Handling Evolution in Digital Libraries.

Developing and maintaining a digital library requires substantial in- vestments which are not simply a matter of technological decisions, but include also organizational aspects (which user roles are involved in content production, which workflows are needed, and so on). Moreover, starting a digital library ini- tiative requires to handle several evolution issues (the need of new roles, work- flows, and types of contents, the availability of new applications to integrate on the top of digital archives, etc.). To catch all these aspects, we outline a concep- tual model based on three complementary domains: informational, technological, and social. This model tackles the typical issues affecting a digital library, espe- cially concerning the evolution (i.e. change) of content, infrastructure (software tools), user roles, and related workflows in content creation, publication, and ex- ploitation. These issues are addressed in the model by means of three elements: a suitable XML data metamodel, a service-oriented architecture, and a multi-agent infrastructure. The XML metamodel abstracts the physical representation from the logical defi- nition of data, making easier future changes. The multi-agent infrastructure helps to preserve the consistency of the stored archives when their schemata need to be changed. Finally, the service-oriented architecture simplifies the integration of new applications at the top of the digital library. As part of this architecture, we describe in particular a specific component: the PIRATES framework. This mod- ule introduces in the digital library a set of semantic services aimed at assisting final users to select from the archives the most appropriate content. Integrating se- mantic aspects helps to handle the evolution of both contents and user needs (i.e. interests). Techniques of user modeling, adaptive personalization, and knowledge representation are exploited to build the PIRATES services in order to fill the gap existing between traditional and semantic digital libraries.