Web services for things

In this chapter, we introduce an interesting type of Web services for "things". Existing Web services are applications across the Web that perform functions mainly to satisfy users' social needs "from simple requests to complicated business processes". Throughout history, humans have accumulated lots of knowledge about diverse things in the physical world. However, human knowledge about the world has not been fully used on the current Web which focuses on social communication; the prospect of interacting with things other than people on the future Web is very exciting. The purpose of Web services for "things" is to provide a tunnel for people to interact with things in the physical world from anywhere through the Internet. Extending the service targets from people to anything challenges the existing techniques of Web services from three aspects: first, an unified interface should be provided for people to describe the needs of things; then basic components should be designed in a Web service for things; finally, implementation of a Web service for things should be optimized when mashing up multiple sub Web services. We tackle the challenges faced by a Web service for things and make the best use of human knowledge from the following aspects. We first define a context of things as an unified interface. The users' description (semantic context) and sensors (sensing context) are two channels for acquiring the context of things. Then, we define three basic modules for a Web service for things: ontology Web services to unify the context of things, machine readable domain knowledge Web services and event report Web services (such as weather report services and sensor event report services). Meanwhile, we develop a Thing-REST framework to optimally mashup structures to loosely couple the three basic modules. We employ a smart plant watering service application to demonstrate all the techniques we have developed.