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Article invitéInternational audienceThe ACID (Atomicity, Consistency, Isolation, and Durability) model has played a cornerstone role in service composition to guarantee that Composite Services (CSs) have transactional support and consistent outcomes (”all-or-nothing”property). However, the classical ”all-or-nothing” model is too restrictive for loosely coupled and distributed environments as Internet. Some approaches have been proposed to relax atomicity based on transactional properties of services, using compensation mechanisms or providing checkpointing techniques. In this article, we propose a model that measures the fuzzy atomicity of a composite service based on transactional properties and on the checkpointing mechanism, relaxing the ”all-or-nothing” property into a new a fuzzy ”all-something-or-(almost) nothing” property.The proposed measure takes into account the acceptable fuzzy atomicity expressed in the user requirements (i.e., the minimum result that user can accept), but also the state of the composite service execution. As far as we know, no such a model exists

LNCS n°8194International audienceWeb Services (WSs) are the most used implementation of service-oriented architectures allowing the construction and the sharing of independent and autonomous software. WS composition consists in combining several WSs into a Composite one, which becomes a value-added service, in order to satisfy complex users queries. Thus, the WS composition process may imply several phases to identify how and which WSs will conform the Composite WS, including specification, verification, evaluation, WSs selection, and execution. As it is known, Petri Nets are the main formal models used to describe static vision of a system and dynamic behavior of processes. Then, Petri Nets are well suited to model internal operations of WSs and interactions among them as well as to model the processes in all phases of the WS composition process. In this article we present a review of approaches using Petri Nets for WS composition. Moreover, we describe our experiences in this field: a transactional-QoS-driven WS selection approach and a framework for reliable execution of Composite WSs based on Colored Petri Nets