A Unified Multimedia and Semantic Perspective for Data Retrieval in the Semantic Web

In recent years, the emerging diffusion of peer-to-peer networks is going beyond the single-domain paradigm like, for instance, the monothematic file sharing one (e.g., Napster for music). Peers are more and more heterogeneous data sources which need to share data with commercial, educational, and/or collaboration purposes, just to mention a few. Moreover, in current information processing applications data can not be meaningfully searched by precise database queries that would return exact matches (e.g., when dealing with multimedia, proteomic, statistical data). In this paper we move a step towards multi-domain multi-type data sharing systems by introducing an advanced technological infrastructure which enables users to meet these new emerging needs. A fundamental issue in this context is data heterogeneity, which is pervasive and intrinsically present both at intensional level where, due to peers' autonomy, different semantic descriptions of the available information are provided, and at extensional level, where multiple data types can coexist, also including content-based searchable data types such as multimedia data. Our proposal relies on a Peer Data Management Systems (PDMS) framework to present innovative network organization and query routing mechanisms which exploit both peers' data description and data content to achieve effective and efficient network management and data retrieval in such a context. The validity of our proposal is demonstrated by an absolutely satisfactory experimental evaluation on a real setting.