1.2 System architecture according to the MVC model (Model-View-Control)

The MVC model refers to an approach of software systems, which divide their sections of information into data model' (Model), 'presentationen of data (View) and 'controlling of the application' (Control). Concerning to the Agora system we have asegmentation as follows:

Model

• The Agora repository contains data structure, metadata and index of the application

View

• Presentation of the data via Agora HTML templates

Control

• The Agora server (servlet) is responsible for the control of the system

This separation in form and content together with the using of templates and stylesheets allows to present complex information, which can be organised user-oriented and according to individual needs. In the same way it is possible to create special views onto the presented information relevant to certain users and certain processes.

The superior object of a typical Agora project usually is defined as the ‚digital collection’. This digital collection contains objects which form the character of the collection. An unlimited number of digital collections can be created. The objects wihtin the collection are addressed as ‚elements’. Those elements stand for the document types of the existing documents. They can be associated additionaly with an arbitrarily number of subelements. Those subelements can hold subelements as well, etc. In this way a hierarchical document structure of an unlimited depth can be generated. While ‚elements’ form the structure of the Agora data model, the ‚attributes’ descibe their appearance. Every element can be furnished with any attributes. The summation of all attribute contents and of element entries per document makes the set of metadata.

Illustration of a digital collection: ‚miscellany of articles’

Additionally also other electronical documents, such as images, audio files and videos. Those files will be assigned to the Agora element and will be stored within the file system of the server.