Federation services for heterogeneous digital libraries accessing cooperative and non-cooperative sources

Today, bibliographical information is kept in a variety of digital libraries available on the Internet. The integration of bibliographical data is considered as one of the most important tasks in the area of digital library community. The available sources of data vary widely in terms of data representation and access interfaces. To overcome this heterogeneity during the last years attempts were made to apply methods developed for information system integration. We describe our approach of a federation service for digital libraries using the loosely coupled federated system FRAQL that offers a variety of conflict resolution mechanisms. Furthermore, we present different kinds of adapters for accessing cooperative and noncooperative sources of bibliographical information. In order to integrate systems with limited query capabilities we introduce concepts for source descriptions