Introducing Pergamos: A Fedora-Based DL System Utilizing Digital Object Prototypes

The idea

The University of Athens' material is heterogeneous in the extreme — a Senate archive, a theatrical collection, a folklore collection, a papyri collection — and a digital library that models each of those with bespoke code becomes a maintenance problem immediately. Pergamos, built on the Fedora repository in Java, puts the typing information in Digital Object Prototypes: XML declarations of a type's metadata sets, its supported content formats, the relationships its instances may take part in, and the behaviours they expose.

How it works

A dictionary component loads the prototype definitions at startup and turns them into Java artefacts. At run time it loads stored objects from the repository and produces instances that conform to their prototype automatically. Because the application logic only ever sees typed instances, one uniform service implementation operates on any prototype-defined material — which is what makes a new collection or a new object type a matter of writing a prototype rather than an implementation.

What the demonstration shows

The high-level services built this way — collection management, web-based cataloguing, browsing, batch ingestion, automatic content conversion — from the perspectives of the end user, the cataloguer, the designer and the developer at once, with the emphasis on how inexpensive adding a collection turns out to be. Collections are themselves digital objects, so aggregation falls out of the same mechanism.