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.

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. We study the verification problem for e-service (and workflow) specifications, aiming at efficient techniques for guiding the construction of composite e-services to guarantee desired properties (e.g., deadlock avoidance, bounds on resource usage, response times). Based on previously proposed e-service frameworks such as AZTEC and e-FLow, decision flow language Vortex, and our early work on verifying Vortex specifications using model checking and infinite state verification tools, we introduce a very simple e-service model for our investigation of verification issues. We first show how three different model checking techniques are applied to verification of specifications in simple e-service model, where the number of processes is limited to a predetermined number. We then introduce pid quantified constraints, a new symbolic representation that can encode infinite system states, to verify systems with unbounded and dynamic process instantiations. We think that it is a versatile technique and more suitable for verification of e-service specifications. If this is combined with other techniques such as abstraction and widening, it is possible to solve a large category of interesting verification problems for e-services. 1

To run a smart E-Business or provide efficient Web service, a web services composition model is needed. Web services composition refers to the process of collaborating the heterogeneous web services. This paper presents a model of web services composition by using Case-Based Reasoning (CBR) techniques. CBR is applied in the process of service discovery, which is the crucial composition process. Our service composition model integrates the two behaviours of proactive and reactive service compositions. We will address dynamic composition and collaboration among services. The similarity feature of CBR is used for efficient service discovery .

We distinguish between two broad categories of e-services: discrete services (e.g., add item to shopping cart, charge a credit card), and sessionoriented ones (teleconference, collaborative text chat, streaming video, ccommerce interactions). Discrete services typically have short duration, and cannot respond to external asynchronous events. Session-oriented services have longer duration (perhaps hours), and typically can respond to asynchronous events (e.g., the ability to add a new participant to a teleconference). When composing discrete e-services it usually suffices to use a process model and engine that composes the e-services as relatively independent tasks. But when composing session-oriented e-services, the engine must be able to receive asynchronous events and determine how and whether to impact the active sessions. For example, if a teleconference participant loses his wireless connection then it might be appropriate to trigger an announcement to some or all of the other participants. In this paper we propose a process model and architecture for flexible composition and execution of discrete and session-oriented services. Unlike previous approaches, our model permits the specification of scripted "active flowcharts" that can be triggered by asynchronous events, and can appropriately impact active sessions. We introduce here a model and language for specifying process schemas (essentially a collection of active flowcharts) that combine multiple e-services, and describe a prototype engine for executing these process schemas.

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Due to the distributed nature of modern composite web services, designers are facing new challenges in both requirement specification as well as logic validation. This paper proposes a top-down design/verification strategy that helps construct composite web services to meet preset system goals. The key to this approach is to specify desired global behaviors with a "conversation protocol" and verify preset system goals on the global protocol. Then peer implementations are synthesized from the conversation protocol. Three realizability conditions are provided to guarantee that the composition of synthesized peers will satisfy the previously verified system goals.

Dynamic virtual enterprises (VE) involve rapid, on-demand, teaming of business partners in pursuit of specific business objectives defined by the customer. Current literature confirms the need for new coordination structures and tools to be used to support management of a shared business process in these emerging forms of organisations. The main objectives of this paper are to investigate coordination requirements in dynamic VE and to propose a mechanism called the time-map that can be used to support coordination during all phases of the VE life cycle. 1.