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Karl Pauls	6721c02	2008-12-20 17:15:21 +0000	[diff] [blame]	10	<div class="title"><div class="logo"><a href="http://felix.apache.org/site/index.html"><img alt="Apache Felix" src="apache-felix-framework-launching-and-embedding_files/logo.png" border="0"></a></div><div class="header"><a href="http://www.apache.org/"><img alt="Apache" src="apache-felix-framework-launching-and-embedding_files/apache.png" border="0"></a></div></div>
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Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	15	<li><a href="http://felix.apache.org/site/downloads.cgi" class="external-link" rel="nofollow">downloads</a></li>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	16	<li><a href="http://felix.apache.org/site/documentation.html" title="documentation">documentation</a></li>
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Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	28	<div class="main">
				29	<h1><a name="ApacheFelixFrameworkLaunchingandEmbedding-ApacheFelixFrameworkLaunchingandEmbedding"></a>Apache Felix Framework Launching and Embedding</h1>
				30
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	31	<p><em>[This document describes framework launching introduced in Felix
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	32	Framework 2.0.0 and continuing with the latest releases; it is
				33	incompatible with older versions of the Felix framework.]</em></p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	34
				35	<ul>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	36	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-introduction">Introduction</a></li>
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	37	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-overview">OSGi Launching and Embedding API Overview</a>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	38	<ul>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	39	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-creatingandconfiguring">Creating and Configuring the Framework Instance</a></li>
				40	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-startinginstance">Starting the Framework Instance</a></li>
				41	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-stoppinginstance">Stopping the Framework Instance</a></li>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	42	</ul>
				43	</li>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	44	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-launching">Launching Felix</a>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	45	<ul>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	46	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-standardlauncher">Standard Felix Launcher</a></li>
				47	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-customlauncher">Custom Felix Launcher</a></li>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	48	</ul>
				49	</li>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	50	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-embedding">Embedding Felix</a>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	51	<ul>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	52	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-hostinteraction">Host/Felix Interaction</a></li>
				53	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-hostservices">Providing Host Application Services</a></li>
				54	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-hostserviceusage">Using Services Provided by Bundles</a>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	55	<ul>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	56	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-servicereflection">Using Bundle Services via Reflection</a></li>
				57	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-serviceother">Other Approaches</a></li>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	58	</ul>
				59	</li>
				60	</ul>
				61	</li>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	62	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-caveat">Caveat</a></li>
				63	<li><a href="#ApacheFelixFrameworkLaunchingandEmbedding-feedback">Feedback</a></li>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	64	</ul>
				65
				66
				67	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-introduction"></a></p>
				68
				69	<h1><a name="ApacheFelixFrameworkLaunchingandEmbedding-Introduction"></a>Introduction</h1>
				70
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	71	<p>The Apache Felix Framework is intended to be easily launchable and
				72	embeddable. For example, the Felix framework implementation avoids the
				73	use of system properties for configuration, since these are globals and
				74	can cause interference if multiple framework instances are created in
				75	the same VM. The framework also tries to multiplex singleton
				76	facilities, like the URL stream handler factory. The goal is to make it
				77	possible to use the framework in a variety of scenarios; however, this
				78	is still just a goal. In other words, this is a work in progress and if
				79	any issues arise, it would be greatly appreciated if they are brought
				80	to the attention of the Felix community. The next section provides an
				81	overview of the standard OSGi launching and embedding API for
				82	frameworks, while the remainder of the document is divided into two
				83	sections, one focusing on how to launch Felix and one focusing on how
				84	to embed Felix into a host application.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	85
				86	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-overview"></a></p>
				87
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	88	<h1><a name="ApacheFelixFrameworkLaunchingandEmbedding-OSGiLaunchingandEmbeddingAPIOverview"></a>OSGi Launching and Embedding API Overview</h1>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	89
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	90	<p>The Felix framework is implemented by the <tt>org.apache.felix.framework.Felix</tt> class or just <tt>Felix</tt>
				91	for short. As part of the R4.2 OSGi specification, the launching and
				92	embedding API of the OSGi framework has been standardized. The approach
				93	is to have the framework implement the <tt>org.osgi.framework.launch.Framework</tt> interface, which extends the <tt>org.osgi.framework.Bundle</tt> interface. These interfaces provide the necessary means to launch and manage framework instances. The <tt>Bundle</tt> interface is defined as:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	94
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	95	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	96	<pre class="code-java"><span class="code-keyword">public</span> <span class="code-keyword">interface</span> Bundle
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	97	{
				98	BundleContext getBundleContext();
				99	<span class="code-object">long</span> getBundleId();
				100	URL getEntry(<span class="code-object">String</span> name);
				101	Enumeration getEntryPaths(<span class="code-object">String</span> path);
				102	Enumeration findEntries(<span class="code-object">String</span> path, <span class="code-object">String</span> filePattern, <span class="code-object">boolean</span> recurse);
				103	Dictionary getHeaders();
				104	Dictionary getHeaders(<span class="code-object">String</span> locale);
				105	<span class="code-object">long</span> getLastModified();
				106	<span class="code-object">String</span> getLocation();
				107	URL getResource(<span class="code-object">String</span> name);
				108	Enumeration getResources(<span class="code-object">String</span> name) <span class="code-keyword">throws</span> IOException;
				109	ServiceReference[] getRegisteredServices();
				110	ServiceReference[] getServicesInUse();
				111	<span class="code-object">int</span> getState();
				112	<span class="code-object">String</span> getSymbolicName();
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	113	Version getVersion();
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	114	<span class="code-object">boolean</span> hasPermission(<span class="code-object">Object</span> obj);
				115	<span class="code-object">Class</span> loadClass(<span class="code-object">String</span> name) <span class="code-keyword">throws</span> ClassNotFoundException;
				116	void start() <span class="code-keyword">throws</span> BundleException;
				117	void stop() <span class="code-keyword">throws</span> BundleException;
				118	void uninstall() <span class="code-keyword">throws</span> BundleException;
				119	void update() <span class="code-keyword">throws</span> BundleException;
				120	void update(InputStream is) <span class="code-keyword">throws</span> BundleException;
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	121	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	122	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	123	</div></div>
				124
				125	<p>The <tt>Framework</tt> interface is defined as:</p>
				126
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	127	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	128	<pre class="code-java"><span class="code-keyword">public</span> <span class="code-keyword">interface</span> Framework <span class="code-keyword">extends</span> Bundle
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	129	{
				130	void init();
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	131	FrameworkEvent waitForStop(<span class="code-object">long</span> timeout);
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	132	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	133	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	134	</div></div>
				135
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	136	<p>To actually construct a framework instance, the R4.2 specification defines the <tt>FrameworkFactory</tt> interface:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	137
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	138	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	139	<pre class="code-java"><span class="code-keyword">public</span> <span class="code-keyword">interface</span> FrameworkFactory
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	140	{
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	141	Framework newFramework(Map config);
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	142	}
				143	</pre>
				144	</div></div>
				145
				146	<p>The framework factory can be used to create configured framework instances. It is obtained following the standard <tt>META-INF/services</tt> approach.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	147
				148	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-creatingandconfiguring"></a></p>
				149
				150	<h2><a name="ApacheFelixFrameworkLaunchingandEmbedding-CreatingandConfiguringtheFrameworkInstance"></a>Creating and Configuring the Framework Instance</h2>
				151
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	152	<p>You use the framework factory to construct and configure a framework
				153	instance (or by directly instantiating the Felix class). The
				154	configuration map may contain the following OSGi standard properties:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	155
				156	<ul>
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	157	<li><tt>org.osgi.framework.system.packages</tt> - specifies a
				158	list of packages the system bundle should export from the environment;
				159	if this is not set, then the framework uses a reasonable default fault.</li>
				160	<li><tt>org.osgi.framework.system.packages.extra</tt>
				161	- specifies a list of additional packages the system bundle should
				162	export from the environment that are appended to the packages specified
				163	in <tt>org.osgi.framework.system.packages</tt>; there is no default value for this property.</li>
				164	<li><tt>org.osgi.framework.bootdelegation</tt>
				165	- specifies a list of packages that should be made implicitly available
				166	to all bundles from the environment (i.e., no need to import them);
				167	there is no default value for this property and its use should be
				168	avoided.</li>
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	169	<li><tt>org.osgi.framework.bundle.parent</tt> - Specifies which class loader is used for boot delegation. Possible values are: <tt>boot</tt> for the boot class loader, <tt>app</tt> for the application class loader, <tt>ext</tt> for the extension class loader, and <tt>framework</tt> for the framework's class loader. The default is <tt>boot</tt>.</li>
				170	<li><tt>org.osgi.framework.storage</tt>
				171	- specifies the path to a directory, which will be created if it does
				172	not exist, to use for bundle cache storage; the default value for this
				173	property is "<tt>felix-cache</tt>" in the current working directory.</li>
				174	<li><tt>org.osgi.framework.storage.clean</tt> - specifies whether the bundle cache should be flushed; the default value for this property is "<tt>none</tt>", but it can be changed to "<tt>onFirstInit</tt>" to flush the bundle cache when the framework is initialized.</li>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	175	<li><tt>org.osgi.framework.startlevel.beginning</tt> - specifies the start level the framework enters upon startup; the default value for this property is 1.</li>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	176	</ul>
				177
				178
				179	<p>Felix also has the following, non-standard configuration properties:</p>
				180
				181	<ul>
				182	<li><tt>felix.cache.rootdir</tt> - specifies which directory should be used to calculate absolute paths when relative paths are used for the <tt>org.osgi.framework.storage</tt> property; the default value for this property is the current working directory.</li>
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	183	<li><tt>felix.systembundle.activators</tt> - specifies a <tt>List</tt> of <tt>BundleActivator</tt>
				184	instances that are started/stopped when the System Bundle is
				185	started/stopped; the specified instances will receive the System
				186	Bundle's <tt>BundleContext</tt> when invoked.</li>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	187	<li><tt>felix.log.logger</tt> - specifies an instance of <tt>org.apache.felix.framework.util.Logger</tt> that the framework uses as its default logger.</li>
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	188	<li><tt>felix.log.level</tt> - specifies an integer <tt>String</tt>
				189	whose value indicates the degree of logging reported by the framework;
				190	the default value is "1" and "0" turns off logging completely,
				191	otherwise log levels match those specified in the OSGi Log Service
				192	(i.e., 1 = error, 2 = warning, 3 = information, and 4 = debug).</li>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	193	<li><tt>felix.startlevel.bundle</tt> - specifies the start level for newly installed bundles; the default value is 1.</li>
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	194	<li><tt>felix.bootdelegation.implicit</tt>
				195	- specifies whether or not the framework should try to guess when to
				196	boot delegate when external code tries to load classes or resources;
				197	the default value is "<tt>true</tt>".</li>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	198	<li><tt>framework.service.urlhandlers</tt> - specifies whether or not to activate the URL Handlers service for the framework instance; the default value is "<tt>true</tt>", which results in the <tt>URL.setURLStreamHandlerFactory()</tt> and <tt>URLConnection.setContentHandlerFactory()</tt> being called.</li>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	199	</ul>
				200
				201
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	202	<p>The configuration map is copied and the keys are treated as case
				203	insensitive. You are not able to change the framework's configuration
				204	after construction. If you need a different configuration, you must
				205	create a new framework instance.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	206
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	207	<div class="panelMacro"><table class="warningMacro"><colgroup><col width="24"><col></colgroup><tbody><tr><td valign="top"><img src="apache-felix-framework-launching-and-embedding_files/forbidden.gif" alt="" align="absmiddle" border="0" height="16" width="16"></td><td><b>WARNING</b><br>Felix configuration properties have change considerably starting from <tt>1.4.0</tt>; if you are upgrading from an earlier version, the <a href="http://felix.apache.org/site/apache-felix-framework-usage-documentation.html#ApacheFelixFrameworkUsageDocumentation-migrating">usage document</a> describes the configuration property changes.</td></tr></tbody></table></div>
Karl Pauls	6721c02	2008-12-20 17:15:21 +0000	[diff] [blame]	208
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	209	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-startinginstance"></a></p>
				210
				211	<h2><a name="ApacheFelixFrameworkLaunchingandEmbedding-StartingtheFrameworkInstance"></a>Starting the Framework Instance</h2>
				212
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	213	<p>The <tt>start()</tt> method is used to start the framework instance. If the <tt>init()</tt> method was not invoked prior to calling <tt>start()</tt>, then it is invoked by <tt>start()</tt>. The two methods result in two different framework state transitions:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	214
				215	<ul>
				216	<li><tt>init()</tt> results in the framework instance in the <tt>Bundle.STARTING</tt> state.</li>
				217	<li><tt>start()</tt> results in the framework instance in the <tt>Bundle.ACTIVE</tt> state.</li>
				218	</ul>
				219
				220
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	221	<p>The <tt>init()</tt> method is necessary since the framework does not have a <tt>BundleContext</tt> when it is first created, so a transition to the <tt>Bundle.STARTING</tt> state is required to acquire its context (via <tt>Bundle.getBundleContext()</tt>) for performing various tasks, such as installing bundles. Note that the Felix framework also provides the <tt>felix.systembundle.activators</tt> property that serves a similar purpose, but is not standard. After the <tt>init()</tt> method completes, the follow actions have been performed:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	222
				223	<ul>
				224	<li>Event handling is enabled.</li>
				225	<li>The security manager is installed if it is enabled.</li>
				226	<li>The framework is set to start level 0.</li>
				227	<li>All bundles in the bundle caches are reified and their state is set to <tt>Bundle.INSTALLED</tt>.</li>
				228	<li>The framework gets a valid <tt>BundleContext</tt>.</li>
				229	<li>All framework-provided services are made available (e.g., PackageAdmin, StartLevel, etc.).</li>
				230	<li>The framework enters the <tt>Bundle.STARTING</tt> state.</li>
				231	</ul>
				232
				233
				234	<p>A call to <tt>start()</tt> is necessary to start the framework instance, if the <tt>init()</tt> method is invoked manually. Invoking <tt>init()</tt> or <tt>start()</tt> on an already started framework as no effect.</p>
				235
				236	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-stoppinginstance"></a></p>
				237
				238	<h2><a name="ApacheFelixFrameworkLaunchingandEmbedding-StoppingtheFrameworkInstance"></a>Stopping the Framework Instance</h2>
				239
				240	<p>To stop the framework instance, invoke the <tt>stop()</tt> method, which will asynchronously stop the framework. To know when the framework has finished its shutdown sequence, use the <tt>waitForStop()</tt> method to wait until it is complete. A stopped framework will be in the <tt>Bundle.RESOLVED</tt> state. It is possible to restart the framework, using the normal combination of <tt>init()</tt>/<tt>start()</tt> methods as previously described.</p>
				241
				242	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-launching"></a></p>
				243
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	244	<h1><a name="ApacheFelixFrameworkLaunchingandEmbedding-LaunchingaFramework"></a>Launching a Framework</h1>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	245
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	246	<p>Launching a framework is fairly simple and involves only four steps:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	247
				248	<ol>
				249	<li>Define some configuration properties.</li>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	250	<li>Obtain framework factory.</li>
				251	<li>Use factory to create framework with the configuration properties.</li>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	252	<li>Invoke the <tt>Framework.start()</tt> method.</li>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	253	</ol>
				254
				255
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	256	<p>In reality, the first step is optional, since all properties will
				257	have reasonable defaults, but if you are creating a launcher you will
				258	generally want to more than that, such as automatically installing and
				259	starting bundles when you start the framework instance. The default
				260	Felix launcher defines reusable functionality to automatically install
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	261	and/or start bundles upon framework startup; see the <a href="http://felix.apache.org/site/apache-felix-framework-usage-documentation.html#ApacheFelixFrameworkUsageDocumentation-configuringfelix">usage document</a> for more information on configuring the Felix framework and on the various configuration properties.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	262
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	263	<p>The remainder of this section describes how the standard Felix launcher works as well as how to create a custom launcher.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	264
				265	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-standardlauncher"></a></p>
				266
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	267	<h2><a name="ApacheFelixFrameworkLaunchingandEmbedding-StandardFelixFrameworkLauncher"></a>Standard Felix Framework Launcher</h2>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	268
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	269	<p>The standard Felix framework launcher is very simple and is not
				270	intended to solve every possible requirement; it is intended to work
				271	for most standard situations. Most special launching requirements
				272	should be resolved by creating a custom launcher. This section
				273	describes how the standard launcher works. The following code
				274	represents the complete <tt>main()</tt> method of the standard launcher, each numbered comment will be described in more detail below:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	275
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	276	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	277	<pre class="code-java"><span class="code-keyword">public</span> <span class="code-keyword">static</span> void main(<span class="code-object">String</span>[] args) <span class="code-keyword">throws</span> Exception
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	278	{
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	279	<span class="code-comment">// (1) Check <span class="code-keyword">for</span> command line arguments and verify usage.
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	280	</span> <span class="code-object">String</span> bundleDir = <span class="code-keyword">null</span>;
				281	<span class="code-object">String</span> cacheDir = <span class="code-keyword">null</span>;
				282	<span class="code-object">boolean</span> expectBundleDir = <span class="code-keyword">false</span>;
				283	<span class="code-keyword">for</span> (<span class="code-object">int</span> i = 0; i < args.length; i++)
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	284	{
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	285	<span class="code-keyword">if</span> (args[i].equals(BUNDLE_DIR_SWITCH))
				286	{
				287	expectBundleDir = <span class="code-keyword">true</span>;
				288	}
				289	<span class="code-keyword">else</span> <span class="code-keyword">if</span> (expectBundleDir)
				290	{
				291	bundleDir = args[i];
				292	expectBundleDir = <span class="code-keyword">false</span>;
				293	}
				294	<span class="code-keyword">else</span>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	295	{
				296	cacheDir = args[i];
				297	}
				298	}
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	299
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	300	<span class="code-keyword">if</span> ((args.length > 3) \|\| (expectBundleDir && bundleDir == <span class="code-keyword">null</span>))
				301	{
				302	<span class="code-object">System</span>.out.println(<span class="code-quote">"Usage: [-b <bundle-deploy-dir>] [<bundle-cache-dir>]"</span>);
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	303	<span class="code-object">System</span>.exit(0);
				304	}
				305
				306	<span class="code-comment">// (2) Load system properties.
				307	</span> Main.loadSystemProperties();
				308
				309	<span class="code-comment">// (3) Read configuration properties.
				310	</span> Properties configProps = Main.loadConfigProperties();
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	311	<span class="code-keyword">if</span> (configProps == <span class="code-keyword">null</span>)
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	312	{
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	313	<span class="code-object">System</span>.err.println(<span class="code-quote">"No "</span> + CONFIG_PROPERTIES_FILE_VALUE + <span class="code-quote">" found."</span>);
				314	configProps = <span class="code-keyword">new</span> Properties();
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	315	}
				316
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	317	<span class="code-comment">// (4) Copy framework properties from the system properties.
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	318	</span> Main.copySystemProperties(configProps);
				319
				320	<span class="code-comment">// (5) Use the specified auto-deploy directory over <span class="code-keyword">default</span>.
				321	</span> <span class="code-keyword">if</span> (bundleDir != <span class="code-keyword">null</span>)
				322	{
				323	configProps.setProperty(AutoProcessor.AUTO_DEPLOY_DIR_PROPERY, bundleDir);
				324	}
				325
				326	<span class="code-comment">// (6) Use the specified bundle cache directory over <span class="code-keyword">default</span>.
				327	</span> <span class="code-keyword">if</span> (cacheDir != <span class="code-keyword">null</span>)
				328	{
				329	configProps.setProperty(Constants.FRAMEWORK_STORAGE, cacheDir);
				330	}
				331
				332	<span class="code-comment">// (7) Add a shutdown hook to clean stop the framework.
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	333	</span> <span class="code-object">String</span> enableHook = configProps.getProperty(SHUTDOWN_HOOK_PROP);
				334	<span class="code-keyword">if</span> ((enableHook == <span class="code-keyword">null</span>) \|\| !enableHook.equalsIgnoreCase(<span class="code-quote">"<span class="code-keyword">false</span>"</span>))
				335	{
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	336	<span class="code-object">Runtime</span>.getRuntime().addShutdownHook(<span class="code-keyword">new</span> <span class="code-object">Thread</span>(<span class="code-quote">"Felix Shutdown Hook"</span>) {
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	337	<span class="code-keyword">public</span> void run()
				338	{
				339	<span class="code-keyword">try</span>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	340	{
				341	<span class="code-keyword">if</span> (m_fwk != <span class="code-keyword">null</span>)
				342	{
				343	m_fwk.stop();
				344	m_fwk.waitForStop(0);
				345	}
				346	}
				347	<span class="code-keyword">catch</span> (Exception ex)
				348	{
				349	<span class="code-object">System</span>.err.println(<span class="code-quote">"Error stopping framework: "</span> + ex);
				350	}
				351	}
				352	});
				353	}
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	354
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	355	<span class="code-keyword">try</span>
				356	{
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	357	<span class="code-comment">// (8) Create an instance and initialize the framework.
				358	</span> FrameworkFactory factory = getFrameworkFactory();
				359	m_fwk = factory.newFramework(configProps);
				360	m_fwk.init();
				361	<span class="code-comment">// (9) Use the system bundle context to process the auto-deploy
				362	</span> <span class="code-comment">// and auto-install/auto-start properties.
				363	</span> AutoProcessor.process(configProps, m_fwk.getBundleContext());
				364	<span class="code-comment">// (10) Start the framework.
				365	</span> m_fwk.start();
				366	<span class="code-comment">// (11) Wait <span class="code-keyword">for</span> framework to stop to exit the VM.
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	367	</span> m_fwk.waitForStop(0);
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	368	<span class="code-object">System</span>.exit(0);
				369	}
				370	<span class="code-keyword">catch</span> (Exception ex)
				371	{
				372	<span class="code-object">System</span>.err.println(<span class="code-quote">"Could not create framework: "</span> + ex);
				373	ex.printStackTrace();
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	374	<span class="code-object">System</span>.exit(0);
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	375	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	376	}
				377	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	378	</div></div>
				379
				380	<p>The general steps of the standard launcher are quite straightforward:</p>
				381
				382	<ol>
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	383	<li>The launcher supports setting the auto-deploy directory (with the <tt>-b</tt>
				384	switch) and setting the bundle cache path with a single argument, so
				385	check for this and issue a usage message it there are more than one
				386	arguments.</li>
				387	<li>Load any system properties specified in the <tt>system.properties</tt> file; this file is typically located in the <tt>conf/</tt> directory of the Felix installation directory, but it can be specified directly using the <tt>felix.system.properties</tt>
				388	system property. This file is not needed to launch Felix and is
				389	provided merely for convenience when system properties must be
				390	specified. The file is a standard Java properties file, but it also
				391	supports property substitution using <tt>${<property-name</tt>} syntax. Property substitution can be nested; only system properties will be used for substitution.</li>
				392	<li>Load any configuration properties specified in the <tt>config.properties</tt> file; this file is typically located in the <tt>conf/</tt> directory of the Felix installation directory, but it can be specified directly using the <tt>felix.config.properties</tt>
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	393	system property. This file is used to configure the framework instance
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	394	created by the launcher. The file is a standard Java properties file,
				395	but it also supports property substitution using "<tt>${<property-name></tt>}"
				396	syntax. Property substitution can be nested; configuration and system
				397	properties will be used for substitution with configuration properties
				398	having precedence.</li>
				399	<li>For convenience, any configuration
				400	properties that are set as system properties are copied into the set of
				401	configuration properties. This provide an easy way to add to or
				402	override configuration properties specified in the <tt>config.properties</tt> file, since the Felix instance will never look at system properties for configuration.</li>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	403	<li>If the <tt>-b</tt> switch was used to specify an auto-deploy directory, then use that to set the value of <tt>felix.auto.deploy.dir</tt>.</li>
				404	<li>If a single command-line argument is specified, then use that to set the value of <tt>org.osgi.framework.storage</tt>; relative paths are relative to the current directory unless the <tt>felix.cache.rootdir</tt> property is set.</li>
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	405	<li>Add a shutdown hook to cleanly stop the framework, unless the hook is disabled.</li>
				406	<li>Create a framework instance using the <tt>FrameworkFactory</tt> passing in the configuration properties, then initialize the factory instance; see the <a href="#ApacheFelixFrameworkLaunchingandEmbedding-customlauncher">custom launcher example</a> below to see how the META-INF/services <tt>FrameworkFactory</tt> is obtained.</li>
				407	<li>Use <tt>org.apache.felix.main.AutoProcessor</tt>, which will automatically deploy any bundles in the auto-deploy directory as well as bundles specified in the <tt>felix.auto.install</tt> and <tt>felix.auto.start</tt>
				408	configuration properties during framework startup to automatically
				409	install and/or start bundles; see the usage document for more
				410	information <a href="http://felix.apache.org/site/apache-felix-framework-usage-documentation.html#ApacheFelixFrameworkUsageDocumentation-configuringframework">configuration properties</a> and <a href="http://felix.apache.org/site/apache-felix-framework-usage-documentation.html#ApacheFelixFrameworkUsageDocumentation-autodeploy">bundle auto-deploy</a>.</li>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	411	<li>Invoke <tt>waitForStop()</tt> to wait for the framework to stop to force the VM to exit; this is necessary because the framework never calls <tt>System.exit()</tt> and some libraries (e.g., Swing) create threads that will not allow the VM to exit.</li>
				412	</ol>
				413
				414
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	415	<p>The framework is not active until the <tt>start()</tt> method is
				416	called. If no shell bundles are installed and started or if there is
				417	difficulty locating the shell bundles specified in the auto-start
				418	property, then it will appear as if the framework is hung, but it is
				419	actually running without any way to interact with it since the shell
				420	bundles provide the only means of interaction.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	421
				422	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-customlauncher"></a></p>
				423
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	424	<h2><a name="ApacheFelixFrameworkLaunchingandEmbedding-CustomFrameworkLauncher"></a>Custom Framework Launcher</h2>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	425
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	426	<p>This section creates a bare-bones launcher to demonstrate the
				427	minimum requirements for creating an interactive launcher for the Felix
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	428	framework. This example uses the standard Gogo shell bundles for
				429	interactivity, but any other bundles could be used instead. This
				430	example launcher project has the following directory structure:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	431
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	432	<div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent">
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	433	<pre>launcher/
				434	lib/
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	435	org.apache.felix.main-3.0.0.jar
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	436	bundle/
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	437	org.apache.felix.gogo.command-0.6.0.jar
				438	org.apache.felix.gogo.runtime-0.6.0.jar
				439	org.apache.felix.gogo.shell-0.6.0.jar
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	440	src/
				441	example/
				442	Main.java
				443	</pre>
				444	</div></div>
				445
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	446	<p>The <tt>lib/</tt> directory contains Felix' main JAR file, which
				447	also contains the OSGi core interfaces. The main JAR file is used so
				448	that we can reuse the default launcher's auto-install/auto-start
				449	configuration property handling; if these capabilities are not needed,
				450	then it would be possible to use the framework JAR file instead of the
				451	main JAR file. The <tt>bundle/</tt> directory contains the shell
				452	service and textual shell interface bundles that will be used for
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	453	interacting with the framework instance. Note: If you do not launch the
				454	framework with interactive bundles, it will appear as if the framework
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	455	instance is hung, but it is actually just sitting there waiting for
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	456	someone to tell it to do something. The <tt>src/example/</tt> directory contains the following <tt>Main.java</tt> file, which is a very simplistic framework launcher.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	457
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	458	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	459	<pre class="code-java"><span class="code-keyword">package</span> example;
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	460
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	461	<span class="code-keyword">import</span> java.io.*;
				462	<span class="code-keyword">import</span> org.osgi.framework.launch.*;
				463	<span class="code-keyword">import</span> org.apache.felix.main.AutoProcessor;
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	464
				465	<span class="code-keyword">public</span> class Main
				466	{
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	467	<span class="code-keyword">private</span> <span class="code-keyword">static</span> Framework m_fwk = <span class="code-keyword">null</span>;
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	468
				469	<span class="code-keyword">public</span> <span class="code-keyword">static</span> void main(<span class="code-object">String</span>[] argv) <span class="code-keyword">throws</span> Exception
				470	{
				471	<span class="code-comment">// Print welcome banner.
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	472	</span> <span class="code-object">System</span>.out.println(<span class="code-quote">"\nWelcome to My Launcher"</span>);
				473	<span class="code-object">System</span>.out.println(<span class="code-quote">"======================\n"</span>);
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	474
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	475	<span class="code-keyword">try</span>
				476	{
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	477	m_fwk = getFrameworkFactory().newFramework(<span class="code-keyword">null</span>);
				478	m_fwk.init()
				479	AutoProcessor.process(<span class="code-keyword">null</span>, m_fwk.getBundleContext());
				480	m_fwk.start();
				481	m_fwk.waitForStop();
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	482	<span class="code-object">System</span>.exit(0);
				483	}
				484	<span class="code-keyword">catch</span> (Exception ex)
				485	{
				486	<span class="code-object">System</span>.err.println(<span class="code-quote">"Could not create framework: "</span> + ex);
				487	ex.printStackTrace();
				488	<span class="code-object">System</span>.exit(-1);
				489	}
				490	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	491
				492	<span class="code-keyword">private</span> <span class="code-keyword">static</span> FrameworkFactory getFrameworkFactory() <span class="code-keyword">throws</span> Exception
				493	{
				494	URL url = Main.class.getClassLoader().getResource(
				495	<span class="code-quote">"META-INF/services/org.osgi.framework.launch.FrameworkFactory"</span>);
				496	<span class="code-keyword">if</span> (url != <span class="code-keyword">null</span>)
				497	{
				498	BufferedReader br = <span class="code-keyword">new</span> BufferedReader(<span class="code-keyword">new</span> InputStreamReader(url.openStream()));
				499	<span class="code-keyword">try</span>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	500	{
				501	<span class="code-keyword">for</span> (<span class="code-object">String</span> s = br.readLine(); s != <span class="code-keyword">null</span>; s = br.readLine())
				502	{
				503	s = s.trim();
				504	<span class="code-comment">// Try to load first non-empty, non-commented line.
				505	</span> <span class="code-keyword">if</span> ((s.length() > 0) && (s.charAt(0) != '#'))
				506	{
				507	<span class="code-keyword">return</span> (FrameworkFactory) <span class="code-object">Class</span>.forName(s).newInstance();
				508	}
				509	}
				510	}
				511	<span class="code-keyword">finally</span>
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	512	{
				513	<span class="code-keyword">if</span> (br != <span class="code-keyword">null</span>) br.close();
				514	}
				515	}
				516
				517	<span class="code-keyword">throw</span> <span class="code-keyword">new</span> Exception(<span class="code-quote">"Could not find framework factory."</span>);
				518	}
				519	}
				520	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	521	</div></div>
				522
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	523	<p>This launcher relies on the default behavior of <tt>AutoProcessor</tt>
				524	to automatically deploy the shell bundles. This simple, generic
				525	launcher provides a good starting point if the default Felix launcher
				526	is not sufficient. Since very few configuration properties are
				527	specified, the default values are used. For the bundle auto-deploy
				528	directory, "<tt>bundle</tt>" in the current directory is used, while for the framework bundle cache, "<tt>felix-cache</tt>" in the current directory is used.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	529
				530	<p>By breaking down the above source code into small chunks, it is quite easy to see what is going on.</p>
				531
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	532	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	533	<pre class="code-java"> m_fwk = getFrameworkFactory().newFramework(<span class="code-keyword">null</span>);
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	534	m_fwk.init()
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	535	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	536	</div></div>
				537
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	538	<p>These steps get a the framework factory service and use it to create
				539	a framework instance with a default configuration. Once the framework
				540	instance is created, it is initialized with <tt>init()</tt>.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	541
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	542	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	543	<pre class="code-java"> AutoProcessor.process(<span class="code-keyword">null</span>, m_fwk.getBundleContext());
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	544	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	545	</div></div>
				546
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	547	<p>The <tt>AutorProcessor</tt> will automatically deploy bundles in the
				548	auto-deploy directory and any referenced from the auto-install/start
				549	properties. Since we are using an empty configuration, the auto-deploy
				550	directory is the <tt>bundle</tt> directory in the current directory
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	551	and there are no auto properties. Therefore, in this case, the shell
				552	bundles will be installed.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	553
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	554	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	555	<pre class="code-java"> m_fwk.start();
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	556	m_fwk.waitForStop();
				557	<span class="code-object">System</span>.exit(0);
				558	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	559	</div></div>
				560
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	561	<p>These final steps start the framework and cause the launching
				562	application thread to wait for the framework to stop and when it does
				563	the launching thread calls <tt>System.exit()</tt> to make sure the VM actually exits.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	564
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	565	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	566	<pre class="code-java"> <span class="code-keyword">private</span> <span class="code-keyword">static</span> FrameworkFactory getFrameworkFactory() <span class="code-keyword">throws</span> Exception
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	567	{
				568	...
				569	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	570	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	571	</div></div>
				572
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	573	<p>This method retrieves the framework factory service by doing a
				574	META-INF/services resource lookup, which it can use to obtain the
				575	concrete class name for the factory. If you are using Java 6, then you
				576	can use the <tt>ServiceLoader</tt> API in the JRE to further simplify the factory service lookup.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	577
				578	<p>The following command compiles the launcher when run from the root directory of the launcher project:</p>
				579
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	580	<div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent">
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	581	<pre>javac -d . -classpath lib/org.apache.felix.main-3.0.0.jar src/example/Main.java
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	582	</pre>
				583	</div></div>
				584
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	585	<p>After executing this command, an <tt>example/</tt> directory is
				586	created in the current directory, which contains the generated class
				587	file. The following command executes the simple launcher when run from
				588	the root directory of the launcher project:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	589
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	590	<div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent">
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	591	<pre>java -cp .:lib/org.apache.felix.main-3.0.0.jar example.Main
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	592	</pre>
				593	</div></div>
				594
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	595	<p>After executing this command, a "<tt>felix-cache/</tt>" directory is created that contains the cached bundles, which were installed from the <tt>bundle/</tt> directory.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	596
				597	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-embedding"></a></p>
				598
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	599	<h1><a name="ApacheFelixFrameworkLaunchingandEmbedding-EmbeddingtheFelixFramework"></a>Embedding the Felix Framework</h1>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	600
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	601	<p>Embedding the Felix framework into a host application is a simple
				602	way to provide a sophisticated extensibility mechanism (i.e., a plugin
				603	system) to the host application. Embedding the Felix framework is very
				604	similar to launching it as described above, the main difference is that
				605	the host application typically wants to interact with the framework
				606	instance and/or installed bundles/services from the outside. This is
				607	fairly easy to achieve, but there are some subtle issues to understand.
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	608	This section presents the mechanisms for embedding Felix into a host
				609	application and the issues in doing so.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	610
				611	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-hostinteraction"></a></p>
				612
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	613	<h2><a name="ApacheFelixFrameworkLaunchingandEmbedding-Host/FelixInteraction"></a>Host/Felix Interaction</h2>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	614
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	615	<p>In the section on <a href="#ApacheFelixFrameworkLaunchingandEmbedding-launching">launching</a> the framework above, the <tt>Felix</tt> class accepts a configuration property called <tt>felix.systembundle.activators</tt>,
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	616	which is a list of bundle activator instances. These bundle activator
				617	instances provide a convenient way for host applications to interact
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	618	with the Felix framework.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	619
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	620	<div class="panelMacro"><table class="warningMacro"><colgroup><col width="24"><col></colgroup><tbody><tr><td valign="top"><img src="apache-felix-framework-launching-and-embedding_files/forbidden.gif" alt="" align="absmiddle" border="0" height="16" width="16"></td><td><b>WARNING</b><br>The <tt>felix.systembundle.activators</tt>
				621	configuration property is specific to the Felix framework
				622	implementation. If you want your code to work with other framework
				623	implementations, you should call <tt>init()</tt> on the framework instance and use <tt>getBundleContext()</tt> directly. Otherwise, the approach would be very similar.</td></tr></tbody></table></div>
				624
				625	<p>Each activator instance passed into the constructor effectively becomes part of the system bundle. This means that the <tt>start()</tt>/<tt>stop()</tt> methods of each activator instance in the list gets invoked when the system bundle's activator <tt>start()</tt>/<tt>stop()</tt> methods gets invoked, respectively. Each activator instance will be given the system bundle's <tt>BundleContext</tt> object so that they can interact with the framework. Consider following snippet of a bundle activator:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	626
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	627	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	628	<pre class="code-java"><span class="code-keyword">public</span> class HostActivator <span class="code-keyword">implements</span> BundleActivator
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	629	{
				630	<span class="code-keyword">private</span> BundleContext m_context = <span class="code-keyword">null</span>;
				631
				632	<span class="code-keyword">public</span> void start(BundleContext context)
				633	{
				634	m_context = context;
				635	}
				636
				637	<span class="code-keyword">public</span> void stop(BundleContext context)
				638	{
				639	m_context = <span class="code-keyword">null</span>;
				640	}
				641
				642	<span class="code-keyword">public</span> Bundle[] getBundles()
				643	{
				644	<span class="code-keyword">if</span> (m_context != <span class="code-keyword">null</span>)
				645	{
				646	<span class="code-keyword">return</span> m_context.getBundles();
				647	}
				648	<span class="code-keyword">return</span> <span class="code-keyword">null</span>;
				649	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	650	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	651	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	652	</div></div>
				653
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	654	<p>Given the above bundle activator, it is now possible to embed the
				655	Felix framework into a host application and interact with it as the
				656	following snippet illustrates:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	657
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	658	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	659	<pre class="code-java"><span class="code-keyword">public</span> class HostApplication
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	660	{
				661	<span class="code-keyword">private</span> HostActivator m_activator = <span class="code-keyword">null</span>;
				662	<span class="code-keyword">private</span> Felix m_felix = <span class="code-keyword">null</span>;
				663
				664	<span class="code-keyword">public</span> HostApplication()
				665	{
				666	<span class="code-comment">// Create a configuration property map.
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	667	</span> Map config = <span class="code-keyword">new</span> HashMap();
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	668	<span class="code-comment">// Create host activator;
				669	</span> m_activator = <span class="code-keyword">new</span> HostActivator();
				670	List list = <span class="code-keyword">new</span> ArrayList();
				671	list.add(m_activator);
				672	configMap.put(FelixConstants.SYSTEMBUNDLE_ACTIVATORS_PROP, list);
				673
				674	<span class="code-keyword">try</span>
				675	{
				676	<span class="code-comment">// Now create an instance of the framework with
				677	</span> <span class="code-comment">// our configuration properties.
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	678	</span> m_felix = <span class="code-keyword">new</span> Felix(config);
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	679	<span class="code-comment">// Now start Felix instance.
				680	</span> m_felix.start();
				681	}
				682	<span class="code-keyword">catch</span> (Exception ex)
				683	{
				684	<span class="code-object">System</span>.err.println(<span class="code-quote">"Could not create framework: "</span> + ex);
				685	ex.printStackTrace();
				686	}
				687	}
				688
				689	<span class="code-keyword">public</span> Bundle[] getInstalledBundles()
				690	{
				691	<span class="code-comment">// Use the system bundle activator to gain external
				692	</span> <span class="code-comment">// access to the set of installed bundles.
				693	</span> <span class="code-keyword">return</span> m_activator.getBundles();
				694	}
				695
				696	<span class="code-keyword">public</span> void shutdownApplication()
				697	{
				698	<span class="code-comment">// Shut down the felix framework when stopping the
				699	</span> <span class="code-comment">// host application.
				700	</span> m_felix.stop();
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	701	m_felix.waitForStop(0);
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	702	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	703	}
				704	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	705	</div></div>
				706
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	707	<p>Notice how the <tt>HostApplication.getInstalledBundles()</tt> method
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	708	uses its activator instance to get access to the system bundle's
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	709	context in order to interact with the embedded Felix framework
				710	instance. This approach provides the foundation for all interaction
				711	between the host application and the embedded framework instance.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	712
				713	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-hostservices"></a></p>
				714
				715	<h2><a name="ApacheFelixFrameworkLaunchingandEmbedding-ProvidingHostApplicationServices"></a>Providing Host Application Services</h2>
				716
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	717	<p>Providing services from the host application to bundles inside the
				718	embedded Felix framework instance follows the basic approach laid out
				719	in <a href="#ApacheFelixFrameworkLaunchingandEmbedding-hostinteraction">above</a>.
				720	The main complication for providing a host application service to
				721	bundles is the fact that both the host application and the bundles must
				722	be using the same class definitions for the service interface classes.
				723	Since the host application cannot import classes from a bundle, this
				724	means that the service interface classes <b>must</b> be accessible on
				725	the class path, typically as part of the host application itself. The
				726	host application then must export the service interface package via the
				727	system bundle so that bundles installed into the embedded framework
				728	instance can import it. This is achieved using the <tt>org.osgi.framework.system.packages.extra</tt> configuration property previously presented.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	729
				730	<p>Consider the follow simple property lookup service:</p>
				731
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	732	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	733	<pre class="code-java"><span class="code-keyword">package</span> host.service.lookup;
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	734
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	735	<span class="code-keyword">public</span> <span class="code-keyword">interface</span> Lookup
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	736	{
				737	<span class="code-keyword">public</span> <span class="code-object">Object</span> lookup(<span class="code-object">String</span> name);
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	738	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	739	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	740	</div></div>
				741
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	742	<p>This package is simply part of the host application, which is potentially packaged into a JAR file and started with the "<tt>java -jar</tt>"
				743	command. Now consider the following host application bundle activator,
				744	which will be used to register/unregister the property lookup service
				745	when the embedded framework instance starts/stops:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	746
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	747	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	748	<pre class="code-java"><span class="code-keyword">package</span> host.core;
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	749
				750	<span class="code-keyword">import</span> java.util.Map;
				751	<span class="code-keyword">import</span> org.osgi.framework.BundleActivator;
				752	<span class="code-keyword">import</span> org.osgi.framework.BundleContext;
				753	<span class="code-keyword">import</span> org.osgi.framework.ServiceRegistration;
				754	<span class="code-keyword">import</span> host.service.lookup;
				755
				756	<span class="code-keyword">public</span> class HostActivator <span class="code-keyword">implements</span> BundleActivator
				757	{
				758	<span class="code-keyword">private</span> Map m_lookupMap = <span class="code-keyword">null</span>;
				759	<span class="code-keyword">private</span> BundleContext m_context = <span class="code-keyword">null</span>;
				760	<span class="code-keyword">private</span> ServiceRegistration m_registration = <span class="code-keyword">null</span>;
				761
				762	<span class="code-keyword">public</span> HostActivator(Map lookupMap)
				763	{
				764	<span class="code-comment">// Save a reference to the service's backing store.
				765	</span> m_lookupMap = lookupMap;
				766	}
				767
				768	<span class="code-keyword">public</span> void start(BundleContext context)
				769	{
				770	<span class="code-comment">// Save a reference to the bundle context.
				771	</span> m_context = context;
				772	<span class="code-comment">// Create a property lookup service implementation.
				773	</span> Lookup lookup = <span class="code-keyword">new</span> Lookup() {
				774	<span class="code-keyword">public</span> <span class="code-object">Object</span> lookup(<span class="code-object">String</span> name)
				775	{
				776	<span class="code-keyword">return</span> m_lookupMap.get(name);
				777	}
				778	};
				779	<span class="code-comment">// Register the property lookup service and save
				780	</span> <span class="code-comment">// the service registration.
				781	</span> m_registration = m_context.registerService(
				782	Lookup.class.getName(), lookup, <span class="code-keyword">null</span>);
				783	}
				784
				785	<span class="code-keyword">public</span> void stop(BundleContext context)
				786	{
				787	<span class="code-comment">// Unregister the property lookup service.
				788	</span> m_registration.unregister();
				789	m_context = <span class="code-keyword">null</span>;
				790	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	791	}
				792	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	793	</div></div>
				794
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	795	<p>Given the above host application bundle activator, the following
				796	code snippet shows how the host application could create an embedded
				797	version of the Felix framework and provide the property lookup service
				798	to installed bundles:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	799
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	800	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	801	<pre class="code-java"><span class="code-keyword">package</span> host.core;
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	802
				803	<span class="code-keyword">import</span> java.util.List;
				804	<span class="code-keyword">import</span> java.util.ArrayList;
				805	<span class="code-keyword">import</span> java.util.Map;
				806	<span class="code-keyword">import</span> java.util.HashMap;
				807	<span class="code-keyword">import</span> host.service.lookup.Lookup;
				808	<span class="code-keyword">import</span> org.apache.felix.framework.Felix;
				809	<span class="code-keyword">import</span> org.apache.felix.framework.util.FelixConstants;
				810	<span class="code-keyword">import</span> org.osgi.framework.Constants;
				811
				812	<span class="code-keyword">public</span> class HostApplication
				813	{
				814	<span class="code-keyword">private</span> HostActivator m_activator = <span class="code-keyword">null</span>;
				815	<span class="code-keyword">private</span> Felix m_felix = <span class="code-keyword">null</span>;
				816	<span class="code-keyword">private</span> Map m_lookupMap = <span class="code-keyword">new</span> HashMap();
				817
				818	<span class="code-keyword">public</span> HostApplication()
				819	{
				820	<span class="code-comment">// Initialize the map <span class="code-keyword">for</span> the property lookup service.
				821	</span> m_lookupMap.put(<span class="code-quote">"name1"</span>, <span class="code-quote">"value1"</span>);
				822
				823	m_lookupMap.put(<span class="code-quote">"name2"</span>, <span class="code-quote">"value2"</span>);
				824	m_lookupMap.put(<span class="code-quote">"name3"</span>, <span class="code-quote">"value3"</span>);
				825	m_lookupMap.put(<span class="code-quote">"name4"</span>, <span class="code-quote">"value4"</span>);
				826
				827	<span class="code-comment">// Create a configuration property map.
				828	</span> Map configMap = <span class="code-keyword">new</span> HashMap();
				829	<span class="code-comment">// Export the host provided service <span class="code-keyword">interface</span> <span class="code-keyword">package</span>.
				830	</span> configMap.put(Constants.FRAMEWORK_SYSTEMPACKAGES_EXTRA,
				831	<span class="code-quote">"host.service.lookup; version=1.0.0"</span>);
				832	<span class="code-comment">// Create host activator;
				833	</span> m_activator = <span class="code-keyword">new</span> HostActivator(m_lookupMap);
				834	List list = <span class="code-keyword">new</span> ArrayList();
				835	list.add(m_activator);
				836	configMap.put(FelixConstants.SYSTEMBUNDLE_ACTIVATORS_PROP, list);
				837
				838	<span class="code-keyword">try</span>
				839	{
				840	<span class="code-comment">// Now create an instance of the framework with
				841	</span> <span class="code-comment">// our configuration properties.
				842	</span> m_felix = <span class="code-keyword">new</span> Felix(configMap);
				843	<span class="code-comment">// Now start Felix instance.
				844	</span> m_felix.start();
				845	}
				846	<span class="code-keyword">catch</span> (Exception ex)
				847	{
				848	<span class="code-object">System</span>.err.println(<span class="code-quote">"Could not create framework: "</span> + ex);
				849	ex.printStackTrace();
				850	}
				851	}
				852
				853	<span class="code-keyword">public</span> void shutdownApplication()
				854	{
				855	<span class="code-comment">// Shut down the felix framework when stopping the
				856	</span> <span class="code-comment">// host application.
				857	</span> m_felix.stop();
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	858	m_felix.waitForStop(0);
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	859	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	860	}
				861	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	862	</div></div>
				863
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	864	<p>Rather than having the host application bundle activator register
				865	the service, it is also possible for the the host application to simply
				866	get the bundle context from the bundle activator and register the
				867	service directly, but the presented approach is perhaps a little
				868	cleaner since it allows the host application to register/unregister the
				869	service when the system bundle starts/stops.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	870
				871	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-hostserviceusage"></a></p>
				872
				873	<h2><a name="ApacheFelixFrameworkLaunchingandEmbedding-UsingServicesProvidedbyBundles"></a>Using Services Provided by Bundles</h2>
				874
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	875	<p>Using services provided by bundles follows the same general approach
				876	of using a host application bundle activator. The main complication for
				877	the host application using a service from a bundle is the fact that
				878	both the host application and the bundle must be using the same class
				879	definitions for the service interface classes. Since the host
				880	application cannot import classes from a bundle, this means that the
				881	service interface classes <b>must</b> be accessible on the class path,
				882	typically as part of the host application itself. The host application
				883	then must export the service interface package via the system bundle so
				884	that bundles installed into the embedded framework instance can import
				885	it. This is achieved using the <tt>org.osgi.framework.system.packages.extra</tt> configuration property previously presented.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	886
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	887	<p>Consider the following simple command service interface for which
				888	bundles provide implementations, such as might be used to create an
				889	extensible interactive shell:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	890
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	891	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	892	<pre class="code-java"><span class="code-keyword">package</span> host.service.command;
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	893
				894	<span class="code-keyword">public</span> class Command
				895	{
				896	<span class="code-keyword">public</span> <span class="code-object">String</span> getName();
				897	<span class="code-keyword">public</span> <span class="code-object">String</span> getDescription();
				898	<span class="code-keyword">public</span> <span class="code-object">boolean</span> execute(<span class="code-object">String</span> commandline);
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	899	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	900	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	901	</div></div>
				902
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	903	<p>This package is simply part of the host application, which is potentially packaged into a JAR file and started with the "<tt>java -jar</tt>"
				904	command. Now consider the previously introduced host application bundle
				905	activator below, which simply provides access to the system bundle
				906	context:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	907
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	908	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	909	<pre class="code-java"><span class="code-keyword">package</span> host.core;
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	910
				911	<span class="code-keyword">import</span> org.osgi.framework.BundleActivator;
				912	<span class="code-keyword">import</span> org.osgi.framework.BundleContext;
				913
				914	<span class="code-keyword">public</span> class HostActivator <span class="code-keyword">implements</span> BundleActivator
				915	{
				916	<span class="code-keyword">private</span> BundleContext m_context = <span class="code-keyword">null</span>;
				917
				918	<span class="code-keyword">public</span> void start(BundleContext context)
				919	{
				920	m_context = context;
				921	}
				922
				923	<span class="code-keyword">public</span> void stop(BundleContext context)
				924	{
				925	m_context = <span class="code-keyword">null</span>;
				926	}
				927
				928	<span class="code-keyword">public</span> BundleContext getContext()
				929	{
				930	<span class="code-keyword">return</span> m_context;
				931	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	932	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	933	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	934	</div></div>
				935
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	936	<p>With this bundle activator, the host application can use command
				937	services provided by bundles installed inside its embedded Felix
				938	framework instance. The following code snippet illustrates one possible
				939	approach:</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	940
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	941	<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	942	<pre class="code-java"><span class="code-keyword">package</span> host.core;
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	943
				944	<span class="code-keyword">import</span> java.util.List;
				945	<span class="code-keyword">import</span> java.util.ArrayList;
				946	<span class="code-keyword">import</span> java.util.Map;
				947	<span class="code-keyword">import</span> host.service.command.Command;
				948	<span class="code-keyword">import</span> org.apache.felix.framework.Felix;
				949	<span class="code-keyword">import</span> org.apache.felix.framework.util.FelixConstants;
				950	<span class="code-keyword">import</span> org.apache.felix.framework.cache.BundleCache;
				951	<span class="code-keyword">import</span> org.osgi.framework.Constants;
				952	<span class="code-keyword">import</span> org.osgi.util.tracker.ServiceTracker;
				953
				954	<span class="code-keyword">public</span> class HostApplication
				955	{
				956	<span class="code-keyword">private</span> HostActivator m_activator = <span class="code-keyword">null</span>;
				957	<span class="code-keyword">private</span> Felix m_felix = <span class="code-keyword">null</span>;
				958	<span class="code-keyword">private</span> ServiceTracker m_tracker = <span class="code-keyword">null</span>;
				959
				960	<span class="code-keyword">public</span> HostApplication()
				961	{
				962	<span class="code-comment">// Create a configuration property map.
				963	</span> Map configMap = <span class="code-keyword">new</span> HashMap();
				964	<span class="code-comment">// Export the host provided service <span class="code-keyword">interface</span> <span class="code-keyword">package</span>.
				965	</span> configMap.put(Constants.FRAMEWORK_SYSTEMPACKAGES_EXTRA,
				966	<span class="code-quote">"host.service.command; version=1.0.0"</span>);
				967	<span class="code-comment">// Create host activator;
				968	</span> m_activator = <span class="code-keyword">new</span> HostActivator();
				969	List list = <span class="code-keyword">new</span> ArrayList();
				970	list.add(m_activator);
				971	configMap.put(FelixConstants.SYSTEMBUNDLE_ACTIVATORS_PROP, list);
				972
				973	<span class="code-keyword">try</span>
				974	{
				975	<span class="code-comment">// Now create an instance of the framework with
				976	</span> <span class="code-comment">// our configuration properties.
				977	</span> m_felix = <span class="code-keyword">new</span> Felix(configMap);
				978	<span class="code-comment">// Now start Felix instance.
				979	</span> m_felix.start();
				980	}
				981	<span class="code-keyword">catch</span> (Exception ex)
				982	{
				983	<span class="code-object">System</span>.err.println(<span class="code-quote">"Could not create framework: "</span> + ex);
				984	ex.printStackTrace();
				985	}
				986
				987	m_tracker = <span class="code-keyword">new</span> ServiceTracker(
				988	m_activator.getContext(), Command.class.getName(), <span class="code-keyword">null</span>);
				989	m_tracker.open();
				990	}
				991
				992	<span class="code-keyword">public</span> <span class="code-object">boolean</span> execute(<span class="code-object">String</span> name, <span class="code-object">String</span> commandline)
				993	{
				994	<span class="code-comment">// See <span class="code-keyword">if</span> any of the currently tracked command services
				995	</span> <span class="code-comment">// match the specified command name, <span class="code-keyword">if</span> so then execute it.
				996	</span> <span class="code-object">Object</span>[] services = m_tracker.getServices();
				997	<span class="code-keyword">for</span> (<span class="code-object">int</span> i = 0; (services != <span class="code-keyword">null</span>) && (i < services.length); i++)
				998	{
				999	<span class="code-keyword">try</span>
				1000	{
				1001	<span class="code-keyword">if</span> (((Command) services[i]).getName().equals(name))
				1002	{
				1003	<span class="code-keyword">return</span> ((Command) services[i]).execute(commandline);
				1004	}
				1005	}
				1006	<span class="code-keyword">catch</span> (Exception ex)
				1007	{
				1008	<span class="code-comment">// Since the services returned by the tracker could become
				1009	</span> <span class="code-comment">// invalid at any moment, we will <span class="code-keyword">catch</span> all exceptions, log
				1010	</span> <span class="code-comment">// a message, and then ignore faulty services.
				1011	</span> <span class="code-object">System</span>.err.println(ex);
				1012	}
				1013	}
				1014	<span class="code-keyword">return</span> <span class="code-keyword">false</span>;
				1015	}
				1016
				1017	<span class="code-keyword">public</span> void shutdownApplication()
				1018	{
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	1019	<span class="code-comment">// Shut down the felix framework when stopping the
				1020	</span> <span class="code-comment">// host application.
				1021	</span> m_felix.stop();
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	1022	m_felix.waitForStop(0);
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	1023	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	1024	}
Karl Pauls	3992b55	2009-09-06 22:21:18 +0000	[diff] [blame]	1025	</pre>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	1026	</div></div>
				1027
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	1028	<p>The above example is overly simplistic with respect to concurrency
				1029	issues and error conditions, but it demonstrates the overall approach
				1030	for using bundle-provided services from the host application.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	1031
				1032	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-servicereflection"></a></p>
				1033
				1034	<h3><a name="ApacheFelixFrameworkLaunchingandEmbedding-UsingBundleServicesviaReflection"></a>Using Bundle Services via Reflection</h3>
				1035
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	1036	<p>It possible for the host application to use services provided by
				1037	bundles without having access to the service interface classes and thus
				1038	not needing to put the service interface classes on the class path. To
				1039	do this, the host application uses the same general approach to acquire
				1040	the system bundle context object, which it can use to look up service
				1041	objects. Using either an LDAP filter or the service interface class
				1042	name, the host application can retrieve the service object and then use
				1043	standard Java reflection to invoke methods on the service object.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	1044
				1045	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-serviceother"></a></p>
				1046
				1047	<h3><a name="ApacheFelixFrameworkLaunchingandEmbedding-OtherApproaches"></a>Other Approaches</h3>
				1048
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	1049	<p>The <a href="http://code.google.com/p/transloader/" class="external-link" rel="nofollow">Transloader</a> project is another attempt at dealing with issues of classes loaded from different class loaders and may be of interest.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	1050
				1051	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-caveat"></a></p>
				1052
				1053	<h1><a name="ApacheFelixFrameworkLaunchingandEmbedding-Caveat"></a>Caveat</h1>
				1054
Karl Pauls	feff79c	2009-10-11 20:18:06 +0000	[diff] [blame]	1055	<p>The code in this document has not been thoroughly tested nor even
				1056	compiled and may be out of date with respect to the current Felix
				1057	source code. If you find errors please report them so the that they can
				1058	be corrected.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	1059
				1060	<p><a name="ApacheFelixFrameworkLaunchingandEmbedding-feedback"></a></p>
				1061
				1062	<h2><a name="ApacheFelixFrameworkLaunchingandEmbedding-Feedback"></a>Feedback</h2>
				1063
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	1064	<p>Subscribe to the Felix users mailing list by sending a message to <a href="mailto:users-subscribe@felix.apache.org" class="external-link" rel="nofollow">users-subscribe@felix.apache.org</a>; after subscribing, email questions or feedback to <a href="mailto:users@felix.apache.org" class="external-link" rel="nofollow">users@felix.apache.org</a>.</p>
Karl Pauls	3d69979	2008-11-06 16:22:54 +0000	[diff] [blame]	1065	</div>
Karl Pauls	9edcb3a	2010-06-06 21:44:50 +0000	[diff] [blame^]	1066	</body></html>