Design and development of Distributed Virtual Geographic Environment system based on web services☆
Introduction
A Geographic information system (GIS) is designed to provide storage, retrieval, analysis, visualization, and mapping capabilities for spatial information data, such as road networks, power transmission networks, and land use information data [27]. Virtual Reality (VR) derives from three-dimensional (3D) computer graphics and provides an intuitive human-computer interface that gives the user the impression of being in a computer-generated virtual world [16]. VR technologies, when used as a medium for geographic visualization and analysis, have considerable potential to extend the geo-information visualization methods of 2D maps or traditional GIS. Thus, the applications and importance of VR technology have increasingly attracted the interest of researchers in the field of geographic information science.
Virtual Geographic Environment (VGE) was first proposed in 1999. In contrast to current data-centered GIS, a VGE is a human-centered environment. From the perspective of geography, VGE is an environment concerned with the relationship between avatar-based humans and 3D virtual worlds [7], [6]. From the perspective of information systems, VGE is an advanced information system that combines GIS with VR technology [14]. At present, there has been much research into VGE, allowing for VGE application systems to be successfully designed and implemented [13]. However, these systems are dependent upon specific platforms and programming languages that lack interoperability, making the sharing of resources and collaborative work difficult. To address this, we aim to design and develop a distributed VGE (DVGE) system. A DVGE system is a virtual Internet-based 2D and 3D environment that provides users with shared space and a collaborative platform for publishing multidimensional geo-data, and for simulating and analyzing complex geo-phenomena. Users logging into the system can be from different clients, which are often not in the same geographic area, but can nevertheless share distributed geo-information resources, including geo-data and geo-models, and can also complete collaborative tasks.
There are two key challenges to a DVGE system: sharing geo-information resources and implementing collaborative work. These two key problems can be solved using new computer technologies, such as web services and grid computing. Using certain specific regulations, grid computing aims to share all kinds of resources, including data, applications, and computing capacity; these regulations can ensure the compatibility of all the resources in the grid system [3]. But, grid computing is derived from distributed parallel computing and high-performance network computing, both of which depend on computer hardware that are too expensive to be used universally. Despite this, the Global Grid Forum began to improve the possibility of converging grid services with web services, to ultimately merge into a single service [12]. Web services are platform-independent and language-independent, since they use standard Extensible Markup Language (XML) languages. Besides web services’ natural capability for cross-platform interoperation, they also have the following advantages: (1) sharing not only programs, but also data; (2) easy integration with other programs; (3) easy re-use of software; (4) simple configuration and deployment [11]. Web services are thus highly suitable for constructing an Internet-scale DVGE system. This paper reports the construction of a DVGE system, which is based on web services technology, and which allows traditional geographers to carry out efficient and innovative research, on comprehensive and complex geo-problems, using a data and graphics-driven distributed and collaborative platform.
The paper is organized as follows: Section 2 briefly introduces VGE and reviews related work on VGE, and the relevant technologies, such as web services, grid services, OpenGIS, and GML. Section 3 describes the DVGE system architecture based on web services, and the working mechanisms of DVGE system. Section 4 describes a prototype DVGE system that was established to illustrate the effectiveness of the DVGE system using Jbuilder9.0, Java3D1.0, Weblogic Platform 8.1. Section 5 discusses our research. Finally, Section 6 concludes with a discussion of our research.
Section snippets
Virtual Geographic Environment
Geographic space is the environment around us and the greater world in which we live. We can directly experience many things in geographic space, but its scale is so large that we cannot experience everything at once. Cartographic maps have been used for centuries as a method to communicate spatial information between cartographers and map users, by providing a visual representation of geographical distributions in a world that is too large and too complex to be seen directly. The widespread
Distributed VGE system design
We aim to design the architecture of DVGE and resolve its key problems, using web services technology [24], [25]. The DVGE system is an Internet-based collaborative platform for users, especially for geo-experts to conduct collaborative geo-work. From the viewpoint of technologies for geo-collaboration, we argue that geo-collaboration is involved in four components: geographic environment, geo-tasks, task-related geo-problems, and multi-participants. Multi-participants mediated by collaborative
Architecture of the prototype system
In this paper, we choose Java 2 Platform Enterprise Edition (Java2 EE) and the web services for J2EE 1.0 standard to construct a prototype DVGE system. Fig. 5 depicts its architectural overview, based on web services and J2EE technology. There are three major layers: the client layer, the web service container layer, and the back-end systems layer. The client layer includes web browsers, applets, and applications. The clients (e.g., applications or applets) can connect to a web service in a
Discussion
To date, there are no commercial GIS systems available for collaborative work. In this paper, we design and develop a DVGE system by integrating GIS, virtual environments and distributed computing technology, in order to implement resource sharing and geo-collaboration. As an integrated framework and technology, DVGE is involved in heterogeneous data, application models of complicated geographic environments, complex geographic problems, and dynamic change factors related to human collaboration
Conclusions
Constructing a DVGE system is a large project that involves different technologies, different specifications, and different fields of research. Based on the characteristics of DVGE systems and the development of current web services, we design the architecture of a DVGE system using web services and OpenGIS, where we use GML as a main geo-information description language for internet communication. We then study the implementation of distributed resources and of a shared DVGE system based on
References (28)
- et al.
A hierarchically structured and constraint-based data model for intuitive and precise solid modeling in a virtual reality environment
Comput. Aided Design
(2004) - D. Booth, W3C Fellow, Web services Architecture, 2004....
- K. Czajkowski, D. Ferguson, I. Foster, et al., From OGSI to WS-Resource Framework: Refactoring and Evolution....
- I. Foster, What is the grid? A three point checklist, 2002....
- Global Grid Forum, Open Grid Service Infrastructure Primer, 2003....
- et al.
- J.H. Gong, H. Lin, Virtual geographical environments and virtual geography, in: Proceedings 9th International Symposium...
- J.H. Gong, H. Lin, Virtual geographical environments: concept, design, and applications, in: Proceedings of the...
- et al.
Building design services in a distributed architecture
Comput. Civil Eng.
(1999) - O. Hertzberger, Research Infrastructures & Grid, 2003....
Java distributed components for numerical visualization in VisAD
Commun. ACM
Distributed virtual environments for managing country parks in Hong Kong – a case study of the Shing Mun Country Park
Photogramm. Eng. Rem. Sens.
Cited by (0)
- ☆
Sponsored by the National Natural Science Foundation Project No. 40471103, the National Key Technologies R&D Program of China Project No. 2004BA718B06, and the Beijing’s Natural Science Key Foundation Project No. 7061005.