Author: buildbot
Date: Fri Jul 27 20:02:21 2012
New Revision: 827230
Log:
Staging update by buildbot for sling
Modified:
websites/staging/sling/trunk/content/ (props changed)
websites/staging/sling/trunk/content/documentation/development/embedding-sling.html
Propchange: websites/staging/sling/trunk/content/
------------------------------------------------------------------------------
--- cms:source-revision (original)
+++ cms:source-revision Fri Jul 27 20:02:21 2012
@@ -1 +1 @@
-1366516
+1366518
Modified:
websites/staging/sling/trunk/content/documentation/development/embedding-sling.html
==============================================================================
---
websites/staging/sling/trunk/content/documentation/development/embedding-sling.html
(original)
+++
websites/staging/sling/trunk/content/documentation/development/embedding-sling.html
Fri Jul 27 20:02:21 2012
@@ -85,9 +85,12 @@
<h1>Embedding Sling</h1>
<p>The Sling Launchpad Launcher can be used to embed the OSGi Framework
startup in your own Java application. This functionality is implemented in the
<a href="">Sling Launchpad Base project</a>. This project has the following
features:</p>
<ul>
-<li>Builds three artifacts:
-<strong> A standalone Java Application with the artifact qualifier
<em>app</em>; e.g.
<code>org.apache.sling.launchpad.base-2.3.1-SNAPSHOT-app.jar</code></strong> A
Web Application with the artifact qualifier <em>webapp</em>; e.g
<code>org.apache.sling.launchpad.base-2.3.1-SNAPSHOT-wepabb.war</code>
-** The primary artifact without an artifact qualifier; e.g.
<code>org.apache.sling.launchpad.base-2.3.1-SNAPSHOT.jar</code></li>
+<li>Builds three artifacts:<ul>
+<li>A standalone Java Application with the artifact qualifier <em>app</em>;
e.g. <code>org.apache.sling.launchpad.base-2.3.1-SNAPSHOT-app.jar</code></li>
+<li>A Web Application with the artifact qualifier <em>webapp</em>; e.g
<code>org.apache.sling.launchpad.base-2.3.1-SNAPSHOT-wepabb.war</code></li>
+<li>The primary artifact without an artifact qualifier; e.g.
<code>org.apache.sling.launchpad.base-2.3.1-SNAPSHOT.jar</code></li>
+</ul>
+</li>
<li>Embeds the OSGi Framework (Apache Felix) in the primary artifact</li>
<li>Encapsulates the OSGi Framework in its own <code>URLClassLoader</code></li>
<li>Supports Framework restart</li>
@@ -95,10 +98,12 @@
</ul>
<p>This page is about the internal details of the Sling Launchpad Base module.
To get an outside overview of the Sling Launchpad you might want to refer to <a
href="/documentation/the-sling-engine/the-sling-launchpad.html">The Sling
Launchpad</a> page.</p>
<h1 id="structure">Structure</h1>
-<p>The Launcher is based on three parts:
-1. The external part which is for example the standalone Java application's
main class or the servlet deployed into the servlet container
-1. The internal part which is the OSGi framework plus helper classes to
control the framework and run initial installations
-1. The bridging part, which contains API common to the external and internal
part.</p>
+<p>The Launcher is based on three parts:</p>
+<ol>
+<li>The external part which is for example the standalone Java application's
main class or the servlet deployed into the servlet container</li>
+<li>The internal part which is the OSGi framework plus helper classes to
control the framework and run initial installations</li>
+<li>The bridging part, which contains API common to the external and internal
part.</li>
+</ol>
<p>The external part uses the bridging part to create the class loader into
which the internal part is loaded. The bidirectional communication between the
external and internal part is implement based on two interfaces:</p>
<ul>
<li>The <code>Launcher</code> interface is implemented by a class in the
internal part which is loaded through the bridge class loader. This interface
allows setting, starting and stopping of the framework.</li>
@@ -106,12 +111,36 @@
</ul>
<h1 id="the-bridging-part">The Bridging Part</h1>
<p>The bridging part is provided in the
<code>org.apache.sling.launchpad.base.shared</code> package:</p>
-<p>| Class | Description |
-| Launcher | The interface implemented by the internal class matching the
external class being called to start/stop the framework. |
-| LauncherClassLoader | <code>URLClassLoader</code> implementing the class
loader to load the internal part (along with the OSGi framework). This class
loader only delegates to the parent class loader any packages not contained in
the launchpad library (primary artifact of the Launchpad Base project). |
-| Loader | Helper class to find the launchpad library and to create the
<code>LauncherClassLoader</code> with that library. This class is also used to
actually load the <code>Launcher</code> implementation to be called from the
external launcher class. |
-| Notifiable | The interface implemented in the external part and handed over
to the internal part. |
-| SharedConstants | Constants naming various properties and classes. |</p>
+<table>
+<thead>
+<tr>
+<th>Class</th>
+<th>Description</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td>Launcher</td>
+<td>The interface implemented by the internal class matching the external
class being called to start/stop the framework.</td>
+</tr>
+<tr>
+<td>LauncherClassLoader</td>
+<td><code>URLClassLoader</code> implementing the class loader to load the
internal part (along with the OSGi framework). This class loader only delegates
to the parent class loader any packages not contained in the launchpad library
(primary artifact of the Launchpad Base project).</td>
+</tr>
+<tr>
+<td>Loader</td>
+<td>Helper class to find the launchpad library and to create the
<code>LauncherClassLoader</code> with that library. This class is also used to
actually load the <code>Launcher</code> implementation to be called from the
external launcher class.</td>
+</tr>
+<tr>
+<td>Notifiable</td>
+<td>The interface implemented in the external part and handed over to the
internal part.</td>
+</tr>
+<tr>
+<td>SharedConstants</td>
+<td>Constants naming various properties and classes.</td>
+</tr>
+</tbody>
+</table>
<h1 id="the-internal-part">The Internal Part</h1>
<p>The main class from the internal class directly used is <a
href=""><code>Sling</code></a> which instantiated to start the OSGi Framework.
This class is responsible for setting up the environment to finally start the
OSGi Framework:</p>
<ul>
@@ -124,10 +153,28 @@
<p>The external part is comprised of a main class started from the environment
-- main class of the Java applicaction or the servlet deployed in the servlet
container -- and a corresponding delegate class located inside of the launchpad
base library. This delegate class is instantiated by the <code>Loader</code>
loading from the <code>LauncherClassLoader</code>.</p>
<h3 id="standalone-java-application">Standalone Java Application</h3>
<p>The standalone Java Application makes use of three classes:</p>
-<p>| Class | Description |
-| Main | This is the main class whose <code>main</code> method is called by
the Java VM. This class is itself the <code>Notifiable</code> and finds the
<code>sling.home</code> location from the environment (command line parameter,
system property, or environment variable). |
-| MainDelegate | This class is loaded by the <code>Loader</code> from the
<code>LauncherClassLoader</code> to actually complete the initial setup before
creating the <code>Sling</code> class to start the framework. |
-| ControlListener | This class is used by the <code>Main</code> class to open
a server socket to be able to start and stop Sling as a server. This class
allows for starting (opening the server socket), status check (connecting to
the socket asking for status), and shutdown (connecting to the socket asking
for shutdown). |</p>
+<table>
+<thead>
+<tr>
+<th>Class</th>
+<th>Description</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td>Main</td>
+<td>This is the main class whose <code>main</code> method is called by the
Java VM. This class is itself the <code>Notifiable</code> and finds the
<code>sling.home</code> location from the environment (command line parameter,
system property, or environment variable).</td>
+</tr>
+<tr>
+<td>MainDelegate</td>
+<td>This class is loaded by the <code>Loader</code> from the
<code>LauncherClassLoader</code> to actually complete the initial setup before
creating the <code>Sling</code> class to start the framework.</td>
+</tr>
+<tr>
+<td>ControlListener</td>
+<td>This class is used by the <code>Main</code> class to open a server socket
to be able to start and stop Sling as a server. This class allows for starting
(opening the server socket), status check (connecting to the socket asking for
status), and shutdown (connecting to the socket asking for shutdown).</td>
+</tr>
+</tbody>
+</table>
<p>At the moment these classes are not directly suitable to be embedded in an
existing application (or custom application launcher framework) unless that
embedding prepares command line arguments in a <code>String[]()</code> and
calls the <code>Main.main</code> method. To allow for custom embeddings or
extensions, the work distriubtions between the three classes should be
refactored.</p>
<h3 id="embedding-the-standalone-java-application">Embedding the Standalone
Java Application</h3>
<p>{info}
@@ -164,9 +211,28 @@ This work is being done as part of <a hr
<p>By using control actions, the Sling Launcher may open or connect to a
control port to communicate. The <code>doControlAction()</code> method together
with the <code>sling.control.action</code> and
<code>sling.control.socket</code> properties is able to setup this
communication.</p>
<p>The <code>sling.control.socket</code> is either a normal port number, in
which case the connection is opened on the <code>localhost</code> interface
(usually 127.0.0.1). Otheriwse, it may also be a value of the form
<em>host:port</em> where <em>host</em> is the name or IP address of the
interface to connect to and port is the port number. For security reasons it is
suggested to not use an interface which is available remotely. So the default
of <code>localhost</code> is usually the best choice.</p>
<p>The <code>sling.control.action</code> takes either of three values:</p>
-<p>| <code>start</code> | Starts a server socket as specified by the
<code>sling.control.socket</code> property. If the socket cannot be bound to
(because the port is in use) an error message is printed. Using the
<code>start</code> action only makes sense when starting the application. |
-| <code>stop</code> | The <code>stop</code> action is used to stop a running
application. For that a connection is opened to the server running on the
socket specified by the <code>sling.control.socket</code> property. On this
connection the server is instructed to shut down. After executing the
<code>stop</code> action, the Java application should be terminated. |
-| <code>status</code> | The <code>status</code> action is used to check the
status of a running application. For that a connection is opened to the server
running on the socket specified by the <code>sling.control.socket</code>
property. On this connection the server is queried on its status. After
executing the <code>stop</code> action, the Java application should be
terminated. |</p>
+<table>
+<thead>
+<tr>
+<th>Value</th>
+<th>Description</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td><code>start</code></td>
+<td>Starts a server socket as specified by the
<code>sling.control.socket</code> property. If the socket cannot be bound to
(because the port is in use) an error message is printed. Using the
<code>start</code> action only makes sense when starting the application.</td>
+</tr>
+<tr>
+<td><code>stop</code></td>
+<td>The <code>stop</code> action is used to stop a running application. For
that a connection is opened to the server running on the socket specified by
the <code>sling.control.socket</code> property. On this connection the server
is instructed to shut down. After executing the <code>stop</code> action, the
Java application should be terminated.</td>
+</tr>
+<tr>
+<td><code>status</code></td>
+<td>The <code>status</code> action is used to check the status of a running
application. For that a connection is opened to the server running on the
socket specified by the <code>sling.control.socket</code> property. On this
connection the server is queried on its status. After executing the
<code>stop</code> action, the Java application should be terminated.</td>
+</tr>
+</tbody>
+</table>
<h4 id="conversion-of-commandline-arguments-to-properties">Conversion of
Commandline Arguments to Properties</h4>
<p>When calling the Main class through the JVM startup the
<code>Main.main(String[]() args)</code> methods is called which reads the
command line arguments and converts them into a <code>Map<String,
String></code> suitable for the constructore as follows:</p>
<table>
@@ -221,15 +287,39 @@ This work is being done as part of <a hr
</table>
<h3 id="web-application">Web Application</h3>
<p>The web application makes use of 5 classes:</p>
-<p>| Class | Description |
-| SlingServlet | This is the servlet registered in the <code>web.xml</code>
descriptor and loaded by the servlet container into which Sling is deplyoed.
This class locates the <code>sling.home</code> folder and loads the
<code>SlingServletDelagate</code> to actually launch the framework. |
-| SlingSessionListener | This -- somewhat inappropriately named -- class is
registered as a listener by the Sling <code>web.xml</code> descriptor. It is
called by the servlet container and forwards events to the
<code>SlingHttpSessionListenerDelegate</code> which in turn forwards the events
to the respective Servlet API listener services registered in the OSGi
Framework. |
-| SlingBridge | Simple extension of the <code>Sling</code> class which
registers the system bundle's <code>BundleContext</code> as a servlet context
attribute of the Sling web application. This allows Servlet Container bridging
to properly work. |
-| SlingHttpSessionListenerDelegate | This class is loaded by the
<code>LauncherClassLoader</code> called from the
<code>SlingSessionListener</code>. It is called by the
<code>SlingSessionListener</code> to forward servlet container events to
registered Servlet API listener services. |
-| SlingServletDelegate | This class is loaded by the <code>Loader</code> from
the <code>LauncherClassLoader</code> to actually complete the initial setup
before creating the <code>SlingBridge</code> class to start the framework. |</p>
+<table>
+<thead>
+<tr>
+<th>Class</th>
+<th>Description</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td>SlingServlet</td>
+<td>This is the servlet registered in the <code>web.xml</code> descriptor and
loaded by the servlet container into which Sling is deplyoed. This class
locates the <code>sling.home</code> folder and loads the
<code>SlingServletDelagate</code> to actually launch the framework.</td>
+</tr>
+<tr>
+<td>SlingSessionListener</td>
+<td>This -- somewhat inappropriately named -- class is registered as a
listener by the Sling <code>web.xml</code> descriptor. It is called by the
servlet container and forwards events to the
<code>SlingHttpSessionListenerDelegate</code> which in turn forwards the events
to the respective Servlet API listener services registered in the OSGi
Framework.</td>
+</tr>
+<tr>
+<td>SlingBridge</td>
+<td>Simple extension of the <code>Sling</code> class which registers the
system bundle's <code>BundleContext</code> as a servlet context attribute of
the Sling web application. This allows Servlet Container bridging to properly
work.</td>
+</tr>
+<tr>
+<td>SlingHttpSessionListenerDelegate</td>
+<td>This class is loaded by the <code>LauncherClassLoader</code> called from
the <code>SlingSessionListener</code>. It is called by the
<code>SlingSessionListener</code> to forward servlet container events to
registered Servlet API listener services.</td>
+</tr>
+<tr>
+<td>SlingServletDelegate</td>
+<td>This class is loaded by the <code>Loader</code> from the
<code>LauncherClassLoader</code> to actually complete the initial setup before
creating the <code>SlingBridge</code> class to start the framework.</td>
+</tr>
+</tbody>
+</table>
<p>At the moment these classes, particularly the <code>SlingServlet</code>
class, are not particularly well suited to be extended by a servlet slightly
modifying the launcher.</p>
<div class="timestamp" style="margin-top: 30px; font-size: 80%;
text-align: right;">
- Rev. 1341376 by fmeschbe on Tue, 22 May 2012 09:41:06 +0000
+ Rev. 1366518 by fmeschbe on Fri, 27 Jul 2012 20:02:17 +0000
</div>
<div class="trademarkFooter">
Apache Sling, Sling, Apache, the Apache feather logo, and the Apache
Sling project
