'Overridden by the sub-class to handle connection requests.
This class creates a thread-pool using a Windows completion port,
and dispatches requests via this port.  Sub-classes can generally
implement each connection request using blocking reads and writes, and
the thread-pool will still provide decent response to the end user.
The sub-class can set a max_workers attribute (default is 20).  Note
that this generally does *not* mean 20 threads will all be concurrently
running, via the magic of Windows completion ports.
There is no default implementation - sub-classes must implement this.'

def Dispatch(self, ecb):

    raise NotImplementedError('sub-classes    should    override    Dispatch')
