ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS", Bangkok, May 23-25, 2001 
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BUILDING OF B/S-BASED OBJECT ORIENTED ELECTRONIC CHART DATABASE 
Guangru LI 1 Shaopeng SUN 2 Depeng ZHAO 3 
1 Nautical Science and Technology Institute 
Dalian Maritime University, Dalian, China, 116026 
Tel:86-411-4729297 
E-mail: creatlgr@sina.com 
2 Nautical Science and Technology Institute 
Dalian Maritime University, Dalian, China, 116026 
Tel:86-411-4729297 
E-mail: sun_sp@usa.net 
3 Nautical Science and Technology Institute 
Dalian Maritime University, Dalian, China, 116026 
Tel: 86-411-4729297 
KEY WORDS: Web-GIS Web-Chart, Electronic Chart Database (ECDB), Spatial Searching 
ABSTRACT 
This paper researches in system architecture of Internet-based Electronic Chart, and mainly discusses how to establish object-oriented 
chart database, how to search useful spatial data from chart database. 
1. INTRODUCTION 
With the development of Internet, how to realize Electronic Chart 
application through INTERNET makes more attention than before. 
The rapid development of satellite communications provides an 
unprecedented chance to the development of communications 
between land and ship. Therefore, building IIS Electronic Chart 
Server and the related technologies become pop technologies in 
research of Electronic Chart. Web-Chart is the Electronic Chart 
that based on Browser/Server structure, and Web-Chart realizes 
the rapid display of vector graph and the seamless connection of 
dynamic data. Browsers download this system from server into 
client through INTERNET, and load graphic data, build database 
link. When user uses data and graph, it produces dynamic SQL 
language, and accesses database server through INTERNET, 
then user can operate vector graph and dynamic data. 
Database Server's realization is based on file system and 
Database Management System (DBMS). It can satisfy request of 
accessing database, especially accessing the structure data. 
Application Server is commonly a server who can provide 
universal or professional function based on all sorts of application 
models or computing technology in professional field. It was built 
based on basic data management function of file and database, 
Web-chart, Site Server, WAP Gateway, and some other 
applications are all members of this application server category. 
They commonly need append function modules of different 
professional fields. For example, the web application need user 
to convey computing result to web server with HTTP protocol, 
and make farther respond in web server. These functions 
commonly were realized by systemfs Remote Procession Call 
(RPC) or service progress. They provide functional modules to 
interact with exterior and coordinate interior. Intelligent 
information agent acts as this kind of functional module. 
Web server is the core part of building of a web computing 
platform. It provides many service functions supported by file 
server, database server and application server. Ifs main aim is to 
realize the connect interface of application service functions and 
the call of HTTP. 
Client is the front end to users access and process all sorts of 
web service functions. It can realize many interactive functions to 
users, and make these interactive functions to communicate with 
HTTP protocol and web server. Commonly, client use directly 
HTML language or Java ScriptA/B Script, but it will need ActiveX 
control or Plug-in to deal with sophisticated computing to satisfy 
the need of client function. In Web-GIS, we should satisfy the 
distributed computing function. For this sophisticated function, we 
use ActiveX or Plug-in to realize it. 
Web-Chart can conveniently operate vector graph, such as zoom 
out, zoom in, roam, pan and some other basic function. 
Web-Chart also has some other merits: 
1) The broader browse ability: Internet makes user can browse 
the newest data from multi-server in different place 
simultaneously. This feature facilitates the management of 
Electronic Chart Data, makes management and combination 
of distributed multi-data source become easier to achieve. 
2) Platform independent: Don’t care what kind of machine the 
server or client is, and what kind of chart software the 
Web-chart server use, through Web browser, user can browse 
Web-chart data transparently, dynamically assemble 
distributed components and manage and analyze spatial data 
cooperatively, to achieve the sharing of remote heterogeneous 
data in spite of hardware and software. To achieve platform 
independent, it is the key technology to build the 
object-oriented ECDB. 
2. BUILDING OF OBJECT ORIENTED ELECTRONIC 
CHART DATABASE 
Using object-oriented technology, we can extract information 
from geographic object in Electronic Chart to create different 
class, build the relations among them, and encapsulate attributes 
and operations of classes. Using object-oriented data model, we 
can define three-dimension spatial data model, spatial-temporal 
data model and some other models and build the Internet-based 
distributed spatial data model. Object-oriented technology is 
based on object in concept. It combines the similar objects as 
different classes. By generalizing the object class, we can create 
hyper-class, these object classes were named sub-class. 
Sub-class can inherit the method and attribute of hyper-class. 
Object-oriented technology also provides the approach to extract 
data, that is to say the generalization and aggregation of objects 
or classes. We can build the hierarchy of objects by using 
generalization and aggregation repeatedly to extract data. There 
is the one-multi relation between every object and its member. 
Object-oriented data extraction technology provides the 
computing ability in lengthways spatial relations and realize the 
object’s classing, unit, generalization, aggregation and class’s