ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001 
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economic and effective solution for both the system developer 
and end-user. 
By ActiveX technique, the system developer has a flexible way to 
provide their production. They develop ActiveX Controls and 
assemble application systems in need. For GIS data exchange, 
there is another more important advantage. In GIS data 
exchange, the difficulty lies in model interpretation. All users 
have their own interpretation. Solution provider of ActiveX 
structure reserves this interpretation to the end-user or the 
customization of these ActiveX Controls. 
By ActiveX technique, we also benefit from the simplicity of code 
maintenance. ActiveX supports object-oriented technique and 
provides a mechanism of upgrading easily. For example, while 
the AutoCAD was upgrading from Version 12.0 to Version 14.0, 
we can promptly upgrade the ActiveX Control GeoDxf and 
GeoDwg by simply upgrading the previous methods or adding 
new methods. The old version end-users ActiveX Control 
GeoDxf and GeoDwg can be upgraded via Internet. This 
upgrading does not affect the proper running of customized 
application, meanwhile the customized application system can 
add new function during to the upgrading of its referred ActiveX 
Controls. 
In one word, component is the most significant trend of software 
engineering. Its reusability provides a totally new way to develop 
economic systems. This technique also breaks the traditional 
way of developing software. Small companies or even a single 
person can have chances to join the software market competition. 
GIS industry will also inevitably be affect by this trend. Our 
experience of using ActiveX Control to develop GIS module 
partially confirmed this conclusion. 
REFERENCES 
Namir Clement Shammas, Secrets of Visual C++ Master, 
Pentice Hall, 1994 
David J. Krugliski, etc., Programming C++, Microsoft Press, 1999