Motivation

    The present web has a certain shortcoming that although it is successful at describing conceptual space, it does a poor job of describing physical space. Let us say, for example that we are interested in answers to queries such as "Find the closest Chinese Restaurant with the minimum waiting time", "Inform me whenever this freeway becomes congested within two miles or less", "How many allied troops are within a one mile radius?". The current web architecture does not support such location dependent queries, depending on dynamically generated data from various kinds of sensor networks. Obtaining such rapid, accurate and useful information in response to location-dependent questions as these would provide a whole new level of convenience and empowerment to individuals who ask them.

The WebDust Architecture

    Our architecture forms an innovative information infrastructure capable of providing any service that obtains, maintains, manages and delivers spatially-constrained data. It proposes that all information resides at the physical location in which it is produced, and assumes that all the information sources have a network presence. A common scenario in our vision is that of information sources and the users who query them to be mobile, thus making the response to queries dynamic in nature. This architecture also assumes that information sources can have unbounded heterogeneity; they may be as simple as embedded sensor devices that store & communicate only a single bit of information, or they may be as complex as full-scale databases. 

    The WebDust system is comprised of 4 key technologies which are described below:

•  DataSpaces : are massively distributed databases that strongly couple the physical space with the information space. They shift elementary database operations closer to the transactions that normally take place in the underlying network.
•  Infodispensers : are data aggregation & distribution devices that blanket the physical landscape and act as information-sprinklers, sprinkling important local information on users as they pass nearby. They do this by caching frequently queried data from the local dataspace and dispensing it to passing users based on users' previously specified preferences. 
• Spatial Web : This provides a mechanism for organizing & representing information aggregated by Infodispensers. Web pages in the spatial web differ from the normal web pages as they possess the following properties :

• All Spatial web pages have a limited physical "DataScope"  

• Links between the Spatial Web pages mirror the relevant structure in the physical space. 

        The DataScope is represented by a SPOT (SPatial ObjecT), namely an abstract data type of a spatial database viz. polygons, convex hull, etc. SPOTs provide for a method to encode the spatial information about the data collected from sensors. SPOTs are mapped on to Spatial Tags, which are simple human readable strings and allow for the construction of a spatial database over all spatial web documents. The link structure enables one to traverse between documents, in effect being to spatially-crawl the physical space. 

Here are slides describing concepts of the Spatial Web.