ncclient:NETCONF Python client

# Copyright 2009 Shikhar Bhushan

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

#    http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

from Queue import Queue

from threading import Thread, Lock, Event

from ncclient.capabilities import Capabilities

from ncclient.content import parse_root

from hello import HelloHandler

import logging

logger = logging.getLogger('ncclient.transport.session')

class Session(Thread):

    "TODO: docstring"

    def __init__(self, capabilities):

        "Subclass constructor should call this"

        Thread.__init__(self)

        self.setDaemon(True)

        self._listeners = set() # TODO(?) weakref

        self._lock = Lock()

        self.setName('session')

        self._q = Queue()

        self._client_capabilities = capabilities

        self._server_capabilities = None # yet

        self._id = None # session-id

        self._connected = False # to be set/cleared by subclass implementation

        logger.debug('%r created: client_capabilities=%r' %

                     (self, self._client_capabilities))

    def _dispatch_message(self, raw):

        "TODO: docstring"

        try:

            root = parse_root(raw)

        except Exception as e:

            logger.error('error parsing dispatch message: %s' % e)

            return

        with self._lock:

            listeners = list(self._listeners)

        for l in listeners:

            logger.debug('dispatching message to %r' % l)

            try:

                l.callback(root, raw)

            except Exception as e:

                logger.warning('[error] %r' % e)

    def _dispatch_error(self, err):

        "TODO: docstring"

        with self._lock:

            listeners = list(self._listeners)

        for l in listeners:

            logger.debug('dispatching error to %r' % l)

            try:

                l.errback(err)

            except Exception as e:

                logger.warning('error %r' % e)

    def _post_connect(self):

        "Greeting stuff"

        init_event = Event()

        error = [None] # so that err_cb can bind error[0]. just how it is.

        # callbacks

        def ok_cb(id, capabilities):

            self._id = id

            self._server_capabilities = Capabilities(capabilities)

            init_event.set()

        def err_cb(err):

            error[0] = err

            init_event.set()

        listener = HelloHandler(ok_cb, err_cb)

        self.add_listener(listener)

        self.send(HelloHandler.build(self._client_capabilities))

        logger.debug('starting main loop')

        self.start()

        # we expect server's hello message

        init_event.wait()

        # received hello message or an error happened

        self.remove_listener(listener)

        if error[0]:

            raise error[0]

        logger.info('initialized: session-id=%s | server_capabilities=%s' %

                     (self._id, self._server_capabilities))

    def add_listener(self, listener):

        "TODO: docstring"

        logger.debug('installing listener %r' % listener)

        with self._lock:

            self._listeners.add(listener)

    def remove_listener(self, listener):

        "TODO: docstring"

        logger.debug('discarding listener %r' % listener)

        with self._lock:

            self._listeners.discard(listener)

    def get_listener_instance(self, cls):

        '''This is useful when we want to maintain one listener of a particular

        type per subject i.e. a multiton.

        '''

        with self._lock:

            for listener in self._listeners:

                if isinstance(listener, cls):

                    return listener

    def connect(self, *args, **kwds):

        "Subclass implements"

        raise NotImplementedError

    def run(self):

        "Subclass implements"

        raise NotImplementedError

    def send(self, message):

        "TODO: docstring"

        logger.debug('queueing %s' % message)

        self._q.put(message)

    ### Properties

    @property

    def client_capabilities(self):

        return self._client_capabilities

    @property

    def server_capabilities(self):

        return self._server_capabilities

    @property

    def connected(self):

        return self._connected

    @property

    def id(self):

        return self._id

    @property

    def can_pipeline(self):

        return True