J2ME and Location-Based Services
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Location-based services (LBS) provide users of mobile devices personalized services tailored to their current location. They open a new market for developers, cellular network operators, and service providers to develop and deploy value-added services: advising users of current traffic conditions, supplying routing information, helping them find nearby restaurants, and many more.
This article introduces you to the field of LBS and to the Location API for J2ME (JSR 179), a set of generic APIs that can be used for developing location-based services. In addition, the article offers guidelines for designing location-based services.
What Location-Based Services Do
Location-based services answer three questions: Where am I? What's around me? How do I get there? They determine the location of the user by using one of several technologies for determining position, then use the location and other information to provide personalized applications and services. As an example, consider a wireless 911 emergency service that determines the caller's location automatically. Such a service would be extremely useful, especially to users who are far from home and don't know local landmarks. Traffic advisories, navigation help including maps and directions, and roadside assistance are natural location-based services. Other services can combine present location with information about personal preferences to help users find food, lodging, and entertainment to fit their tastes and pocketbooks.
There are two basic approaches to implementing location-based services:
Process location data in a server and deliver results to the device.
Obtain location data for a device-based application that uses it directly.
This article focuses on device-based location services.
Determining the Device's Location
To discover the location of the device, LBS must use real-time positioning methods. Accuracy depends on the method used.
