ServerIOHandler is a
TIdServerIOHandler property that represents the input / output handler used by listener threads that accept client connections for the server. ServerIOHandler will get an instance of
TIdServerIOHandlerSocket assigned to the property when the server becomes
Active, if another class instance has not already been assigned. Applications can assign another
TIdServerIOHandler descendant to the property prior to setting
Active to True.
TIdListenerThread uses the ServerIOHandler for the server when the listener thread is executed.