access to the geographic data. Beyond this are additional 
services or software to support applications of the data. To 
make an SDI functional, it must also include the organizational 
agreements needed to coordinate and administer it on a local, 
regional, national, and or trans-national scale. 
In this paper, we argue that the development of SDI is possible 
by using open source software. It is not our aim to present the 
plethora of various output formats for presentation and other 
issues that change swiftly. We concentrate on the concept that 
an effective infrastructure should be based on a spatially 
enabled database, stable operating system with network 
capabilities and couple of middleware applications. Getting all 
these products without license fee with additional costs only for 
education of personnel seems to be a viable alternative to 
importing very expensive proprietary software. 
2. OPEN SOURCE SOFTWARE 
Free and open source software entails a new kind of 
competition, separated from that of traditional business in that 
the product generally is not owned by any single company and 
therefore cannot be purchased of the market. Furthermore, the 
software itself is not constricted by any cost or fee. It can be 
obtained free of charge on the Internet. 
The recent recommendation of the Swedish Agency for Public 
Management (Statskontoret, 2003) is that free and open source 
software in many ways, both functionally and qualitatively, is 
quite equivalent to — or better than — proprietary products. Free 
and open source software should therefore be judged on an even 
par with proprietary software in a procurement process in order 
to establish better market competition. It is also necessary to 
place demands on open standards and file formats in order to 
achieve interoperability between different systems. 
Proprietary software is mainly sold nowadays without any 
guarantees, and producers exclude responsibility for, more or 
less, all errors and bugs in the product. The producer dictates 
conditions for changes and corrections, and the lifetime of a 
product is usually short before new versions are released. If the 
software producer goes out of business, all development and 
support disappear and the user has to look for alternative 
solutions. With free and open source software these 
dependencies can be avoided (Statskontoret, 2003). 
One of the strongest arguments for using free and open source 
software is the opportunity to arrive at a higher degree of 
independence regarding price and licensing conditions. In a 
situation with economic restraint, new and more rigorous 
licensing conditions, and with software that becomes replaced 
by newer versions more often than before, the software 
environment becomes increasingly more expensive. 
Free and open source software enjoys a significant market share 
in many areas. Notably, Apache is used for more than 6596 of 
all Internet web servers, often with Linux as operating system. 
Free and open source software often has higher dependability, 
and in many cases better performance when directly compared 
to its proprietary counterpart. 
Scalability and flexibility within the model for the development 
of free and open source software enables it to be developed for 
a large number of platforms and environments. 
194 
An area difficult to measure and compare is security, but it has 
been found that it is just as good, if not better, than proprietary 
alternatives. Free and open source software is less prone to 
attacks and virus over the Internet. As far as costs are 
concerned, it is to the advantage of free and open source 
software, especially if one looks exclusively at direct costs. 
An important independent report (Dravis Group, 2003), 
confirmed following assumptions about Open Source software 
use: 
e Cost is a significant factor driving adoption. 
e Control and flexibility are considered benefits as well. 
e Implementation of open solutions is evolutionary, not 
revolutionary. 
e Open source extends across the entire software stack. 
e Product support is not a significant concern. 
e Open source is not a magic solution. 
e Open standards may be more important than open 
source. 
Recent reports prepared for governments of Great Britain 
(Peeling and Satchell, 2001) and New Zealand clearly showed 
that at least equal opportunity should be given to open source 
solutions when compared with proprietary software in all 
application areas. Without going into details of office 
applications (text-processor, spreadsheets and mail programs), 
we proceed to the spatial applications having in mind that Linux 
as operating system and Apache Web-server provide stable 65% 
increasing majority of Web-servers in the world. 
2.1 Open Source DBMS 
PostgreSQL is an object-relational database management 
system (ORDBMS) based on POSTGRES, Version 4.2, 
developed at the University of California at Berkeley Computer 
Science Department. The POSTGRES project, led by Professor 
Michael Stonebraker, was sponsored by the Defense Advanced 
Research Projects Agency (DARPA), the Army Research Office 
(ARO), the National Science Foundation (NSF), and ESL, Inc. 
PostgreSQL is an open-source descendant of this original 
Berkeley code. It provides SQL92/SQL99 language support and 
other modern features. 
POSTGRES pioneered many of the object-relational concepts 
now becoming available in some commercial databases. 
Traditional relational database management systems (RDBMS) 
support a data model consisting of a collection of named 
relations, containing attributes of a specific type. In current 
commercial systems, possible types include floating point 
numbers, integers, character strings, money, and dates. It is 
commonly recognized that this model is inadequate for future 
data-processing applications. The relational model successfully 
replaced previous models in part because of its "Spartan 
simplicity". However, this simplicity makes the implementation 
of certain applications very difficult. PostgreSQL offers 
substantial additional power by incorporating the following 
additional concepts in such a way that users can easily extend 
the system: 
e inheritance 
e data types 
e functions 
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