About the OpenEJB Tomcat Integration

Plug-in, not a bundle

Typically ejb servers have embedded Tomcat into their platforms, requiring you to switch platforms and use the Tomcat version they ship. We've taken the opposite approach and have created an integration that embeds OpenEJB into your existing Tomcat setup. This gives you several advantages:

Advantages for you

	You can keep your working Tomcat installation.
	No need to port webapps over to a platform where Tomcat has been embedded.
	You can use whatever version of Tomcat you want.
	Upgrade to different Tomcat versions whenever you feel like it.
	No need to convince anyone to switch platforms to use EJB.
	No change to your Tomcat install.
	You can plug-in OpenEJB and unplug it without modifying your Tomcat configs.

On the technical side

The integration consists of a servlet in this webapp that is configured to load on startup. When loaded, it locates the OpenEJB installation via the openejb.home init-param you set in the web.xml file. Once it finds the OpenEJB installation, it walks up the classloader tree to the Tomcat common classloader and loads OpenEJB and your EJBs into the VM. After all the classes are loaded, OpenEJB is automatically started in Tomcat's VM.

When the entire process completes, you will magically have access to all you EJB class definitions from your webapp. No need to put them in the WEB-INF directories at all!. All your servlets and JSPs will have fast, network-free access to all the EJBs in OpenEJB.

The process of embedding

This is just one of the ways OpenEJB can be embedded. OpenEJB can be embedded into any VM! Read here for more details.