The PLAN-X 2009 workshop is the forum to present and discuss
bleeding-edge research at the intersection of programming language and
data base technology with an emphasis on tree-shaped data structures
and their XML representation. Topics of interest are all aspects of
XML processing and querying: theories, methodologies, paradigms,
language designs, types, analyses, runtime aspects, implementations,
tools, applications.

This edition of PLAN-X is particularly interested in blending the XML
processing approaches developed by the programming languages and data
management communities. Expressive power and high performance are
among the common goals that these communities pursue. We encourage the
submission of crosscutting contributions that apply techniques from
one community to problems from the other.

The primary criteria for paper selection are originality, relevance,
and timeliness to ensure that we can enjoy reports on ongoing and
unfinished work with high potential in the workshop.