مدلسازي شبكه براي اشياي متحرك در پايگاه هاي داده به همراه پياده سازي انواع داده ها و عملگرها

Network Modeling for Moving Objects Databases with Implementation of Respective Abstract Data Types and Operations

Moving objects databases (MODs) is a new research area that came up during the second half of the 1990s. The goal of research on these databases is to extend database technology for representing any kind of moving entity and answer to spatial, temporal, and spatio-temporal questions that are posed about moving entitiesʹ positions and geometries. Moving entities produce huge volume of movementsʹ information that can be used for spatiotemporal analysis in Geospatial Information System (GIS). For modeling and querying moving objects, we need a comprehensive framework of respective Abstract Data Types (ADTs) and operations. That means for representing objects moving freely in the 2D plane, special data types should be provided. However in many applications people or vehicles move along transportation network, it makes a lot of sense to model the network explicitly and describe movements relative to the network rather than unconstrained space. So, in the first stage, we have to model network and design appropriate data types in this context. The main purpose in this paper is to present a proper model for network modeling with designing and implementing respective abstract data types. Therefore, the database can represent the objects that move along transportation networks. Also, we have implemented some abstract data types and operations on these data types so that users can formulate any kind of questions about such movements and analyze them easily. As the moving entitiesʹ positions and geometries are changing continuously, we will face large amount of data. So, we selected Oracle as a platform for implementation because it is a powerful object-relational database for managing large amount of data. As a result, we extend the interface of Oraclellg with Moving Object Package which can model spatial network for moving objects and contains spatio-temporal ADTs and operations for asking queries. We have tested the model on a district in Tehran Metropolitan Area (TMA).