[PerAdaMagazine] The article of Simon Dobson, Graeme Stevenson, Graham Williamson, Stephen Knox, Matthew Stabeler, Lorcan Coyle, Steve Neely, and Paddy Nixon gives a very interesting perspective to the issues showing up with research and pratice in building up infrastructure for pervasive computing:
Pervasive computing provides a means of broadening and deepening the reach of information technology (IT) in society. It can be used to simplify interactions with Web sites, provide advanced location-specific services for people on the move, and support all aspects of citizens’ life in the community. Integrating IT services into everyday life requires that we can sense the environment where services are offered, and tailor them as the environment changes. People are not automata, however, and will often perform the same activity in slightly different ways. Moreover, the methods used to sense a person’s actions are inherently error-prone and imprecise, and the same events may be observed from different sensors or information sources. Users’ support needs also evolve over time. These triple problems of situation identification, context fusion, and behavioural evolution constitute the major challenges to building robust pervasive applications or services.
Implementing individual pervasive applications, such as tour guides(1) or healthcare (2), has been straightforward. But it has proved more difficult to build pervasive systems in which a dynamic population of services share infrastructure, sensing, and capabilities. Each new system requires a considerable investment of time to acquire expertise and money to create the necessary infrastructure. We aim to reduce these barriers and simplify the construction of extensible, long-lived pervasive systems.
We have developed our system, Construct, by identifying the best-of-breed techniques that have been successfully implemented for pervasive systems. We have collected these together into a middleware platform, an intermediary between sensors and services. Construct provides a uniform framework for situation identification and context fusion, while providing transparent data dissemination and node management (3).
Figure 1:

Data from sensors like Bluetooth or RFID is aggregated by nodes, which then disseminate the information.
Construct’s basic architecture (see Figure 1) relies on services and sensors that access a distributed collection of nodes, which are responsible for aggregating data from the sensors. Construct regards all data sources as sensors: for example, physical ones for temperature, pressure, and location are included along with virtual ones that access digital and Web resources.
More Information:
http://www.perada-magazine.eu/view.php?article=1262-2008-09-22&category=Middleware
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