User: schulze
Date: 00/11/07 12:49:37
Modified: . getting_startedJB2.htm
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<p><a href="JMX.Connector.Howto.html"><font face="Myriad
Web,Arial">JMX Connector Howto</font></a></p>
<p><a href="EJX.HowTo.Getting-Started.html"><font
face="Myriad Web,Arial">EJX HowTo: Introduction</font></a></p>
+
<p><a href="J2eeDeployment_howto.html"><font face="Myriad
Web,Arial">J2eeDeployment HowTo: Introduction</font></a></p>
<p></p>
<p><font face="Myriad Web,Arial"><b>Container developer
documentation</b></font></p>
<p><a href="container.html"><font face="Myriad
Web,Arial">jboss container architecture.</font></a></p>
1.1 jbossweb/J2eeDeployment_howto.html
Index: J2eeDeployment_howto.html
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<h1>Deployment on jBoss</h1>
<p align="right"><font size="-2">written by <a
href="mailto:[EMAIL PROTECTED]">Daniel Schulze</a></font></p>
<hr width=100%>
<p>The application deployment on jBoss is managed by the J2eeDeployer MBean.
The J2eeDeployer is able to deploy ejb.jar packages, webapplication.war
packages and j2ee application.ear packages. Furthermore he is able to deploy
unpacked ejb.jar files for development purposes.</p>
<p>The deployment is url based, so it is possible to deploy from whatever source as
long
as there is a url handler for that source available in your environment.<br>(ie.
http://somehost/applications/app.ear or file:///home/user/development/myapp.ear)</p>
<h2>The J2eeDeployer in general</h2>
<p>The J2eeDeployer currently provides 3 methods:
<ul>
<li>
<font face="Courier New,Courier">void <b>deploy</b> (URL)<br>
</font>this method starts the deployment process for the application this
URL points to. The URL can be a file: or a http:// or any other type
of url your environment is capable to handle. In case of deploying a unpacked
ejb.jar package the URL type is currently limited to file.<br>
The deployment of an already deployed application (the name of the app
is significant) will result in an undeployment of this app followed by
a redeployment.</li>
<li>
<font face="Courier New,Courier">void <b>undeploy</b> (URL or Application
name)<br>
</font>use this to undeploy an application. the parameter can be the URL
that was used to deploy this application or just the name (application name = file
name of the app package or directory name in case of unpacked) of the
application.</li>
<li>
<font face="Courier New,Courier">boolean <b>isDeployed</b> (URL or
Application name)<br>
</font>use this method to ask for the state of an application. The argument
follows the same rules as for the undeploy method.</li>
</ul>
</p>
<p>
These 3 methods can be used via the web interface of jBoss at port 8082
at the host jBoss is running on.</p>
<h2>The AutoDeployer as helper</h2>
<p>The AutoDeployer MBean is a helper for the J2eeDeployer to allow doing
administration smoothly via drag and drop or to automate the redeployment
in case of development. He observes the given directories for changes and
calls the appropriate methods on the J2eeDeployer.
<br>The AutoDeployer observes the timestamps of the application packages
or the timestamp of the META-INF/ejb-jar.xml file in case of unpacked ejb.jar
files.</p>
<p>The AutoDeployer is configured whether static by the MLET configuration or
dynamic by adding urls to watch for in its web interface (port 8082 at the host
jBoss is running on).</p>
<p>In its current version the AutoDeployer supports only local directories to
observe.</p>
<p>To deploy an ejb, web or ear package simply drop it in one of the observed
directories.
To autodeploy an unpacked ejb application, add the base directory of that application
(base directory = the directory which containes the META-INF directory) to the
AutoDeployers
observed urls.</p>
<p><i>Note: There is still a misbehavior when the autodeployer thread wins
the race against the copy thread which modifies a package!</i>
<br>
<hr WIDTH="100%">
<h2>Creating J2EE applications</h2>
<p> j2ee applications or .ear files are jar archives containing a collection of ejb,
web, client, connector and/or other library packages. Currently jBoss only supports
ejb, web
and other library packages (client and connector packages are ignored if
present).<br>
Other Library packages are class packages that are needed by your application and
are not
provided by the j2ee runtime environment (ie: some xml tools)</p>
<p>This document will only describe the jBoss relevant stuff in creating j2ee
packages
for a detailed description of how to build such applications see the <a
href="http://java.sun.com/j2ee/download.html#platformspec">
J2EE specification under chapter 8</a>!</p>
<p>First create all ejb, war and library archives you want to put together to make
up your
application. Make sure that all dependencies are solved, means: all classes that are
needed
by your application must be contained in your application (besides the classes that
made up the
J2EE platform (java core, javax.transaction, javax.sql, javax.servlet ...). Its up
to you
to create an arbitrary directory structure for your application to make it easier to
maintain.
Once you ve created your structure and moved all files on their place you have to
create a
deployment descriptor. This file must reside in the
<code><your_app_dir>/META-INF</code>
directory and must be named <code>application.xml</code>.
</p>
<table bgcolor="#eeeeee">
<tr><td>example:</td></tr>
<tr><td>
<p>the content of a simple <code>application.xml</code> file:
<pre>
<application>
<display-name>My Application</display-name>
<module>
<web>
<web-uri>web-app.war</web-uri>
<context-root>/myapp</context-root>
</web>
</module>
<module>
<ejb>ejb-app.jar</ejb>
</module>
</application>
</pre></p>
</td></tr>
</table>
<p>This descriptor describes an application that contains a web application package
(JSPs/Servlets/HTML) and an ejb application (EJBs).<br>
The web applications war package is located at the root of the .ear file and is
named <code>
web-app.war</code>. It will be deployed under the webcontext <i>/myapp</i>.<br> The
ejb package
also resides in the applications root directory and is called
<code>ejb-app.jar</code>.</p>
<p><strong>understanding the shared classloader architecture in jBoss</strong></p>
<p>When an application in jBoss gets deployed, every module will get deployed by a
separate
container.<br>
Every container will get its own classloader - this means that a call from one
module to
an other must be an remote call and all parameters must be serialized, because the
classes
(even if they are loaded from the same physical file) are not compatible across
container
boundaries.
To allow optimized interaction across container boundaries (local calls with
parameter ... per
reference) the classes that are involved in this communication must be loaded by the
same classloader.</p>
<p>In jBoss we achieve this issue with the following classloader architecture:
<ul>
<li>On deployment one - <i>common</i> - classloader is created. This classloader
will get all archives in its
classpath that are referenced (<code>MANIFEST.MF/Class-Path</code>)by any module
contained in this
application.</li>
<li>When afterwards all modules become deployed in their containers, the
classloaders created by these
containers are all children of the <i>common</i> classloader. </li>
<li>Now on runtime the communication between modules across container boundaries can
be optimized when
the classes used for the communication are loaded by the <i>common</i>
classloader.</li>
</ul></p>
<table bgcolor="#eeeeee">
<tr><td>example (continued):</td></tr>
<tr><td>
<p>To allow our previous mentioned simple example to make use of the optimization,
we must provide the
classes the web module needs to communicate with the ejb module in an separate third
package, lets call
it <code>ejb-client.jar</code>. This ejb-client.jar archive contains the remote
interfaces of the ejbs
and special method parameter types that are needed for the communication (if any).
Now we put this
package in the directory <code>/lib</code> of our application.</p>
<p>To make sure that this package is now loaded by the common classloader, we
reference it from within
the web package by adding a <code>Class-Path:</code> entry to the web packages
MANIFEST.MF file that
it looks something like that:
<pre>
Manifest-Version: 1.0
Class-Path: ./lib/ejb-client.jar
</pre>
</p>
<p>Now you just jar your applications directory, name it <anyhow>.ear, and
drop it in one of
jBoss' autodeploy directories...
</p>
<p>the content of our simple applications archive:
<pre>
META-INF/
META-INF/MANIFEST.MF
META-INF/application.xml
ejb-app.jar
web-app.war
lib/
lib/ejb-client.jar
</pre>
</p>
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