Since its first edition in 2003, the XML Database Symposium series
(XSym) has been a forum for academics, practitioners, users and vendors
to discuss the use of and synergy between databases and XML. The
previous symposia have provided opportunities for timely discussions on
a broad range of topics pertaining to the theory and practice of XML
data management and its applications. XSym 2007 continues this tradition
with a program consisting of three research sessions, two keynote talks
and a panel. We received 28 full paper submissions, out of which 8 were
accepted for publication in these proceedings. Each submitted paper
underwent a rigorous and careful review by a minimum of 4 independent
referees. The contributions in these proceedings are a fine sample of
the very best current research in XPath and XQuery processing, XML
Updates, Temporal XML and Constraints. This volume also contains two
invited short papers by the XSym 2007 keynote speakers: Leonid Libkin
(University of Edinburgh, UK) contributed a thorough discussion of
Normalization Theory for XML, while Erhard Rahm (University of Leipzig,
Germany) contributed an interesting overview of the work on Dynamic
Fusion of Web Data carried out at his - search group. This year, XSym
will top its program off by an exciting panel with the title "The
Generation Y of XML Schema Matching". It was proposed and is organized
by Avigdor Gal from Technion - Israel Institute of Techn- ogy.