What
is XSL?
XSL
stands for eXtensible Stylesheet Language which is much like XML. XSL is a
language for expressing stylesheets. It consist of XSLT, is an application for
specifying rules by which one XML document is transformed into another XML
document; Xpath, Expression language used by XSLT to locate elements and
attributes in an XML document. It also tests Boolean conditions, perform
numerical calculations; XSL-FO (Formatting Objects), which specifies formatting
properties for rendering the document to some other format.
Advantages:
Easy display formatted XML data in browser
Easier
to modify when XML data format changes than to modify DOM and SAX parsing code
Can be used with database queries that
return XML
Disadvantages:
Memory exhaustive, performance hit.
Difficult to implement complex
business rules
XSLT:
eXetensible Stylsheet Language for
Transformation specifies rules for conversion i.e. template or template rules.
There are two types of template rules for transformation: Matching and
selection templates, and Branching elements.
Matching and
selection templates
xsl:template
xsl:apply-templates
xsl:value-of
Branching elements
xsl:for-each
xsl:if
xsl:choose
Matching and
selection templates
xsl:template :
xsl:template match=“XPath” :
Defines a template rule for producing output. It is applied only to nodes that match the pattern.
It is invoked by using
<xsl:apply-templates/>
<xsl:template
match="/">
<html><body>
<xsl:apply-templates/>
</body></html>
</xsl:template>
<xsl:template
match=“name">
Your
name is <xsl:value-of select=“first”/>
</xsl:template>
xsl:value-of select:
xsl:value-of select=“expression” :
It evaluates the expression as a string and outputs the result. It is applied only to the first match. The “.” selects the text value of the current node.
e.g.
<name
prefix=“Mr.”>Joo</name>
xsl:for-each
select:
xsl:for-each select=“expression”:
It processes each node selected by the XPath expression. It is applied only to the first match. The “.” selects the text value of the current node
e.g.
<class>
<student>kk</student>
<student>kkd</student>
</class>
xsl:if test:
xsl:if test=“expression”:
It evaluates the expression and if true applies the template.
<xsl:template
match=“class">
<!--
Select the first node in the set. -->
<xsl:if
select=“position() = first()">
<b><xsl:value-of
select=“."/></b>
</xsl:if>
</xsl:template>
xsl:choose
:
It selects any number of
alternatives. It is used instead of if-else, or switch statement used in other
programming languages.
<xsl:choose>
<xsl:when
test=“not(text())">
Missing
value!
</xsl:when>
<xsl:otherwise>
<xsl:value-of
select=“.”/>
</xsl:otherwise>
</xsl:choose>
