init and destroy functions in an application scope axis2 service

[Gul Onural]

 
I see init and destroy functions implemented in one of the samples
(servicelifecycle) in Axis2 distro.
 
public void init(ServiceContext serviceContext) 
public void destroy(ServiceContext serviceContext) throws AxisFault
 
When are these functions get invoked for a service that is deployed as
"application" scope service?
What happens if an "application" scope service doesn't implement those
functions?
 
Gul