client PC (Dickmann, 2001). Such components are embedded in 
user’s Web browser environment and can provide substantial 
GIS functionality. Performance of Java technology is not as 
good as the one provided by ActiveX components (compiled 
code), but it must be noted that Java technology is not limited to 
Windows only environments (Dickmann, 2001; Prastacos, 
2001). This is of great importance. In some other cases, users 
can opt for standalone GIS viewers providing extended GIS 
functionality. In this situation, the downloaded GIS software 
works independently of the user’s Web browser type and 
version. 
The server-side approach is ideal for Internet GIS applications, 
since the result of a user request is a standard HTML page and 
as such supported in different software and hardware 
environments. One major drawback of the server-side approach 
is a frequent communication between the server and a client, 
which may in cases of a slow network communication cause 
significant waiting times (Dickmann, 2001). Figure 1 depicts a 
possible communication between a client and a GIS data server 
namely for the server-side approach. 
  
Web browser 
DBMS 
HTML Request 
il document 
€ Response 
UE 
a 
HTML Server-side 
^ document program 
URL with request 
parameters B 
Request 
Web server parameters 
  
  
  
Figure 1. The server-side approach requires frequent client- 
server communication 
Commercially available Web GIS solutions may be 
distinguished according to several factors. All of them should 
be considered with greatest care when considering which of 
many available GIS solutions to choose or buy. Beside certain 
technical and system oriented requirements (for example, in 
which operating systems and Web browsers can product 
operate, the number of spatial data formats the product 
supports, software and hardware deployment costs etc.), the 
need to be easy-to-use is very high on the list of user priorities 
(Limp 2001). 
For now, commercially available Web GIS solutions are 
expensive and require a substantial amount of knowledge for 
the purpose of administering them. The migration of the 
specific GIS functionality to the core of a database management 
systems or the possibility of extending a database management 
system’s bussines logic with spatial functionality with a 
combination of freely available standards technologies such as 
GML (Geography Markup Language), SVG (Scalable Vector 
Graphics), XSL (eXtensible Stylesheet Language) and some 
others offer a competitive alternative (Plewe, 2002). For 
example, many organizations own and use data warehouses 
purely for bussiness purposes. Upgrading existent and powerful 
database management systems with commercially available 
  
“spatially-aware” software modules and with the help of 
previously mentioned standards technologies, enables the 
development of a distributed GIS at reasonably low costs. 
Figure 2 depicts Web GIS technology based on SVG standard 
and a database management system. 
  
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Figure 2. Example of the client-side Web GIS based on the 
SVG standard utilizing the Adobe® SVG Viewer 3.0 and a 
database management system 
3. STANDARDS 
People of different profiles and professions start to realize, that 
most of the data they deal with professionally and 
nonprofessionally should be indexed and later on referenced by 
its spatial component. This applies to the in the introduction 
mentioned statement, that more than 80% of all data relates to 
issues that can be placed somewhere in a geometrically defined 
space. 
For this and similar reasons international organizations, such as 
ISO (TC211), OpenGIS Consortium in cooperation with other 
standards organizations (IEEE, W3C, W3D etc.) are seeking the 
best way to put GIS in the mainstream of information 
technology (Hstensen 2001). Currently, the biggest challenge of 
the GIS community is to provide an open architecture, which 
would assure integration and interoperability among different 
GIS data and processing solutions. 
Many standards and specifications have already been agreed on, 
but a lot of work still remains to be done in this field. So far, 
much attention has been paid to a syntactic interoperability 
(data language) in contrast to the semantic interoperability (data 
meaning). The results of data formats (for example GML) and 
algorithm interface standardization (OpenGIS interface 
specifications) have been recognized as unsufficient. To ensure 
the necessary integration of disparate spatial datasets and 
processiong capabilities new approaches, which are based on 
ontologies and address semantic interoperability, are proposed. 
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