blob: 99aa35bcc4f3aa8cbea347f5b935e8954676e0d0 [file] [log] [blame]
<!DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html><head>
<title>Apache Felix - Extender Pattern Handler</title>
<link rel="stylesheet" href="extender-pattern-handler_files/site.css" type="text/css" media="all">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head><body>
<div class="title"><div class="logo"><a href="http://felix.apache.org/site/index.html"><img alt="Apache Felix" src="extender-pattern-handler_files/logo.png" border="0"></a></div><div class="header"><a href="http://www.apache.org/"><img alt="Apache" src="extender-pattern-handler_files/apache.png" border="0"></a></div></div>
<div class="menu">
<ul>
<li><a href="http://felix.apache.org/site/news.html" title="news">news</a></li>
<li><a href="http://felix.apache.org/site/license.html" title="license">license</a></li>
<li><a href="http://felix.apache.org/site/downloads.cgi" rel="nofollow">downloads</a></li>
<li><a href="http://felix.apache.org/site/documentation.html" title="documentation">documentation</a></li>
<li><a href="http://felix.apache.org/site/mailinglists.html" title="mailinglists">mailing lists</a></li>
<li><a href="http://felix.apache.org/site/contributing.html" title="Contributing">contributing</a></li>
<li><a href="http://www.apache.org/" rel="nofollow">asf</a></li>
<li><a href="http://www.apache.org/foundation/sponsorship.html" rel="nofollow">sponsorship</a></li>
<li><a href="http://www.apache.org/foundation/thanks.html" rel="nofollow">sponsors</a>
<!-- ApacheCon Ad -->
<iframe src="extender-pattern-handler_files/button.html" style="border-width: 0pt; float: left;" scrolling="no" frameborder="0" height="135" width="135"></iframe>
<p style="height: 100px;">
<!-- ApacheCon Ad -->
</p></li></ul> </div>
<div class="main">
<style type="text/css">
@import url(http://people.apache.org/~clement/ipojo/site/superfish.css);
</style>
<style type="text/css">
@import url(http://people.apache.org/~clement/ipojo/site/style.css);
</style>
<p>
<script class="javascript" src="extender-pattern-handler_files/shCore.js"></script>
<script class="javascript" src="extender-pattern-handler_files/shBrushCSharp.js"></script>
<script class="javascript" src="extender-pattern-handler_files/shBrushPhp.js"></script>
<script class="javascript" src="extender-pattern-handler_files/shBrushJScript.js"></script>
<script class="javascript" src="extender-pattern-handler_files/shBrushVb.js"></script>
<script class="javascript" src="extender-pattern-handler_files/shBrushSql.js"></script>
<script class="javascript" src="extender-pattern-handler_files/shBrushXml.js"></script>
<script class="javascript" src="extender-pattern-handler_files/shBrushShell.js"></script>
<script class="javascript" src="extender-pattern-handler_files/shBrushDelphi.js"></script>
<script class="javascript" src="extender-pattern-handler_files/shBrushPython.js"></script>
<script class="javascript" src="extender-pattern-handler_files/shBrushJava.js"></script>
<script type="text/javascript" src="extender-pattern-handler_files/jquery-1.js"></script>
<script type="text/javascript" src="extender-pattern-handler_files/hoverIntent.js"></script>
<script type="text/javascript" src="extender-pattern-handler_files/superfish.js"></script>
<script type="text/javascript" src="extender-pattern-handler_files/supersubs.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$("ul.sf-menu").supersubs({
minWidth: 14, // minimum width of sub-menus in em units
maxWidth: 30, // maximum width of sub-menus in em units
extraWidth: 1 // extra width can ensure lines don't sometimes turn over
// due to slight rounding differences and font-family
}).superfish(); // call supersubs first, then superfish, so that subs are
// not display:none when measuring. Call before initialising
// containing tabs for same reason.
});
</script>
</p><div class="main">
<div class="page-header">
<img src="extender-pattern-handler_files/header.png" class="header">
<a href="http://ipojo.org/"><img src="extender-pattern-handler_files/ipojo.png" class="header-logo" width="225"></a>
<ul class="sf-menu sf-js-enabled sf-shadow" id="ipojo-menu">
<li class="current">
<!-- Menu Overview -->
<a href="" class="sf-with-ul">Overview<span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span></a>
<ul style="float: none; width: 14em; display: none; visibility: hidden;">
<li style="white-space: normal; float: left; width: 100%;">
<a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo.html" title="Apache Felix iPOJO">Home</a>
</li>
<li style="white-space: normal; float: left; width: 100%;">
<a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo-why-choose-ipojo.html" title="apache-felix-ipojo-why-choose-ipojo">Why choose iPOJO</a>
</li>
<li style="white-space: normal; float: left; width: 100%;">
<a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo-successstories.html" title="apache-felix-ipojo-successstories">Success stories</a>
</li>
<li style="white-space: normal; float: left; width: 100%;">
<a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo-feature-overview.html" title="Apache Felix iPOJO Feature Overview">Features</a>
</li>
</ul>
</li>
<li class="">
<!-- Menu download -->
</li><li>
<a href="http://felix.apache.org/site/download.html" title="Download">Download </a>
</li>
<li class="">
<!-- Menu Documentation -->
<a href="" class="sf-with-ul">Documentation<span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span></a>
<ul style="float: none; width: 14em; display: none; visibility: hidden;">
<!-- sub- menu : getting started -->
<li style="white-space: normal; float: left; width: 100%;" class="">
<a style="float: none; width: auto;" href="" class="sf-with-ul">Getting Started<span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span></a>
<ul style="left: 14em; float: none; width: 14em; display: none; visibility: hidden;">
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/ipojo-in-10-minutes.html" title="iPOJO in 10 minutes">iPOJO in 10 minutes</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/how-to-use-ipojo-annotations.html" title="How to use iPOJO Annotations">Using Annotations</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/ipojo-hello-word-maven-based-tutorial.html" title="iPOJO Hello Word (Maven-Based) tutorial">Maven tutorial</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/ipojo-advanced-tutorial.html" title="iPOJO Advanced Tutorial">Advanced tutorial</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo-dosgi.html" title="apache-felix-ipojo-dosgi">Using Distributed OSGi</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/ipojo-composition-tutorial.html" title="iPOJO Composition Tutorial">Application Composition</a></li>
</ul>
</li> <!-- end of getting started -->
<!-- sub menu : Describing Components -->
<li style="white-space: normal; float: left; width: 100%;" class="">
<a style="float: none; width: auto;" href="http://felix.apache.org/site/describing-components.html" class="sf-with-ul">Describing components<span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span></a>
<ul style="left: 14em; float: none; width: 14em; display: none; visibility: hidden;">
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/service-requirement-handler.html" title="Service Requirement Handler">Requiring a service</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/providing-osgi-services.html" title="Providing OSGi services">Providing a service</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/lifecycle-callback-handler.html" title="Lifecycle Callback Handler">Lifecycle management</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/configuration-handler.html" title="Configuration Handler">Configuration</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/architecture-handler.html" title="Architecture Handler">Introspection</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/controller-lifecycle-handler.html" title="Controller Lifecycle Handler">Impacting the lifecycle</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/event-admin-handlers.html" title="Event Admin Handlers">Asynchronous communication</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/ipojo-jmx-handler.html" title="iPOJO JMX Handler">JMX management</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="" title="Extender Pattern Handler">Extender pattern</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/white-board-pattern-handler.html" title="White Board Pattern Handler">Whiteboard pattern</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/temporal-service-dependency.html" title="Temporal Service Dependency">Temporal dependencies</a></li>
</ul>
</li> <!-- End of describing components -->
<!-- sub- menu : User Guide -->
<li style="white-space: normal; float: left; width: 100%;" class="">
<a style="float: none; width: auto;" href="" class="sf-with-ul">User Guide<span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span></a>
<ul style="left: 14em; float: none; width: 14em; display: none; visibility: hidden;">
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/using-xml-schemas.html" title="Using XML Schemas">XML Schemas</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo-api.html" title="apache-felix-ipojo-api">API</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo-testing-components.html" title="apache-felix-ipojo-testing-components">Testing components</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo-eclipse-integration.html" title="apache-felix-ipojo-eclipse-integration">Eclipse Integration</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/ipojo-faq.html" title="iPOJO FAQ">FAQ</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/ipojo-reference-card.html" title="iPOJO-Reference-Card">Reference Card</a></li>
</ul>
</li> <!-- end of user guide -->
<!-- sub- menu : Dev Guide -->
<li class="" style="white-space: normal; float: left; width: 100%;">
<a style="float: none; width: auto;" href="" class="sf-with-ul">Advanced Topics<span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span></a>
<ul style="left: 14em; float: none; width: 14em; display: none; visibility: hidden;">
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/ipojo/api/1.2.0" rel="nofollow">Javadoc</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/how-to-write-your-own-handler.html" title="How to write your own handler">Handler development</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/how-to-use-ipojo-manipulation-metadata.html" title="How to use iPOJO Manipulation Metadata">Manipulation Metadata </a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/dive-into-the-ipojo-manipulation-depths.html" title="Dive into the iPOJO Manipulation depths">Dive into the iPOJO Manipulation depths</a></li>
</ul>
</li> <!-- End of Dev guide -->
</ul>
</li> <!-- End of doc -->
<!-- Menu 4 : Tools -->
<li class="">
<a href="" class="sf-with-ul">Tools<span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span></a>
<ul style="float: none; width: 14em; display: none; visibility: hidden;">
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/ipojo-ant-task.html" title="iPOJO Ant Task">Ant Task</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/ipojo-eclipse-plug-in.html" title="iPOJO Eclipse Plug-in">Eclipse Plugin</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/ipojo-maven-plug-in.html" title="iPOJO Maven Plug-in">Maven Plugin</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/ipojo-arch-command.html" title="iPOJO-Arch-Command"><tt>arch</tt> shell command</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo-online-manipulator.html" title="apache-felix-ipojo-online-manipulator">Online Manipulator</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/ipojo-webconsole-plugin.html" title="iPOJO Webconsole Plugin">Webconsole plugin</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo-junit4osgi.html" title="apache-felix-ipojo-junit4osgi">Junit4OSGi</a></li>
</ul>
</li><!-- End of tools -->
<!-- Menu 5 : Misc -->
<li class="">
<a href="" class="sf-with-ul">Misc<span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span><span class="sf-sub-indicator"> »</span></a>
<ul style="float: none; width: 14em; display: none; visibility: hidden;">
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo-issuestracker.html" title="apache-felix-ipojo-issuestracker">Issues Tracker</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo-supportedvms.html" title="apache-felix-ipojo-supportedVMs">Supported JVMs</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/apache-felix-ipojo-supportedosgi.html" title="apache-felix-ipojo-supportedOSGi">Supported OSGi Implementations</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://ipojo-dark-side.blogspot.com/" rel="nofollow">iPOJO's Dark Side Blog</a></li>
<li style="white-space: normal; float: left; width: 100%;"><a style="float: none; width: auto;" href="http://felix.apache.org/site/article-presentations.html" title="Article &amp; Presentations">Article &amp; Presentations</a></li>
</ul>
</li><!-- End of misc -->
</ul> <!-- End of the menu -->
</div> <!-- Page header -->
<div class="content">
<h1><a name="ExtenderPatternHandler-Theextenderpatternhandler"></a>The extender pattern handler</h1>
<p><em>The objective of this handler is to simplify the development of
extender-based architecture. This architecture-style is based on two
different roles:</em></p>
<ul>
<li><em>The extender</em></li>
<li><em>The extensions</em></li>
</ul>
<div class="toc">
<ul>
<li><a href="#ExtenderPatternHandler-TheExtenderpattern">The Extender pattern</a></li>
<li><a href="#ExtenderPatternHandler-Usingthehandler">Using the handler</a></li>
<li><a href="#ExtenderPatternHandler-Configuration">Configuration</a></li>
<li><a href="#ExtenderPatternHandler-Download">Download</a></li>
<li><a href="#ExtenderPatternHandler-Configuringthehandlerwithannotations">Configuring the handler with annotations</a></li>
<li><a href="#ExtenderPatternHandler-Amorerealisticexample">A more realistic example</a></li>
</ul></div>
<h2><a name="ExtenderPatternHandler-TheExtenderpattern"></a>The Extender pattern</h2>
<p>This architecture-style is based on two different roles:</p>
<ul>
<li>The extender</li>
<li>The extension</li>
</ul>
<p><img src="extender-pattern-handler_files/extender.png" border="0" align="absmiddle"></p>
<p>The relation is basically a 1..n relation. The extender tracks
extensions. The particularity of this architecture-style is that
extensions are packaged in different bundles. An extension is detected
by analyzing the bundle. Indeed these bundles can have a special mark
in their manifest of a special file...<br>
Implementing an extender pattern could be complex as the extender needs
to track these marks dynamically. When a bundle starts, it needs to
look at the mark. Then a bundle leave, the extender must release all
object created from this bundle.<br>
This handler tracks bundle for you based on the specified required
mark. At each time a matching bundle appears or disappears, a callback
is invoked. The mark is currently a header in the bundle manifest.<br>
Nowadays, a lot of frameworks use this pattern such as iPOJO it-self
(to find both bundles containing components and bundles adding a new
implementation type), Spring-DM ...</p>
<h2><a name="ExtenderPatternHandler-Usingthehandler"></a>Using the handler</h2>
<p>First of all, you need to configure the component type to use the handler such as:</p>
<div class="code">
<div class="dp-highlighter"><table class="dp-xml" border="0" cellpadding="0" cellspacing="0"><tbody><tr><td class="line1"><span></span><span class="tag">&lt;</span><span>iPOJO&nbsp;xmlns:</span><span class="attribute">extender</span><span>=</span><span class="attribute-value">"org.apache.felix.ipojo.extender"</span><span>&gt;&nbsp;</span></td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;<span class="tag">&lt;</span><span>component&nbsp;</span></td></tr><tr><td class="line1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="attribute">classname</span><span>=</span><span class="attribute-value">"org.apache.felix.ipojo.extender.myextender"</span><span>&gt;&nbsp;</span></td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td></tr><tr><td class="line1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="comments">&lt;!--&nbsp;Extender&nbsp;Pattern&nbsp;handler&nbsp;configuration&nbsp;--&gt;</span><span>&nbsp;</span></td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="tag">&lt;</span><span>extender:extender&nbsp;&nbsp;</span></td></tr><tr><td class="line1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="attribute">extension</span><span>=</span><span class="attribute-value">"My-Extension"</span><span>&nbsp;</span></td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="attribute">onArrival</span><span>=</span><span class="attribute-value">"onBundleArrival"</span><span>&nbsp;&nbsp;</span></td></tr><tr><td class="line1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="attribute">onDeparture</span><span>=</span><span class="attribute-value">"onBundleDeparture"</span><span>&nbsp;&nbsp;</span></td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="tag">/&gt;</span><span>&nbsp;</span></td></tr><tr><td class="line1">&nbsp;</td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="tag">&lt;</span><span>callback&nbsp;</span><span class="attribute">transition</span><span>=</span><span class="attribute-value">"invalidate"</span><span>&nbsp;</span><span class="attribute">method</span><span>=</span><span class="attribute-value">"stopping"</span><span>&nbsp;</span><span class="tag">/&gt;</span><span>&nbsp;</span></td></tr><tr><td class="line1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="tag">&lt;</span><span>callback&nbsp;</span><span class="attribute">transition</span><span>=</span><span class="attribute-value">"validate"</span><span>&nbsp;</span><span class="attribute">method</span><span>=</span><span class="attribute-value">"starting"</span><span>&nbsp;</span><span class="tag">/&gt;</span><span>&nbsp;</span></td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="tag">&lt;</span><span>provides&nbsp;</span><span class="tag">/&gt;</span><span>&nbsp;</span></td></tr><tr><td class="line1">&nbsp;&nbsp;&nbsp;&nbsp;<span class="tag">&lt;/</span><span>component</span><span class="tag">&gt;</span><span>&nbsp;</span></td></tr><tr><td class="line2"><span class="tag">&lt;/</span><span>iPOJO</span><span class="tag">&gt;</span><span>&nbsp;</span></td></tr></tbody></table></div><textarea style="display: none;" name="newcodemacro" class="xml:nocontrols:nogutter" rows="10" readonly="readonly">&lt;iPOJO xmlns:extender="org.apache.felix.ipojo.extender"&gt;
&lt;component
classname="org.apache.felix.ipojo.extender.myextender"&gt;
&lt;!-- Extender Pattern handler configuration --&gt;
&lt;extender:extender
extension="My-Extension"
onArrival="onBundleArrival"
onDeparture="onBundleDeparture"
/&gt;
&lt;callback transition="invalidate" method="stopping" /&gt;
&lt;callback transition="validate" method="starting" /&gt;
&lt;provides /&gt;
&lt;/component&gt;
&lt;/iPOJO&gt;</textarea>
<script class="javascript">
if(!window.newcodemacro_initialised)
{
window.newcodemacro_initialised = true;
window.oldonloadmethod = window.onload;
window.onload = function(){
dp.SyntaxHighlighter.HighlightAll('newcodemacro');
if(window.oldonloadmethod)
{
window.oldonloadmethod();
}
}
}
</script>
</div>
<p>Notice that, this handler is an external handler. So, it uses the "org.apache.felix.ipojo.extender" namespace.<br>
Once described, you can implement your component. The methods specified
methods will be called when a matching bundle arrives or leaves.<br>
In the previous example, these methods could be: </p>
<div class="code">
<div class="dp-highlighter"><table class="dp-c" border="0" cellpadding="0" cellspacing="0"><tbody><tr><td class="line1"><span></span><span class="keyword">void</span><span>&nbsp;onBundleArrival(Bundle&nbsp;bundle,&nbsp;String&nbsp;header)&nbsp;{&nbsp;</span></td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="comment">//&nbsp;Do&nbsp;something</span><span>&nbsp;</span></td></tr><tr><td class="line1">}&nbsp;</td></tr><tr><td class="line2">&nbsp;</td></tr><tr><td class="line1"><span class="keyword">void</span><span>&nbsp;onBundleDeparture(Bundle&nbsp;bundle)&nbsp;{&nbsp;</span></td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="comment">//&nbsp;Do&nbsp;something</span><span>&nbsp;</span></td></tr><tr><td class="line1">}&nbsp;</td></tr></tbody></table></div><textarea style="display: none;" name="newcodemacro" class="java:nocontrols:nogutter" rows="10" readonly="readonly">void onBundleArrival(Bundle bundle, String header) {
// Do something
}
void onBundleDeparture(Bundle bundle) {
// Do something
}</textarea>
<script class="javascript">
if(!window.newcodemacro_initialised)
{
window.newcodemacro_initialised = true;
window.oldonloadmethod = window.onload;
window.onload = function(){
dp.SyntaxHighlighter.HighlightAll('newcodemacro');
if(window.oldonloadmethod)
{
window.oldonloadmethod();
}
}
}
</script>
</div>
<p>Notice the different signatures of the methods. The arrival method
is called with the arriving bundle and the matching header value (i.e.
the value of the My-Extension header of the bundle manifest). The
departure method just receives the leaving bundle.</p>
<h2><a name="ExtenderPatternHandler-Configuration"></a>Configuration</h2>
<p>The handler has only three mandatory attributes:</p>
<ul>
<li>Extension: declaring the looked manifest header.</li>
<li>onArrival: declaring the method to invoke when a matching bundle arrives</li>
<li>onDeparture: declaring the method to invoke when a matching bundle leaves</li>
</ul>
<div class="box">
<div class="box-yellow-header">
<div class="box-yellow-title">
<img src="extender-pattern-handler_files/warning.gif"> <b>Called despite being invalid</b>
</div>
</div>
<div class="box-yellow-content">
The implementation will be notified of arrivals and departures despite
the instance is invalid. Indeed, the implementation must release all
objects created from another bundle as soon it leaves. </div>
<div class="box-yellow-footer"></div>
</div>
<h2><a name="ExtenderPatternHandler-Download"></a>Download</h2>
<p>The handler is available on the <a href="http://felix.apache.org/site/download.html" title="Download">download</a> page.<br>
Sources are available on the Felix trunk at the following location: <a href="http://svn.apache.org/repos/asf/felix/trunk/ipojo/handler/extender/" rel="nofollow">http://svn.apache.org/repos/asf/felix/trunk/ipojo/handler/extender/</a></p>
<h2><a name="ExtenderPatternHandler-Configuringthehandlerwithannotations"></a>Configuring the handler with annotations</h2>
<p>It is possible to configure the handler with a simple annotation
available in the annotation pack ('annotation' project in the iPOJO
trunk). Here is an example of usage:</p>
<div class="code">
<div class="dp-highlighter"><table class="dp-c" border="0" cellpadding="0" cellspacing="0"><tbody><tr><td class="line1"><span></span><span class="keyword">import</span><span>&nbsp;org.apache.felix.ipojo.annotations.Component;&nbsp;</span></td></tr><tr><td class="line2"><span class="keyword">import</span><span>&nbsp;org.osgi.framework.Bundle;&nbsp;</span></td></tr><tr><td class="line1"><span class="preprocessor"></span></td></tr><tr><td class="line2"><span class="preprocessor">@Component</span><span>&nbsp;</span></td></tr><tr><td class="line1"><span class="preprocessor">@org.apache.felix.ipojo.extender.Extender(extension="foo",&nbsp;onArrival="onArrival",&nbsp;onDeparture="onDeparture")</span><span>&nbsp;</span></td></tr><tr><td class="line2"><span class="keyword">public</span><span>&nbsp;</span><span class="keyword">class</span><span>&nbsp;Extender&nbsp;{&nbsp;</span></td></tr><tr><td class="line1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;<span class="keyword">public</span><span>&nbsp;</span><span class="keyword">void</span><span>&nbsp;onArrival(Bundle&nbsp;bundle,&nbsp;String&nbsp;foo)&nbsp;{&nbsp;</span></td></tr><tr><td class="line1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="comment">//&nbsp;do&nbsp;something</span><span>&nbsp;</span></td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;}&nbsp;</td></tr><tr><td class="line1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;<span class="keyword">public</span><span>&nbsp;</span><span class="keyword">void</span><span>&nbsp;onDeparture(Bundle&nbsp;bundle)&nbsp;{&nbsp;</span></td></tr><tr><td class="line1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="comment">//&nbsp;do&nbsp;something</span><span>&nbsp;</span></td></tr><tr><td class="line2">&nbsp;&nbsp;&nbsp;&nbsp;}&nbsp;</td></tr><tr><td class="line1">}&nbsp;</td></tr></tbody></table></div><textarea style="display: none;" name="newcodemacro" class="java:nocontrols:nogutter" rows="10" readonly="readonly">import org.apache.felix.ipojo.annotations.Component;
import org.osgi.framework.Bundle;
@Component
@org.apache.felix.ipojo.extender.Extender(extension="foo", onArrival="onArrival", onDeparture="onDeparture")
public class Extender {
public void onArrival(Bundle bundle, String foo) {
// do something
}
public void onDeparture(Bundle bundle) {
// do something
}
}</textarea>
<script class="javascript">
if(!window.newcodemacro_initialised)
{
window.newcodemacro_initialised = true;
window.oldonloadmethod = window.onload;
window.onload = function(){
dp.SyntaxHighlighter.HighlightAll('newcodemacro');
if(window.oldonloadmethod)
{
window.oldonloadmethod();
}
}
}
</script>
</div>
<p>The <tt>extension</tt> attribute allows setting the bundle filter.</p>
<h2><a name="ExtenderPatternHandler-Amorerealisticexample"></a>A more realistic example</h2>
<p>The Junit4OSGi framework, available <a href="https://svn.apache.org/repos/asf/felix/trunk/ipojo/examples/junit4osgi" rel="nofollow">here</a>
, uses this handler to track Junit Test Suite offered by the installed
bundles. The Junit4Osgi bundle has a component using this handler to be
notified when a bundle with the <tt>Test-Suite</tt> header appears or leaves.
<br clear="all">
<br clear="all"></p>
</div>
<img src="extender-pattern-handler_files/footer.png" class="footer">
</div>
<script type="text/javascript">
var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");
document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
</script><script src="extender-pattern-handler_files/ga.js" type="text/javascript"></script>
<script type="text/javascript">
try{
var pageTracker = _gat._getTracker("UA-1518442-4");
pageTracker._trackPageview();
} catch(err) {}
</script>
</div>
</body></html>