The development of new services through the integration of existing ones has gained a considerable momentum as a means to create and streamline business-to-business collaborations. Unfortunately, as Web services are often autonomous and heterogeneous entities, connecting and coordinating them in order to bu ild integrated services is a delicate and time-consu ing task. In this paper, we describe the design and implementation of a system throuk which existing Web services can be declaratively composed, and the resu lting composite services can be execu ted following a peer-to-peer paradigm, within a dynamic environment. This system provides tools for specifying composite services throu. statecharts, data conversion ru les, and provider selection policies. These specifications are then translated into XMLdocu ents that can be interpreted by peer-to-peer inter-connected software components, in order to provision the composite service without requiring a central authority.

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Abstract. The connectivity generated by the Internet is opening unprecedented opportunities of automating business-to-business collaborations. As a result, organisations of all sizes are forming online alliances in order to deliver integrated value-added services. Unfortunately, due to a lack of tools and methodologies offering an adequate level of abstraction, the development of these integrated services is currently ad hoc and requires a considerable effort of low-level programming, especially when dealing with coordination, communication, and execution tracing issues. In this paper, we present a framework through which business services can be declaratively composed, and the resulting composite services can be executed in a fully traceable manner. The traces of a composite service executions are collected incrementally through peer-to-peer interactions between the involved providers. Once collected, these traces are stored as linked objects in distributed repositories, which are made available for auditing, customer feedback and quality assessment. 1

The development of new Web services through the composition of existing ones has gained a considerable momentum as a means to realise business-to-business collaborations. Unfortunately, given that services are often developed in an ad hoc fashion using manifold technologies and standards, connecting and coordinating them in order to build composite services is a delicate and time-consuming task. In this paper, we describe the design and implementation of a system in which services are composed using a model-driven approach, and the resulting composite services are orchestrated following a peer-to-peer paradigm. The system provides tools for specifying composite services through statecharts, data conversion rules, and multi-attribute provider selection policies. These specifications are interpreted by software components that interact in a peer-to-peer way to coordinate the execution of the composite service. We report results of an experimental evaluation showing the relative advantages of this peer-to-peer approach with respect to a centralised one.

The ability to efficiently and effectively share services on the Web is a critical step towards the development of the on-line economy. Virtually every organisation needs to interact with manifold other organisations in order to request their services. Reciprocally, an organisation providing a service is often required to interact with a large and dynamic set of service requestors. The lack of high level abstractions and functionalities for Web service integration has triggered a considerable amount of research and development efforts. This has resulted in a number of products, standards, frameworks and prototypes addressing sometimes overlapping, sometimes complementary aspects of service integration. In this report we summarise some of the challenges and recent developments in the area of Web service integration, and we abstract some of them in the form of software design patterns. Specically we present patterns for both bilateral service-based interactions, multilateral service composition, and execution of composite services both in a centralised and in a fully distributed environment. The report also shows how these patterns map into a variety of implementation technologies including object-based approaches (e.g. CORBA and EJB), EAI and ERP suites, cross-enterprise workflows, EDI and XML-based B2B frameworks. 2 1

Abstract: Many E-business applications are based on increased cooperation between various organisational units and partners. System support for such applications can be provided using concepts from the area of service oriented computing – thus lifting inter-organisational integration to a higher level of effectiveness and efficiency. E-services provide means for modularisation of arbitrary organisational assets into components that can be dynamically offered, discovered, negotiated, accessed, and composed in an open application environment. Technically, E-services are software systems that are implemented on top of conventional information and communication technology. As an important step into that direction, Web Services have laid the foundation for interoperable communication between arbitrary systems. This paper introduces an approach to plan, build, and run such application-level services efficiently. Therefore, a fundamental notion of service, originating from distributed systems, is being extended by a specific concept of cooperative interaction processes. Accordingly, an application-level service model and corresponding service engineering mechanisms are proposed and realised as system software middleware based on OGSA Web Services and BPEL4WS processes.

The development of new Web services by composition of existing ones is becoming a widespread approach to realise business-to-business collaborations.

Abstract: Component-based software composition offers a development approach with reduced time-to-market and cost while achieving enhanced productivity, quality and maintainability. Existent work on the composition paradigm focuses on static composition, which is not sufficient in a distributed environment, in which both constituent components and the assembled distributed system are subject to dynamic adaptation. This paper presents two types of dynamic composition for distributed components: assertive and autonomous over a.NET based Web Services environment. Three case studies are provided to illustrate the use of assertive and autonomous composition.

The growth of Internet technologies has unleashed a wave of innovations that are having tremendous impact on the way organisations interact with their partners and customers. It has undoubtedly opened new ways of automating Businessto -Business (B2B) collaboration. Unfortunately, as electronic commerce applications are most likely autonomous and heterogeneous, connecting and coordinating them in order to build inter-organisational services is a difficult task. To date, the development of integrated B2B services is largely ad-hoc, time-consuming and requires an enormous effort of low-level programming. This approach is not only tedious, but also hardly scalable because of the volatility of the Internet, and the dynamic nature of business alliances. In this paper, we consider the efficient composition and execution of B2B services. Specifically, we present a framework through which services can be declaratively composed, and the resulting composite services can be executed in a decentralised way within a dynamic environment. The underlying execution model supports the incremental collection of the execution trace of each composite service instance. These traces are particularly useful for customer feedback, and for detecting malfunctionings in the constitution of a composite service.

Introduction The automation of Web services interoperation is gaining a considerable momentum as a paradigm for effective Business-to-Business collaboration [2]. Established enterprises are continuously discovering new opportunities to form alliances with other enterprises, by o#ering value-added integrated services. However, the technology to compose Web services in appropriate time-frames has not kept pace with the rapid growth and volatility of available opportunities. Indeed, the development of integrated Web services is often ad-hoc and requires a considerable e#ort of lowlevel programming. This approach is inadequate given the size and the volatility of the Web. Furthermore, the number of services to be integrated may be large, so that approaches where the development of an integrated service requires the understanding of each of the underlying services are inappropriate. In addition, Web services may need to be composed as part of a short term partnership, and disbanded when t