XML Relational Solutions

• Agora: XQuery Normalization (syntax based), INRIA,
  http://www-rocq.inria.fr/~manolesc/AGORA/.
• XPERANTO: XML Views on top of relations (algebra based), IBM, http://xperanto.dfw.ibm.com/demo/mainPage.jsp.
• Jayavel Shanmugasundaram, Department of Computer Science, Cornell University, http://www.cs.cornell.edu/People/jai/.

Commercal Products

• DXX: DB2 XML Extender, by DAD file, IBM,
  http://www-3.ibm.com/software/data/db2/extenders/xmlext/index.html.
• XSU: Oracle XML SQL Utility, Corresponding to our default XML view, Oracle, http://technet.oracle.com/tech/xml/oracle_xsu/content.html.

Native XML Query Solutions

• Galax: Implementation of XQuery working drafts, Lucent Technology,
  http://db.bell-labs.com/galax/.
• XQrl: XML data stream query engine of XQuery, XQrl.com,
  http://xqrl.com/.
• NIAGARA Query Engine: continuous query engine, Computer Science Dept., University of Wisconsin, Madison,
  http://www.cs.wisc.edu/niagara/.
• Kweelt: Quilt query engine without algebra, University of Pennsylvania, http://kweelt.sourceforge.net/.
• TIMBER: Native XML processing system, TAX as algebra, University of Michigan, http://www.eecs.umich.edu/db/timber/introduction.html.

Misc:

• XMLDB.org,
  http://www.xmldb.org/.
  Look at the update,
  http://www.xmldb.org/xupdate.