Activity recognition and monitoring systems based on multi-sensor and multi-device approaches are more and more popular to enhance events production for scenario analysis. Underlying software and hardware infrastructures can be considered as static (any change during the overall recognition process), quasi-static (any change during two reconfigurations of the process) or really dynamic (depending on dynamic appearance and disappearance of numerous sensors and devices in the scene, communicating with the system, during recognition process). In this last case, we need to adapt partially and reactively the application to the evolution of the environment, while preserving invariants required for the validity of the recognition process. In order to address such challenge our research try to federate the inherent constraints of platform devoted to action recognition like SUP with a service oriented middleware approach to deal with dynamic evolutions of the infrastructure of the system. Recent results using a Lightweight Component Architecture (SLCA) [1] to compose services for device and Aspects of Assembly (AA) to adapt them in a reactive way [2] present interesting prospects/ /to deal with multi-device and variable systems. They provide a user-friendly separated description for adaptations that shall be applied and composed at runtime as soon as the corresponding required devices are present (in context-sensitive security middleware layer for example [3]). They underline performances and response times which allow to neglect the time of adaptation and reconfiguration in comparison with delays for research and discovery of services and management of appearance and disappearance of devices [Revues]. However, although composition between these adaptations can verify some properties, the use of black box components in the composition model of SLCA doesn’t allow extracting a model of their behavior. Thus, the existing approaches don't really succeed to ensure that the usage contract of these components is not violated during application adaptation. Only a formal analysis of the component behavior models associated with a well sound modeling of composition operation will allow us to secure the respect of the usage contracts.

In this axis, we propose to rely on a synchronous modeling of component behavior and component assembly to allow the usage of model checking techniques to formally validate services composition.

We began to consider this topic in 2008 through a collaborative action (SynComp) between Rainbow team at UNSA and Inria Pulsar team.

Within the Rainbow team, SLCA/AA experimental platform called WComp, is dedicated to the reactive adaptation of applications in the domain of ubiquitous computing. During this collaboration, the management of concurrent access in WComp has been studied as a main source of disturbance for the invariant properties.. A modeling of the behavior of components and of their accesses in a synchronous model has been defined in WComp. This approach allows us to benefit from model checking techniques to ensure that there are no unpredictable states of WComp components on concurrent access. This year, during his training, Vivien Fighiera (already involved in the SynComp action), has completed the theoretical work done in SynComp. He studies how prove safety properties regarding WComp component models relying on the NuSMV model checker.

This year, the collaboration between Rainbow and Pulsar has been strengthened since Jean Yves Tigli is researcher full time in Pulsar team since September, in sabbatical year sponsored by Inria. We plan to extend the work previously done in modeling also the assembly of WComp components with a synchronous approach to allow the usage of model checking techniques to formally validate application design.

In order to obtain results based on experimental scenarios to evaluate SynComp improvements for adaptive recognition process, we plan to integrate SUP platform as a software services provider.

The SUP platform gathers a set of modules devoted to design applications in the domain of activity recognition. WComp is aimed at assembling services which evolve in a dynamic and heterogeneous environment. Indeed, the services provided by SUP can be seen as complex high-level services whose functionalities depend on the SUP treatments; this latter dealing with the dynamic change of the environment.

Thus, considering SUP services as web services for devices for example, the devices associated with SUP services will be discovered dynamically by WComp and used with other heterogeneous devices.

[1] J.-Y. Tigli, S. Lavirotte, G. Rey, V. Hourdin, M. Riveill,“Lightweight Service Oriented Architecture for Pervasive Computing” IJCSI International Journal of Computer Science Issues, Vol. 4, No. 1, September 2009, ISSN (Online): 1694-0784, ISSN (Print): 1694-0814

[2] J.-Y. Tigli, S. Lavirotte, G. Rey, V. Hourdin, D. Cheung, E. Callegari, M. Riveill “WComp middleware for ubiquitous computing: Aspects and composite event-based Web services” in the journal Annals of Telecommunications, Springer Paris editor, ISSN 0003-4347 (Print) 1958-9395 (Online), Vol. 64, No 3-4, March-April 2009.

[3] Vincent Hourdin, Jean-Yves Tigli, Stéphane Lavirotte, Gaëtan Rey et Michel Riveill. « Context-Sensitive Authorization in Interaction Patterns ». In the proceeedings of the ACM International Conference on Mobile Technology, Applications and Systems (Mobility), Nice, France, September 2009.