A servant manager supplies a POA with the ability
to activate objects on demand when the POA receives
a request targeted at an inactive object. A servant
manager is registered with a POA as a callback object,
to be invoked by the POA when necessary.
ServantManagers can either be ServantActivators or
ServantLocators. A ServantManager object must be
local to the process containing the POA objects
it is registered with.