Distributed aspect-oriented service composition for business compliance governance with public service processes

Service-Oriented Architecture (SOA) offers a technical foundation for Enterprise Application Integration and business collaboration through service-based business components. With increasing process outsourcing and cloud computing, enterprises need process-level integration and collaboration (process-oriented) to quickly launch new business processes for new customers and products. However, business processes that cross organisations’ compliance regulation boundaries are still unaddressed. We introduce a distributed aspect-oriented service composition approach, which enables multiple process clients hot-plugging their business compliance models (business rules, fault handling policy, and execution monitor) to BPEL business processes

Advance BPEL execution adaptation using QoS parameters and collaborative filtering techniques

Στην παρούσα εργασία, προτείνονται πλαίσια που περιλαμβάνουν την προσαρμογή της εκτέλεσης σεναρίων BPEL σε πραγματικό χρόνο. Η προσαρμογή βασίζεται (α) σε χαρακτηριστικά ποιότητας υπηρεσίας των διαθέσιμων παρεχόμενων υπηρεσιών διαδικτύου (β) σε πολιτικές ποιότητας υπηρεσίας που καθορίζονται από τους χρήστες και (γ) σε τεχνικές συνεργατικού φιλτραρίσματος, επιτρέποντας στους πελάτες να εκλεπτύνουν περαιτέρω τη διαδικασία προσαρμογής, εξετάζοντας τις επιλογές υπηρεσιών που έγιναν από άλλους πελάτες στο παρελθόν.In this thesis, frameworks for providing runtime adaptation for BPEL scenarios are proposed. The adaptation is based on (a) quality of service parameters of available web services (b) quality of service policies specified by users and (c) collaborative filtering techniques, allowing clients to further refine the adaptation process by considering service selections made by other clients

A novel workflow management system for handling dynamic process adaptation and compliance

Modern enterprise organisations rely on dynamic processes. Generally these processes cannot be modelled once and executed repeatedly without change. Enterprise processes may evolve unpredictably according to situations that cannot always be prescribed. However, no mechanism exists to ensure an updated process does not violate any compliance requirements. Typical workflow processes may follow a process definition and execute several thousand instances using a workflow engine without any changes. This is suitable for routine business processes. However, when business processes need flexibility, adaptive features are needed. Updating processes may violate compliance requirements so automatic verification of compliance checking is necessary. The research work presented in this Thesis investigates the problem of current workflow technology in defining, managing and ensuring the specification and execution of business processes that are dynamic in nature, combined with policy standards throughout the process lifycle. The findings from the literature review and the system requirements are used to design the proposed system architecture. Since a two-tier reference process model is not sufficient as a basis for the reference model for an adaptive and compliance workflow management system, a three-tier process model is proposed. The major components of the architecture consist of process models, business rules and plugin modules. This architecture exhibits the concept of user adaptation with structural checks and dynamic adaptation with data-driven checks. A research prototype - Adaptive and Compliance Workflow Management System (ACWfMS) - was developed based on the proposed system architecture to implement core services of the system for testing and evaluation purposes. The ACWfMS enables the development of a workflow management tool to create or update the process models. It automatically validates compliance requirements and, in the case of violations, visual feedback is presented to the user. In addition, the architecture facilitates process migration to manage specific instances with modified definitions. A case study based on the postgraduate research process domain is discussed

Integrating Diagnostic and Repair to Ensure the Quality of a Composition of Web Services

Service-Oriented Computing is based on dynamic composition of web services to meet the demand of a user. A major challenge in conditioning actual use of web services is to monitor their performance and enable them to react to unexpected malfunctioning. This can be done using the mechanisms of exception handling. But they do react in a predefined manner and local issues have to be planned at the services design time. However, in dynamic environments like the Internet, web services may be subject to unexpected malfunctioning which may not be handled with repair mechanisms defined at design time. In addition, local management ignores errors during the interactions between services, which limit their effectiveness. Such failures may also propagate through the services before being detected, and the key is to find the problem at the source of the malfunction and repair the service. In this context, this work is dedicated to study a distributed but coordinated and dynamic management of repair mechanisms. The difficulty is that repairs are carried out locally, but a global approach must be ensured to take into account interactions between different services. Our objective is to propose a diagnostic-repair architecture and mechanisms for this feature in detail

An intelligent framework for dynamic web services composition in the semantic web

As Web services are being increasingly adopted as the distributed computing technology of choice to securely publish application services beyond the firewall, the importance of composing them to create new, value-added service, is increasing. Thus far, the most successful practical approach to Web services composition, largely endorsed by the industry falls under the static composition category where the service selection and flow management are done a priori and manually. The second approach to web-services composition aspires to achieve more dynamic composition by semantically describing the process model of Web services and thus making it comprehensible to reasoning engines or software agents. The practical implementation of the dynamic composition approach is still in its infancy and many complex problems need to be resolved before it can be adopted outside the research communities. The investigation of automatic discovery and composition of Web services in this thesis resulted in the development of the eXtended Semantic Case Based Reasoner (XSCBR), which utilizes semantic web and AI methodology of Case Based Reasoning (CBR). Our framework uses OWL semantic descriptions extensively for implementing both the matchmaking profiles of the Web services and the components of the CBR engine. In this research, we have introduced the concept of runtime behaviour of services and consideration of that in Web services selection. The runtime behaviour of a service is a result of service execution and how the service will behave under different circumstances, which is difficult to presume prior to service execution. Moreover, we demonstrate that the accuracy of automatic matchmaking of Web services can be further improved by taking into account the adequacy of past matchmaking experiences for the requested task. Our XSCBR framework allows annotating such runtime experiences in terms of storing execution values of non-functional Web services parameters such as availability and response time into a case library. The XSCBR algorithm for matchmaking and discovery considers such stored Web services execution experiences to determine the adequacy of services for a particular task. We further extended our fundamental discovery and matchmaking algorithm to cater for web services composition. An intensive knowledge-based substitution approach was proposed to adapt the candidate service experiences to the requested solution before suggesting more complex and computationally taxing AI-based planning-based transformations. The inconsistency problem that occurs while adapting existing service composition solutions is addressed with a novel methodology based on Constraint Satisfaction Problem (CSP). From the outset, we adopted a pragmatic approach that focused on delivering an automated Web services discovery and composition solution with the minimum possible involvement of all composition participants: the service provider, the requestor and the service composer. The qualitative evaluation of the framework and the composition tools, together with the performance study of the XSCBR framework has verified that we were successful in achieving our goal

Self-managed Workflows for Cyber-physical Systems

Workflows are a well-established concept for describing business logics and processes in web-based applications and enterprise application integration scenarios on an abstract implementation-agnostic level. Applying Business Process Management (BPM) technologies to increase autonomy and automate sequences of activities in Cyber-physical Systems (CPS) promises various advantages including a higher flexibility and simplified programming, a more efficient resource usage, and an easier integration and orchestration of CPS devices. However, traditional BPM notations and engines have not been designed to be used in the context of CPS, which raises new research questions occurring with the close coupling of the virtual and physical worlds. Among these challenges are the interaction with complex compounds of heterogeneous sensors, actuators, things and humans; the detection and handling of errors in the physical world; and the synchronization of the cyber-physical process execution models. Novel factors related to the interaction with the physical world including real world obstacles, inconsistencies and inaccuracies may jeopardize the successful execution of workflows in CPS and may lead to unanticipated situations. This thesis investigates properties and requirements of CPS relevant for the introduction of BPM technologies into cyber-physical domains. We discuss existing BPM systems and related work regarding the integration of sensors and actuators into workflows, the development of a Workflow Management System (WfMS) for CPS, and the synchronization of the virtual and physical process execution as part of self-* capabilities for WfMSes. Based on the identified research gap, we present concepts and prototypes regarding the development of a CPS WFMS w.r.t. all phases of the BPM lifecycle. First, we introduce a CPS workflow notation that supports the modelling of the interaction of complex sensors, actuators, humans, dynamic services and WfMSes on the business process level. In addition, the effects of the workflow execution can be specified in the form of goals defining success and error criteria for the execution of individual process steps. Along with that, we introduce the notion of Cyber-physical Consistency. Following, we present a system architecture for a corresponding WfMS (PROtEUS) to execute the modelled processes-also in distributed execution settings and with a focus on interactive process management. Subsequently, the integration of a cyber-physical feedback loop to increase resilience of the process execution at runtime is discussed. Within this MAPE-K loop, sensor and context data are related to the effects of the process execution, deviations from expected behaviour are detected, and compensations are planned and executed. The execution of this feedback loop can be scaled depending on the required level of precision and consistency. Our implementation of the MAPE-K loop proves to be a general framework for adding self-* capabilities to WfMSes. The evaluation of our concepts within a smart home case study shows expected behaviour, reasonable execution times, reduced error rates and high coverage of the identified requirements, which makes our CPS~WfMS a suitable system for introducing workflows on top of systems, devices, things and applications of CPS.:1. Introduction 15 1.1. Motivation 15 1.2. Research Issues 17 1.3. Scope & Contributions 19 1.4. Structure of the Thesis 20 2. Workflows and Cyber-physical Systems 21 2.1. Introduction 21 2.2. Two Motivating Examples 21 2.3. Business Process Management and Workflow Technologies 23 2.4. Cyber-physical Systems 31 2.5. Workflows in CPS 38 2.6. Requirements 42 3. Related Work 45 3.1. Introduction 45 3.2. Existing BPM Systems in Industry and Academia 45 3.3. Modelling of CPS Workflows 49 3.4. CPS Workflow Systems 53 3.5. Cyber-physical Synchronization 58 3.6. Self-* for BPM Systems 63 3.7. Retrofitting Frameworks for WfMSes 69 3.8. Conclusion & Deficits 71 4. Modelling of Cyber-physical Workflows with Consistency Style Sheets 75 4.1. Introduction 75 4.2. Workflow Metamodel 76 4.3. Knowledge Base 87 4.4. Dynamic Services 92 4.5. CPS-related Workflow Effects 94 4.6. Cyber-physical Consistency 100 4.7. Consistency Style Sheets 105 4.8. Tools for Modelling of CPS Workflows 106 4.9. Compatibility with Existing Business Process Notations 111 5. Architecture of a WfMS for Distributed CPS Workflows 115 5.1. Introduction 115 5.2. PROtEUS Process Execution System 116 5.3. Internet of Things Middleware 124 5.4. Dynamic Service Selection via Semantic Access Layer 125 5.5. Process Distribution 126 5.6. Ubiquitous Human Interaction 130 5.7. Towards a CPS WfMS Reference Architecture for Other Domains 137 6. Scalable Execution of Self-managed CPS Workflows 141 6.1. Introduction 141 6.2. MAPE-K Control Loops for Autonomous Workflows 141 6.3. Feedback Loop for Cyber-physical Consistency 148 6.4. Feedback Loop for Distributed Workflows 152 6.5. Consistency Levels, Scalability and Scalable Consistency 157 6.6. Self-managed Workflows 158 6.7. Adaptations and Meta-adaptations 159 6.8. Multiple Feedback Loops and Process Instances 160 6.9. Transactions and ACID for CPS Workflows 161 6.10. Runtime View on Cyber-physical Synchronization for Workflows 162 6.11. Applicability of Workflow Feedback Loops to other CPS Domains 164 6.12. A Retrofitting Framework for Self-managed CPS WfMSes 165 7. Evaluation 171 7.1. Introduction 171 7.2. Hardware and Software 171 7.3. PROtEUS Base System 174 7.4. PROtEUS with Feedback Service 182 7.5. Feedback Service with Legacy WfMSes 213 7.6. Qualitative Discussion of Requirements and Additional CPS Aspects 217 7.7. Comparison with Related Work 232 7.8. Conclusion 234 8. Summary and Future Work 237 8.1. Summary and Conclusion 237 8.2. Advances of this Thesis 240 8.3. Contributions to the Research Area 242 8.4. Relevance 243 8.5. Open Questions 245 8.6. Future Work 247 Bibliography 249 Acronyms 277 List of Figures 281 List of Tables 285 List of Listings 287 Appendices 28

Achieving Autonomic Web Service Compositions with Models at Runtime

Over the last years, Web services have become increasingly popular. It is because they allow businesses to share data and business process (BP) logic through a programmatic interface across networks. In order to reach the full potential of Web services, they can be combined to achieve specifi c functionalities. Web services run in complex contexts where arising events may compromise the quality of the system (e.g. a sudden security attack). As a result, it is desirable to count on mechanisms to adapt Web service compositions (or simply called service compositions) according to problematic events in the context. Since critical systems may require prompt responses, manual adaptations are unfeasible in large and intricate service compositions. Thus, it is suitable to have autonomic mechanisms to guide their self-adaptation. One way to achieve this is by implementing variability constructs at the language level. However, this approach may become tedious, difficult to manage, and error-prone as the number of con figurations for the service composition grows. The goal of this thesis is to provide a model-driven framework to guide autonomic adjustments of context-aware service compositions. This framework spans over design time and runtime to face arising known and unknown context events (i.e., foreseen and unforeseen at design time) in the close and open worlds respectively. At design time, we propose a methodology for creating the models that guide autonomic changes. Since Service-Oriented Architecture (SOA) lacks support for systematic reuse of service operations, we represent service operations as Software Product Line (SPL) features in a variability model. As a result, our approach can support the construction of service composition families in mass production-environments. In order to reach optimum adaptations, the variability model and its possible con figurations are verifi ed at design time using Constraint Programming (CP). At runtime, when problematic events arise in the context, the variability model is leveraged for guiding autonomic changes of the service composition. The activation and deactivation of features in the variability model result in changes in a composition model that abstracts the underlying service composition. Changes in the variability model are refl ected into the service composition by adding or removing fragments of Business Process Execution Language (WS-BPEL) code, which are deployed at runtime. Model-driven strategies guide the safe migration of running service composition instances. Under the closed-world assumption, the possible context events are fully known at design time. These events will eventually trigger the dynamic adaptation of the service composition. Nevertheless, it is diffi cult to foresee all the possible situations arising in uncertain contexts where service compositions run. Therefore, we extend our framework to cover the dynamic evolution of service compositions to deal with unexpected events in the open world. If model adaptations cannot solve uncertainty, the supporting models self-evolve according to abstract tactics that preserve expected requirements.Alférez Salinas, GH. (2013). Achieving Autonomic Web Service Compositions with Models at Runtime [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34672TESI

A Framework for Model-Driven Scientific Workflow Engineering

So-called scientific workflows are one important means in the context of data-intensive science for reliable and efficient scientific data processing in distributed computing infrastructures such as Grids. Scientific Workflow Management Systems (SWfMS) help scientists model and run scientific workflows, whereas a domain-specific layer for workflow modeling by a scientist and a technical layer for automated workflow execution can be distinguished. Initially, many SWfMS were developed from scratch using custom workflow technologies languages without application of already existing and established business workflow technologies. Among the reasons were different life cycles for scientific and business workflows as well as incompatible interfaces and communication protocols of the respective execution infrastructures. Meanwhile, several business IT infrastructures have evolved to serviceoriented architectures (SOAs), for which many Web service standards and technologies have been developed. The Web Services Business Process Execution Language (BPEL), for example, is a well-accepted standard for the implementation and execution of business workflows in SOAs. The SOA architecture pattern has been adopted in scientific IT infrastructures by so-called Service Grids based on existing standards and technologies. Due to this development, BPEL is also suitable for the execution of scientific workflows at the technical layer, which has been elaborated on in many publications and projects. However, BPEL is a workflow language for IT experts and is originally not suited for scientific workflow modeling by a scientist at the domain-specific layer. A domain-specific abstraction of BPEL is therefore required that can be specifically tailored for scientific workflow modeling as well as a corresponding mapping to the technical layer. These challenges of the domain-specific abstraction and the mapping are addressed in this thesis with the help of the Business Process Model and Notation (BPMN) standard and technologies from Model-Driven Software Development (MDSD). Therefore, the MoDFlow approach for Model-Driven Scientific WorkFlow Engineering is presented to map domain-specific scientific workflow models via a BPMN-based intermediate layer to an executable workflow model. The intermediate layer is specified by MoDFlow.BPMN, which is a BPMN metamodel subset with custom extensions for the scientific domain. MoDFlow.BPMN2BPEL defines three consecutive transformation steps to map MoDFlow.BPMN to BPEL for workflow execution. Furthermore, different methods to utilize and extend MoDFlow.BPMN and MoDFlow.BPMN2BPEL are described in the MoDFlow approach, in which the definition of so-called domain-specific languages (DSLs) for the modeling of scientific workflows at the domain-specific layer is focused. The MoDFlow framework is an implementation of the MoDFlow approach, which is based on the Eclipse Modeling Framework (EMF). The MoDFlow framework is evaluated in three application scenarios, in which different utilization and extension mechanisms are examined. The first two application scenarios investigate the technical feasibility of the approach and support scientific workflows with parameter sweeps that are executed on a Grid infrastructure. The third application scenario has been conducted in collaboration with the PubFlow project, which aims to create an infrastructure to model and execute data publication workflows. Based on the Xtext framework, a textual DSL and a corresponding language infrastructure is defined for this purpose that supports developers in creating data publication workflows. This scenario aims to illustrate the practicability of the MoDFlow framework. PubFlow currently plans to implement an additional graphical DSL based on the BPMN notation and a corresponding workflow editor for scientists