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A MAP-BASED WEB SERVER FOR THE COLLECTION AND DISTRIBUTION OF ENVIRONMENTAL DATA 
G. Guariso, M. Ferrari, D. Macchi 
Politecnico di Milano, Facoltà di Como, Como, Italy 
KEY WORDS: metadata, data retrieval, world wide web, Internet, client-server architectures. 
ABSTRACT 
Environmental data constitute a very wide and poorly structured knowledge domain. The only characteristic that they 
share is to be associated to a certain geographical object, either a point, or a line, or a polygon. These geographical 
objects have in turn known relationships among them (e.g. inclusion, closeness). A map can thus constitute a unique 
way for structuring such a wide domain, thus allowing an ordered data storage and retrieval. A web server for collecting 
and distributing environmental data has been built on this principle. Its main aim is to facilitate the sharing of information 
among all the subjects and institutions operating on a given territory, for planning, management and also educational 
purposes. The system adopts the classical client-server architecture and the user can contribute to its growth under the 
supervision of an administrator. It has been implemented for the Lombardy region in Northern Italy at the address 
http://pc-ambiente. como.polimi. it. 
1. INTRODUCTION 
Environmental data cover a very wide and heterogeneous 
knowledge domain: they refer to different environmental 
compartments (air pollution, water quality and quantity, 
population dynamics, and so on), they are usually 
collected by different agencies at different locations and 
time intervals and they are stored in different ways. 
Proposals for a standard environmental data format have 
been put forward by several institutions (e.g., FGDC, 
1994: Library of Congress, 1997; Phelps and Wilensky, 
1996; Koschei et al., 1997), but have not been widely 
adopted. Environmental databases are growing up in 
dimension and complexity so as to make any search 
extremely difficult (see, for instance, the US Geophysical 
or Climatic Data Centers or the NOAA Environmental 
Services Data Directory — http://www.edsim.noaa.gov/ 
NOAA-Catalogue/). Their production and maintenance 
requires an effort in terms of economic and human 
resources that cannot be sustained by all institutions. 
It is thus of interest to exploit the only characteristic that 
environmental data share: to be associated to a certain 
geographical object, either a point (for instance, a rain 
gauge) or a line (the flow rate of a river), or a polygon (the 
population of a municipality). These geographical objects 
have in turn some known relationships among them (e.g. 
inclusion, closeness), that can also be automatically 
managed. A map can thus be used to provide some 
structuring to such a wide information domain, which in 
turn may allow for an easier data storage and retrieval. 
A web server for collecting and distributing environmental 
data has been built on this principle. Its main aim is to 
facilitate the sharing of information among all the subjects 
and institutions operating on a given territory, for planning, 
management and also educational purposes. 
The storage and retrieval system is based on the classical 
client-server architecture, but cannot be considered as a 
standard database since it grows up with the participation 
of the users, on the client side, and is only supervised by 
an administrator, on the server side. Additionally, there is 
no specific structure for the data stored in the system, 
except their reference to a geographical entity. 
After briefly revising some map-based environmental 
information systems in Section 2, the paper presents in 
the following sections, first the data structures and then 
the architecture of the web site. Section 4 gives some 
technical detail on the system implementation and Section 
5 provides some examples of its use. 
2. WEB BASED GIS SYSTEMS 
The diffusion of the Internet has significantly changed the 
approach to storage and distribution of environmental 
data. Problems related to the planning, management and 
conservation of the environment are, for their own nature, 
distributed in space. Various public authorities and 
agencies, as well as private citizens are normally involved 
in any such problem. The Internet is thus a natural mean 
to share the information, support the debate, create 
consensus and thus ease the implementation of solutions. 
Unfortunately, the set of data required for a specific 
environmental problem is relative unique, in many 
instances, and thus it is almost impossible to structure a 
classical database that may be useful in different 
situations. 
Fig. 1 - Berkeley's Digital Environmental Library. The photo 
is obtained by clicking the required position on the map