No abstract

With the emergence of the Internet of Things, environmental sensing has been gaining interest, promising to improve agricultural practices by facilitating decision-making based on gathered environmental data (i.e., weather forecasting, crop monitoring, and soil moisture sensing). Environmental sensing, and by extension what is referred to as precision or smart agriculture, pose new challenges, especially regarding the collection of environmental data in the presence of connectivity disruptions, their gathering, and their exploitation by end-users or by systems that must perform actions according to the values of those collected data. In this paper, we present a middleware platform for the Internet of Things that implements disruption tolerant opportunistic networking and computing techniques, and that makes it possible to expose and manage physical objects through Web-based protocols, standards and technologies, thus providing interoperability between objects and creating a Web of Things (WoT). This WoT-based opportunistic computing approach is backed up by a practical experiment whose outcomes are presented in this article.

International audienceThe Web of Things (WoT) extends the Internet of Things (IoT) considering that each physical object can be accessed and controlled using Web-based languages and protocols. However, due to the mobility of physical objects and to the short radio range of the wireless interfaces they are equipped with, frequent and unpredictable connectivity disruptions may occur between the physical objects and the Web clients used to control and access these objects. This paper presents a disruption-tolerant RESTful support for the WoT, in which resources offered by physical objects are identified by URIs and accessed through stateless services. Service requests and responses are forwarded using the store-carry-and-forward principle. A complete service invocation model is provided, allowing to perform unicast, anycast, mul-ticast and broadcast service invocations either using HTTP or CoAP, which makes it particularly suited for the WoT. This disruption-tolerant support is illustrated by a case study in the context of agricultural robotics