KEYWORDS: Geographic information systems, Data modeling, Performance modeling, Web services, Data hiding, Computing systems, Software, Interfaces, Pollution control, Switches
Spatial Data Grid is an ideal environment to handle the data-intensive and computing-intensive geo-spatial processes. In
this heterogeneous and distributed environment, the requirements of service scheduling are dynamic and diverse. Therefore, an appropriate scheduling mechanism should be adopted, which would be able to deal with the resources properties of a grid environment, such as the data size, network capabilities, and the capabilities of processors, and meet the need of specific GIS (Geographic Information System) applications. This paper proposes a scheduling mechanism based on utility of Quality of Service (QoS). And, this scheduling mechanism, wrapped into a standard WSRF service, provides a transparent way to select the appropriate spatial data service providers in a dynamic spatial data grid and hides the complexity of the scheduling strategy from users to coordinate those required services. Experiments show that our scheduling mechanism can provide services selection and performance guarantees and lead to better spatial resource sharing and significant service performance.
KEYWORDS: Databases, Data storage, Distributed computing, Geographic information systems, Data modeling, Data processing, Systems modeling, Process modeling, Legal, Prototyping
This paper introduced a SQL level approach to resolve global spatial query in Web based heterogeneous distributed
spatial database environment. The main prohibit of this SQL level approach was its widespread compatibility and
standardization. Firstly, a SQL based Equivalent Distributed Program (EDP) was introduced to express distributed
spatial processing transactions. Then global resource directories for virtual global view describing were discussed to
organize information that resolving need. The contents of global resource directories included data storage directory,
hosts directory and working status directory. With these mechanisms, relational algebra expression equivalence
principles were utilized to resolve global spatial queries to EDPs. Finally, several samples were presented to show the
process of resolving. This approach was suitable to all sorts of distributed computing environments either centralized
such as CORBA or decentralized such as P2P computing platforms.
KEYWORDS: Databases, Data storage, Geographic information systems, Control systems, Remote sensing, Distributed computing, Geoinformatics, Information science, Plutonium, Neodymium
To make the diverse organizations access the massive distributed heterogeneous spatial data easily, we build a Spatial Data Grid in peer-to-peer way, which composed of several spatial datacenters distributed in different agencies. Given a query, which often a range query in spatial application, the query parser will decompose the global query into several sub-queries and disseminate them to the peers who take responsibility for storing data of that area. In order to accelerate the query dissemination process, we utilize distributed index to locate object more quickly and accurately. We propose an adaptive indexing mechanism, Fully Distributed R-Tree Index, which is appropriate for efficient range query dissemination. It composes of two layers, on top of which is the spatial range of each peer. The under layer stores part of the R-Tree of each peer's neighbors, which can be adjusted according to the capacity of peer. There is no centralized control on top of the entire system, and it could adaptive to the environment change.
KEYWORDS: Data modeling, Databases, Data storage, Geographic information systems, Systems modeling, Process modeling, Remote sensing, Analytical research, Prototyping, Geoinformatics
Recently, there has been a fast proliferation of applications creating spatio-temporal data that has to be processed, stored and queried efficiently. Consequently, there is a need for spatio-temporal data management systems that are able to support such storage or query operations. Spatio-temporal data management based on ORDB was derived in this paper. After bringing forward the structure model of spatio-temporal data management, one actual STDMS (Spatio-Temporal Database Management System) TspatialService was designed and then implemented. The system is based on data model of Dynamic Field and accomplished through spatio-temporal extension on PostgreSQL. Various spatio-temporal operations could be carried out in the system through simple SQL statements as well. By using the system, effective spatio-temporal data management was achieved.
KEYWORDS: Databases, Data modeling, Data storage, Human-machine interfaces, Visualization, Prototyping, Remote sensing, Geographic information systems, Geoinformatics, Satellite navigation systems
Based on discussion on general methods of constructing global directory in DSMDS (Distributed Spatial Database Management System), a new approach based on relation model was brought forward. It specifies three main components of the global directory, including directory organization, directory update and extern interface. Then the authors implemented an actual global directory named SDirectoryService as well, key approaches and techniques in implementation were discussed in detail. Some experiments were designed and performed to check the efficiency, correctness and feasibility of the global directory, which reveal the directory works well on each aspect. By using the directory effective global query processing was achieved in DSMDS.
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