Conflict Detection in Call Control using First-Order Logic Model Checking

Feature interaction detection methods, whether online or offline, depend on previous knowledge of conflicts between the actions executed by the features. This knowledge is usually assumed to be given in the application domain. A method is proposed for identifying potential conflicts in call control actions, based on analysis of their pre/post-conditions. First of all, pre/postconditions for call processing actions are defined. Then, conflicts among the pre/post-conditions are defined. Finally, action conflicts are identified as a result of these conflicts. These cover several possibilities where the actions could be simultaneous or sequential. A first-order logic model-checking tool is used for automated conflict detection. As a case study, the APPEL call control language is used to illustrate the approach, with the Alloy tool serving as the model checker for automated conflict detection. This case study focuses on pre/post-conditions describing call control state and media state. The results of the method are evaluated by a domain expert with pragmatic understanding of the system’s behavior. The method, although computationally expensive, is fairly general and can be used to study conflicts in other domains

Feature specification and static analysis for interaction resolution

International audienceTelecommunication operators provide services and enable customers to compose their own packages of services. While designing a service-oriented system, deciding whether a service interaction is desired or harmful is a subjective choice which depends on the requirements expressed by the user with respect to the service integration. In this paper, we define both a formalism and a methodology which, respectively, allow us to automatically analyse interactions based on specification consistency. For the latter (i.e. the methodology), we take advantage of both specifier expertise and formal methods.Hence, adding a new service on a system consists in a static design step providing a consistent specification and thus aiming to reinforce the specification quality, taking into account the expert choices. Service requirements are expressed by means of an axiomatic formalism which includes variables, invariant properties and state transition rules, also called pre-post formulas. The interaction analysis is based on algorithms which check specification consistency. Each detected interaction is then avoided thanks to an expert choice correcting the anomaly