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1.4.2. Requesting and Receiving Content

Push and Pull Services

Pull Services deliver information directly requested from the user. This is similar to call a website in the Internet by fill in its address in the web browser-address field. For pull services a further separation can be done into functional services, like ordering a taxi or an ambulance by just pressing a button on the device, or information services, like the search for a close Chinese restaurant (Virrantaus et al. 2001).

Push Services deliver information which are only not or indirectly requested from the user. Such push services are activated by an event, which could be triggered if a specific area is entered or triggered by a timer. An example for an indirectly requested service is a news service subscription which contains event information with respect to the actual city. A not requested service could be advertisement messages if a specific area in a shopping mall is entered or warning messages if weather conditions change (e.g. hurricane warnings). Since push services are not bound on previous user interaction with the service, they are more complex to establish. Here, the background information like user needs and preferences have to be sensed by the push system.

Content

The needed data can be very different and depends on the kind of services offered, that is on its global or specialized application character.

Purpose Specific LBS Applications are for instance services which help localizing handicapped people or services provided by a national park. For the first example, monitoring handicap people, only the position and mapping data is necessary, to display the person's position on a map. Further the monitoring service could introduce (own) risk zones where an alert is activated if the patient enters the zone. For the second example, a national park LBS, again some background data for positioning information is useful. Such mapping data could be obtained from the country mapping agencies. Other national park services which answer questions like: What kind of tree is it? and Where to find an owl? can probably be found in the park's own information data bases. Additional information could be provided by an electronic encyclopaedia system of a publishing company.

General LBS Applications are offered by telecommunication providers like NTT DoCoMo, Telecom, Vodaphone, AT & T or specialized companies, which provide their services to user of different telecom networks. Examples of these general data are shown in the figure below. Considering the core services types of the previous sub section we can allocate different data providers:

  • Directory Service: Yellow Pages provider with local, national and international focus; transportation companies (rail and bus); Internet search services (e.g. Google.com, Yahoo.com); Internet consumer information services (Ciao.com) and Personal Websites (restaurant website, company website); electronic libraries like Wikipedia (www.wikipedia.org); weather services; entertainment and news information services; and so forth.
  • Gateway Service: positioning services / position providers.
  • Location Utility Service: provider of postal data (National Post Agencies) and street data (NAVTEQ, Tele Atlas).
  • Presentation Service: aerial and satellite photo provider (National Space Agencies, National Surveying Agencies) and map provider (National Mapping Agencies, mapping companies and publishers).
  • Route Service: street data providers (NAVTEQ, Tele Atlas, National Road Administrations) and routing services which can be combined with presentation (mapping) services (e.g. Michelin.com, Map24.com).
  • The non core service function "Friend Finder" does not necessary need external information. Here, the position of friends can be determined by using solely mobile network information. In contrast, other services like "Real-Time Traffic" information could be directly exchanged between specialized data provider and user, without needing any additional data sources and processing, after obtaining the location from a positioning service.

The integration of the data - so called data conflation - from the mentioned different providers needs the definition of suitable data exchange formats and interfaces. The data conflation will be one of the challenging tasks for the next years.

Different data for LBSs from various data providers:

transport timetables (www.bahn.de)transport timetables (www.bahn.de)postal data (www.gis.zh.ch)postal data (www.gis.zh.ch) routing & traffic data (www.map24.de)routing & traffic data (www.map24.de)road network dataroad network data points of interest (restaurand, book store)points of interest (restaurand, book store)weather data (www.wetter-online.de)weather data (www.wetter-online.de)


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