from __future__ import print_function, division, absolute_import
from abc import ABCMeta, abstractmethod
from six import with_metaclass
[docs]class Backend(with_metaclass(ABCMeta)):
"""
A communication backend, selected by a given URI scheme (e.g. 'tcp').
"""
# I/O
@abstractmethod
[docs] def get_connector(self):
"""
Get a connector object usable for connecting to addresses.
"""
@abstractmethod
[docs] def get_listener(self, loc, handle_comm, deserialize, **connection_args):
"""
Get a listener object for the scheme-less address *loc*.
"""
# Address handling
@abstractmethod
[docs] def get_address_host(self, loc):
"""
Get a host name (normally an IP address) identifying the host the
address is located on.
*loc* is a scheme-less address.
"""
@abstractmethod
[docs] def resolve_address(self, loc):
"""
Resolve the address into a canonical form.
*loc* is a scheme-less address.
Simple implementations may return *loc* unchanged.
"""
[docs] def get_address_host_port(self, loc):
"""
Get the (host, port) tuple of the scheme-less address *loc*.
This should only be implemented by IP-based transports.
"""
raise NotImplementedError
@abstractmethod
[docs] def get_local_address_for(self, loc):
"""
Get the local listening address suitable for reaching *loc*.
"""
# The {scheme: Backend} mapping
backends = {}
def get_backend(scheme):
"""
Get the Backend instance for the given *scheme*.
"""
backend = backends.get(scheme)
if backend is None:
raise ValueError("unknown address scheme %r (known schemes: %s)"
% (scheme, sorted(backends)))
return backend