INLS 760 Web Databases Lecture 12 XML, XPATH, XSLT

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1 INLS 760 Web Databases Lecture 12 XML, XPATH, XSLT Robert Capra Spring 2013 Note: These lecture notes are based on the tutorials on XML, XPath, and XSLT at W3Schools: and from the book, XML in a Nutshell, 3 rd Edition, by Harold and Means. 1

2 HTML HTML <html> <head> <title>chaucer DOM Example</title> </head> <body> <h1>the Canterbury Tales</h1> <h2>by Geoffrey Chaucer</h2> <table> <tr> <td>whan that Aprill</td> <td>with his shoures soote</td> </tr> <tr> <td>the droghte of March</td> <td>hath perced to the roote</td> </tr> </table> <body> </html> 1. Hierarchical structure 2. Common understanding of tags TITLE text: Chaucer DOM Example HEAD H1 text: The Canterbury Tales TR TR H2 text: By Geoffrey Chaucer TBODY BODY TD TD TD TD TABLE 2

3 EXtensible Markup Language (XML) <?xml version="1.0" encoding="iso "?> <release> <title>punch the Clock</title> <artist>elvis Costello and The Attractions</artist> <date><day>5</day> <month>august</month> <year>1983</year> </date> <label>f-beat/columbia</label> </release> lect10/music1.xml 1. Data description language 2. Hierarchical structure 3. Tags and meanings are NOT pre-defined 3

4 Viewing XML documents Current versions of Firefox and Internet Explorer will display XML documents Documents are parsed and may generate errors Ex: lect10/music0.xml 4

5 XHTML HTML <HTML> <body> <h1>title</h1> <p> This is a paragraph <ul> <li>item 1 <li>item 2 </ul> <hr> <b><u>bold underline</b></u> regular text </html> lect10/bad.html XHTML <html> <body> <h1>title</h1> <p> This is a paragraph </p> <ul> <li>item 1</li> <li>item 2</li> </ul> <hr /> <b><u>bold underline</u></b> regular text </body> </html> 5

6 Valid XML Documents XML documents are stricter than HTML Balanced tags/closing tags required Case-sensitive Proper nesting DTDs and XML Schemas XML documents must conform to a DTD or XML Schema 6

7 XML Attributes HTML: <a href="lect10.pdf">lect 10</a> <form name="fred"> XML: <fruit type="tropical"> <name>papaya</name> </fruit> Attributes are used less often in XML than in HTML: <fruit> <type>tropical</type> <name>papaya</name> </fruit> However, id attributes are good for having an easy way to access an element (i.e. using getelementbyid) 7

8 Child Nodes and Rich Structure <article> <title></title> <authors> <author> <firstname></firstname> <lastname></lastname> </author> <author> <firstname></firstname> <lastname></lastname> </author> </authors> <abstract></abstract> <body> <section> <subsect></subsect> </section> <section></section> </body> <references> <reference> <authors></authors> <title></title> <publication> </publication> <year></year> </reference> </references> </article> 8

9 XML Namespaces <apple> <color>red</color> <name>macintosh</name> <size>medium</size> <country>usa<country> </apple> <apple> <color>red</color> <name>macintosh</name> <size>medium</size> <country>usa<country> <havested>may<harvested> <orchard>apple Farms</orchard> </apple> <apple> <color>red</color> <name>macintosh</name> <size>medium</size> <country>usa<country> </apple> <apple> <color>red</color> <name>macintosh</name> <size>medium</size> <country>usa<country> <processor>intel</processor> <screen>17in</screen> </apple> What if we tried to combine these in the same XML document? 9

10 General form: Namespace syntax xmlns:prefix="uri" Example: xmlns:fred=" The URI can reference a location where information about the namespace (such as a DTD or XML Schema) is located, but XML does not rely on that being the case. 10

11 Namespaces <frt:apple xmlns:frt=" <frt:color>red</frt:color> <frt:name>macintosh</frt:name> <frt:size>medium</frt:size> <frt:country>usa</frt:country> <frt:havested>may</frt:harvested> <frt:orchard>apple Farms</frt:orchard> </frt:apple> <cmp:apple xmlns:cmp=" <cmp:color>red</cmp:color> <cmp:name>macintosh</cmp:name> <cmp:size>medium</cmp:size> <cmp:country>usa</cmp:country> <cmp:processor>intel</cmp:processor> <cmp:screen>17in</cmp:screen> </cmp:apple> 11

12 Default Namespaces <apple xmlns=" <color>red</color> <name>macintosh</name> <size>medium</size> <country>usa</country> <havested>may</harvested> <orchard>apple Farms</orchard> <apple> <apple xmlns:cmp=" <color>red</color> <name>macintosh</name> <size>medium</size> <country>usa</country> <processor>intel</processor> <screen>17in</screen> </apple> Using the default namespace syntax shown here, you do NOT need to include the prefix in the child elements 12

13 XML-based Languages VoiceXML WML RSS MathML SVG Many many others 13

14 SVG XML Examples RDF RSS VoiceXML 14

15 Is XML a Database? Pros Cons 15

16 Storing XML Documents From Elmasri, p : Using a DBMS to store documents as text. then use keyword indexing/processing Using a DBMS to store the document contents as data elements. requires a schema and mapping Designing a specialized system for storing native XML data Creating or publishing customized XML documents form preexisting relational databases 16

17 MySQL XML Support MySQL dump XML output option dump.html#option_mysqldump_xml Load XML (in MySQL 6) 17

18 XML Tutorials W3Schools Intro Tree Validation Viewing 18

19 XPath XPath is a way to specify a particular node in an XML document 19

20 XPath Resources Chapter 9, XML in a Nutshell, 3 rd ed. by E.R. Harold, W.S. Means UNC Library Electronic Access XPath Tutorial, W3Schools RIT IT722 Zvon XpathTutorial TopXML Copyright 2007, Robert G. Capra III 20

21 XPath <?xml version="1.0" encoding= ISO ?> <collection> <release country="usa"> <title>look Sharp!</title> <artist>joe Jackson</artist> <date>1979</date> <label>a&m</label> </release> <release> <title>night and Day</title> <artist>joe Jackson</artist> <date>1982</date> <label>a&m</label> </release> </collection> Node Relationships 1. Parent 2. Children 3. Siblings 4. Ancestors 5. Decendants Xpath Node Types 1. Element 2. Attribute 3. Text 4. Namespace 5. Processing-Instruction 6. Comment 7. Document (root) 21

22 Document node XPath <?xml version="1.0" encoding= ISO ?> <collection> <release country="usa"> <title>look Sharp!</title> <artist>joe Jackson</artist> <date>1979</date> <label>a&m</label> </release> <release> <title>night and Day</title> <artist>joe Jackson</artist> <date>1982</date> <label>a&m</label> </release> </collection> Attribute node Element node 22

23 XPath Tree <?xml version="1.0" encoding="iso "?> <?xml-stylesheet type="text/xsl" href="music1.xsl"?> <collection> <release country="usa"> <title>look Sharp!</title> <artist>joe Jackson</artist> <date><month>april</month><year>1979</year></date> <label>a&m</label> </release> <release> <title>night and Day</title> <artist>joe Jackson</artist> <date><year>1982</year></date> </release> </collection> <release>..</release> Root node <collection>..</collection> Root node: / Root element: collection <?xml-stylesheet?> <release>..</release> <title>.. </title> <artist>.. </artist> <date>.. </date> <label>.. </label> <title>.. </title> <artist>.. </artist> <date>.. </date> <month>.. </month> <year>.. </year> <year>.. </year> 23

24 XPath Selection General/examples.html 24

25 XPath Location Path Basics <?xml version="1.0" encoding="iso "?> <?xml-stylesheet type="text/xsl" href="music1.xsl"?> <collection> <release country="usa"> <title>look Sharp!</title> <artist>joe Jackson</artist> <date><month>april</month><year>1979</year></date> <label>a&m</label> </release> <release> <title>night and Day</title> <artist>joe Jackson</artist> <date><year>1982</year></date> </release> </collection> Root node / selects the root node, regardless of context node element_node selects child elements of the current node that have that name //foo selects all foo nodes in the document, regardless of context node. current (context) node.. parent of current node <release>.. </release> <collection>.. </collection> <?xml-stylesheet?> <release>.. selects all attribute nodes named foo in the current context [foo] select using predicate foo <title>.. </title> <artist>.. </artist> <date>.. </date> <label>.. </label> <title>.. </title> <artist>.. </artist> <date>.. </date> 25

26 Exensible Stylesheet Language (XSL) CSS for XML documents QTP: HTML tags are defined, XML tags are created by users. How to create a stylesheet for XML? 26

27 XSL Transformations (XSLT) Very powerful XSLT provides a way to transform one XML document into another XML document or into some other format (such as HTML) Allows manipulation of XML elements Uses XPath Supported by Firefox, IE, other browsers 27

28 XSLT Resources Chapter 8, XML in a Nutshell, 3 rd ed. by E.R. Harold, W.S. Means UNC Library Electronic Access XSLT Tutorial, W3Schools Zvon XpathTutorial TopXML 28

29 XSLT Examples XML file <?xml version="1.0" encoding="iso "?> <?xml-stylesheet type="text/xsl" href="music1.xsl"?> <collection> <release country="usa"> <title>look Sharp!</title> <artist>joe Jackson</artist> <date> <month>april</month> <year>1979</year> </date> <label>a&m</label> </release> <release> <title>night and Day</title> <artist>joe Jackson</artist> <date> <year>1982</year> </date> </release> </collection> stylesheet link lect10/music1.xml 29

30 XSLT Example 1 Simple stylesheet lect10/music1.xsl <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl=" <xsl:template match="release"> <text>fred</text> </xsl:template> Template rule Template </xsl:stylesheet> Traverses the XML document Looks at every node If node matches the template rule, then process and output the template 30

31 XSLT Example 2 Match eats the node it matches i.e. child nodes do not get templates applied to them <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl=" <xsl:template match="collection"> <b>fred</b> </xsl:template> <xsl:template match="artist"> <b>ethel</b> </xsl:template> </xsl:stylesheet> lect10/music2.xsl 31

32 XSLT Example 1 Revisited lect10/music1.xsl <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl=" <xsl:template match="release"> <b>fred</b> </xsl:template> </xsl:stylesheet> Differences in XSLT processors (e.g. IE & Firefox) text/xsl vs. application/xsl-xml Default processing rules Try: match on collection, release, artist in both IE and Firefox 32

33 XSLT Example 3 value-of Value-of returns the value of the entire node specified by the select <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl=" <xsl:template match="date"> <b> <xsl:value-of select="."/> </b> </xsl:template> </xsl:stylesheet> lect10/music3.xsl 33

34 XSLT Example 4 Order of Eval By default, XSLT looks for matches using a preorder traversal of the XML Tree lect10/music4.xsl <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl=" <xsl:template match= text( )"> <b> <xsl:value-of select="."/> </b> </xsl:template> </xsl:stylesheet> Selects any node with text QTP: What if match= date/text( )? 34

35 XSLT Ex. 5 Change Order Use apply-templates to change the evaluation order Applies all the templates to the children of the current node; optional select to filter children <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl=" <xsl:template match="date"> <i> <xsl:value-of select="month"/> </i> <b> <xsl:value-of select="year"/> </b> </xsl:template> lect10/music5.xsl <xsl:template match="release"> <xsl:apply-templates select="date"/> </xsl:template> </xsl:stylesheet> 35

36 Ex. 6 More Apply Templates Use apply-templates to change the evaluation order Applies all the templates to the children of the current node; optional select to filter children lect10/music6.xsl <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl=" <xsl:template match="* /"> <p> <b> <xsl:value-of select="."/> </b> </p> <xsl:apply-templates/> </xsl:template> </xsl:stylesheet> 36

37 XSLT Ex. 7 Create HTML <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl=" <xsl:template match="collection"> <html> <h1>my CD Collection</h1> <table border="1"> <xsl:apply-templates/> </table> </html> </xsl:template> <xsl:template match="release"> <tr> <td> <xsl:value-of select="title"/> </td> <td> <xsl:value-of select="artist"/> </td> </tr> </xsl:template> </xsl:stylesheet> lect10/music7.xsl Use apply-templates to control the evaluation order and placement in a template 37

38 XSLT Ex. 8 for-each for-each iterates through a set of nodes <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl=" <xsl:template match="/"> <html> <xsl:for-each select="//date"> <p><b> <xsl:value-of select="year"/> </b></p> </xsl:for-each> </html> </xsl:template> </xsl:stylesheet> lect10/music8.xsl 38

39 Default rules Resources XML in a Nutshell, 3rd ed., section 8.7 Harold and Means, O'Reilly, xample73_ch2.html MIME type for stylesheet XML in a Nutshell, 3rd ed., section 8.3 Harold and Means, O'Reilly,

40 XSLT Examples XML file <?xml version="1.0" encoding="iso "?> <?xml-stylesheet type="text/xsl" href="music1.xsl"?> <collection> <release country="usa"> <title>look Sharp!</title> <artist>joe Jackson</artist> <date> <month>april</month> <year>1979</year> </date> <label>a&m</label> </release> <release> <title>night and Day</title> <artist>joe Jackson</artist> <date> <year>1982</year> </date> </release> </collection> lect10/music1.xml type is important IE: "text/xsl" Firefox: "application/xml" Eventually: "application/xslt+xml" This affects the application of the DEFAULT RULES 40

41 XSLT lect12/foo.xsl <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl=" <xsl:template <text><xsl:value-of select="."/></text> </xsl:template> <xsl:template match="artist"> <b>foo</b> </xsl:template> </xsl:stylesheet> Default rules Two important ones: 1. For text nodes 2. For root/element nodes See XML in a Nutshell, section

XSL Languages. Adding styles to HTML elements are simple. Telling a browser to display an element in a special font or color, is easy with CSS.

XSL Languages. Adding styles to HTML elements are simple. Telling a browser to display an element in a special font or color, is easy with CSS. XSL Languages It started with XSL and ended up with XSLT, XPath, and XSL-FO. It Started with XSL XSL stands for EXtensible Stylesheet Language. The World Wide Web Consortium (W3C) started to develop XSL