Design and implementation of a gateway for Web-based interaction and management of embedded devices
Samuel Wieland · Repository for Publications and Research Data (ETH Zurich) · 2009
Embedding and integrating wireless sensor networks into the Web is ongoing research with many problems to be resolved.Although the Web by design provides scalability, extensibility and evolvability, we cannot directly apply these features to legacy sensor networks.Sensors and embedded devices have constrained resources in terms of CPU, memory and computational power, possibly interact in mobile environments, and most of the times they are not Web-enabled.Many solutions have been proposed and existing middlewares come up with promising ideas and concepts.Despite that fact, we think that no current solution properly integrates with the design principles of the Web.We therefore present the smart gateway -A framework that simplifies the integration of sensors and wireless sensor networks into the Web.The smart gateway helps rapid development and deployment of Web-mash-ups from existing sensor resources.The smart gateway represents physical devices with existing Web technology, giving access and control to low-level devices to anyone through the Web browser.By implementing a device abstraction that allows to integrate any kind of device, we enrich the Web with first class citizens capable to sense and interact with the real world.The smart gateway therefore provides the first building blocks to empower users to create the next generation of the World Wide Web, namely the vision of the Web of Things. Chapter 2Infrastructures for the Web of Things "It would appear that we have reached the limits of what is possible to achieve with computer technology, although one should be careful with such statements, as they tend to sound pretty silly in 5 years." von Neumann (1903von Neumann ( -1957) ) Historically grown, there are two different architectural styles to build distributed systems for the Internet and the Web, namely WS-* and REST.A good introduction to WS-* can be found in [2] whereas [30] gives an overview to REST.In [26] an objective comparison has been performed between the two.This chapter shall give a short overview to both styles.We present the technology and a selection of middlewares built with WS-* or REST. Services and Service Oriented ArchitectureIn the early days of computer science, programs were developed to run on single machines.This approach was perfectly well, as long as computers could be seen as isolated islands without communication in between.With the development of the ARPANET, data could be transferred more conveniently from one computer to another, using network infrastructures.The next logical step was to abstract from inter-connecting computers to computers, towards connecting and distributing software.First approaches to inter-link software (RPC 1 , CORBA 2 , DCOM 3 , RMI 4 ) proposed the idea of wrapping a software component behind an interface.The software 7