Section: New Results

Service Oriented Middleware facing the Challenges of the Internet of Things

Participants : Benjamin Billet, Nikolaos Georgantas, Sara Hachem, Valérie Issarny, Yesid Jarma Alvis, Cong Kinh Nguyen, George Mathioudakis.

In our vision, The Future Internet can be defined as the union and cooperation of the Internet of Content, Internet of Services, Internet of Things, and 3D interactive Internet, supported by an expanding network infrastructure foundation [6] . In ARLES, we chose to pay special attention to the Internet of Things (IoT). IoT is characterized by the integration of large numbers of real-world objects (or “things") onto the Internet, with the aim of turning high-level interactions with the physical world into a matter as simple as is interacting with the virtual world today. As such, two devices that will play a key role in the IoT are sensors and actuators. In fact, such devices are already seeing widespread adoption in the highly localized systems within our cars, mobile phones, laptops, home appliances, etc. In their current incarnation, however, sensors and actuators are used for little more than low-level inferences and basic services. This is partly due to their highly specialized domains (signal processing, estimation theory, robotics, etc.), which demand application programmers to also be domain experts, and partly due to a glaring lack of interconnectivity between all the different devices. Our work within this domain has been focused on two related directions:

• Architecture of a Service Oriented Middleware for the Mobile Internet of Things: Adopting the service-oriented architecture (SOA) approach towards middleware (see §  3.3 ), is an adequate solution towards addressing the heterogeneity and the unknown network topology issues in the IoT. SOA is commonly used in IoT solutions to abstract things or their measurements as services. The service-oriented paradigm decouples the functionalities of things from their hardware information or other technical details, and supports three core functionalities: Discovery and Composition of, and Access to services. Typically, in traditional uses of SOA, even if millions of services are registered, there is no need to select and access them all simultaneously. However, in the IoT, discovery, composition and access are undoubtedly more complicated. In fact, it is unlikely for a single or even a few services to be sufficient when providing real world measurements. In most cases, to accurately represent a real-world feature, a large number of services are selected to provide their measurements, and subsequently, all acquired values should be properly aggregated. As a consequence, discovery will return a large set of accessible services, redundant as they may be. Consumers are then expected to access the numerous providers to acquire their measurements, over which they should know the exact aggregation/fusion logic to apply. Furthermore, such logic requires precise knowledge and understanding of the real world and its governing physics and mathematics laws. Clearly, performing discovery, composition and access tasks as presented above incurs high communication and computation costs and is thus not realistic within the large scale IoT. In light of the above issues, we have been revisiting the SOA and its interaction patterns to support better scalability and exempt consumers from directly interacting with providers. Specifically, we introduce a thing-based SOA to wrap access and computation activities in a middleware that, unlike traditional SOA middleware, is aware of the real world, its physics and its mathematics rules; this has further led to our initial work on the components of such a middleware.

• Probabilistic Registration for Large Scale Mobile Participatory Sensing: An increasingly important component of the Internet of Things are modern smart phones, whose constituent sensors and wireless connectivity make them ideal candidates for mobile participatory sensing, which aids in providing increased knowledge about the real world while relying on a large number of mobile devices. Those devices can host different types of sensors incorporated in every aspect of our lives. However, given the increasing number of capable mobile devices, any participatory sensing approach should be, first and foremost, scalable. To address this challenge, we present an approach to decrease the participation of (sensing) devices in a manner that does not compromise the accuracy of the real-world information while increasing the efficiency of the overall system. To reduce the number of the devices involved, we present a probabilistic registration approach [20] , based on a realistic human mobility model, that allows devices to decide whether or not to register their sensing services depending on the probability of other, equivalent devices being present at the locations of their expected path. We used our techniques as the basis of the design and implementation of a registration middleware, using which mobile devices can base their registration decision. Through experiments performed on real and simulated datasets, we show that our approach scales, while not sacrificing significant amounts of sensing coverage.

Our IoT middleware is currently being used by the industrial partners in the FP7 IP CHOReOS project. Complementary to our research on this service oriented middleware for the Internet of Things, we have also been working on suitable abstractions for enabling easy application development for the IoT, discussed next.