XML Processing Moves Forward XSLT 2.0 and XQuery 1.0 Michael Kay Prague 2005

2 About me Database background Started using XML in 1998 for content management applications Author of XSLT Programmer’s Reference Developer of Saxon XSLT processor Member of W3C XSL and XQuery Working Groups Founded SAXONICA March 2004

3 Contents A tour of the new specs What’s significant about XSLT 2.0 A quick demo Why XQuery?

4 The QT Specification Family XSLT 2.0 XQuery 1.0 XPath 2.0 Data Model XML Schema Functions and Operators

5 XSLT 1.0 XPath 1.0 Standards maturity Maturity Time XQuery XSLT 2.0 XPath 2.0 XML Schema XML REC CR

6 XML Schema A family of standards XPath 1.0 XPath 2.0 XQuery 1.0 XSLT 1.0 XSLT 2.0

7 XSLT and XQuery DocumentsData XSLT XQuery

8 What’s new in XSLT 2.0 New Processing Model Major Features –grouping –regular expressions –functions –schema support Many “minor” features

9 Some “minor” features XSLT 2.0 Temporary trees Multiple Output Files Format date/time Tunnel parameters Declared variable types Multi-mode templates xsl:next-match conditional compilation XHTML serialization xsl:namespace separator=“,” character maps XPath 2.0 Sequences if..then..else for $x in X return f($x) some/every except/intersect $n is $m Function library String functions Regex functions Date/time arithmetic URI handling min(), max(), avg()

10 Handling unstructured text unparsed-text() function –reads a text file into a string tokenize() function –splits a string into substrings xsl:analyze-string –parses a string and generates markup

11 Regular expression functions matches() test if a string matches a regex if (matches($in, ‘[A-Z]{3}[0-9]{3}’) tokenize() split a string into substrings regex matches the separator for $s in tokenize($in, ‘,\s?’)... replace() replace every occurrence of a match replace($in, ‘\s’, ‘%20’)

12 Grouping Takes any sequence as input Divides the items into groups Applies processing to each group group-by: items with a common value for a grouping key group-adjacent: adjacent items with a common grouping key group-starting-with: pattern to match first item in each group group-ending-with: pattern to match last item in each group

13 Grouping by Value <xsl:for-each-group select=“book” group-by=“publisher”> Publisher: author: title:

14 User-defined Functions Written like named templates Called from XPath Return a result <xsl:sequence select=“xs:date(concat( substring($in, 8, 4), ‘-’ format-number(index-of((“JAN”, “FEB”,...), substring($in, 4, 3)), ’00’), ‘-’, substring($in, 1, 2)))”/>

15 XQuery 1.0 Designed to query XML databases Also handles in-memory transformations Well supported by database vendors

16 XQuery Example Join two tables xquery version 1.0; { for $p in doc ("auction.xml")/site/people/person let $a := for $t in doc("auction.xml") /site/closed_auctions/closed_auction where = return $t return {count ($a)} } XMark Q8

17 XSLT Equivalent <xsl:variable name="a" select="/site/closed_auctions/closed_auction = XMark Q8

18 Optimization With multi-GB databases, using indexes is essential XQuery does not have template rules This makes it possible to do static analysis and join optimization

19 XMark Q8 results (msecs) 1Mb Xalan xt MSXML Saxon 8.4 XSLT XQuery Saxon 8.4 Qizx Galax Mb Mb O(n 2 ) O(n)

20 Two can play at that game! Xalan xt MSXML Saxon 8.5 1Mb XSLT XQuery Saxon 8.5 Qizx Galax Mb Mb O(n 2 ) O(n) caveat: this is one query only!

21 Conclusions XSLT 2.0 and XQuery 1.0 are nearly ready XSLT 2.0 has many powerful new features, making new applications possible XQuery 1.0 designed for optimization against very large databases