Geospatial publish / subscribe systems for the Internet of Things

The concept of the Internet of Things (IoT) describes the physical objects (smart mobile devices, various types of sensor devices) which have a range of sensors and are connected to the Internet. One of the main challenges for data processing in the Internet of things is to quickly and effectively provide the delivery of sensor data to interested parties in real time. Publish/subscribe systems are seen as appropriate for this purpose as they offer an infrastructure for almost immediate delivery of notifications to interested subscribers. In traditional publish/subscribe systems, subscriptions define content which is interesting to the user and that is usually a multidimensional interval of an attribute space in which the notifications are defined. This type of subscriptions is not appropriate to the Internet of things, where the sensor data, except for the value of the measured quantity, usually include a geospatial component (e.g. a point, line or polygon) which refers to the geographical area in which the measurement was made. Therefore, the subscription should also consist of a geospatial object that represents a geographic area of interest to subscribers and additional data in the form of traditional attribute space intervals that are used for continuous comparison with the upcoming notifications. This paper presents the existing centralized and distributed publish/subscribe systems, and proposes the idea of geospatial publish/subscribe systems.