XML - Day 3

• Cascade precedence
  1. inline reference (override in the tag itself)
  2. internal reference (in head tag)
  3. external reference (external CSS)
  4. browser defaults
• CSS syntax: Selector {}, property, value. (nn|67)

  sometag, anothertag 
  	{color: red; font-family: "san serif";}
  

• stylesheet reference declaration (see bottom of p395|83). The css itself needs no declaration (not xml)
• selectors
  • * = every element
  • element = named element
  • parent child = named child of an indeterminate parent
  • parent > child = named child of an immediate parent
  • element:first-child = first child element of named element
  • element[attribute] = named element with an attribute
  • element[attribute=value] = named element with an attribute of that value
  • element#id = named element matching a given ID
  • element, element, element = any of the named elements
• classes: element ".myclass" from <sometag class="myclass">
• id attributes: element "#a101" from <sometag ID="a101">
• colors can be called by name, hex or rgb
• a working example with CSS

XSL

XSL is still under development. The XSL language has changed radically in the past, and will change again in the future... To make matters worse, no software implements all of the Candidate Recommendation of XSL.... There are no Web browsers that can display a document written with XSL formatting objects. Eventually, of course, this should be straightened out as the standard evolves toward its final incarnation and more vendors implement XSL formatting objects.

• MSXML 3.0 is W3 XSL compliant
• XSL documents are XML rather than DTD-like
• function of XSL
  • transform - XSLT
  • formatting - XSL Flow/Formatting Objects - minimally supported by IE.

    The XSL FO markup is quite complex. It is also verbose; virtually the only practical way to produce an XSL FO file is to use XSLT to produce a source document. Finally, once you have this XSL FO file, you need some way to render it to an output medium. There are few tools available to do this final step. For these reasons, XML FO has not caught on as quickly as XSLT.

    
    
  • define - XPath identifies nodes within an XML document for use with XPointer, complex XSLT etc. Not covered in our text
• CSS uses selectors to associate objects with a rule. XSL uses templates to associate objects with a rule:

XSLT - transformation

• How it works
  • declare the XML stylesheet <?xml:stylesheet href="petxslt2.xsl" type="text/xsl" ?>
  • match attribute associates the template with an element

    	<xsl:template match="match expression">
    		[transformation here]
    	</xsl:template>
    

  • <xsl:value-of select="xsl pattern"> element inlines xml content into the transformed document
  • <xsl:for-each select="xsl pattern"> element provides iteration
• Hands-on
  • make a copy of your petstore.xml called petxsl.xml
  • create an XSL document to display part or all of your xml as HTML
  • add a sort <xsl:for-each select="xsl pattern" sort-by="+/-element">
  • add a filter: <xsl:for-each select="xsl pattern[element='foo']"> Note use of different delimiter. Comparator can be >, <, =, !=.
  • use a conditional: <xsl:if match=".[ARTIST='Bob Dylan']">your stuff here</xsl:if >
  • use choose: (case)

    	<xsl:choose>
    	<xsl:when test=".[ARTIST='Bob Dylan']">
    		... some code ...
    	</xsl:when>
    	<xsl:when test=".[ARTIST='Yngwie Malmsteen']">
    		... some code ...
    	</xsl:when>
    	<xsl:otherwise>
    	... some code ....
    	</xsl:otherwise>
    	<xsl:choose>
    	
• A working example with XSLT

Homework

Remember, your login is based on your machine's hostname, not on any other number.
~/[initials] refers to the subdirectory under your homedir, named after your initials. Everything except for .dotfiles will be stored in your ~/[initials] directory.

© 1995-2001 jason carr
Distributed under the terms of the GNU Free Documentation License.