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XML Part 2

XML Part 2. Josh Steele CS 6704, Spring 2002. XML Part 2. XSL/XSLT Structure Revisited Definition Example Components XML’s Linking Languages XML’s Uses. Structure Revisited. Structure. Information. XML File. XML Schema (.xsd) File. Display. XSL File. XSL.

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XML Part 2

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  1. XML Part 2 Josh Steele CS 6704, Spring 2002

  2. XML Part 2 • XSL/XSLT • Structure Revisited • Definition • Example • Components • XML’s Linking Languages • XML’s Uses

  3. Structure Revisited Structure Information XML File XML Schema (.xsd) File Display XSL File

  4. XSL • Stands for Extensible Stylesheet Language • Parts: • XSLT – handles transformations • XPath – used to access or refer to parts of an XML document • Formatting objects – XML Vocabulary for specifying formatting semantics • Compatible with CSS2 (uses different syntax though)

  5. XSLT • Transforms one set of XML tags to another set of XML tags • Benefits of this?

  6. Example - XML <?xml version=“1.0”?> <?xml-stylesheet type=“text/xsl” href=“myxsl.xsl”?> <Recipe xmlns:rec=“http://www.mysite.org/Recipe” xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance xsi:schemaLocation=“myxsd.xsd” > <rec:Recipe cook = “XML Gourmet”> <rec:Title>Bean Burrito</Title> <rec:Category name = “tex-mex” /> <rec:Ingredients> <rec:Item>1 can refried beans</Item> <rec:Item>1 cup longhorn colby cheese, shredded</Item> …… </rec:Ingredients> <rec:Cooking Instructions> Empty can of refried beans </rec:Cooking Instructions> …… </rec:Recipe>

  7. XML Schema <?xml version="1.0" encoding="utf-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name=“recipe"> <xs:complexType> <xs:sequence> <xs:element name=“Title" type="xs:string"/> <xs:element name=“Category" type="xs:string"/> <xs:element name=“Ingredients" type="xs:string"> <xs:complexType> <xs:element name=“Item" minOccurs=“1" maxOccurs="unbounded“ type=“xs:string”/> </xs:complexType> </xs:element> <xs:element name=“CookingInstructions" type="xs:string"/> </xs:sequence> </xs:complexType> </xs:element> </xs:schema>

  8. Example - XSLT <xsl:stylesheet version = “1.0” xmlns:xsl=“http://www.w3.org/1999/XSL/Transform” xmlns=“http://www.w3.org/TR/xhtml1/strict”> <xsl: output method=“xml” encoding=“iso-8859-1” /> <xsl: template match = “Recipe”> <html> <head> <title> <xsl value-of select=“Recipe/Title” /> </title> </head> <body> <xsl:apply-templates /> </body> </html> </xsl: template>

  9. Example - XSLT (cont) <xsl:template match=“Recipe/Title”> <h1> <xsl:apply-templates /> </h1> </xsl:template> <xsl:template match=“Recipe/Ingredients”> <h2>Ingredients</h2> <ul> <xsl:for-each select=“Item”> <li> <xsl:apply-templates /> </li> </xsl:for-each> </ul> </xsl:template> <xsl:template match = “Recipe/CookingInstructions”> <h2> Cooking Instructions </h2> <p> <xsl:apply-templates /> </p> </xsl:template> ………

  10. Components • Template • Defines what should be changed, and how • Pattern • Uses “match=“ attribute in template tag to point to a specific element (uses XPath, more later) • Results • Includes the HTML tags specified • <xsl: apply templates /> - applies template to the text encapsulated by the tag (i.e. <CookingInstructions>)

  11. Components (cont) • Text • Literal text can be captured with the <xsl:value-of> tag • Repetition • Handled by use of the <xsl:for-each> tag

  12. XML’s Linking Languages • XLink • Alternative to XHTML for linking (the <a> tag) • <xmlns:xlink=http://www.w3.org/1999/xlink/namespace> • <xlink:simple> – works just like <a> (with some more features) • <xlink:extended>, <xlink:locator>, <xlink:arc > - provides a whole new set of linking policies

  13. XLink: Simple • Attributes: • href - resource you are linking to • role - string used to describe element’s role • title – optional title of link • show - opens the new resource in its own window (new), embeds it in the current window (embed), or replaces the current window with the new one (replace) • actuate – onRequest (click a link) or auto (like loading in <img>)

  14. XLink:Extended • Attributes: • Role, title – as in <xlink:simple> • showdefault – default value of show for all locator elements • actuatedefault – default value of actuate for all child elements • Needs helpers: <xlink:locator>, <xlink:arc>

  15. XLink:Locator These <xlink:extended role=“weapon list” title=“Description of Weapons” showdefault=“new” show actuate=“onRequest”>weapons <xlink:locator title=“Longbow” href= “longbow.htm”/> <xlink:locator title=“Crossbow” href= “crossbow.htm”/> <xlink:extended> revolutionized medieval warefare……

  16. XLink:arc • Locators can be specified out-of-line • <xlink:locator href=“weaponlinkset.xml”/> • Allows different show and actuate parameters for each locator • xlink:arc specifies those values in above file: xlink:arc from=“sourcedoc” to=“longbowpic” show=“embed” actuate=“auto”/>

  17. XPath • Purposes: • To find and describe a section in the XML file (used in XSLT) • To be able to point to a certain part of the document (used in XPointers) • In essence makes a parse tree describing the relationships between tags in the file

  18. XPointers • Allows one to point into a document (similar to anchors in HTML), but without any special notation (like id=“mytaghere”) • Also allows selection of a section of the file (i.e. if you want section 25, it only downloads section 25, not the whole file)

  19. XPointers (cont) • 3 ways to reference: • #anchor (like in HTML) • #/1/3/4 (3rd tag under root, 4th tag under that) • #xptr (XPath expression) • If you aren’t sure if there is an ID, you can concatenate different reference methods together • Range: XPtr(id(“c2”) to id(“c3”))

  20. XML Uses • MathML – allows math expressions in web pages (www.w3.org/Math) • XML-Data – provides mechanism to reference binary data within XML docs • XHTML – a merging of XML and HTML • WIDL – Web Interface Definition Language – allowed direct access to Web data from e-commerce or business apps • And many more!

  21. References • XML for Dummies, 2nd edition (Ed Tittel, Frank Boumphrey) • http://www.w3.org/TR/WD-xptr - XPointer • http://www.w3.org/TR/xslt - XSLT • http://www.w3.org/Style/XSL/ - XSL • http://www.w3.org/XML/ - XML

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