An LBMS delivery system can direct information, advertising, and safety warnings to mobile devices at specific locations (and times). Maps or three-dimensional displays of a person s surroundings can be delivered to support independent local travel or to provide context for more detailed guidance. Many wireless carriers, automobile manufacturers, and map data companies see LBMS as a broad new market opportunity comparable in size to voice telephone services in potential size.
In the last two years, efforts to standardize the delivery of the core geographic content and computations via XML and SOAP have moved to the point of demonstrated usability for commercial mass-market applications.
Some characteristics of LBMS are common across delivery platforms. The .NET framework and compatible delivery architectures allow the corresponding low-level core geographic computations ("navigation services") to be provided by dedicated service providers. This ability to specialize is very important in creating an economically viable means to collect the necessary information about the world, make it internally consistent and deliver it in the right form to wireless operators and other mobile services providers with end-user applications. At the same time, much of the complexity in designing and building delivery systems comes from the diverse technical approaches to both locating the geographic position of the mobile terminalthe "location" part of LBMS and this is compounded by the patchwork of technical means that are used to implement wireless data communications. Microsoft Mobile Information Server abstracts the latter and provides a single platform with easy adaptation to individual wireless carriers. So far there are few if any equivalent server products that can act as a platform for delivering the core geographic services. There are several characteristics of the location side of location-based mobile services that require a basic understanding before beginning the design of a delivery system using the Microsoft .NET framework and associated server products.
Geographic data collection and integration are often very expensive and it is a great advantage to be able to leverage an investment in a geographic database and corresponding computational algorithms across the broadest possible range of location-aware mobile applications. Some applications require delivery via transports with a native capability to support asynchronous messaging and to pass through corporate firewalls without either security risk or the need for special handling. Other applications are able to operate within the synchronous model of standard web services via HTTP on TCP port 80.
This chapter considers these common characteristics and the development of a solution architecture for the navigation service provider based on a particular .NET compatible delivery modelthe MAGIC Services Protocol. Most of the content applies in general to delivery of core geographic services to mobile applications via XML and SOAP. The back-end must be scalable from a low-load or prototyping configuration to a load-balanced high availability system capable of reliably supporting high loading without failing to meet time-sensitive delivery requirements. A Visual Studio .NET solution with a sample application capable of fully exercising a .NET MSP 2.0 server is included.