OpenEJB Tomcat Integration

There are a few approaches to integrate OpenEJB and Jakarta Tomcat. The difference between them is in the visibility of EJBs (deployed onto OpenEJB) amongst web applications (deployed onto Tomcat). The term visibility means what classloaders handle loading of the EJBs.
OpenEJB configuration by its visibility

	OpenEJB per Tomcat instance - deployed EJBs are shared amongst all of the web apps
	OpenEJB per webapp - deployed EJBs are visible only to the web apps that declared to load OpenEJB
	OpenEJB Tomcat resource factory - an implementation of Tomcat's resource factory mechanism

Configure OpenEJB per Tomcat instance requires the following steps:

1. Copy the war/openejb-loader-1.0-SNAPSHOT.war into the webapps dir of a running Tomcat install

Under Unix

$ cd $OPENEJB_HOME $ cp war/openejb-loader-1.0-SNAPSHOT.war $CATALINA_HOME/webapps

or

Under Windows

c:/> cd %OPENEJB_HOME% %OPENEJB_HOME%> cp war/openejb-loader-1.0-SNAPSHOT.war %CATALINA_HOME%/webapps

2. Update the openejb.home init param (inside the WEB-INF/web.xml file) to point to where OpenEJB was installed.
   If OpenEJB has been built from the source you can skip it (during the build procedure it is updated automatically)
   

Under Unix

$ cd $CATALINA_HOME/webapps $ jar -xvf openejb-loader-1.0-SNAPSHOT.war WEB-INF/web.xml ...edit WEB-INF/web.xml... $ jar -uvf openejb-loader-1.0-SNAPSHOT.war WEB-INF/web.xml $ rm -rf WEB-INF

or

Under Windows

c:/> cd %CATALINA_HOME%/webapps %CATALINA_HOME%/webapps> jar -xvf openejb-loader-1.0-SNAPSHOT.war WEB-INF/web.xml ...edit WEB-INF/web.xml... %CATALINA_HOME%/webapps> jar -uvf openejb-loader-1.0-SNAPSHOT.war WEB-INF/web.xml %CATALINA_HOME%/webapps> rmdir /S /Q WEB-INF

3. Create the temp directory under Tomcat's home directory

NOTE

This is because the beans that's been successfully validated are deployed. During validation OpenEJB creates temporary files under the temp.dir directory, which is overriden by Tomcat to its temp directory. Unfortunatelly, the directory doesn't exist and needs to be created manually.

4. Deploy your webapps that are using the beans deployed onto OpenEJB
5. Start up Tomcat and have fun with the EJBs

Configure OpenEJB per webapp requires the following steps:

1. Copy the openejb-loader-*.jar into the WEB-INF/lib directory of the webapp that is to use EJBs deployed onto OpenEJB
2. Add the loader servlet definition to the WEB-INF/web.xml file of the webapp with a valid value for openejb.home init-param.

   <servlet> <servlet-name>loader</servlet-name> <servlet-class>org.openejb.loader.LoaderServlet</servlet-class> <init-param> <param-name>openejb.loader</param-name> <param-value>tomcat-webapp</param-value> </init-param> <init-param> <param-name>openejb.home</param-name> <param-value>...define OPENEJB_HOME here...</param-value> </init-param> <load-on-startup>0</load-on-startup> </servlet>

   Should you define other OpenEJB configuration settings use another <init-param> stanza. It's just for that. These parameters are directly passed to OpenEJB at initialization of the servlet. Think about the loader servlet as a bridge between OpenEJB's world (EJBs) and Tomcat's world (servlets, JSPs).

   At startup OpenEJB prints out all of the configuration settings to Tomcat logs:

   INFO: Installing web application at context path /openejb from URL file:C:\webapps\openejb OpenEJB init-params: param-name: openejb.home, param-value: c:\openejb param-name: openejb.configuration, param-value: conf\openejb.cfg param-name: openejb.base, param-value: c:\webapps\openejb\WEB-INF\openejb param-name: openejb.loader, param-value: tomcat-webapp

3. Start up Tomcat and have fun with the EJBs

Read about it here.

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, please email the text to the OpenEJB User list.

	How does the integration work
	Where to put your ejb classes
	How to configure java:comp/env lookups (short)
	How to configure java:comp/env lookups (detailed)

Misc:

	Basic info
	Servlets FAQ