Information Retrieval in vernetzten heterogenen Datenbanken
With the field capabilities of freeWAIS-sf it became difficult to query more than one database in parallel. The set of searchable fields can differ for different databases, they may have heterogeneous schemas. An important concept in database systems is data independence. Based on this concept a unifying view on multiple freeWAIS-sf databases is presented: the aspect of heterogeneity of different databases is hidden from the user. SFgate is a gateway between the World Wide Web and freeWAIS-sf which implements this approach.