Besides time, location is one of the major quantities determining our everyday life. People make use of it when navigating through cities or on highways, for making appointments, for ordering goods or services, or simply for informing other people about their whereabouts. Thus, the concept of location is essential for orientation in the real world. On the other hand, the emergence of the Internet has shown us how to overcome this concept. At least with regard to communication and information exchange between people, it does not play a role where these people are located in the world or by what distances they are separated from each other. The Internet shadows the location of its participants, and that is why it is often also referred to as global village or cyberspace.
Mobility means change of location (at least in the context considered here). Cellular networks like GSM owe their success to people who want to communicate while being on the move, and provide several mechanisms for supporting mobility, for example, location management for routing incoming telephone calls to the base station the subscriber is connected to. Initially planned for telephony only, cellular networks have been extended with data services like GPRS or UMTS packet-switched in the recent years and are now increasingly used for Internet access.
The added-value of mobile services can be significantly increased if the user’s current location is taken into consideration during service execution, and that is what the main idea behind location-based services (LBSs) is. By using LBSs, the user’s location is not shadowed any longer, but it is used to adapt services to the special situation and needs of a user. Real-world and cyberspace merge by the use of LBSs, and thus they represent a significant core function for achieving mobile intelligence. LBSs can be defined as services that create, compile, select, or filter information based on the current locations of the users or those of other persons or mobile objects.
In this article I provide an insight into a web 2.0 supply chain for LBS (Location based services).
Web 2.0 can be seen as a new paradigm that represents a user-centric approach of how Web services and related content are created and published. While the plain old Web since its emergence in the mid-1990s was dominated by professional service, application, and content providers, Web 2.0 now shifts the focus more toward the user as the main driving force behind the further development of theWeb. As a result, Web 2.0 is often also associated with terms like democratization, openness, and social networking.
Generally, there may be many actors involved in the operation of an LBS, and it is therefore useful to describe their interactions in a supply chain. An illustration indication a general model for an LBS supply chain, which follows the Web 2.0 approach and which identifies the participating roles and their relationships.
The supply chain follows the approach of user-centricity and mashups as proclaimed by Web 2.0, that is, content from several sources is combined at the user’s device to built a newservice. Location data of targets are considered to be another kind of content besides images, videos, or text. The supply chain contains the following roles:
• Target: a target is a mobile individual or object that is to be located, tracked, or sighted. For this purpose, it is equipped with a mobile device, which besides communication facilities, can perform positioning.
• Positioning enabler: The positioning enabler maintains a positioning infrastructure for controlling and coordinating the positioning process.In a user-centric approach illustrated below here, this infrastructure enables terminal-based positioning and may be given by the network of GPS satellites or a WiFi network for performing fingerprinting.
• Content provider. A content provider offers geographic and non-geographic content. Examples of geographic content are maps, routing data for navigation, or points of interest. Non-geographic content may be available in form of news, blogs, or videos. The latter might be of interest in the context of a LBS if it refers to a certain location.
• Location provider. Targets are connected to a location provider for publishing their locations. The location provider is basically another content provider that acts as an intermediary between target and user. It offers so-called location services to the users of an LBS for accessing a target’s location either in a reactive or proactive fashion and under consideration of the target’s privacy rules. Advanced location services may also provide information about the geographic correlation of several targets, for example, about whether or not a pair of targets is located in the same city. Each target is assumed to have a subscription with a location provider that manages and control her location data on behalf of her.
• LBS provider. The LBS provider prepares the service logic for realizing a LBS. In the context of Web 2.0, this service logic is given by Ajax scripts, which are passed to the user’s Web browser and there interlink content from different providers. For mobile devices, a simplified version might be offered in HTML or as dedicated client application making use of the Java2 Micro Edition (J2ME) engine installed in many devices. In order to be independent of a certain technology, scripts, Web pages, or client applications are subsumed under the term front end in the following text. The LBS provider maintains subscriptions with LBS users and, if required, also provides auxiliary functions like accounting, session, and identity management.
• LBS user. The LBS user is the actor that consumes a LBS. The front end delivered by the LBS provider is executed at her device. Content and location data from different sources are then requested, received, processed, and aggregated according to the instructions given in this front end.
The relationships between roles are referred to as reference points. They can be regarded as service level agreements (SLAs) negotiated between the participating actors, charging conditions, and trust models, while technical relationships cover communication links, interfaces, protocols, and transactions being of relevance during the operation of an LBS. Below are two illustrations indicting how this model is applied two examples of services;
