Extending BPEL for Interoperable Pervasive Computing

The widespread deployment of mobile devices like PDAs and mobile phones has created a vast computation and communication platform for pervasive computing applications. However, these devices feature an array of incompatible hardware and software architectures, discouraging ad-hoc interactions among devices. The Business Process Execution Language (BPEL) allows users in wired computing settings to model applications of significant complexity, leveraging Web standards to guarantee interoperability. However, BPEL\u27s inflexible communication model effectively prohibits its deployment on the kinds of dynamic wireless networks used by most pervasive computing devices. This paper presents extensions to BPEL that address these restrictions, transforming BPEL into a versatile platform for interoperable pervasive computing applications. We discuss our implementation of these extensions in Sliver, a lightweight BPEL execution engine that we have developed for mobile devices. We also evaluate a pervasive computing application prototype implemented in BPEL, running on Sliver

A Survey on Service Composition Middleware in Pervasive Environments

The development of pervasive computing has put the light on a challenging problem: how to dynamically compose services in heterogeneous and highly changing environments? We propose a survey that defines the service composition as a sequence of four steps: the translation, the generation, the evaluation, and finally the execution. With this powerful and simple model we describe the major service composition middleware. Then, a classification of these service composition middleware according to pervasive requirements - interoperability, discoverability, adaptability, context awareness, QoS management, security, spontaneous management, and autonomous management - is given. The classification highlights what has been done and what remains to do to develop the service composition in pervasive environments

Object Technology for Ambient Intelligence : Workshop Reader for OT4Aml at ECOOP 2007

This reader comprises the submissions to the third workshop on object-technology for Ambient Intelligence and Pervasive Computing held at ECOOP 2007

Dynamic process fragment injection in a service orchestration engine

The EU Project Allow Ensembles aims to develop a new design principle for large-scale collective systems (CAS) based on the concepts of cells and ensembles, where cells represent a concrete functionality in a system, and the ensembles are collections of cells which collaborate in order to fulfill a certain goal in a given context. Adaptive Pervasive Flows (APF) are based on workflow technology and utilized in pervasive environments to model the cell's behavior. During runtime, APF instances must be able to adapt their behavior, e.g. due to failures or changes in their environment, in order to be able to fulfill a certain goal. For this purpose, APFs may contain a particular type of activities, known as abstract activities. Abstract activities partially specify the flow behavior, which must then be resolved during runtime into one or multiple concrete activities, which in turn must be injected into the running flow. In the scope of this thesis, APFs are specified using an extension of the WS-BPEL language. The WS-BPEL language, provide the necessary mechanisms for extending the language for modeling custom process activities and specifying their behavior. In this thesis we focus on the WS-BPEL language and on an extended version of the Apache ODE orchestration engine, for business process modeling and execution respectively. With respect to the injection of pervasive process fragments, which contain one or multiple activities and properties, the language and execution engine requirements and constraints are investigated. For this purpose, a State-of-the-Art analysis on generic process fragment injection approaches is first driven. Once the constraints are detected, we present the formalization of the required language extension based on WS-BPEL language, and conduct a specification of requirements and architectural design of the final prototype based on the Apache Orchestration Director Engine (Apache ODE). For integration purposes in the overall required execution environment, the Enterprise Service Bus Apache ServiceMix 4.3 is used

WS-Pro: a Petri net based performance-driven service composition framework

As an emerging area gaining prevalence in the industry, Web Services was established to satisfy the needs for better flexibility and higher reliability in web applications. However, due to the lack of reliable frameworks and difficulties in constructing versatile service composition platform, web developers encountered major obstacles in large-scale deployment of web services. Meanwhile, performance has been one of the major concerns and a largely unexplored area in Web Services research. There is high demand for researchers to conceive and develop feasible solutions to design, monitor, and deploy web service systems that can adapt to failures, especially performance failures. Though many techniques have been proposed to solve this problem, none of them offers a comprehensive solution to overcome the difficulties that challenge practitioners. Central to the performance-engineering studies, performance analysis and performance adaptation are of paramount importance to the success of a software project. The industry learned through many hard lessons the significance of well-founded and well-executed performance engineering plans. An important fact is that it is too expensive to tackle performance evaluation, mostly through performance testing, after the software is developed. This is especially true in recent decades when software complexity has risen sharply. After the system is deployed, performance adaptation is essential to maintaining and improving software system reliability. Performance adaptation provides techniques to mitigate the consequence of performance failures and therefore is an important research issue. Performance adaptation is particularly meaningful for mission-critical software systems and software systems with inevitable frequent performance failures, such as Web Services. This dissertation focuses on Web Services framework and proposes a performance-driven service composition scheme, called WS-Pro, to support both performance analysis and performance adaptation. A formalism of transformation from WS-BPEL to Petri net is first defined to enable the analysis of system properties and facilitate quality prediction. A state-transition based proof is presented to show that the transformed Petri net model correctly simulates the behavior of the WS-BPEL process. The generated Petri net model was augmented using performance data supplied by both historical data and runtime data. Results of executing the Petri nets suggest that optimal composition plans can be achieved based on the proposed method. The performance of service composition procedure is an important research issue which has not been sufficiently treated by researchers. However, such an issue is critical for dynamic service composition, where re-planning must be done in a timely manner. In order to improve the performance of service composition procedure and enhance performance adaptation, this dissertation presents an algorithm to remove loops in the reachability graphs so that a large portion of the computation time of service composition can be moved to a pre-processing unit; hence the response time is shortened during runtime. We also extended the WS-Pro to the ubiquitous computing area to improve fault-tolerance

Critical analysis of vendor lock-in and its impact on cloud computing migration: a business perspective

Vendor lock-in is a major barrier to the adoption of cloud computing, due to the lack of standardization. Current solutions and efforts tackling the vendor lock-in problem are predominantly technology-oriented. Limited studies exist to analyse and highlight the complexity of vendor lock-in problem in the cloud environment. Consequently, most customers are unaware of proprietary standards which inhibit interoperability and portability of applications when taking services from vendors. This paper provides a critical analysis of the vendor lock-in problem, from a business perspective. A survey based on qualitative and quantitative approaches conducted in this study has identified the main risk factors that give rise to lock-in situations. The analysis of our survey of 114 participants shows that, as computing resources migrate from on-premise to the cloud, the vendor lock-in problem is exacerbated. Furthermore, the findings exemplify the importance of interoperability, portability and standards in cloud computing. A number of strategies are proposed on how to avoid and mitigate lock-in risks when migrating to cloud computing. The strategies relate to contracts, selection of vendors that support standardised formats and protocols regarding standard data structures and APIs, developing awareness of commonalities and dependencies among cloud-based solutions. We strongly believe that the implementation of these strategies has a great potential to reduce the risks of vendor lock-in