Managing environmental knowledge and the necessary IT tools - Environmental Deterioration and Contamination: Problems and their Management - page 439

content, these three parts can be changed independently. Authorized users can extend
the content of the WEB portal without having technical information about HTML
and WEB technology. A number of Drupal extension modules are used to make the
ENFO portal more attractive and comfortable (Eccher et al ., 2005). For some tasks
which cannot be solved in the CMS, extra components/servers are used and PHP and
JavaScript codes were developed.
The presentation tier is the browser program (e.g., Firefox, IE, Google Chrome,
Opera) used on the client side. JavaScripts run on the client computer to handle client-
side events. AJAX (Asynchronous JavaScript and XML) (Crane & Pascarello, 2006)
technology is widely used to download data from the server. In the interactive map-
ping applications, JavaScripts are also used. Currently, a single server is used for the
database and the application tier, as the traffic is not yet too heavy for the presently
applied quad core server. As the customers' number increases, the hardware back-
ground can be extended. Except the Google Maps API 3 only open source software
(OSS) is used on the server side. The reason for this is not only to save money but to
enjoy the benefits of an open and extendable system and open standards.
In the development of ENFO portal, several OSS products were used such as:

- Fedora Core (Linux) operating system;

- Apache web server;

- MySQL relational database system;

- PostGIS spatial database server;

- PHP script language for server-side programming;

- JavaScript language for client-side programming;

- JavaScript libraries (Tree Menu, OverLib, OpenLayers);

- Drupal CMS;

- MapServer WMS/WFS WEB services.

These software components are available on different operating systems (Win-
dows, OS X, Unix/Linux), so the portal and database can be ported easily to other
operating systems.

3.2 The developed applications
Various services are provided for the customers. All services are available from the
entry page of the ENFO portal (Figure 12.5). The pages of the portal and the services
are available in English and Hungarian. However, the contents of the English and
Hungarian pages are not identical. Not all publications have been translated into both
languages yet.
The dynamic pages of the ENFO portal are collected into three groups from the
accessibility'spoint of view:

- All pieces of information are available for reading by every visitor;

- Registered users can add new datasheets to the risk management database and

modify their own datasheets; and add notes to the forum;

- A limited number of authors can update the content of the Drupal-maintained

pages and the glossary.