Bridging objects and relations: a mediator for an OO front- end to RDBMSs Leonid Stoimenov Faculty of Electronic Engineering, University of Nis Beogradska 14 18000 Nis Yugoslavia E-mail: leni@elfak.ni.ac.yu Antonija Mitrovic Department of Computer Science, University of Canterbury, New Zealand E-mail: tanja@cosc.canterbury.ac.nz Slobodanka Djordjevic-Kajan Faculty of Electronic Engineering, University of Nis E-mail: slobodanka@elfak.ni.ac.yu Dejan Mitrovic Department of Computer Science, University of Canterbury, New Zealand E-mail: dmi24@cosc.canterbury.ac.nz