effective for context modelling and knowledge management. Nevertheless, they are not meant for any kind of model simulations. The latter, instead, can be achieved by using a well-known workflow-oriented mathematical modelling language such as Petri Net (PN), which brings in modelling and analytical features suitable for creating a digital copy of an industrial system (also known as "digital twin"). The theoretical framework presented in this dissertation aims to exploit W3C standards, such as Semantic Web Rule Language (SWRL) and Web Ontology Language (OWL), to transform each piece of knowledge regarding a manufacturing system into Petri Net modelling primitives. In so doing, it supports the semantics-driven instantiation, analysis and simulation of what we call semantically-enriched PN-based manufacturing system digital twins. The approach proposed by this exploratory research is therefore based on the exploitation of the best features introduced by state-of-the-art developments in W3C standards for Linked Data, such as OWL and SWRL, together with a multipurpose graphical and mathematical modelling tool known as Petri Net. The former is used for gathering, classifying and properly storing industrial data and therefore enhances our PN-based digital copy of an industrial system with advanced reasoning features. This makes both the system modelling and analysis phases more effective and, above all, paves the way towards a completely new field, where semantically-enriched PN-based manufacturing system digital twins represent one of the drivers of the digital transformation already in place in all companies facing the industrial revolution. As a result, it has been possible to outline a list of indications that will help future efforts in the application of complex digital twin support oriented solutions, which in turn is based on semantically-enriched manufacturing information systems. Through the application cases, five key topics have been tackled, namely: (i) semantic enrichment of industrial data using the most recent ontological models in order to enhance its value and enable new uses; (ii) context-awareness, or context-adaptiveness, aiming to enable the system to capture and use information about the context of operations; (iii) reusability, which is a core concept through which we want to emphasize the importance of reusing existing assets in some form within the industrial modelling process, such as industrial process knowledge, process data, system modelling primitives, and the like; (iv) the ultimate goal of semantic Interoperability, which can be accomplished by adding data about the metadata, linking each data element to a controlled, shared vocabulary; finally, (v) the impact on modelling and simulation applications, which shows how we could automate the translation process of industrial knowledge into a digital manufacturing system and empower it with quantitative and qualitative analytical technics

La vérification de patrons de workflow métier basés sur les flux de contrôle : une approche utilisant les systèmes à base de connaissances

This thesis tackles the problem of modelling semantically rich business workflow templates and proposes a process for developing workflow templates. The objective of the thesis is to transform a business process into a control flow-based business workflow template that guarantees syntactic and semantic validity. The main challenges are: (i) to define formalism for representing business processes; (ii) to establish automatic control mechanisms to ensure the correctness of a business workflow template based on a formal model and a set of semantic constraints; and (iii) to organize the knowledge base of workflow templates for a workflow development process. We propose a formalism which combines control flow (based on Coloured Petri Nets (CPNs)) with semantic constraints to represent business processes. The advantage of this formalism is that it allows not only syntactic checks based on the model of CPNs, but also semantic checks based on Semantic Web technologies. We start by designing an OWL ontology called the CPN ontology to represent the concepts of CPN-based business workflow templates. The design phase is followed by a thorough study of the properties of these templates in order to transform them into a set of axioms for the CPN ontology. In this formalism, a business process is syntactically transformed into an instance of the CPN ontology. Therefore, syntactic checking of a business process becomes simply verification by inference, by concepts and by axioms of the CPN ontology on the corresponding instance.Cette thèse traite le problème de la modélisation des patrons de workflow sémantiquement riche et propose un processus pour développer des patrons de workflow. L'objectif est de transformer un processus métier en un patron de workflow métier basé sur les flux de contrôle qui garantit la vérification syntaxique et sémantique. Les défis majeurs sont : (i) de définir un formalisme permettant de représenter les processus métiers; (ii) d'établir des mécanismes de contrôle automatiques pour assurer la conformité des patrons de workflow métier basés sur un modèle formel et un ensemble de contraintes sémantiques; et (iii) d’organiser la base de patrons de workflow métier pour le développement de patrons de workflow. Nous proposons un formalisme qui combine les flux de contrôle (basés sur les Réseaux de Petri Colorés (CPNs)) avec des contraintes sémantiques pour représenter les processus métiers. L'avantage de ce formalisme est qu'il permet de vérifier non seulement la conformité syntaxique basée sur le modèle de CPNs mais aussi la conformité sémantique basée sur les technologies du Web sémantique. Nous commençons par une phase de conception d'une ontologie OWL appelée l’ontologie CPN pour représenter les concepts de patrons de workflow métier basés sur CPN. La phase de conception est suivie par une étude approfondie des propriétés de ces patrons pour les transformer en un ensemble d'axiomes pour l'ontologie. Ainsi, dans ce formalisme, un processus métier est syntaxiquement transformé en une instance de l’ontologie

A Semantic Framework for Declarative and Procedural Knowledge

In any scientic domain, the full set of data and programs has reached an-ome status, i.e. it has grown massively. The original article on the Semantic Web describes the evolution of a Web of actionable information, i.e.\ud information derived from data through a semantic theory for interpreting the symbols. In a Semantic Web, methodologies are studied for describing, managing and analyzing both resources (domain knowledge) and applications (operational knowledge) - without any restriction on what and where they\ud are respectively suitable and available in the Web - as well as for realizing automatic and semantic-driven work\ud ows of Web applications elaborating Web resources.\ud This thesis attempts to provide a synthesis among Semantic Web technologies, Ontology Research, Knowledge and Work\ud ow Management. Such a synthesis is represented by Resourceome, a Web-based framework consisting of two components which strictly interact with each other: an ontology-based and domain-independent knowledge manager system (Resourceome KMS) - relying on a knowledge model where resource and operational knowledge are contextualized in any domain - and a semantic-driven work ow editor, manager and agent-based execution system (Resourceome WMS).\ud The Resourceome KMS and the Resourceome WMS are exploited in order to realize semantic-driven formulations of work\ud ows, where activities are semantically linked to any involved resource. In the whole, combining the use of domain ontologies and work ow techniques, Resourceome provides a exible domain and operational knowledge organization, a powerful engine for semantic-driven work\ud ow composition, and a distributed, automatic and\ud transparent environment for work ow execution

Pattern based software development

Tese de Doutoramento em InformáticaSeveral types of approaches support the software development process. Special interest should be paid to model driven development methodologies, of which Model Driven Architecture (MDA) is a main example. The usage of software models in these methodologies improves the quality of the produced solutions. On the one hand, models are formal artifacts to represent the software to develop. On the other hand, models represented in computable formats are amenable to the application of systematic transformation techniques, in order to produce other models or source code as output. The architectural models used in the MDA are derived from requirement specifications, and are achieved through manual processes. The negative effects of manual transformation steps are well known, since they are susceptible to interpretation errors and subjectivity. Errors resulting from this process are propagated through all of the development process, and reflected in the produced solutions. Since requirement models specify the system to be developed, naturally, they should not be disconnected from the development process itself. Formalizing requirement specifications in computable formats would enable their operationalization. Such would provide the possibility to analyze and manipulate them, and also to perform a requirement patterns inference process. Requirement patterns represent well known solutions for recurring problems, and their nature provides architectural hints. If software patterns can be derived from the requirement patterns, then through the composition of the resulting software patterns, architectural models can be achieved. As a result, requirements models will be better integrated into the MDA chain, thus extending the advantages of the MDA to requirement models, providing a software development process which starts from requirements and through rigorous transformations results in software solutions. This work presents an approach that aims to provide such an integration of requirements models into theMDA. The approach starts with the formalization of software requirements in a controlled natural language. The requirements are then transformed into an intermediary representation (namely, an ontology), with support for information extraction. Such makes it possible to perform requirement pattern inference, in order to understand, at a higher level of abstraction, the features required in the software solution. Associating the requirement patterns with software patterns, makes it possible to instantiate and compose such patterns, in order to produce architectural artifacts as output. The presented approach is supported by a tool, designed to support the several steps of the approach. Furthermore, the tool provides the required automation level to produce the architectural models. Two validation studies and a case study in the eCommerce domain are also presented, in order to illustrate the viability of both the tool and the approach.Diferentes tipos de abordagens suportam o processo de desenvolvimento de software. Especial interesse deve ser dado às metodologias baseadas em modelos, das quais a Model Driven Architecture (MDA) é um exemplo relevante. O uso de modelos de software nestas metodologias melhora a qualidade das soluções obtidas. Por um lado, os modelos são artefactos formais para representar o software a ser desenvolvido. Por outro lado, os modelos representados em formatos computáveis podem ser manipulados utilizando técnicas de transformação sistemáticas, de modo a obter como resultado outros modelos, ou código fonte. Os modelos arquitecturais usados na MDA derivam das especificações de requisitos, sendo obtidos através de processos manuais. O impacto negativo da aplicação de transformações manuais é bem conhecido, uma vez que estas são suscetíveis a erros de interpretação e subjectividade. Os erros resultantes deste processo são propagados através do processo de desenvolvimento, e reflectem-se nas soluções produzidas. Uma vez que os modelos de requisitos especificam os sistemas a desenvolver, naturalmente, estes não devem estar desligados do processo de desenvolvimento. A formalização dos modelos de requisitos em formatos computáveis possibilitaria a sua operacionalização. Tal forneceria a capacidade de analisar e manipular os modelos, e também suportaria a inferência de padrões de requisitos. Padrões de requisitos representam soluções bem conhecidas, para problemas recorrentes, e a sua natureza fornece indicações arquitecturais. Se for possível obter padrões de software, através de padrões de requisitos, então através de um processo de composição de padrões de software, é possível obter modelos arquitecturais. Como resultado, os padrões de requisitos podem ser integrados na cadeia MDA, estendendo assim as vantagens desse processo aos modelos de requisitos, e obtendo um processo de desenvolvimento que inicia nos requisitos, e fornece transformações rigorosas que levam a soluções de software. Este trabalho apresenta uma abordagem que tem como objectivo fornecer tal integração de modelos de requisitos, na MDA. A abordagem inicia com a formalização de requisitos de software numa linguagem natural controlada. Os requisitos são então transformados numa representação intermedia (nomeadamente, uma ontologia), com suporte para extração de informação. Tal fornece a possibilidade de efetuar inferência de padrões de requisitos, de modo a perceber, a um alto nível de abstração, as funcionalidades necessárias nas soluções de software. Associando os padrões de requisitos com padrões de software, é possível instanciar e compor esses padrões, de modo a obter artefactos arquitecturais. A abordagem apresentada ´e suportada por uma ferramenta, desenhada para suportar os diferentes passos da abordagem. Para além disso, a ferramenta fornece a automação necessária para produzir os modelos arquiteturais. São também apresentados dois estudos de validação e um caso de estudo na área de e-Commerce, de modo a ilustrar a viabilidade da abordagem e da ferramenta

Quality of process modeling using BPMN: a model-driven approach

Dissertação para obtenção do Grau de Doutor em Engenharia InformáticaContext: The BPMN 2.0 specification contains the rules regarding the correct usage of the language’s constructs. Practitioners have also proposed best-practices for producing better BPMN models. However, those rules are expressed in natural language, yielding sometimes ambiguous interpretation, and therefore, flaws in produced BPMN models. Objective: Ensuring the correctness of BPMN models is critical for the automation of processes. Hence, errors in the BPMN models specification should be detected and corrected at design time, since faults detected at latter stages of processes’ development can be more costly and hard to correct. So, we need to assess the quality of BPMN models in a rigorous and systematic way. Method: We follow a model-driven approach for formalization and empirical validation of BPMN well-formedness rules and BPMN measures for enhancing the quality of BPMN models. Results: The rule mining of BPMN specification, as well as recently published BPMN works, allowed the gathering of more than a hundred of BPMN well-formedness and best-practices rules. Furthermore, we derived a set of BPMN measures aiming to provide information to process modelers regarding the correctness of BPMN models. Both BPMN rules, as well as BPMN measures were empirically validated through samples of BPMN models. Limitations: This work does not cover control-flow formal properties in BPMN models, since they were extensively discussed in other process modeling research works. Conclusion: We intend to contribute for improving BPMN modeling tools, through the formalization of well-formedness rules and BPMN measures to be incorporated in those tools, in order to enhance the quality of process modeling outcomes

Examining the Application of Modular and Contextualised Ontology in Query Expansions for Information Retrieval

This research considers the ongoing challenge of semantics-based search from the perspective of how to exploit Semantic Web languages for search in the current Web environment. The purpose of the PhD was to use ontology-based query expansion (OQE) to improve search effectiveness by increasing search precision, i.e. retrieving relevant documents in the topmost ranked positions in a returned document list. Query experiments have required a novel search tool that can combine Semantic Web technologies in an otherwise traditional IR process using a Web document collection

Goal-based Workflow Adaptation for Role-based Resources in the Internet of Things

In recent years, the Internet of Things (IoT) has increasingly received attention from the Business Process Management (BPM) community. The integration of sensors and actuators into Process-Aware Information Systems (PAIS) enables the collection of real-time data about physical properties and the direct manipulation of real-world objects. In a broader sense, IoT-aware workflows provide means for context-aware workflow execution involving virtual and physical entities. However, IoT-aware workflow management imposes new requirements on workflow modeling and execution that are outside the scope of current modeling languages and workflow management systems. Things in the IoT may vanish, appear or stay unknown during workflow execution, which renders their allocation as workflow resources infeasible at design time. Besides, capabilities of Things are often intended to be available only in a particular real-world context at runtime, e.g., a service robot inside a smart home should only operate at full speed, if there are no residents in direct proximity. Such contextual restrictions for the dynamic exposure of resource capabilities are not considered by current approaches in IoT resource management that use services for exposing device functionalities. With this work, we aim at providing the modeling and runtime support for defining such restrictions on workflow resources at design time and enabling the dynamic and context-sensitive runtime allocation of Things as workflow resources. To achieve this goal, we propose contributions to the fields of resource management, i.e., resource perspective, and workflow management in the Internet of Things (IoT), divided into the user perspective representing the workflow modeling phase and the workflow perspective representing the runtime resource allocation phase. In the resource perspective, we propose an ontology for the modeling of Things, Roles, capabilities, physical entities, and their context-sensitive interrelations. The concept of Role is used to define non-exclusive subsets of capabilities of Things. A Thing can play a certain Role only under certain contextual restrictions defined by Semantic Web Rule Language (SWRL) rules. At runtime, the existing relations between the individuals of the ontology represent the current state of interactions between the physical and the cyber world. Through the dynamic activation and deactivation of Roles at runtime, the behavior of a Thing can be adapted to the current physical context. In the user perspective, we allow workflow modelers to define the goal of a workflow activity either by using semantic queries or by specifying high-level goals from a Tropos goal model. The goal-based modeling of workflow activities provides the most flexibility regarding the resource allocation as several leaf goals may fulfill the user specified activity goal. Furthermore, the goal model can include additional Quality of Service (QoS) parameters and the positive or negative contribution of goals towards these parameters. The workflow perspective includes the Semantic Access Layer (SAL) middleware to enable the transformation of activity goals into semantic queries as well as their execution on the ontology for role-based Things. The SAL enables the discovery of fitting Things, their allocation as workflow resources, the invocation of referenced IoT services, and the continuous monitoring of the allocated Things as part of the ontology. We show the feasibility and added value of this work in relation to related approaches by evaluation within several application scenarios in a smart home setting. We compare the fulfillment of quantified criteria for IoT-aware workflow management based on requirements extracted from related research. The evaluation shows, that our approach enables an increase in the context-aware modeling of Things as workflow resources, in the query support for workflow resource allocation, and in the modeling support of activities using Things as workflow resources.:1 Introduction 15 1.1 Background 17 1.2 Motivation 17 1.3 Aim and Objective 19 1.3.1 Research Questions and Scope 19 1.3.2 Research Goals 20 1.4 Contribution 20 1.5 Outline 21 2 Background for Workflows in the IoT 23 2.1 Resource Perspective 24 2.1.1 Internet of Things 24 2.1.2 Context and Role Modeling 27 2.2 User Perspective 37 2.2.1 Goal Modeling 38 2.2.2 Tropos Goal Modeling Language 38 2.3 Workflow Perspective 39 2.3.1 Workflow Concepts 39 2.3.2 Workflow Modeling 40 2.3.3 Internet of Things-aware Workflow Management 43 2.4 Summary 44 3 Requirements Analysis and Approach 45 3.1 Requirements 45 3.1.1 IoT Resource Perspective 46 3.1.2 Workflow Resource Perspective 50 3.1.3 Relation to Research Questions 51 3.2 State of the Art Analysis 53 3.2.1 Fulfillment Criteria 54 3.2.2 IoT-aware workflow management 56 3.3 Discussion 65 3.4 Approach 70 3.4.1 Contribution to IoT-aware workflow management 71 3.5 Summary 73 4 Concept for Adaptive Workflow Activities in the IoT 75 4.1 Resource Perspective 75 4.1.1 Role-based Things 75 4.1.2 Semantic Modeling Concepts 79 4.1.3 SWRL Modeling Concepts 81 4.2 User Perspective 81 4.2.1 Semantic Queries in Workflow Activites 81 4.2.2 Goals for Workflow Activites 81 4.2.3 Mapping from Goals to Semantic Queries 82 4.3 Workflow Perspective 83 4.3.1 Workflow metamodel Extensions 83 4.3.2 Middleware for Dynamic Resource Discovery and Allocation 85 4.4 Summary 86 5 Modeling Adaptive Workflow Activities in the IoT 87 5.1 Resource Perspective 87 5.1.1 Role-based Modeling of Context-sensitive Things 87 5.1.2 Ontology Classes 90 5.1.3 Ontology Object properties 93 5.1.4 Ontology Data properties 99 5.1.5 DL-safe SWRL Rules 100 5.2 Discussion of Role Modeling Features 101 5.3 Example Application Scenario Modeling 102 5.3.1 Resource Perspective 102 5.3.2 User Perspective 105 5.3.3 Workflow Perspective 109 5.4 Summary 113 6 Architecture for Adaptive Workflow Activities in the IoT 115 6.1 Overview of the System Architecture 115 6.2 Specification of System Components 117 6.2.1 Resource Perspective 118 6.2.2 User Perspective 118 6.2.3 Workflow Perspective 118 6.3 Summary 123 7 Implementation of Adaptive Workflow Activities in the IoT 125 7.1 Resource Perspective 125 7.2 Workflow Perspective 125 7.2.1 PROtEUS 125 7.2.2 Semantic Access Layer 127 7.3 User Perspective 128 7.4 Summary 128 8 Evaluation 129 8.1 Goal and Evaluation Approach 129 8.1.1 Definition of Test Cases 130 8.2 Scenario Evaluation 134 8.2.1 Ambient Assisted Living Setting 135 8.2.2 Resource Perspective 135 8.2.3 User Perspective 137 8.2.4 Workflow Perspective 138 8.2.5 Execution of Test Cases 139 8.2.6 Discussion of Results 146 8.3 Performance Evaluation 148 8.3.1 Experimental Setup 148 8.3.2 Discussion of Results 151 8.4 Summary 152 9 Discussion 153 9.1 Comparison of Solution to Research Questions 153 9.2 Extendability of the Solutions 155 9.3 Limitations 156 10 Summary and Future Work 157 10.1 Summary of the Thesis 157 10.2 Future Work 159 Appendix 161 Example Semantic Context Model for IoT-Things 171 T-Box of Ontology for Role-based Things in the IoT 178 A-Box for Example Scenario Model 201 A-Box for Extended Example Scenario Model 21