Synthy: A system for end to end composition of web services

The demand for quickly delivering new applications is increasingly becoming a business imperative today. However, application development is often done in an ad hoc manner resulting in poor reuse of software assets and longer time-to-delivery. Web services have received much interest due to their potential in facilitating seamless business-to-business or enterprise application integration. A web service composition system can help automate the process, from specifying business process functionalities, to developing executable workflows that capture non-functional (e.g. Quality of Service (QoS)) requirements, to deploying them on a runtime infrastructure. Intuitively, web services can be viewed as software components and the process of web service composition similar to software synthesis. In addition, service composition needs to address the build-time and runtime issues of the integrated application, thereby making it a more challenging and practical problem than software synthesis. However, current solutions based on business web services (using WSDL, BPEL, SOAP, etc.) or semantic web services (using ontologies, goal-directed reasoning, etc.) are both piecemeal and insufficient. We formulate the web service composition problem and describe the first integrated system for composing web services end to end, i.e., from specification to deployment. The proposed solution is based on a novel two-staged composition approach that addresses the information modeling aspects of web services, provides support for contextual information while composing services, employs efficient decoupling of functional and non-functional requirements, and leads to improved scalability and failure handling. We also present Synthy, a prototype of the service composition system, and demonstrate its effectiveness with the help of an application scenario from the telecom domain.     

A formal and visual modeling approach to choreography based web services composition and conformance verification

Web services have emerged as the building blocks of a service-oriented architecture that supports not only enterprise application integration (EAI) and business process management (BPM) within an organization but also B2B collaboration based on business process integration. The web services choreography approach to B2B process integration allows business partners to orchestrate their own web services privately, while conforming with an agreed specification of the common ordering conditions and constraints under which messages are exchanged among partners’ web services. In this approach, choreography conformance is an essential requirement for the successful implementation of collaborative processes. A formal approach to web services composition and conformance verification based on WS-CDL and WS-BPEL is presented. This approach involves model checking as an automated means of verifying choreography conformance. The main contributions include a precise notion of choreography conformance on which verification is based as well as support for the complementary use of visual modeling (e.g. UML) and standard WS-¹ notations in composition.     

基于代理和BPEL4WS的Web服务合成与实现

Web服务的交互和实现被推荐通过软件代理来实现.Web服务目前还不能很好地支持动态、自适应的服务组合和分布式业务流程.软件代理在建模、知识表达和交互等技术上的优势,能够强化Web服务的交互和动态应用能力.基于代理和面向流程建模的BPEL4WS,可以实现Web服务面向业务应用的合成与执行,支持多个协同的业务流程及其动态配置.系统分析了代理、BPEL4WS和Web服务整合的技术与实现方案,利用JADE平台开发了相关的测试模型,并且以网上拍卖为案例,验证了所提方案及实现.     

A simulation-based approach for dynamic process management at web service platforms

Web services technology is being adopted as a viable deployment approach for future distributed software systems that enable business-to-business and business-to-consumer interactions across the open and dynamic internet environment. Recent research is focused on developing support technologies for web service discovery, on-demand service composition, and robust execution to facilitate web services based deployment of business processes. Developing techniques to cope with the volatile and open nature of the web during execution of composite services at the service platform is essential for delivering reliable and acceptable performance in this new process delivery framework. In this paper, we propose a simulation-based framework to guide scheduling of composite service execution. Online simulation of the dynamics of the open environment is used for scheduling service requests at the service platform. Comparison of the look-ahead simulation for different scheduling policies with the current execution state provides guidelines for service execution in order to cope with system volatility. We have implemented a prototype of the proposed framework and illustrate the feasibility of our approach with experimental studies.     

Process-context aware matchmaking for web service composition

Web service composition can help software developer design more powerful and flexible applications according to requirements of enterprise. But during compositing, how to discover suitable web services is a critical problem in design and implementing application-oriented web service technologies. The traditional keyword-based matchmaking approach is difficult to help developer to find suitable service. Current researches find that to attaching semantics to each registered service can help improve the precision of matchmaking. The improvement can help developer find more suitable service for business process. This paper proposes a novel approach of semantics-based matchmaking, which is named process-context aware matchmaking. The process-context aware matchmaking discovers the suitable service during web service composite modeling. During matchmaking, the approach utilizes not only semantics of technical process but also that of business process of a registered service, thus further improving the precision of matchmaking. We integrate the process-context aware matchmaking with business-process-driven web service composition in an integrated development environment based on Eclipse. The performance evaluation shows that performance overhead of this novel approach is acceptable.     

Dynamic composition and optimization of Web services

Process-based composition of Web services has recently gained significant momentum for the implementation of inter-organizational business collaborations. In this approach, individual Web services are choreographed into composite Web services whose integration logics are expressed as composition schema. In this paper, we present a goal-directed composition framework to support on-demand business processes. Composition schemas are generated incrementally by a rule inference mechanism based on a set of domain-specific business rules enriched with contextual information. In situations where multiple composition schemas can achieve the same goal, we must first select the best composition schema, wherein the best schema is selected based on the combination of its estimated execution quality and schema quality. By coupling the dynamic schema creation and quality-driven selection strategy in one single framework, we ensure that the generated composite service comply with business rules when being adapted and optimized.     

EFSOC: A Layered Framework for Developing Secure Interactions between Web-Services

Enterprises are rapidly extending their relatively stable and internally-oriented business processes and applications with loosely-coupled enterprise software services in order to support highly dynamic, cross-organizational business processes. These services are no longer solely based on internal enterprise systems, but often implemented, deployed and executed by diverse, external service providers. The ability to dynamically configure cross-organizational business processes with a mixture of internal and external services imposes new security requirements on existing security models. In this paper, we address the problem of defining and enforcing access control rules for securing service invocations in the context of a business process. For this purpose, we amortize existing role-based access control models that allow for dynamic delegation and retraction of authorizations. Authorizations are assigned on an event-driven basis, implementing a push-based interaction protocol between services. This novel security model is entitled the Event-driven Framework for Service Oriented Computing (EFSOC). In addition, this article presents an experimental prototype that is explored using a realistic case study. This work has been partially funded by the Netherlands Organization for Scientific Research (NWO) as part of the PRONIR project. Recommended by: Asuman Dogac     

Goal-based business service composition

As organizations operate under a highly dynamic business world, they can only survive by optimizing their business processes (BPs) and outsourcing complementary functionality to their core business. To this end, they adopt service-orientation as the underlying mechanism enabling BP optimization and evolution. BPs are now seen as business services (BSs) that span organization boundaries and ought to satisfy cross-organizational objectives. As such, various BS design approaches have been proposed. However, these approaches cannot re-use existing business and software services (SSs) to realize the required BS functionality. Moreover, non-functional requirements and their impact on BS design are not considered. This research gap is covered by a novel, goal-oriented method able to discover those BS and SS compositions fulfilling the required BS functional and non-functional goals at both the business and IT level. This method coherently integrates the design steps involved and properly handles the lack of required BS components. It also advances the state-of-the-art in service composition by being able to both select the best composition plan and the best services realizing the plan tasks based on novel plan and service selection criteria.     

Security architecture for virtual organizations of business web services

Virtual organizations (VO) temporarily aggregate resources of different domains to achieve a common goal. Web services are being positioned as the technological framework for achieving this aggregation in the context of cross-organizational business applications. Numerous architectures have been proposed for securing VOs, mostly for scientific research, such that they do not address all the requirements of business-oriented applications. This paper describes these additional requirements and proposes a novel architecture and approach to managing VO access control policies. Business users can focus on designing business processes, exposing web services and managing their VO partnerships, while the architecture supports and secures the web service interactions involved.     

Applying intelligent agents and semantic web services in eGovernment environments

The increasing volume of eGovernment‐related services is demanding new approaches for service integration and interoperability in this domain. Semantic web (SW) technologies and applications can leverage the potential of eGovernment service integration and discovery, thus tackling the problems of semantic heterogeneity characterizing eGovernment information sources and the different levels of interoperability. eGovernment services will therefore be semantically described in the foreseeable future. In an environment with semantically annotated services, software agents are essential as the entities responsible for exploiting the semantic content in order to automate some tasks, and so enhance the user's experience. In this paper, we present a framework that provides a seamless integration of semantic web services and intelligent agents technologies by making use of ontologies to facilitate their interoperation. The proposed framework can assist in the development of powerful and flexible distributed systems in complex, dynamic, heterogeneous, unpredictable and open environments. Our approach is backed up by a proof‐of‐concept implementation, where the breakthrough of integrating disparate eGovernment services has been tested.     

Web服务动态组合方法研究与设计

目前基于工作流的Web服务组合方法大多要求预先定义流程结构,不能适应现代企业业务流程复杂多变的需求.提出了一种Web服务动态组合方法,将流程中动态部分用黑盒子流程进行封装,在执行时根据预定义规则和用户需求将黑盒子流程自动组合展开为实际运行流程.对具体服务、抽象服务、黑盒子流程等概念和服务选取规则、服务组合规则进行了定义,详细描述黑盒子流程展开算法,并设计了一个实现动态服务流程组合的框架结构.     

An agent-based service-oriented integration architecture for collaborative intelligent manufacturing

The rapidly changing needs and opportunities of today's global market require unprecedented levels of interoperability to integrate diverse information systems to share knowledge and collaborate among organizations. The combination of Web services and software agents provides a promising computing paradigm for efficient service selection and integration of inter-organizational business processes. This paper proposes an agent-based service-oriented integration architecture to leverage manufacturing scheduling services on a network of virtual enterprises. A unique property of this approach is that the scheduling process of an order is orchestrated on the Internet through the negotiation among agent-based Web services. A software prototype system has been implemented for inter-enterprise manufacturing resource sharing. It demonstrates how the proposed service-oriented integration architecture can be used to establish a collaborative environment that provides dynamic resource scheduling services.     

基于过程本体论的网格应用集成

网格环境中面向服务的应用集成要求高度自动化、动态性和智能化。文章提出了网格服务集成的框架及方法,在过程本体论中进行从抽象到具体的层次匹配,以解决高层次的任务分解、目标规划问题;业务过程的原子活动通过语义相容性查找策略动态地绑定到WebServices上,可适应网格环境的变化性。     

Specifying and verifying contract-driven service compositions using commitments and model checking

The paper proposes a novel model checking-based approach towards verifying the compliance of intelligent agent-based web services with contracts regulating their compositions specified in the Business Process Execution Language (BPEL). Unlike the existing approaches in the literature, the main contribution and impact of the introduced approach is the ability to verify intelligent and autonomous composite web services by capturing and describing in details both compliance and violation behaviors, how the system can distinguish between them, and how the system reacts and can be recovered after each violation. The approach encompasses three contributing parts, namely: 1) the marking process of an extended BPEL; 2) the transformation of the extended and marked BPEL to an automata model; and 3) the encoding of the resulting automata model into the Interpreted Systems Programming Language (ISPL), the input language of the MCMAS model checker for intelligent and autonomous multi-agent systems. In the first part, we extend BPEL that specifies the business process of the composition by creating custom activities called labels. We use those labels as means to represent the specifications and mark the points the developer aims to verify. A significant advantage of this labeling is the ability to highlight specific points in the design to be verified and to distinguish compliance behaviors from violations, which makes this verification focused and highly efficient. In the second part, we introduce new transformation rules to transform the extended and marked BPEL to an automata model. This transformation requires a prior modeling of agent-based web services composition using automata definitions. In the third part, we introduce algorithmic translation rules encoding the resulting automata model into ISPL. This translation makes model checking the behavior of our contract-driven compositions possible. A novel characteristic of the proposed approach is the automatic generation of the properties against which the system is verified from the composition’s implementation, which is technically challenging. The verification properties are expressed in the Computation Tree Logic of Commitments (CTLC). Technically, CTLC provides a powerful representation to formally model 1) interactions among multi-agent based web services and 2) compliance and violation behaviors within composite business contracts by making use of communicative commitment operators. CTLC also includes a fulfillment operator which helps formally check the compliance with business contracts and specify the system recovery. A detailed case study from expert and intelligent systems domain along with experimental results are also reported in the paper. Finally, the main impact and significance of the paper on expert and intelligent systems is the ability to use these systems safely since there is a way to verify if the intelligent components behave according to and in compliance with the underlying regulating contracts.     

Through Personalized Web Service Composition Specification: From BPEL to C-BPEL

Over the last few years, Web services technologies offered a new and successful way for interoperability among web applications. A Web service is a software system designed in a way that other software components and humans can discover and invoke to satisfy different needs. The vision of WS as a software component allows to combine several WS, providing a global value-added WS, called composite WS.Although there are several researches in web services composition, more effort should be focused on its personalization, particularly regarding how well the composition results correspond to what the user really wants. Accordingly, we present in this paper an approach that may contribute to the personalization of web services composition specification. Our approach is a context-based proposal that makes services composition specification more efficient by taking into account both user context, needs, and preferences and web services context, and by integrating them to the composition process. In addition, to permit the reuse of specifications, we enhance BPEL by developing a specification language based on context to be used in composition that we called C-BPEL.     

Meta web service: building web-based open decision support system based on web services

Web services are currently one of the trends in network-based business services, which intuitively will be applied to build a semantic web-based decision support system (DSS). Since web services are self-contained, modular business process applications, based on open standards, enable integration models for facilitating program-to-program interactions. Decision modules in a semantic web-based DSS can be viewed as a web service. However, according to the current features, web services know only about themselves, they are neither autonomous, nor are they designed to use ontologies; they are passive until invoked, and they do not provide for composing functionalities. These lead to the motivation on building a sophisticated web service to contain these features and to utilize web services on behalf of the user. This paper aims to propose a new concept of Meta Web Service, a web service-based DSS. The meta web service understands the user's problem statement with ontology, performs web service discovery, web service composition, and automatically generates codes for composite web service execution. Case-based reasoning is applied to quickly find past histories of successful service compositions. A prototype of research web service has been developed to show the feasibility of the proposed idea.     

AGENT ENABLED ADAPTIVE MANAGEMENT OF QoS ASSURED PROVISION OF COMPOSITE SERVICES

The assurance of quality-of-service (QoS) is critical for the successful deployment of service-oriented applications, especially in open, dynamic, and distributed cross-organizational environments. Adaptive management of the QoS assured provision of composite services is required for more reliable, fault-tolerant, and flexible service delivery in such environments. It can be realized with software agents offering a unified framework and necessary capabilities for carrying out different adaptive management tasks across the whole lifecycle of composite service provision.     

PDC-Agent支持的动态自组织系统

提出一种基于政策（P）、愿望（D）和合同（C）的扩展Agent模型（PDC-Agent），并以它为基础，建立用于网络服务自动合成的方法体系．PDC-Agent根据3个因素（P，D和C），运用基于优先级的决策机制，理性地选择将要执行的服务和特性。并参与虚拟组织的建立和服务的合成．最后给出服务自组织的过程和实例分析．该系统能够适应商业需求的变化，在开放、动态、异构的虚拟组织环境中进行即时的服务集成．