= Tomcat
:jbake-type: page
:jbake-status: published

== Introduction

The OpenEJB plugin for Tomcat makes all of the OpenEJB features available to Servlets, including:

* @Annotations ** @Resource ** @PersistenceUnit ** @PersistenceContext ** @EJB
* JPA - Java Persistence Architecture
* JMS - Java Messaging Service
* JTA - Transaction Processing ** TransactionManager ** Container Managed Transactions ** XA Support
* JavaMail

In addition, WAR files can contain EJB modules and JPA persistence units eliminating the annoying construction of .ear files.
Adding EJBs and JPA Persistence beans to your application is as simple as adding the @Stateless, @Stateful, @MessageDriven or @Entity to a class.
The packaging is refered to as xref:collapsed-ear.adoc[Collapsed EAR]  style as the war file, ejb jar, and persistence unit files are merged into one archive and share the same classloader.

_Requirements:_

* OpenEJB 3.x
* Tomcat 6.x or 5.5
* Java 1.5 or 1.6

== Installation for the Impatient

Assuming you have a xref:tomcat-installation.adoc[normal working Tomcat 6.x or 5.5 installation] :

. Download xref:download-ng.adoc[openejb.war]
. Copy openejb.war to ${catalina.base}/webapps/openejb.war (Note: the file _must_ be named openejb.war)
. Start Tomcat if it is not already running
. (optional) Visit http://localhost:8080/openejb/installer  and click the 'install' button

== Examples, Tutorials and Tests

=== ejb-examples.war

See the webapps/ejb-examples/ directory in the xref:download-ng.adoc[openejb-examples zip] .

== Problems?

=== HTTP Status 403

Did you get a "HTTP Status 403" error page containing the description "Access to the specified resource () has been forbidden." when visiting http://localhost:8080/openejb ?

The openejb.war is protected by a Tomcat valve that restricts access to the application to the computer on which Tomcat is running.
If your browser is running on the same computer as Tomcat, try accessing OpenEJB using this link instead http://127.0.0.1:8080/openejb .

If you want to access the openejb.war from another computer, you will need to either remove the valve, or modify the IP list in the valve declaration.

The easiest way to remove the valve it to simply delete the webapps/openejb/META-INF/context.xml file and the webapps/openejb.war file _while Tomcat is stopped_.
Warning that Tomcat keeps a copy of all context.xml files under conf/Catalina/localhost/+++<appname>+++.xml, so you may need to delete the conf/Catalina/localhost/openejb.xml file as well.
The openejb.war file must be removed because some versions of Tomcat will use the context.xml file packed in the openejb.war file regardless of what is in the unpacked directory.+++</appname>+++

=== DuplicateDeploymentIdException:

If you try to deploy the same ejb in two different web applications, then you will get the following exception (in conf/openejb.log):

 org.apache.openejb.DuplicateDeploymentIdException: Application cannot be deployed as it contains deployment-ids which are in use:

To fix the issue, do the following:

. Create a file named system.properties under the conf directory
. Add the following to the system.properties file and save
+
openejb.deploymentId.format=\{moduleId}/\{ejbName}

=== java.lang.OutOfMemoryError: PermGen space

By default, the JVM starts with a small PermGen.
Tomcat does not increase this limit, so you may encounter this exception by the time Tomcat deploys and executes your application.
If you get this exception, you should consider increasing the PermGen allocation for the Tomcat JVM.
You can achieve this by adding "-XX:MaxPermSize=256m" to the CATALINA_OPTS environment variable before starting Tomcat.

=== Other Issues

If you are having problems with the installation, please send a message to the OpenEJB users xref:mailing-lists.adoc[mailing list]  containing any error message(s) and the following information:

* OpenEJB Version
* Tomcat Version
* Java Version (execute java -version)
* Operating System Type and Version

== Limitations

_JavaAgent_ - OpenEJB uses OpenJPA to provide JPA and CMP persistence, and OpenJPA currently requires a JavaAgent to function properly.
This requirement is something that the OpenJPA project is working on removing.
Once removed, the OpenEJB plugin for Tomcat will no longer need to modify the startup shell scripts and you will not need to restart Tomcat after the OpenEJB installation.

== Misc

This document is a starting point for using OpenEJB in Tomcat and will evolve based on user contributions.
If you wish to contribute to this document, feel very welcome to click the 'Edit' link in the lower right and make changes and add new HOWTO's and other docs.

== JSF Injection Support

Now you can inject EJB's into JSF managed beans.
Currently we have tested with JSF 1.2 RI (Mojarra) and MyFaces v1.2.3 . We would definitely appreciate any feedback on other JSF implementations.