Section: New Results

Composing Applications in the Internet of Things

Participants : Aness Bajia, Pankesh Patel, Animesh Pathak, Françoise Sailhan.

As introduced above, the Internet of Things integrates the physical world with the existing Internet, and is rapidly gaining popularity, thanks to the increased adoption of smart phones and sensing devices. Several IoT applications have been reported in recent research, and we expect to see increased adoption of IoT concepts in the fields of personal health, inventory management, and domestic energy usage monitoring, among others.

An important challenge to be addressed in the domain of IoT is to enable domain experts (health-care professionals, architects, city planners, etc.) to develop applications in their fields rapidly, with minimal support from skilled computer science professionals. An ideal application development abstraction of the IoT will allow (domain expert) developers to intuitively specify the rich interactions between the extremely large number of disparate devices in the future Internet of Things. The goal of our research is then to propose a suitable application development framework, where our work this year covered the two following related areas.

Multi-stage model-driven approach for IoT application development: We have proposed a multi-stage model-driven approach for IoT application development based on a precise definition of the role to be played by each stakeholder involved in the process: domain expert, application designer, application developer, device developer, and network manager [22] . The metamodels/abstractions available to each stakeholder are further customized using the inputs provided in the earlier stages by other stakeholders. We have also implemented code-generation and task-mapping techniques to support our approach. Our evaluation based on two realistic scenarios shows that the use of our techniques/framework succeeds in improving productivity in the IoT application development process. More details of our approach can be found in [8] .

Integrating support for non-functional requirements while programming IoT applications: Given that devices and networks constituting the IoT are prone to failure and consequent loss of performance, it is natural that IoT applications are expected to encounter and tolerate several classes of faults - something that still largely remains within the purview of low-level-protocol designers. As part of our work on the MURPHY project (§  8.1.1.1 ), we are addressing this issue by proposing: i) a set of abstractions that can be used during macroprogramming to express fault tolerance requirements, and ii) a runtime system that employs adaptive fault tolerance (AFT) to provide fault tolerance to the sensing application. Complementary to this, we have proposed task mapping algorithms to satisfy those requirements through a constraint programming approach [19] . Through evaluations on realistic application task graphs, we show that our constraint programming model can effectively capture the end-to-end requirements and efficiently solves the combinatorial problem introduced.

We have continually incorporating our research results in the above areas into Srijan (§  5.6 ), which provides an easy-to-use graphical front-end to the various steps involved in developing an application using the ATaG macroprogramming framework.