On integrating existing bibliographic databases and structured databases

It is widely accepted that future digital library applications have to be built upon different kinds of database servers to draw different forms of data from them. These data include bibliographic data, text data, multimedia data, and structured data. We address the problem of integrating existing bibliographic and structured databases which reside at different locations in the network. To integrate bibliographic data and structured data, we extended the well-known SQL model to represent bibliographic related attributes and queries. In particular, we have added a new data type to model attributes in the bibliographic database. We have also designed specialized predicates and functions that can be used to formulate queries on bibliographic data alone as well as queries on both bibliographic and structured data. By combining our SQL extensions with the other SQL extensions that model general text data, we believe that a versatile query language layer can be made available to our future digital library application development.