TAILIEUCHUNG - Query Processing in RDF/S-based P2P Database Systems

Memex, with links and comments holding a central role, served as our blueprint for MyLifeBits. Faced with folders full of documents, messages, phone calls, photos, songs, etc., with inherent or potential metadata such as author, camera, comments, location, and time, we needed a framework to hold and link all of these objects in the web-like and almost arbitrary fashion that Bush described. We deemed search to be the most critical requirement. Furthermore, we realized that metadata are often a key part of user recall, ., that an email was sent during a certain year, that a song was. | Query Processing in RDF S-based P2P Database Systems George Kokkinidis Lefteris Sidirourgos and Vassilis Christophides Institute of Computer Science - FORTH Vassilika Vouton PO Box 1385 GR 71110 Heraklion Greece and Department of Computer Science University of Crete GR 71409 Heraklion Greece kokkinid Isidir christop @ 1 Introduction Peer-to-peer P2P computing is currently attracting enormous attention spurred by the popularity of file sharing systems such as Napster 31 Gnutella 15 Freenet 9 Morpheus 30 and Kazaa 25 . In P2P systems a very large number of autonomous computing nodes the peers pool together their resources and rely on each other for data and services. P2P computing introduces an interesting paradigm of decentralization going hand in hand with an increasing self-organization of highly autonomous peers. This new paradigm bears the potential to realize computing systems that scale to very large numbers of participating nodes while ensuring fault-tolerance. However existing P2P systems offer very limited data management facilities. In most of the cases searching relies on simple selection conditions on attribute-value pairs or IR-style string pattern matching. These limitations are acceptable for file-sharing applications but in order to support highly dynamic ever-changing autonomous social organizations . scientific or educational communities we need richer facilities in exchanging querying and integrating semi- structured data hosted by peers. To this end we essentially need to adapt the P2P computing paradigm to a distributed data management setting. More precisely we would like to support loosely coupled communities of peer bases where each base can join and leave the network at free will while groups of peers can collaboratively undertake the responsibility of query processing. The importance of intensional . schema information for integrating and querying peer bases has been highlighted by a number of recent projects 4 34 17 1 . A

• Cơ sở dữ liệu
• estate professionals
• keynote speaker
• Composite Natural Material
• Wood Polymer Composites
• Engineered Membranes
• Transporters