1.4.3. OpenLS Services
In the previous sub sections we discussed requirements and necessary components of LBSs. To realize a Location Based Service a number of different players ranging from technology providers to data providers have to be involved. This includes hardware and software vendors, content and online service providers, wireless network and infrastructure providers, wireless handset vendors and branded portal sites. To ensure that all the different technologies and devices work together common standards for interfaces and description have to be defined. Such standards with respect to LBSs have been set up by the International Standard Organisation (ISO) and by the Open Geospatial Consortium (OGC). Whereas ISO 19119 provides a general service framework and ISO 19101 gives a classification of geographic services, has the Open Geospatial Consortium released a specification for Open Location Services (OpenLS - (Open Geospatial Consortium 2005)). OpenLS defines core services, their access and abstract data types which form together a framework for a open service platform, the so called GeoMobility server. The server acts as application server and should proceed and answer core service requests. The role of this server is pictured in the figure. It should be noticed that service requests to a GeoMobility server can be send from a mobile user, from Internet users but also from other application servers.
The role of the GeoMobility Server. (modified version from OGC OpenLS Specification 1.1, 2005) (Open Geospatial Consortium 2005)The core services defined in the OpenLS 1.1 specifications (Open Geospatial Consortium 2005) OGC 2005 include five service types:
OpenLS Directory Service | Directory Service(spatial
yellow pages): This service provides subscribers with access to an
online directory to find the nearest or specific place, product or
service.
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OpenLS Gateway Service | Gateway Service: This is the interface between the GeoMobility Server and the Location Server from the Positioning Service (see the Figure). It is useful to request for the current location with different modes (e.g. multi or single terminal, immediate or periodic position) |
OpenLS Location Utility Service | Location Utility Service
(Geocode/ Reverse Geocode): This service performs as a Geocode by
determining a geographic position, if a place name, street address or
postal code is given. It also performs as a reverse Geocode by
determining a complete, normalized place name/street address/postal
code, for a given geographic position.
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OpenLS Presentation Service | Presentation Service:: This
service renders geographic information for display on a Mobile Terminal.
An OpenLS application may call upon this service to obtain a map of a
desired area, with or without map overlays that depict Route Geometry,
Point of Interest, Area of Interest, location, position and/or address.
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OpenLS Route Service | Route Service: This service determines a route for a subscriber. The user must indicate the start point (usually the position acquired through the Gateway Service, but this could also be a specified location, e.g. their home for a planned trip), and the endpoint (any location, like a place for which they only have the phone number or an address, or a place acquired through a search to a Directory Service). The subscriber may optionally specify waypoints, in some manner, the route preference (fastest, shortest, least traffic, most scenic, etc.), and the preferred mode of transport. The returned routing information can be textual, in a presentation code (describing turns and distances) or a geometry, useful for a map. |
These mentioned services are core services, that means different providers will implement further services for their customers. Examples therefore are real-time traffic information, event guides and friend finders.