Book excerpt: This book constitutes the thoroughly refereed joint post-proceedings of five workshops held as part of the 9th International Conference on Extending Database Technology, EDBT 2004, held in Heraklion, Crete, Greece, in March 2004. The 55 revised full papers presented together with 2 invited papers and the summaries of 2 panels were selected from numerous submissions during two rounds of reviewing and revision. In accordance with the topical focus of the respective workshops, the papers are organized in sections on database technology in general (PhD Workshop), database technologies for handling XML information on the Web, pervasive information management, peer-to-peer computing and databases, and clustering information over the Web.