On the Effective Manipulation of Digital Objects: A Prototype-Based Instantiation Approach

Abstract

Abstract. This paper elaborates on the design and development of an effective digital object manipulation mechanism that facilitates the generation of configurable Digital Library application logic, as expressed by collection manager, cataloguing and browsing modules. Our work aims to resolve the issue that digital objects typing information can be currently utilized only by humans as a guide and not by programs as a digital object type conformance mechanism. Drawing on the notions of the Object Oriented Model, we propose a "type checking" mechanism that automates the conformance of digital objects to their type definitions, named digital object prototypes. We pinpoint the practical benefits gained by our approach in the development of the University of Athens Digital Library, in terms of code reuse and configuration capabilities.

Digital Object Prototypes: An Effective Realization of Digital Object Types

“…As depicted in Figure 1a, DOPs operate atop the repository / storage layer of the DL (in Pergamos we use FEDORA [14]). (a) The 3-tier Pergamos architecture incorporating the "type enforcement" layer of DO Dictionary [13] and (b) A digital object instance as composed by its respective prototype and the underlying stored digital object…”

“…Table 1 provides a summary of the DOPs we generated for modeling the disparate digital object types of each collection, pinpointing the flexibility of our approach. It should be noted that DOPs are defined with a collection-pertinent scope [13] and are supplied with fully qualified identifiers, such as folklore.page and senate.page, avoiding name collisions. These identifiers apply to the object's parts, too; folklore.page.dc metadata set is different from the senate.page.dc set, both containing suitable qualifications of the DC element set for different types of objects.…”

“…What they all have in common is their ability to store and retrieve arbitrary specializations of a digital object's constituent components, namely, files, metadata, behaviors and relationships [9]. The derived digital object typing information -that is, which components constitute each different type of object and how each object behaves -is not realized in a manner suitable for effective use by higher level DL application logic including DL modules and services [13].…”

“…Digital object prototypes (DOPs) [13] provide a mechanism that uniformly resolves digital object typing issues in an automated manner. The latter releases DL users such as cataloguers, developers and designers from dealing with the underlying complexity of typing manually.…”

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

“…Pergamos provides a powerful digital object manipulation mechanism based on Digital Object Prototypes (DOPs) [1]. DOPs focus on the uniform resolution of digital object typing issues in an automated manner, releasing cataloguers, developers and collection designers, from dealing with the underlying typing complexity manually.…”