Application Development XML - XSL

Transcription

1 ITEC 2336 Internet Application Development XML - XSL

2 XML A style sheet is linked to an XML document to format the document. XML processor combines style sheet with XML document to display a formatted document. There are two main style sheet languages used with XML: Cascading Style Sheets (CSS) Extensible Style Sheets (XSL)

3 EXtensible Stylesheet Language (XSL) W3C started to develop XSL because there was a need for an XML-based Stylesheet Language XSL consists of three parts: XSLT - a language for transforming XML documents XPath - a language for navigating in XML documents XSL-FO - a language for formatting XML documents

4 What is XSLT? extensible Stylesheet Language for Transformations Language for transforming XML documents A programming language for XML documents A functional language, based on value substitution Augmented with pattern matching And also template substitution to construct output (based on namespaces) Uses XML syntax

5 Some special transforms XML to HTML for old browsers XML to LaTeX for TeX layout XML to SVG graphs graphs, charts, trees XML to tab-delimited for db/stat packages XML to plain-text occasionally useful XML to FO XSL formatting objects

6 XML Documents as trees of nodes Root Elements Attributes Text Nodes (not characters) Namespaces Processing Instructions Comments

7 XML Document order Root Elements Text Nodes -- First -- Occur in order of their starts -- As if children (leaves) Attributes, namespaces -- Attached to element, unordered PIs, comments -- Leaves like text nodes

8 extensible Stylesheet Language Transformation (XSL) The history of XSL The origins of XSL are in Cascading Style Sheets (CSS), where a "stylesheet" is used to add formatting to an HTML file. The syntax to use a stylesheet in XSLT is similar to the syntax in CSS. XSLT is rule-based For example, a stylesheet could declare that when the XSLT transformation engine finds a 'NAME' element it should add markup by calling the 'NAME' template. <xsl:template match="name">... </xsl:template>

9 XSL MSXML Parser 3.0 is the XML parser shipped with IE and dwindows XP. According to Microsoft, MSXML Parser 3.0 is 100% compatible with the official W3C XSLT Recommendation. <xsl:stylesheet> or <xsl:transform> is the root element that declares the document to be an XSL style sheet. The root node of a stylesheet housing the templates y g p to be applied to the XML tree. Note: <xsl:stylesheet> and <xsl:transform> are synonymous either can be used!

10 XSL The correct way to declare an XSL style sheet is: <xsl:stylesheet version="1.0" xmlns:xsl=" form"> or: <xsl:transform version="1.0" xmlns:xsl=" l /1999/XSL/T form">

11 XSL The <xsl:template> element defines the transformation ti or formatting to be applied. The template s match attribute associates a template with an XML element. The match attribute can also be used to define a template for a whole branch of the XML document (i.e. match="/" defines the whole document). The match="/" attribute associates (matches) the template to the root (/) of the XML source document. Match parameters indicate the path to the element in the XML tree. The <xsl:value-of> element inserts the string value of a named node.

12 XSL The XSL <xsl:for-each> element sets up a loop to iterate through several nodes. Output from an XML file can filtered by adding a criterion i to the select attribute t in the <xsl:for-each> element. For example: <xsl:for-each select="catalog/cd[artist='bob Dylan']"> Legal filter operators are: = (equal)!= (not equal) < less than > greater than

13 XSL To output the XML file as an XHTML file, and sort it at the same time, simply add a sort element inside the for-each element in your XSL file: The select attribute t indicates what XML element to sort on. The <xsl:if> element contains a template that will be applied only if a specified condition is true. To insert a conditional choose test against the content t of the XML file, simply add the <xsl:choose>, <xsl:when>, and <xsl:otherwise> elements to your XSL document.

14 XSL Example: <?xml version="1.0" encoding="iso "?> <?xml-stylesheet type="text/xsl" text/xsl href="cdcatalog.xsl"?>

15 ITEC 2336 Internet Application Development XML - XSL