ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS", Bangkok, May 23-25, 2001 
232 
efficient enough for the Spatial Information Marketplace. 
This paper proposed the usage of mediating server. Thus, 
standardization on structuring multiple servers based on 
mediating server is anticipated. 
• Data semantics: Spatial Information Marketplaces is 
applicability to various disciplines, for instances, planning, 
engineering, and transportation. These disciplines 
possess different meanings on a single entity. GML can 
help to standardize the description and storage of 
geographical information, however, GML does not 
maintain semantic meanings of features. A standard for 
describing features for different domains is required for 
data service providers. 
• Users interface: The user interface of the Spatial 
Information Marketplace accommodates for huge amount 
of services, on the other hand, the interface should be 
friendly enough so that non-experienced customers can 
use the services. This is a great challenge for designers 
to develop the interface. 
• Another component in the infrastructure includes a mobile 
agent. The agent offers add-on services based on the 
services in the marketplace. For examples, effectively 
combining services available in the marketplaces in order 
to accomplish an application, load balancing among 
service providers, providing intelligent spatial information 
to users based on their usual purchasing practices. More 
research efforts in those areas are required. 
ACKNOWLEDGEMENT 
The work described in this paper was supported by a grant The 
Hong Kong Polytechnic University and a fund from the 
Research Grants Council of the Hong Kong SAR (Project No. 
1.34.9709). 
REFERENCES 
[1] S. Fedlman, “Electronic Marketplaces", IEEE Journal of 
Internet Computing, pp. 93-95, July - August 2000 
[2] OGC, “OpenGIS Guide: Introduction to Interoperable 
Geoprocessing”, http://www.opengis.org/, pp. 103, 1998 
[3] D. Abel, “Spatial Internet Marketplaces: A Grand 
Challenge?”, Proc. SSD’97 Conf., pp. 3-8, 1997 
[4] D. Abel, V. Gaede, K. Taylor, X. Zhou, “SMART: 
Towards Spatial Internet Marketplaces”, Geolnformatica, Vol. 3, 
No. 2, pp. 141-164, 1999 
[5] OGC, "Simple Feature Specification for OLE/COM”, 
http://www.openqis.org/, pp. 122, 1999 
[6] OGC, “Simple Feature Specification for CORBA”, 
http://www.openqis.org/. pp. 100, 1998 
[7] OGC, “Simple Feature Specification for SQL”, 
http.V/www.opengis.org/, pp. 78, 1999 
[8] OGC, “Catalog Interface Implementation Specification”, 
http://www.opengis.org/, pp. 187, 1999 
[9] OGC, “Web Map Server Implementation Specification”, 
http://www.openqis.org/. pp. 45, 2000 
[10] OGC, “Geography Markup Language (GML)”, 
http://www.openqis.org/. 2001 11 
[11] S. Shimada, A. Ishii, T. Ikeuchi, W. Clain, ”WMT 
Demostration Scenario of HITACHI”, Presentation made for the 
Demonstrating the Potential of Open Technology, Web 
Mapping Testbed Demostraction Event, 10, Sepember 1999. 
[12] Kemppainen, H., “Designing a Mediator for Managing 
Relationships between Distributed Objects", Proc. INTEROP’ 
99, pp. 253-263, 1999 
[13] W3C, 'W3C Scalable Vector Graphics (SVG)”, 
http://www.w3.org/, 2001 
[14] H. Garcia-Molina, Y. Papakonstantinou, D. Quass et. al, 
“The TSIMMIS Approach to Mediation Data Modelsnand 
Languages”, Journal of Intelligent Information System, Vol. 8, 
pp. 117-132, 1997