Design of Query Language for Location-Based Services

Recently, the need for LBS (Location Based Services) is increasing due to the widespread of mobile computing devices and positioning technologies. In LBS, there are many applications that need to manage moving objects (e.g. taxies, persons). The trajectories or the positions of moving objects are displayed on the map by using GIS. However, it is hard to use GIS or traditional relational database systems to manage moving objects. Modeling consistent information about the location of continuously moving objects and processing motion-specific queries is challenging problem. The previous studies suggested several query languages to retrieve moving objects. However, they do not propose DDL (Data Definition Language) and do not support full functions that are necessary. In this paper, we formally define a data model and data type for moving objects and propose MOQL (Moving Objects Query Language) which is a convenient interface and tool for developers. MOQL has the following features. First, it supports DDL to insert/delete/update the positions of moving objects. Second, it can be used to retrieve the trajectories of moving objects. Third, it defines several functions to manage spatial or temporal properties of moving objects.