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CITA 330 Section 6

CITA 330 Section 6. XSLT. Transforming XML Documents to XHTML Documents. XSLT is an XML dialect which is declared under namespace " http://www.w3.org/1999/XSL/Transform " Its root element is stylesheet or transform Example XSLT stylesheet:

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CITA 330 Section 6

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  1. CITA 330 Section 6 XSLT

  2. Transforming XML Documents to XHTML Documents XSLT is an XML dialect which is declared under namespace "http://www.w3.org/1999/XSL/Transform" Its root element is stylesheet or transform Example XSLT stylesheet: <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="html" version="4.0“ /> <xsl:template match="/"> <html> <head> <title>DVD Library Listing</title> </head>

  3. Transforming XML Documents to XHTML Documents <body> <table border="1"> <tr> <th>Title</th> <th>Format</th> <th>Genre</th> </tr> <xsl:for-each select="/library/dvd"> <xsl:sort select="genre“ /> <tr> <td><xsl:value-of select="title“ /></td> <td><xsl:value-of select="format“ /></td> <td><xsl:value-of select="genre“ /></td> </tr> </xsl:for-each> </table> </body> </html> </xsl:template> </xsl:stylesheet>

  4. Transforming XML Documents to XHTML Documents The root element stylesheet declares a namespace prefix "xsl" for XSL namespace "http://www.w3.org/1999/XSL/Transform" The 2nd line’s xsl:output element specifies that the output file of this transformation should follow the specification of HTML v 4.0 Each xsl:template element specifies a transformation rule: if the document contains nodes satisfying the XPath expression specified by the xsl:template’s match attribute, then they should be transformed based on the value of this xsl:template element Since this particular match attribute has value "/" selecting the root element of the input XML document, the rule applies to the entire XML document

  5. Transforming XML Documents to XHTML Documents The XSLT template uses an xsl:for-each element to loop through the dvd elements selected by the xsl:for-each element’s select attribute In the loop body, the selected dvd elements are first sorted based on their genre value Then the xsl:value-of elements are used to retrieve the values of the elements selected by their select attributes To use a web browser to transform the earlier file library.xml with this XSLT file library.xsl into HTML, you can add the following line after the XML declaration: <?xml-stylesheet type="text/xsl" href="library.xsl" ?>

  6. Transforming XML Documents to XHTML Documents The resulting Web browser presentation

  7. XSLT • An XSLT style sheet contains instructions for transforming the contents of an XML document into another format • An XSLT style sheet document is itself an XML document • An XSLT style sheet document has an extension .xsl

  8. XSLT • An XSLT style sheet converts a source document of XML content into a result document by using the XSLT processor

  9. XSLT • The transformation can be performed by a server or a client • In a server-side transformation, the server receives a request from a client, applies the style sheet to the source document, and returns the result document to the client • In a client-side transformation, a client requests retrieval of both the source document and the style sheet from the server, then performs the transformation, and generates the result document

  10. XSLT • To create an XSLT style sheet, the general structure is: <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> Content of the style sheet </xsl:stylesheet> The <xsl:stylesheet> tag can be substituted for the <xsl:transform> tag

  11. A template is a collection of elements that define how a particular section of the source document should be transformed in the result document The root template sets up the initial code for the result document Root Template

  12. Template • To create a template, the syntax is: <xsl:template match="node set"> styles </xsl:template> • where node set is an XPath expression that references a node set from the source document and styles are the XSLT styles applied to those nodes

  13. Root Template • To create a root template, the syntax is: <xsl:template match="/"> styles </xsl:template>

  14. Template • A template contains two types of content: XSLT elements and literal result elements • XSLT elements are those elements that are part of the XSLT namespace and are used to send commands to the XSLT processor • A literal result element is text sent to the result document, but not acted upon by the XSLT processor

  15. Output Method • By default, the XSLT processor will render the result document as an XML file • To control how the processor formats the source document, you can specify the output method using the <xsl:output> element

  16. xsl:output Attributes

  17. Transforming a Document • A browser with a built-in XSLT processor allows you to view the result document • Alternatively, you can use XML tools (such as XML Spy) to create the result document as a separate file, and then view that file in your browser • Most XSLT processors provide the capability to create the result document as a separate file

  18. Extracting Element Values • To insert a node’s value into the result document, the syntax is: • <xsl:value-of select="expression" /> • where expression is an expression that identifies the node from the source document’s node tree • If the node contains child elements in addition to text content, the text in those child nodes appears as well

  19. To process a batch of nodes, the syntax is: <xsl:for-each select="expression"> styles </xsl:for-each> where expression is an expression that defines the group of nodes to which the XSLT and literal result elements are applied Processing Several Elements

  20. To apply a template in the result document, use the XSLT element <xsl:apply-templates select="expression" /> where expression indicates the node template to be applied Working with Templates

  21. Sorting Node Sets • By default, nodes are processed in document order, by their appearance in the document • To specify a different order, XSLT provides the <xsl:sort> element • This element can be used with either the <xsl:apply-templates> or the <xsl:for-each> element

  22. Sorting Node Sets • The <xsl:sort> element contains several attributes to control how the XSLT process sorts the nodes in the source document • The select attribute determines the criteria under which the context node is sorted • The data-type attribute indicates the type of data • The order attribute indicates the direction of the sorting (ascending or descending)

  23. Conditional Nodes • XSLT supports two kinds of conditional elements: • <xsl:if> • <xsl:choose> • To apply a format only if a particular condition is met, use the <xsl:if> element • To test for multiple conditions and display different outcomes, use the <xsl:choose> element

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