A new class of applications based on smart embedded devices is emerging thanks to advances in microelectronics. There is one common characteristic to most of these new applications: The devices are networked and they are expected to cooperate dynamiclly. As an example, consider yourself driving home in your car. Right as you pull up your driveway, your garage door opens, and the light in the house is turned on. Another example is a mobile robot moving through an instrumented smart environment, e.g. in a factory.
Dynamic cooperation requires awareness and knowledge of the services the environment provides. Device and service descriptions that are available on-line are a suitable means to provide the required information.
Current description languages, esspecially for embedded systems, provide only basic low-level information. They do not allow to describe a system in enough detail, and cannot provide the necessary semantic information.
Device and service descriptions can also have equally important uses during the complete device life-cycle, i.e. they may be usefull during the design and implementations phase of devices, as well as during their integration phase into larger systems. Most current description facilities fail to provide support in such a broad way.
The CODES approach pressented in this Thesis provides a component description language that supports the complete life-cycle of components, and lays the foundation for dynamic cooperation. Togehter with the underlying communication middleware COSMIC, which targets smal autonomous components, it provides a description language for components and their services combined with a range of supporting tools and techniques. The description language is based on XML, and thus easily allows the integration with a number of well tested and widely used technologies. XML also eases the extension of the proposed description language. CODES descriptions capture a component both in terms of the component as a whole with information about e.g. its manufacturer, an in terms of the services the component offers and relies on for its operation. The services descriptions are based on the underlying COSMIC abstractions. While the COSMIC abstractions provide a high-level view of a component’s interface, the descriptions are detailed enough to allow the completely dynamic setup of communication, including the encoding and decoding of the data exchanged. A seamlessly integrated parameterization facility allows the descriptions to be split up into a static part for easy storage, and a variable part for customization. However, whenever the descriptions are actually used at run-time, the parameters are transparently merged into the descriptions, easing interaction for outside parties.
The supporting tools and techniques cover the component’s life-cycle. During the design pahse, an editor for the description documents is provided. Part of the component’s code can be generated from the descriptions during the implementation phase. Compatibility checking eases the integration of multiple components into larger systems. On-line discovery and query mechanisms allow the dynamic use of services. Discovery and query is important both during normal system usage, and during system maintenance.