Source code for autobahn.wamp.serializer

###############################################################################
##
##  Copyright (C) 2013-2014 Tavendo GmbH
##
##  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.
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###############################################################################

from __future__ import absolute_import

## note: __all__ must be a list here, since we dynamically
## extend it depending on availability of more serializers
__all__ = ['Serializer',
           'JsonObjectSerializer',
           'JsonSerializer']

import six
import struct

from autobahn.wamp.interfaces import IObjectSerializer, ISerializer
from autobahn.wamp.exception import ProtocolError
from autobahn.wamp import message



[docs]class Serializer: """ Base class for WAMP serializers. A WAMP serializer is the core glue between parsed WAMP message objects and the bytes on wire (the transport). """ MESSAGE_TYPE_MAP = { message.Hello.MESSAGE_TYPE: message.Hello, message.Welcome.MESSAGE_TYPE: message.Welcome, message.Abort.MESSAGE_TYPE: message.Abort, message.Challenge.MESSAGE_TYPE: message.Challenge, message.Authenticate.MESSAGE_TYPE: message.Authenticate, message.Goodbye.MESSAGE_TYPE: message.Goodbye, message.Heartbeat.MESSAGE_TYPE: message.Heartbeat, message.Error.MESSAGE_TYPE: message.Error, message.Publish.MESSAGE_TYPE: message.Publish, message.Published.MESSAGE_TYPE: message.Published, message.Subscribe.MESSAGE_TYPE: message.Subscribe, message.Subscribed.MESSAGE_TYPE: message.Subscribed, message.Unsubscribe.MESSAGE_TYPE: message.Unsubscribe, message.Unsubscribed.MESSAGE_TYPE: message.Unsubscribed, message.Event.MESSAGE_TYPE: message.Event, message.Call.MESSAGE_TYPE: message.Call, message.Cancel.MESSAGE_TYPE: message.Cancel, message.Result.MESSAGE_TYPE: message.Result, message.Register.MESSAGE_TYPE: message.Register, message.Registered.MESSAGE_TYPE: message.Registered, message.Unregister.MESSAGE_TYPE: message.Unregister, message.Unregistered.MESSAGE_TYPE: message.Unregistered, message.Invocation.MESSAGE_TYPE: message.Invocation, message.Interrupt.MESSAGE_TYPE: message.Interrupt, message.Yield.MESSAGE_TYPE: message.Yield } """ Mapping of WAMP message type codes to WAMP message classes. """ def __init__(self, serializer): """ Constructor. :param serializer: The object serializer to use for WAMP wire-level serialization. :type serializer: An object that implements :class:`autobahn.interfaces.IObjectSerializer`. """ self._serializer = serializer
[docs] def serialize(self, msg): """ Implements :func:`autobahn.wamp.interfaces.ISerializer.serialize` """ return msg.serialize(self._serializer), self._serializer.BINARY
[docs] def unserialize(self, payload, isBinary = None): """ Implements :func:`autobahn.wamp.interfaces.ISerializer.unserialize` """ if isBinary is not None: if isBinary != self._serializer.BINARY: raise ProtocolError("invalid serialization of WAMP message (binary {0}, but expected {1})".format(isBinary, self._serializer.BINARY)) try: raw_msgs = self._serializer.unserialize(payload) except Exception as e: raise ProtocolError("invalid serialization of WAMP message ({0})".format(e)) msgs = [] for raw_msg in raw_msgs: if type(raw_msg) != list: raise ProtocolError("invalid type {0} for WAMP message".format(type(raw_msg))) if len(raw_msg) == 0: raise ProtocolError(u"missing message type in WAMP message") message_type = raw_msg[0] if type(message_type) != int: raise ProtocolError("invalid type {0} for WAMP message type".format(type(message_type))) Klass = self.MESSAGE_TYPE_MAP.get(message_type) if Klass is None: raise ProtocolError("invalid WAMP message type {0}".format(message_type)) ## this might again raise `ProtocolError` .. msg = Klass.parse(raw_msg) msgs.append(msg) return msgs
## ## JSON serialization is always supported ## try: ## try import accelerated JSON implementation ## import ujson _json = ujson _loads = lambda val: ujson.loads(val, precise_float = True) _dumps = lambda obj: ujson.dumps(obj, double_precision = 15, ensure_ascii = False) except ImportError: ## fallback to stdlib implementation ## import json _json = json _loads = json.loads _dumps = lambda obj: json.dumps(obj, separators = (',',':'), ensure_ascii = False) finally:
[docs] class JsonObjectSerializer:
JSON_MODULE = _json """ The JSON module used (either stdib builtin or ujson). """ BINARY = False def __init__(self, batched = False): """ Ctor. :param batched: Flag that controls whether serializer operates in batched mode. :type batched: bool """ self._batched = batched def serialize(self, obj): """ Implements :func:`autobahn.wamp.interfaces.IObjectSerializer.serialize` """ s = _dumps(obj) if isinstance(s, six.text_type): s = s.encode('utf8') if self._batched: return s + b'\30' else: return s def unserialize(self, payload): """ Implements :func:`autobahn.wamp.interfaces.IObjectSerializer.unserialize` """ if self._batched: chunks = payload.split(b'\30')[:-1] else: chunks = [payload] if len(chunks) == 0: raise Exception("batch format error") return [_loads(data.decode('utf8')) for data in chunks] IObjectSerializer.register(JsonObjectSerializer)
[docs]class JsonSerializer(Serializer):
SERIALIZER_ID = "json" MIME_TYPE = "application/json" def __init__(self, batched = False): """ Ctor. :param batched: Flag to control whether to put this serialized into batched mode. :type batched: bool """ Serializer.__init__(self, JsonObjectSerializer(batched = batched)) if batched: self.SERIALIZER_ID = "json.batched" ISerializer.register(JsonSerializer) ## ## MsgPack serialization depends on the `msgpack` package being available ## try: import msgpack except ImportError: pass else:
[docs] class MsgPackObjectSerializer:
BINARY = True """ Flag that indicates whether this serializer needs a binary clean transport. """ ENABLE_V5 = True """ Enable version 5 of the MsgPack specification (which differentiates between strings and binary). """ def __init__(self, batched = False): """ Ctor. :param batched: Flag that controls whether serializer operates in batched mode. :type batched: bool """ self._batched = batched def serialize(self, obj): """ Implements :func:`autobahn.wamp.interfaces.IObjectSerializer.serialize` """ data = msgpack.packb(obj, use_bin_type = self.ENABLE_V5) if self._batched: return struct.pack("!L", len(data)) + data else: return data def unserialize(self, payload): """ Implements :func:`autobahn.wamp.interfaces.IObjectSerializer.unserialize` """ if self._batched: msgs = [] N = len(payload) i = 0 while i < N: ## read message length prefix if i + 4 > N: raise Exception("batch format error [1]") l = struct.unpack("!L", payload[i:i+4])[0] ## read message data if i + 4 + l > N: raise Exception("batch format error [2]") data = payload[i+4:i+4+l] ## append parsed raw message msgs.append(msgpack.unpackb(data, encoding = 'utf-8')) ## advance until everything consumed i = i+4+l if i != N: raise Exception("batch format error [3]") return msgs else: return [msgpack.unpackb(payload, encoding = 'utf-8')] IObjectSerializer.register(MsgPackObjectSerializer) __all__.append('MsgPackObjectSerializer')
[docs] class MsgPackSerializer(Serializer):
SERIALIZER_ID = "msgpack" MIME_TYPE = "application/x-msgpack" def __init__(self, batched = False): """ Ctor. :param batched: Flag to control whether to put this serialized into batched mode. :type batched: bool """ Serializer.__init__(self, MsgPackObjectSerializer(batched = batched)) if batched: self.SERIALIZER_ID = "msgpack.batched" ISerializer.register(MsgPackSerializer) __all__.append('MsgPackSerializer')
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