Managing moving objects in the context of spatio-temporal data streams

Managing moving objects in DSMS has recently been a focus of a relatively intense research. In this paper, we are concerned with data streams containing a location of a moving object at any time instant. Instead of using spatial and time instant data types separately, for representing spatio-temporal characteristics of data streams, we propose a unified approach based on specialized temporal data type constructor. This type constructor, parameterized with a spatial type representing objects location, yields a corresponding type whose values are pairs, consisting of an instant of time and a value of spatial type. With this approach, it is possible to represent temporal development of an objects´ location within one time interval by using two consecutive values of this temporal data type. Since moving object is basically obtained just by assembling these temporal developments whose time intervals are disjoint, we also propose an approach for extracting moving objects out of spatio-temporal data streams based on user-defined aggregate functions (UDAF) over spatio-temporal data types. With this approach, it is possible to manage moving objects encapsulated within spatio-temporal data streams using SQL-like query language.