Generating Collaborative Systems for Digital Libraries: a Model-Driven Approach

Abstract

171from previous experience and from research in software engineering. Wasted effort and poor interoperability can therefore ensue, raising the costs of DLs and jeopardizing the fluidity of information assets in the future.In addition, there is a need for modeling services and data structures as highlighted in the "Digital Library Reference Model" proposed by the DELOS EU network of excellence (also called the "DELOS Manifesto"); 2 in fact, the distribution of DL services over digital networks, typically accessed through Web browsers or dedicated clients, makes the whole theme of interaction between users important, for both individual usage and remote collaboration. Designing and modeling such interactions call for considerations pertaining to the fields of humancomputer interaction (HCI) and computer-supported cooperative work (CSCW). As an example, scenariobased or activity-based approaches developed in the HCI area can be exploited in DL design.To meet these needs we developed CRADLE (Cooperative-Relational Approach to Digital Library Environments), 3 a metamodel-based Digital Library Management System (DLMS) supporting collaboration in the design, development, and use of DLs, exploiting patterns emerging from previous projects. The entities of the CRADLE metamodel allow the specification of collections, structures, services, and communities of users (called "societies" in CRADLE) and partially reflect the DELOS Manifesto. The metamodel entities are based on existing DL taxonomies, such as those proposed by Fox and Marchionini, 4 Gonçalves et al., 5 or in the DELOS Manifesto, so as to leverage available tools and knowledge. Designers of DLs can exploit the domain-specific visual language (DVSL) available in the CRADLE environment-where familiar entities extracted from the referred taxonomies are represented graphically-to model data structures, interfaces and services offered to the final users. The visual model is then processed and transformed, exploiting suitable templates, toward a set of specific languages for describing interfaces and services. The results are finally transformed into platformindependent (Java) code for specific DL applications.CRADLE supports the basic functionalities of a DL through interfaces and service templates for managing, browsing, searching, and updating. These can be further specialized to deploy advanced functionalities as defined by designers through the entities of the proposed visual