Access and Exchange of Hierarchically Structured Resources on the Web with the NESTOR Framework

The paper addresses the problem of representing, managing and exchanging hierarchically structured data in the context of Digital Library (DL) systems in order to enhance the access and exchange DL resources on the Web. We propose the NEsted SeTs for Object hieRarchies (NESTOR) framework, which relies on two set data models — the “Nested Set Model (NS-M)” and the “Inverse Nested Set Model (INS-M)” — to enable the representation of hierarchical data structures by means of a proper organization of nested sets. In particular, we show how NESTOR can be effectively exploited to enhance Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) for better access and exchange of hierarchical resources on the Web.