Web services run in complex contexts where arising events may compromise the quality of the whole system. Thus, it is desirable to count on autonomic mechanisms to guide the self-adaptation of service compositions according to changes in the computing infrastructure. One way to achieve this goal is by implementing variability constructs at the language level. However, this approach may become tedious, difficult to manage, and error-prone. In this paper, we propose a solution based on a semantically rich variability model to support the dynamic adaptation of service compositions. When a problematic event arises in the context, this model is leveraged for decision-making. The activation and deactivation of features in the variability model result in changes in a composition model that abstracts the underlying service composition. These changes are reflected into the service composition by adding or removing fragments of Business Process Execution Language (WS-BPEL) code, which can be deployed at runtime. In order to reach optimum adaptations, the variability model and its possible configurations are verified at design time using Constraint Programming. An evaluation demonstrates several benefits of our approach, both at design time and at runtime.

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International audienceSecurity is an important issue that needs to be taken into account at all stages of information system development, including early requirements elicitation. Early analysis of security makes it possible to predict threats and their impacts and define adequate security requirements before the system is in place. Security requirements are difficult to elicit, analyze, and manage. The fact that analysts' knowledge about security is often tacit makes the task of security requirements elicitation even harder. Ontologies are known for being a good way to formalize knowledge. Ontologies, in particular, have been proved useful to support reusability. Requirements engineering based on predefined ontologies can make the job of requirement engineering much easier and faster. However, this very much depends on the quality of the ontology that is used. Some security ontologies for security requirements have been proposed in the literature. None of them stands out as complete. This paper presents a core and generic security ontology for security requirements engineering. Its core and generic status is attained thanks to its coverage of wide and high-level security concepts and relationships. We implemented the ontology and developed an interactive environment to facilitate the use of the ontology during the security requirements engineering process. The proposed security ontology was evaluated by checking its validity and completeness compared to other ontologies. Moreover, a controlled experiment with end-users was performed to evaluate its usability