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Location Information Services

Location Information Services. Location Information Services:Types. Location-Transparent Location-Tolerant Location-Aware. Location-Transparent Services. Hides the effect of mobility to applications and users.

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Location Information Services

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  1. Location Information Services

  2. Location Information Services:Types • Location-Transparent • Location-Tolerant • Location-Aware

  3. Location-Transparent Services • Hides the effect of mobility to applications and users. • Network services and resources can be transparently accessed by means of a resource and service broker functions which map the application’s service type requests on adequate service provider instances. • Application defined quality-of-service (QoS) for the underlying network connections is sustained through a QoS manager.

  4. Location-Tolerant Services • Allows applications and users to tolerate the effects of mobility that can not be hidden by the platform. • A trader function allows the application to perform a service and service type re-negotiation to achieve a graceful degradation instead of dumb service termination. • A profile handler function allows to retrieve user and terminal characteristics to perform application adaptation according to terminal type currently being used.

  5. Location-Aware Services • Allows applications and users to be aware of their mobility and the absolute and real physicalpositions of real-world objects. • Applications can exploit this information for customizing their functionality and users can benefit from this information for navigation purposes. • This abstraction level is realized by the location information server (LIS) function that allows to query location information and to be notified about the occurrences of predefined location-related events.

  6. mobile application platform mobility manager APIs resource & service broker location manger server QoS manager profile handler application application locating infrastructure wired & wireless networks APIs APIs Platform for Mobile and Location-Aware Applications mobile and location-aware multimedia applications mobility-management services platform access protocols mobility management signalling protocol generic support functions Infrastructure and network interfaces Mobility Management Domain

  7. Acquires information about the – absolute or relative – physical location of real world objects in which an application is interested. Hides from applications which locating technology is being used. Has map and relationship knowledge to translate the low-level position information from the locating infrastructure into location information having meaningful abstraction level for application. Application can query the LIS about current location of objects (LIS directory database) or can request to be notified when certain location-related conditions between objects locations are fulfilled (LIS event handler). location-aware application location-aware application other APIs LIS API LIS API to remote platforms directory access protocol other midlleware components profile handler Location information server (LIS) directory database event handler locater Infrastructure to locate physical objects Location Information Server

  8. A Generic Locating Model • LIS locates objects (identified by object-ID) representing either persons or resources inside areas (identified by area-ID). • Objects have a tag (identified by tag-ID) attached to them that identifies and localizes them. • Resources can serve as tags e.g. badges, cordless telephones, PDAs, or laptops. • A LIS: • maintains relations between objects and tags. • provides graphical map in human-readable format and calculates shortest paths between areas. • finds objects that are nearest to a specified area and fulfill certain conditions. • supports both querying and notification services. • A locator provides the interface between locating infrastructure and LIS.

  9. location information server object  area application relations maps position  area object  tag sensor  area tag  sensor tag  position database/ event handler locator locator sensor sensor positioning system tag tag tag tag tag tag LIS Data Model Locating rules: • A tag is located within an area by means of sensors installed in that area. This information is collected by the locator and published to LIS, which uses a map to translate sensor-ID into area-ID. • A tag may determine its absolute geographical position (e.g. using GPS) and publish this through the locator to LIS, which uses map to translate geographical location into area-ID.

  10. LIS Service Types • Location retrieval service • Location-dependent object and area selection service • Event notification service • Map retrieval service • Identifier mapping service • Relationship service

  11. Location Retrieval Service • Provides physical location of static/mobile object with/without tags, e.g. • In which area is person A (and when was her last sighting)? • How many (or which persons) are present in area B? • Where is equipment C (e.g. printer) in area B?

  12. Location-dependent Object and Area Selection Service • Provides type or class oriented location information, e.g. • Which object of type D is present in area B? • Which one is the nearest object of type D (relative to my own location) and where it is located? • Which (nearest) area fulfils certain condition (e.g. which one is the nearest unoccupied meeting room)?

  13. Event Notification Service • Avoids repeated polling the LIS by an application. This functionality is, e.g., needed to start a function on a mobile device as soon as it enters a certain area. Examples of events are • Inform me when person A enters (or leaves) area B! • Inform me when area B is empty! • Inform me next time person A meets person B anywhere!

  14. Map Retrieval Service • To help users (of navigation based applications) in finding others persons, resources, or areas by providing maps and navigation instructions, e.g. • Provide me with with a (human-readable) map of area A! • Provide me with the shortest-path between area A and area B!

  15. Identifier Mapping Service • Provides mappings between identifiers of areas, sensors, and positions • to support internal LIS operations, • for other support functions of mobile application platform, and • for location-aware applications operating at tag-level.

  16. Relationship Service • Provides relationship information between objects and tags for applications operating at tag level instead of object level, or for applications that want to communicate with objects through its tag,e.g. • Which object is associated with tag A? • Which (if any) tag does object B posses ? • Associate tag A with objet B!

  17. LIS: Implementation Issues • DBMS-based or Directory-based (such as X.500 [Maas MONET 98]) • LIS do not require full functionality of DBMS • Should support distributed implementation on multiple platforms • Communication with external locator • Dramatically increases search time • Minimize the interaction with external locator using • Precise search filters • Location query optimization techniques • Event Monitoring • Active Databases

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