Section: New Results

Service Oriented Middleware facing the Challenges of the Internet of Things

Participants : Benjamin Billet, Nikolaos Georgantas, Sara Hachem, Valérie Issarny, Roberto Speicys Cardoso, Thiago Valladares Sabino Teixeira.

Over the years, the Internet has become the most important networking infrastructure, providing an integrated entity enabling sharing, contributing, creating, using, collaborating and integrating information and knowledge by all. As a result, the Internet is changing at fast pace and is expected to evolve into the Future Internet, i.e., service-aware and self-aware federated networks that provide built-in and integrated capabilities such as: contextualization, reliability, robustness, mobility, security, service support, and self-management of communication resources and services. 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. 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 that domain was focused on three related directions:

• Challenges related to IoT: To prepare the ground for our research on middleware for the Internet of Things, we identified the set of challenges in the IoT, namely [10] : the large scale of the Internet of Things, heterogeneity of things, unknown and dynamic network topology, unknown data-point availability, incomplete or inaccurate metadata, and conflict resolution. The scale issue arises with the millions of devices, millions of users, large amounts of data to share and services to request. The heterogeneity of the IoT is due to the fact that the network will be composed of different types of devices from different vendors with varying sensing/actuating characteristics. The unknown dynamic network topology results from the fact that devices will be mostly mobile and their availability is unknown. A related challenge is the unknown data-point availability as things, which provide the desired measurements, may leave the network or malfunction at any time. A data point is measurement of an entity of interest at a specific time. As for metadata inaccuracy, this issue is a direct result of humans, who are prone to making errors, being the main source of metadata specification. Last but not least, conflict resolution is due to the multiple stakeholders involved in the Internet of Things

• Middleware Requirements for the Internet of Things: The middleware we plan on implementing should abstract things (IoT devices) as services and support dynamic service composition. To handle the IoT challenges, the middleware should also support a probabilistic discovery approach where only a subset, instead of a whole set, of devices is selected in a way that provides a good enough answer that satisfies an application's request [10] . However, and prior to designing the middleware architecture, we extensively surveyed the literature in order to identify research challenges for service-oriented middleware design, therefore investigating service description, discovery, access and composition in the Future Internet of services [7] .

• Ontologies for the Internet of Things: As part of our middleware architecture, we specified a set of ontologies [20] that model real-world entities as physical concepts, along with things that measure those entities. Further, to support a smarter service composition, we also modeled mathematical formulas and physics relations as services to substitute missing thing-based services. Those services will instead compute the value of a desired measurement of an entity of interest. Finally, we also specified an ontology that describes estimation models that can be used to estimate the value of a measurement in case of a missing data point or a missing data source. Estimation models can further be used to define probabilistic discovery functions that will be executed by the middleware.