TomEE - Detecting Webapp Deployment

Setup your environment for a TomEE debugging session

To understand the TomEE startup process

Once TomEE jars are loaded into Tomcat and initialized, There should be a way of detecting deployments of the other webapps. This is again achieved through a Tomcat's favourite Lifecycle Listener named GlobalListenerSupport.

The TomcatWebappBuilder class can be considered as the main contirbutor of this process. When TomEE initialized,

• It creates a new instance of TomcatWebappBuilder.
• The TomcatWebappBulder creates an instance of GlobalListenerSupport.
• GlobalListenerSupport holds a reference to TomcatWebappBulderInstance.
• The GlobalListenerSupport is registered to the Server as a lifecycle listener

Now when a lifecycle event occurred for any webapp,

• The Tomcat will trigger the GlobalListenerSupport since it is a lifecycle listener.
• The GlobalListener will simply filter the relevant events and call the relevant method of the TomcatWebappBuilder  reference.

This is how the TomcatWebappBuilder get to know about webapp deployment & undeployment.