5 Middleware

Developing systems and software for a smart environment is a daunting task. As with any large endeavor, there are many components that comprise modern smart environments. There is sensor hardware and software perceiving the environment, application software that interprets and reasons about that perception data, and effector control software acting upon the environment as well as many support systems. Most of these components are working with an operating system on hardware that makes computation possible with the goal of making the environment " smart. " Here lies the opportunity for software that can provide important services to facilitate rapid development, ease of integration, improved reliability, and increased scalability of systems that make smart environments possible. This software is commonly called middleware and this chapter is motivated by the search for the ideal smart environments middleware. Middleware is connectivity software that joins applications through communication mechanisms creating transparency, scalability, and interoperability and lies between the software applications it assists and the platform it is based upon. Middleware typically resides in a layer built directly upon the operating system of the target hardware platform, but may be built upon other layers of middleware typically forming higher abstractions with each additional layer. Middleware is defined by the API (Application Programming Interface) it provides to applications that utilize it and the protocol(s) it supports [Ber96]. Middleware should be designed to reduce the complexities of the network, host operating system, and any available resource servers creating value in simplifying these for the applications using it and the developers who write them [Lin97]. Middleware should provide a cross-platform infrastructure that facilitates rapid development by providing services and features that would normally have to be developed if not provided by the operating system and a consistent and natural extension to the development of software applications. Overall, middleware should improve the desired characteristics of the target application and the developed system. The goals of this chapter are to provide an understanding of the concept of middleware, present the desirable characteristics, and discuss its forms as well as the positives and negatives of each form. We will introduce some of the technologies in current use, develop an understanding of the importance of standards and where to find them, and present design issues to consider to assist in choosing the proper form and technology for a project. We hope to develop an understanding of the benefits of middleware and will …