Semantic web and databases : second international workshop SWDB 2004 Toronto Canada August 29 30 2004 ; revised selected papers This book constitutes the thoroughly refereed postproceedings of the Second International Workshop on Semantic Web and Databases SWDB 2004 held in Toronto Canada in August 2004 as a satellite workshop of VLDB 2004. The 14 revised full papers presented together with 2 papers by the invited keynote speakers were carefully selected during two rounds of reviewing and improvement from 47 submissions. Among the topics addressed are data semantics semantic Web services service oriented computing workflow composition XML semantics relational tables ontologies semantic Web algebra heterogeneous data sources context mediation OWL ontology engineering data integration semantic Web queries database queries and peer to peer warehouses