Building HyperView wrappers for publisher web sites

Abstract

Electronic journals are becoming a major source of scientific information. Researchers interested only in certain topics do not have time to scan all possibly relevant journals on a regular basis. A digital library can assist them by providing a uniform, search-able interface for electronic journals. To this purpose, a catalogue of metadata on the available journals such as authors and titles of articles must be established by the digital library. If there is no cooperation with journal publishers, this metadata must be extracted from the publishers' Web Sites, overcoming the intrinsic heterogeneity problems. Within the framework of the ongoing Natural Sciences Digital Library project at the Free University of Berlin, we have designed a wrapper- mediator mechanism that copes with the heterogeneity problems of automatic metadata acquisition. It is based on our generic HyperView methodology for integration of Web Sites. From this methodology it inherits two elegant and effective features. First, the structure of the publisher site is specified with abstract graph-schemata, instead of being hard-coded in scripts for data acquisition. Second, a powerful view concept based on declarative graph-transformation rules is used for information extraction.