Towards Run-Time Verification of Compositions in the Web of Things using CEP

Following the vision of the Internet of Things, physical world entities are integrated into virtual world things. Things are expected to become active participants in business and social processes. Then, the Internet of Things could benefit from the Web Service architecture like today’s Web does, so Future service-oriented Internet things will offer their functionality via service-enabled interfaces. In previous work, we demonstrated the need of considering the behaviour of things to develop applications in a more rigorous way, and we proposed a lightweight model for representing such behaviour. Our methodology relies on the service-oriented paradigm and extends the DPWS profile to specify the order with which things can receive messages. We also proposed a static verification technique to check whether a mashup of things respects the behaviour, specified at design-time, of the composed things. However, a change in the behaviour of a thing may cause that some compositions do not fulfill its behaviour anymore. Moreover, given that a thing can receive requests from instances of different mashups at run-time, these requests could violate the behaviour of that thing, even though each mashup fulfills such behaviour, due to the change of state of the thing. To address these issues, we present a proposal based on mediation techniques and complex event processing to detect and inhibit invalid invocations, so things only receive requests compatible with their behaviour.