SMT-based Verification of LTL Specifications with Integer Constraints and its Application to Runtime Checking of Service Substitutability

An important problem that arises during the execution of service-based applications concerns the ability to determine whether a running service can be substituted with one with a different interface, for example if the former is no longer available. Standard Bounded Model Checking techniques can be used to perform this check, but they must be able to provide answers very quickly, lest the check hampers the operativeness of the application, instead of aiding it. The problem becomes even more complex when conversational services are considered, i.e., services that expose operations that have Input/Output data dependencies among them. In this paper we introduce a formal verification technique for an extension of Linear Temporal Logic that allows users to include in formulae constraints on integer variables. This technique applied to the substitutability problem for conversational services is shown to be considerably faster and with smaller memory footprint than existing ones

Multi-Objective Service Composition in Ubiquitous Environments with Service Dependencies

International audienceService composition is a widely used method in ubiquitous computing that enables accomplishing complex tasks required by users based on elementary (hardware and software) services available in ubiquitous environments. To ensure that users experience the best Quality of Service (QoS) with respect to their quality needs, service composition has to be QoS-aware. Establishing QoS-aware service compositions entails efficient service selection taking into account the QoS requirements of users. A challenging issue towards this purpose is to consider service selection under global QoS requirements (i.e., requirements imposed by the user on the whole task), which is of high computational cost. This challenge is even more relevant when we consider the dynamics, limited computational resources and timeliness constraints of ubiquitous environments. To cope with the above challenge, we present QASSA, an efficient service selection algorithm that provides the appropriate ground for QoS-aware service composition in ubiquitous environments. QASSA formulates service selection under global QoS requirements as a set-based optimisation problem, and solves this problem by combining local and global selection techniques. In particular, it introduces a novel way of using clustering techniques to enable fine-grained management of trade-offs between QoS objectives. QASSA further considers: (i) dependencies between services, (ii) adaptation at run-time, and (iii) both centralised and distributed design fashions. Results of experimental studies performed using real QoS data are presented to illustrate the timeliness and optimality of QASSA

Project Final Report Use and Dissemination of Foreground

This document is the final report on use and dissemination of foreground, part of the CONNECT final report. The document provides the lists of: publications, dissemination activities, and exploitable foregroun

Synthesizing adapters for conversational web-services from their WSDL interface

International audienceService-oriented applications are typically built out of existing web-services (WSs) possibly made available by third party vendors. This requires that the application has to be able to evolve when the composing WSs are not anymore available or when new, more useful ones, are published. In this setting, an important problem is to understand how to use WSs showing an interface that differs from the one the application has been built to. The problem becomes even more complex when we consider conversational WSs, i.e., WSs that expose operations that have Input/Output (I/O) data dependencies among them. This paper presents a complete development methodology to the automatic synthesis of adapters for conversational WSs starting from their WSDL interface. The result is a tool-supported methodology that takes as input the WSDL of a pair of services and automatically builds a script that maps a sequence of operation invocations on a “WS to be replaced” into an equivalent sequence of operation invocations on the “replacing WS”. The overall approach is presented by applying it to two existing WSs that realize two distinct, but equivalent, search engines for lyric music