Browse Prior Art Database

Location-based Services with Publish/Subscribe Disclosure Number: IPCOM000018649D
Original Publication Date: 2003-Jul-30
Included in the Prior Art Database: 2003-Jul-30
Document File: 5 page(s) / 112K

Publishing Venue



This article discloses a technique that makes use of the publish/subscribe programming model to implement location-based services.

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Location-based Services with Publish/Subscribe

To date, there exist millions of mobile wireless telecommunication service subscribers. A recent study showed that in many countries this number is larger than the number of Internet/PC users. A single US mobile carrier is reported to have had 27 million subscribers in April 2000. In Japan on August 6, 2000, 18 months after the introduction of i-mode, the number of subscribers to NTT DoCoMo's i-mode mobile wireless service topped 10 million.

Location-based services extend information services, such as online route planning, monitoring, financial information, news, travel, and tourist information with the ability to correlate an information request with location information of the requester and the information sought.

Location-based services are information services that primarily target information dissemination applications for mobile wireless networks, such as the ones referred to above. However, nothing precludes their use for wired networks, or a combination of wired and non-wired networks, as well. For example, a request to find an IP-based device in a large campus, may equally well be modeled as a location-based service request in a wired or in a hybrid network (networks of wired and wireless components.) Location-based services are characterized by the large number of perspective subscribers, asynchronous interactions, the de-coupled nature of all system entities
(i.e., devices of various kinds must interact, devices come online and go offline in a priori unpredictable patterns, interacting devices do not know each other) and its event-driven nature.

The publish/subscribe paradigm models these characteristics extremely well. This paradigm, is a simple to use interaction model that consists of information providers (i.e., suppliers), who publish events to the publish/subscribe system, and of information consumers, who subscribe to events of interest within the system. The publish/subscribe system ensures the timely notification of subscribers upon event occurrence. In this sense the publish/subscribe paradigm is a ramification of an event-based architecture style. The system server reacts to events that asynchronously occur during system operation. Figure 1 summarizes the interacting entities in a publish/subscribe system.

Figure 1. Entities in a publish/subscribe system

The problems in implementing location-based services consists in correlating asynchronously changing location information of millions of subscribers with the dynamic information that is of relevance for subscribers in a particular area and the profile of each subscriber. This is a


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computationally very difficult problem. The following figure illustrates this in an example.

Figure 2. Example of a location-based alerting service for traffic accidents

The example shows the event of a traffic disturbance at Young & Bloor and a number of subscribers...