Weaving aspects into web service orchestrations

Web Service orchestration engines need to be more open to enable the addition of new behaviours into service-based applications. In this paper, we illus- trate how, in a BPEL engine with aspect-weaving ca- pabilities, a process-driven application based on the Google Web Service can be dynamically adapted with new behaviours and hot-fixed to meet unforeseen post- deployment requirements. Business processes (the ap- plication skeletons) can be enriched with additional fea- tures such as debugging, execution monitoring, or an application-specific GUI. Dynamic aspects are also used on the processes themselves to tackle the problem of hot-fixes to long running processes. In this manner, composing a Web Service ’on-the-fly’ means weaving its choreography in- terface into the business process

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

Towards an aspect weaving BPEL engine

This position paper proposes the use of dynamic aspects and the visitor design pattern to obtain a highly configurable and extensible BPEL engine. Using these two techniques, the core of this infrastructural software can be customised to meet new requirements and add features such as debugging, execution monitoring, or changing to another Web Service selection policy. Additionally, it can easily be extended to cope with customer-specific BPEL extensions. We propose the use of dynamic aspects not only on the engine itself but also on the workflow in order to tackle the problems of Web Service hot deployment and hot fixes to long running processes. In this way, composing aWeb Service "on-the-fly" means weaving its choreography interface into the workflow

Quality-aware model-driven service engineering

Service engineering and service-oriented architecture as an integration and platform technology is a recent approach to software systems integration. Quality aspects ranging from interoperability to maintainability to performance are of central importance for the integration of heterogeneous, distributed service-based systems. Architecture models can substantially influence quality attributes of the implemented software systems. Besides the benefits of explicit architectures on maintainability and reuse, architectural constraints such as styles, reference architectures and architectural patterns can influence observable software properties such as performance. Empirical performance evaluation is a process of measuring and evaluating the performance of implemented software. We present an approach for addressing the quality of services and service-based systems at the model-level in the context of model-driven service engineering. The focus on architecture-level models is a consequence of the black-box character of services

Engineering Secure Adaptable Web Services Compositions

Service-oriented architecture defines a paradigm for building applications by assembling autonomous components such as web services to create web service compositions. Web services are executed in complex contexts where unforeseen events may compromise the security of the web services composition. If such compositions perform critical functions, prompt action may be required as new security threats may arise at runtime. Manual interventions may not be ideal or feasible. To automatically decide on valid security changes to make at runtime, the composition needs to make use of current security context information. Such security changes are referred to as dynamic adaptation. This research proposes a framework to develop web services compositions that can dynamically adapt to maintain the same level of security when unforeseen security events occur at runtime. The framework is supported by mechanisms that map revised security requirements arising at runtime to a new security configuration plan that is used to adapt the web services composition

Self-supervising BPEL Processes

Service compositions suffer changes in their partner services. Even if the composition does not change, its behavior may evolve over time and become incorrect. Such changes cannot be fully foreseen through prerelease validation, but impose a shift in the quality assessment activities. Provided functionality and quality of service must be continuously probed while the application executes, and the application itself must be able to take corrective actions to preserve its dependability and robustness. We propose the idea of self-supervising BPEL processes, that is, special-purpose compositions that assess their behavior and react through user-defined rules. Supervision consists of monitoring and recovery. The former checks the system's execution to see whether everything is proceeding as planned, while the latter attempts to fix any anomalies. The paper introduces two languages for defining monitoring and recovery and explains how to use them to enrich BPEL processes with self-supervision capabilities. Supervision is treated as a cross-cutting concern that is only blended at runtime, allowing different stakeholders to adopt different strategies with no impact on the actual business logic. The paper also presents a supervision-aware runtime framework for executing the enriched processes, and briefly discusses the results of in-lab experiments and of a first evaluation with industrial partners

Aspect oriented service composition for telecommunication applications

This PhD dissertation investigates how to overcome the negative effects of cross cutting concerns in the development of composite service applications. It proposes a combination of dynamic aspect oriented programming with a rules driven service composition mechanism. This combination allows very flexible utilization of aspects based on run-time data. The thesis contributes a join-point model and it integrates techniques for weaving and advice definition into the underlying composition language and execution engine. A particular focus of the thesis is telecommunication applications with their unique model for utilizing heterogeneous constituent services and their severe real-time requirements. Next to its primary use for modular implementation and flexible deployment of concerns in telecommunication applications, the dissertation discusses AOP as a feature for automated management and customization of service applications. The verification of the proposed solution contributes a detailed assessment of run-time performance, including a theoretical model of the AOP implementation. It allows predicting the performance of various alternative solutions. The proposed solution for combined AOP and service composition provides properties, which directly address challenges in pervasive computing and the Internet of things. Thus, this dissertation advances beyond the telecommunication domain with results applicable to various highly relevant technical developments

Model-driven performance evaluation for service engineering

Service engineering and service-oriented architecture as an integration and platform technology is a recent approach to software systems integration. Software quality aspects such as performance are of central importance for the integration of heterogeneous, distributed service-based systems. Empirical performance evaluation is a process of measuring and calculating performance metrics of the implemented software. We present an approach for the empirical, model-based performance evaluation of services and service compositions in the context of model-driven service engineering. Temporal databases theory is utilised for the empirical performance evaluation of model-driven developed service systems

Automatic quality of service adaptation for composite web services

Quality of Services (QoS) management has become an important issue for Web services. Indeed, QoS is becoming a crucial and a distinguishing criterion among functionally equivalent Web services. QoS Management consists of two complementary tasks: monitoring and adaptation. Both are very challenging because of the unpredictable and dynamic nature of Web service composition. We are motivated to solve the QoS problem by taking advantage of some characteristics of composite Web services, such as their similarity to traditional workflows. In this thesis, we propose a broker based architecture that enables dynamic QoS monitoring and adaptation for composite Web services. Our approach consists of dynamically changing the execution paths of composed Web services by instrumenting the BPEL process. A new construct flexPath is introduced for supporting alternate execution paths definition in BPEL. We developed a BPEL compiler allowing automatic instrumentation for BPEL definition files. The BPEL process is deployed using the instrumented definition files in order to interact with the QoS broker during execution. The QoS broker is a key component in our architecture and is responsible of monitoring the QoS and managing the adaptation. We propose a broker that enables runtime monitoring of QoS, prediction of potential QoS violation, and the selection of the best execution path of the process in order to improve QoS when needed. We developed a prototype to evaluate our proposed architecture. A case study is also presented through an example BPEL process and a number of partner Web services. The performance of the QoS adaptation has been analyzed and the results showed that the QoS of the BPEL process has been considerably adapted and improved comparing to the original one. In addition, we analyzed the major factors that affect the performance of our prototype tool