non-releases/trunk_before_flattening/src/documentation/src/content/xdocs/c21-selectors/content_en.html - cocoon - Git at Google

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 <META http-equiv="Content-Type" content="text/html; charset=UTF-8">
 <title>Selectors</title>
 <link href="http://purl.org/DC/elements/1.0/" rel="schema.DC">
 <meta content="Carsten Ziegeler" name="DC.Creator">
 <meta content="Gianugo Rabellino" name="DC.Creator">
 <meta content="Diana Shannon, ed." name="DC.Creator">
 <meta content="This document describes all of the available selectors of Cocoon." name="DC.Description">
 </head>
 <body>

 <h1>Goal</h1>

 <p>
       This document lists all of the available selectors of Apache Cocoon and
       describes their purpose.
       You may also wish to read
       <a href="../concepts/matchers_selectors.html">Using and Implementing
       Matchers and Selectors</a>.
       </p>


 <h1>Overview</h1>

 <p>
       Selectors in Apache Cocoon have a role similar to matchers
       with additional flexibility. If you haven't learned about
       matchers yet, read about them <a href="../matchers/matchers.html">here</a>
       before continuing. Selectors are designed to evaluate a
       generally simple boolean expression regarding some
       part of the environment (request URI, headers, or cookies, for example).
       The result of this evaluation determines which pipeline fragments
       should be combined within a given pipeline. Unlike matchers,
       selectors can be active decision-driving components.
       For example, a matcher makes only simple
       "yes/no" decisions. If a match is successful, a
       pipeline is executed. If not, it is ignored.
       Selectors go further by allowing more complex, multiple-choice
       use cases. In short, consider matchers to be simple "if"
       statements. By extension, consider selectors to have all
       the power of an "if-else if-else" or "switch-case" constructs.
       The selector syntax should be familiar to anyone who
       uses XSLT's <span class="codefrag">&lt;xsl:choose&gt;</span> statement.
       </p>

 <p>
       As an example, consider the typical scenario in which a page should
       be rendered differently based on the client browser.
       Given the large number and diversity of available browsers,
       it would be awkward and counterintuitive to address this need
       with a set of matchers. The BrowserSelector tests a given parameter
       against the user-agent request header. Using this single selector,
       we can deploy a consistent and readable setup.
       </p>

 <pre class="code">

 &lt;map:match pattern="docs/*.html"&gt;
   &lt;map:generate src="xdocs/{1}.xml"/&gt;

   &lt;map:select type="browser"&gt;
     &lt;map:when test="netscape"&gt;
       &lt;map:transform src="stylesheets/netscape.xsl" /&gt;
     &lt;/map:when&gt;
     &lt;map:when test="explorer"&gt;
       &lt;map:transform src="stylesheets/ie.xsl" /&gt;
     &lt;/map:when&gt;
     &lt;map:when test="lynx"&gt;
       &lt;map:transform src="stylesheets/text-based.xsl" /&gt;
     &lt;/map:when&gt;
     &lt;map:otherwise&gt;
       &lt;map:transform src="stylesheets/html.xsl" /&gt;
     &lt;/map:otherwise&gt;
   &lt;/map:select&gt;

   &lt;map:serialize/&gt;
 &lt;/map:match&gt;

 </pre>


 <h1>The Selectors in Cocoon</h1>

 <p>
       Available Selectors in Cocoon include the following:
       </p>

 <ul>

 <li>
 <strong>BrowserSelector</strong>: matches the value of the "test"
         parameter against the HTTP User-Agent header, allowing it to
         recognize the browser issuing the request;</li>


 <li>
 <strong>CodeSelector</strong>: matches a snippet of Java code
         given as the "test" parameter against the environment;</li>


 <li>
 <strong>HostSelector</strong>: matches the "test" parameter value
         against the Host request header</li>


 <li>
 <a href="parameter-selector.html">ParameterSelector</a>: matches the string specified
         in the "test" parameter against a specified Cocoon internal
         (e.g. sitemap) parameter;</li>


 <li>
 <strong>HeaderSelector</strong>: same as the Parameter selector,
         but matches against the request headers;</li>


 <li>
 <a href="regular-expression-header-selector.html">RegexpHeaderSelector</a>: same as the Header selector,
         but uses a regular expression for matching;</li>


 <li>
 <strong>RequestSelector</strong>: again, same as the Parameter selector,
         but matches against the Request parameters;</li>


 <li>
 <strong>SessionSelector</strong>: finally, this selector is used as
         the Parameter selector to match against an arbitrary session
         attribute;</li>


 </ul>


 </body>
 </html>
	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
	<html>
	<head>
	<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
	<title>Selectors</title>
	<link href="http://purl.org/DC/elements/1.0/" rel="schema.DC">
	<meta content="Carsten Ziegeler" name="DC.Creator">
	<meta content="Gianugo Rabellino" name="DC.Creator">
	<meta content="Diana Shannon, ed." name="DC.Creator">
	<meta content="This document describes all of the available selectors of Cocoon." name="DC.Description">
	</head>
	<body>

	<h1>Goal</h1>

	<p>
	This document lists all of the available selectors of Apache Cocoon and
	describes their purpose.
	You may also wish to read
	<a href="../concepts/matchers_selectors.html">Using and Implementing
	Matchers and Selectors</a>.
	</p>


	<h1>Overview</h1>

	<p>
	Selectors in Apache Cocoon have a role similar to matchers
	with additional flexibility. If you haven't learned about
	matchers yet, read about them <a href="../matchers/matchers.html">here</a>
	before continuing. Selectors are designed to evaluate a
	generally simple boolean expression regarding some
	part of the environment (request URI, headers, or cookies, for example).
	The result of this evaluation determines which pipeline fragments
	should be combined within a given pipeline. Unlike matchers,
	selectors can be active decision-driving components.
	For example, a matcher makes only simple
	"yes/no" decisions. If a match is successful, a
	pipeline is executed. If not, it is ignored.
	Selectors go further by allowing more complex, multiple-choice
	use cases. In short, consider matchers to be simple "if"
	statements. By extension, consider selectors to have all
	the power of an "if-else if-else" or "switch-case" constructs.
	The selector syntax should be familiar to anyone who
	uses XSLT's <span class="codefrag"><xsl:choose></span> statement.
	</p>

	<p>
	As an example, consider the typical scenario in which a page should
	be rendered differently based on the client browser.
	Given the large number and diversity of available browsers,
	it would be awkward and counterintuitive to address this need
	with a set of matchers. The BrowserSelector tests a given parameter
	against the user-agent request header. Using this single selector,
	we can deploy a consistent and readable setup.
	</p>

	<pre class="code">

	<map:match pattern="docs/*.html">
	<map:generate src="xdocs/{1}.xml"/>

	<map:select type="browser">
	<map:when test="netscape">
	<map:transform src="stylesheets/netscape.xsl" />
	</map:when>
	<map:when test="explorer">
	<map:transform src="stylesheets/ie.xsl" />
	</map:when>
	<map:when test="lynx">
	<map:transform src="stylesheets/text-based.xsl" />
	</map:when>
	<map:otherwise>
	<map:transform src="stylesheets/html.xsl" />
	</map:otherwise>
	</map:select>

	<map:serialize/>
	</map:match>

	</pre>



	<h1>The Selectors in Cocoon</h1>

	<p>
	Available Selectors in Cocoon include the following:
	</p>

	<ul>

	<li>
	<strong>BrowserSelector</strong>: matches the value of the "test"
	parameter against the HTTP User-Agent header, allowing it to
	recognize the browser issuing the request;</li>


	<li>
	<strong>CodeSelector</strong>: matches a snippet of Java code
	given as the "test" parameter against the environment;</li>


	<li>
	<strong>HostSelector</strong>: matches the "test" parameter value
	against the Host request header</li>


	<li>
	<a href="parameter-selector.html">ParameterSelector</a>: matches the string specified
	in the "test" parameter against a specified Cocoon internal
	(e.g. sitemap) parameter;</li>


	<li>
	<strong>HeaderSelector</strong>: same as the Parameter selector,
	but matches against the request headers;</li>


	<li>
	<a href="regular-expression-header-selector.html">RegexpHeaderSelector</a>: same as the Header selector,
	but uses a regular expression for matching;</li>


	<li>
	<strong>RequestSelector</strong>: again, same as the Parameter selector,
	but matches against the Request parameters;</li>


	<li>
	<strong>SessionSelector</strong>: finally, this selector is used as
	the Parameter selector to match against an arbitrary session
	attribute;</li>


	</ul>


	</body>
	</html>