Design and Development of Distributed Virtual Geographic

Environment System Based on Web Services

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Jianqin Zhang(a,c*), Jianhua Gong (a), Hui Lin (b), Gang Wang (c),

JianLing Huang (c), Jun Zhu (a), Bingli Xu (a), Jack Teng (d)

^{a State Key Laboratory of Remote Sensing Science, Jointly Sponsored by the Institute of Remote Sensing}

^{Applications of Chinese Academy of Sciences and Beijing Normal University, Beijing 100101,P.R. China}

^{b Joint Laboratory for Geoinformation Science The Chinese University of Hong Kong Shatin, Hong Kong}

^{c Beijing Transportation Information Center, Beijing 100055,P.R. China}

^{d Resource Management and Environmental Studies, University of British Columbia, Canada}

ABSTRACT

This paper aims to design and develop a Distributed Virtual Geographic Environment (DVGE) system. A DVGE system is an Internet-based virtual 2D and 3D environment that provides users with a shared space and a collaborative platform for publishing multidimensional geo-data, and for simulating and analyzing complex geo-phenomena. Users logging into the system from different clients can share distributed geo-information resources, including geo-data and geo-models, and can complete collaborative tasks. Web service technology provides effective solutions for constructing DVGE systems because of its ability to support multi-platform, multi-architecture, and multi-program-language interoperability on the Internet, but also because of its ability to share programs, data, and software. This paper analyzes the characteristics, relevant technologies, and specifications of web services, such as grid services, Open Geo-data Interoperability Specifications (OpenGIS), and Geography Markup Languages (GML). The rchitecture and working mechanisms of the DVGE system based on web services are then elaborated. To demonstrate DVGE systems based on web services, we examine a case study of water pollution in Yangzhou City, Jiangsu Province, China, using a prototype DVGE system that is developed with Jbuilder9.0 and Java3D 1.0 packages, and the Weblogic platform 8.1.

Keywords: virtual environment, virtual geographic environment, distributed computing, web services, J2EE, grid services

1. 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 3-D 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.