06472 Abstracts Collection - XQuery Implementation Paradigms

From 19.11.2006 to 22.11.2006, the Dagstuhl Seminar 06472 ``XQuery Implementation Paradigms'' was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

06472 Executive Summary -- XQuery Implementation Paradigms

Only a couple of weeks after the participants of seminar No. 06472 met in Dagstuhl, the W3C published the Final Recommendation documents that fix the XQuery 1.0 syntax, data model, formal semantics, built-in function library and the interaction with the XML Schema Recommendations (see W3C\u27s XQuery web site at http://www.w3.org/XML/Query/). With the language\u27s standardization nearing its end and now finally in place, the many efforts to construct correct, complete, and efficient implementations of XQuery finally got rid of the hindering "moving target\u27\u27 syndrome. This Dagstuhl seminar on the different XQuery implementation paradigms that have emerged in the recent past, thus was as timely as it could have possibly been

06472 Executive Summary - XQuery Implementation Paradigms

SQL has been developed as a query language specifically tailored for the relational data model in which all data instances take a regular, tabular shape. Despite this regularity, the efficient translation, optimization, and execution of SQL proved to be a challenging and complex task and thus has kept the database research community as well as industry busy, from the very first days of SQL (the late 70s) until today. The now pervasive XML data model, on the other hand, describes irregular, tree-shaped data. XQuery has been designed as a query language in which such data trees--among other supported data types--are first-class citizens: XQuery features tree (or node) constructors and embeds XPath as an elaborate tree traversal language. As you read this, XQuery has entered the final stages to become an official Recommendation of the World Wide Web Consortium (W3C) and all odds are that XQuery will play the role in high-volume XML data management that SQL assumed for the relational data model. From a computing science perspective, XQuery is a language with many interesting facets. Among these are fully orthogonal syntax, support for nested iteration, variable bindings (the XQuery FLWOR blocks) and recursive user-defined functions, trees (and nodes with identity) as first-class citizens, construction of arbitrary XML fragments, embedded XPath sub-language, order awareness (document and sequence order), and adoption of the expressive XML Schema type system and, in par