WoTPubSub: A web of things middleware with publish subscribe functionality for enabling lightweight and efficient standard web access on constrained device

The web platform can be seen as an auspicious candidate to provide an interoperability layer in an IoT based system with various kind of device specification and client platform leading to the transformation from IoT to WoT (Web of Things). In order to implement web platform on IoT world, we require a web compatible middleware yet still maintaining lightweight and efficient machine-to-machine (M2M) communications. In this paper we propose the web of things (WoT) middleware with publish subscribe functionality or WoTPubSub. As opposed to the existing solution, this middleware offers the utilization of lightweight MQTT protocol to perform a communication with constrained device while still maintaining the compatibility with existing web architecture. The proposed system consists of three actors: the user as Restful HTTP client, the sensing-actuating constrained device as both MQTT publisher-subscriber and the proposed middleware acting as communication bridge which translates user's HTTP request into MQTT publish-subscribe action. We consider two data flow scenarios in the proposed middleware: user obtaining data from sensing device and user giving a command to actuating device. From functional and performance testing, we conclude that the proposed middleware has been able to provide a web compatible intermediary functionality between user and sensing-actuating constrained device with improved performance compared to the existing approaches.