The org.zkoss.zk.ui.util.ExecutionInit interface
From Documentation
Listener:
org.zkoss.zk.ui.util.ExecutionInit interface
A listener could implement ExecutionInit to initialize a new execution.
When ZK Loader and Update Engine created a new execution, it invokes the init method of this interface such that developers could plug the application-specific codes to initialize an execution.
Tip: Executions might be stacked. To know whether it is the first execution since a (Servlet) request is processed, you can check whether the parent argument is null.
A developer can prevent an execution from being created by throwing an exception in the init method.