Source code for volttron.platform.vip.agent.subsystems.hello

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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)