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Abstract. The intrinsic flexibility and dynamism of service-centric applications preclude their pre-release validation and demand for suitable probes to monitor their behavior at run-time. Probes must be suitably activated and deactivated according to the context in which the application is executed, but also according to the confidence we get on its(More)
Service-based approaches are widely used to integrate heterogenous systems. Web services allow for the definition of highly dynamic systems where components (services) can be discovered and QoS parameters negotiated at run-time. This justifies the need for monitoring service compositions at run-time. Research on this issue, however, is still in its infancy.(More)
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(More)
The paper presents a monitoring framework for WS-BPEL processes. It proposes WS-CoL (Web Service Constraint Language) as a domain-independent language, compliant with the WS-Policy framework, for specifying user requirements (constraints) on the execution of Web service compositions. WSPolicy and WS-CoL provide a uniform framework to accommodate both(More)
Many emerging domains such as ambient intelligence, context-aware applications, and pervasive computing are embracing the assumption that their software applications will be deployed in an open-world. By adopting the Service Oriented Architecture paradigm, and in particular its Web service based implementation, they are capable of leveraging components that(More)
Web services support software architectures that can evolve dynamically. In particular, here we focus on architectures where services are composed (orchestrated) through a workflow described in the BPEL language. We assume that the resulting composite service refers to external services through assertions that specify their expected functional and(More)
Dynamo advocates that pre-deployment validation and testing are intrinsically inadequate for tackling the ephemeral and rapidly changing context in which service oriented applications are deployed. Validation must be shifted to run-time and continuous monitoring must be introduced. We propose a simple architecture that, through specific and simple(More)
Modern software architectures are increasingly dynamic. Among them, Service-Oriented Architectures (SOAs) are becoming a dominant paradigm. SOAs allow components to be exported as services for external use. Service descriptions (which include functional and non-functional properties) are published by service providers and are later discovered by potential(More)
Today the current state of the art in querying XML data is represented by XPath and XQuery, both of which rely on Boolean conditions for node selection. Boolean selection is too restrictive when users do not use or even know the data structure precisely, e.g. when queries are written based on a summary rather than on a schema. In this paper we describe a(More)
Web services are becoming progressively popular in the building of both interand intra-enterprise business processes. These processes are composed from existing Web services based on defined requirements. In collecting together the services for such a composition, developers can employ languages and standards for the Web that facilitate the automation of(More)