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from __future__ import absolute_import
import logging
import weakref
from .base import SubsystemBase
from ..errors import VIPError
from ..results import ResultsDictionary
from zmq import ZMQError
from zmq.green import ENOTSOCK
__all__ = ['Hello']
_log = logging.getLogger(__name__)
[docs]class Hello(SubsystemBase):
""" The hello subsystem allows an agent to determine its identity.
The identity is possibly a dynamically generated uuid from which the
executing agent does not know. This subsystem allows the agent to be
able to determine it's identity from a peer. By default that peer is
the connected router, however this could be another agent.
"""
def __init__(self, core):
self.core = weakref.ref(core)
self._results = ResultsDictionary()
core.register('hello', self._handle_hello, self._handle_error)
[docs] def hello(self, peer=b''):
""" Receives a welcome message from the peer (default to '' router)
The welcome message will respond with a 3 element list:
- The vip version (default 1.0)
- The peer who responded (should be the same as `peer` argument
to this function.
- The id of the requester (i.e. this object). This will be the
identity when the agent connects to the router or the specified
identity when the `Agent` is constructed.
:param peer: The peer to receive the response from.
:return: [version, peer, identity]
"""
_log.info('Requesting hello from peer ({})'.format(peer))
socket = self.core().socket
result = next(self._results)
try:
socket.send_vip(peer, b'hello', [b'hello'], msg_id=result.ident)
except ZMQError as exc:
if exc.errno == ENOTSOCK:
_log.debug("Socket send on non socket {}".format(self.core().identity))
return result
__call__ = hello
def _handle_hello(self, message):
_log.info('Handling hello message {}'.format(message))
try:
op = bytes(message.args[0])
except IndexError:
_log.error('missing hello subsystem operation')
return
if op == b'hello':
socket = self.core().socket
message.user = b''
message.args = [b'welcome', b'1.0', socket.identity, message.peer]
socket.send_vip_object(message, copy=False)
elif op == b'welcome':
try:
result = self._results.pop(bytes(message.id))
except KeyError:
return
result.set([bytes(arg) for arg in message.args[1:]])
else:
_log.error('unknown hello subsystem operation')
def _handle_error(self, sender, message, error, **kwargs):
try:
result = self._results.pop(bytes(message.id))
except KeyError:
return
result.set_exception(error)