Transformation of XML Documents

Transformation of XML Documents


Extensible Stylesheet Language (XSL)
Extensible Stylesheet Language Transformations (XSLT)
XML
XML
Document
(X)HTML
XSL
Stylesheet
Text
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
2/21

XML Cooktop
 http://www.xmlcooktop.com/
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
3/21
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
4/21
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
5/21

Default template for elements and root:
<xsl:template match = "*|/">
<xsl:apply-templates/>
</xsl:template>

Default template for text nodes and attributes:
<xsl:template match="text()|@*">
<xsl:value-of select="."/>
</xsl:template>
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
6/21

Default template for comments and processing
instructions:
<xsl:template match="comment()|processing-instruction()">
</xsl:template>

default behaviour for namespace nodes
do not output namespace nodes
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
7/21
<xsl:template match="/DB">
<xsl:apply-templates select="order"/>
</xsl:template>
/
DB
<xsl:template match="order">
<xsl:value-of select="@ID"/>
<xsl:apply-templates select="*"/>
</xsl:template>
order
customer
PC
order
customer
PC
<xsl:template match="customer|PC">
<xsl:value-of select="."/>
Node list: <PC>
<order,
<root>
<customer,
<order>
<customer,
<PC>
order>
PC>
PC>
</xsl:template>
<xsl:template match="/ | ∗">
<xsl:apply-templates/>
</xsl:template>
DBIS 1 - 2007
Output: 23
Meier
Pc500
24
Reich
pc600
Stefan Böttcher and Sebastian Obermeier
8/21

When does a template match?
 Let v be the actual context node.
Let P be an XPath expression within the match attribute
of the tag <xsl:templates>

P matches ,
it exists an ancestor node v’
(v=v’ ok), so that v is
the result of evaluating P
with the actual node v’.
DBIS 1 - 2007
v’
P
Stefan Böttcher and Sebastian Obermeier
v = actual node
9/21
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
10/21
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
11/21
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
12/21
<html>
<body>
<table width="100%" border="1">
<tr>
<td>customer: </td><td>PC : </td>
</tr>
<tr>
<td>Meier</td><td>pc500</td>
</tr>
<tr>
<td>Reich</td><td>pc600</td>
</tr>
</table>
</body>
</html>
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
13/21
first Template
<html>
<body>
<table width="100%" border="1">
<tr>
<td>customer: </td><td> PC : </td>
</tr>
start here for every customer node
repeat
<tr>
<td>Name of customer</td><td>PC</td>
</tr>
until here for every customer node
separate
template
</table>
</body>
</html>
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
14/21
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
15/21
Application in XSL:
XPath location expression
<xsl:template match="Auftrag">
<xsl:value-of select="PC">
<xsl:if test='position() &gt; 1'>...</xsl:if>
</xsl:template>
XPath Boolean expression
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
16/21

location expression in XSL: „output attribute size“


XPath Boolean expressions „if attribute type has the value CHAR ,
output ... “


<xsl:value-of select="@size"/>
<xsl:if test="@type='CHAR'„>
(<xsl:value-of select="@size"/>)
</xsl:if>
„if current is not first within parent (position >1):“

<xsl:if test='position() &gt; 1'>
not the first
</xsl:if>
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
17/21

current() returns a node-set that
contains only the current node.

Usually the current node and the
context node (.) are the same.

But…
Current node
Context node
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
18/21
<xsl:template match="/">
create table order( customer char(10) , PC char(10) ) ;
<xsl:apply-templates/>
</xsl:template>
<xsl:template match=„order">
insert into order values( <xsl:value-of select=„customer"/> ,
<xsl:value-of select="PC"/> ) ;
</xsl:template>
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
19/21

Generate HTML on a web server:
 transform: data.xml + layout.xsl -> x.html

XML is transformable by different XSL files to
generate appropriate output for different
destination formats, e.g. html , pdf , txt, …
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
20/21


Database  XML  PDF or HTML or TXT or XML or…
Database  XML  SQL  Database
Original database
Other database
DBIS 1 - 2007
Stefan Böttcher and Sebastian Obermeier
21/21