sdks/python/apache_beam/io/gcp/pubsub.py - beam - Git at Google

 #
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.
 # The ASF licenses this file to You 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.
 #
 """Google Cloud PubSub sources and sinks.

 Cloud Pub/Sub sources and sinks are currently supported only in streaming
 pipelines, during remote execution.

 This API is currently under development and is subject to change.
 """

 from __future__ import absolute_import

 import re
 from builtins import object

 from past.builtins import unicode

 from apache_beam import coders
 from apache_beam.io.iobase import Read
 from apache_beam.io.iobase import Write
 from apache_beam.runners.dataflow.native_io import iobase as dataflow_io
 from apache_beam.transforms import Map
 from apache_beam.transforms import PTransform
 from apache_beam.transforms.display import DisplayDataItem
 from apache_beam.utils.annotations import deprecated

 try:
   from google.cloud import pubsub
 except ImportError:
   pubsub = None

 __all__ = ['PubsubMessage', 'ReadFromPubSub', 'ReadStringsFromPubSub',
            'WriteStringsToPubSub', 'WriteToPubSub']


 class PubsubMessage(object):
   """Represents a Cloud Pub/Sub message.

   Message payload includes the data and attributes fields. For the payload to be
   valid, at least one of its fields must be non-empty.

   This interface is experimental. No backwards compatibility guarantees.

   Attributes:
     data: (bytes) Message data. May be None.
     attributes: (dict) Key-value map of str to str, containing both user-defined
       and service generated attributes (such as id_label and
       timestamp_attribute). May be None.
   """

   def __init__(self, data, attributes):
     if data is None and not attributes:
       raise ValueError('Either data (%r) or attributes (%r) must be set.',
                        data, attributes)
     self.data = data
     self.attributes = attributes

   def __hash__(self):
     return hash((self.data, frozenset(self.attributes.items())))

   def __eq__(self, other):
     return isinstance(other, PubsubMessage) and (
         self.data == other.data and
         self.attributes == other.attributes)

   def __repr__(self):
     return 'PubsubMessage(%s, %s)' % (self.data, self.attributes)

   @staticmethod
   def _from_proto_str(proto_msg):
     """Construct from serialized form of ``PubsubMessage``.

     Args:
       proto_msg: String containing a serialized protobuf of type
       https://cloud.google.com/pubsub/docs/reference/rpc/google.pubsub.v1#google.pubsub.v1.PubsubMessage

     Returns:
       A new PubsubMessage object.
     """
     msg = pubsub.types.pubsub_pb2.PubsubMessage()
     msg.ParseFromString(proto_msg)
     # Convert ScalarMapContainer to dict.
     attributes = dict((key, msg.attributes[key]) for key in msg.attributes)
     return PubsubMessage(msg.data, attributes)

   def _to_proto_str(self):
     """Get serialized form of ``PubsubMessage``.

     Args:
       proto_msg: str containing a serialized protobuf.

     Returns:
       A str containing a serialized protobuf of type
       https://cloud.google.com/pubsub/docs/reference/rpc/google.pubsub.v1#google.pubsub.v1.PubsubMessage
       containing the payload of this object.
     """
     msg = pubsub.types.pubsub_pb2.PubsubMessage()
     msg.data = self.data
     for key, value in self.attributes.iteritems():
       msg.attributes[key] = value
     return msg.SerializeToString()

   @staticmethod
   def _from_message(msg):
     """Construct from ``google.cloud.pubsub_v1.subscriber.message.Message``.

     https://googleapis.github.io/google-cloud-python/latest/pubsub/subscriber/api/message.html
     """
     # Convert ScalarMapContainer to dict.
     attributes = dict((key, msg.attributes[key]) for key in msg.attributes)
     return PubsubMessage(msg.data, attributes)


 class ReadFromPubSub(PTransform):
   """A ``PTransform`` for reading from Cloud Pub/Sub."""
   # Implementation note: This ``PTransform`` is overridden by Directrunner.

   def __init__(self, topic=None, subscription=None, id_label=None,
                with_attributes=False, timestamp_attribute=None):
     """Initializes ``ReadFromPubSub``.

     Args:
       topic: Cloud Pub/Sub topic in the form
         "projects/<project>/topics/<topic>". If provided, subscription must be
         None.
       subscription: Existing Cloud Pub/Sub subscription to use in the
         form "projects/<project>/subscriptions/<subscription>". If not
         specified, a temporary subscription will be created from the specified
         topic. If provided, topic must be None.
       id_label: The attribute on incoming Pub/Sub messages to use as a unique
         record identifier. When specified, the value of this attribute (which
         can be any string that uniquely identifies the record) will be used for
         deduplication of messages. If not provided, we cannot guarantee
         that no duplicate data will be delivered on the Pub/Sub stream. In this
         case, deduplication of the stream will be strictly best effort.
       with_attributes:
         True - output elements will be :class:`~PubsubMessage` objects.
         False - output elements will be of type ``bytes`` (message
         data only).
       timestamp_attribute: Message value to use as element timestamp. If None,
         uses message publishing time as the timestamp.

         Timestamp values should be in one of two formats:

         - A numerical value representing the number of milliseconds since the
           Unix epoch.
         - A string in RFC 3339 format, UTC timezone. Example:
           ``2015-10-29T23:41:41.123Z``. The sub-second component of the
           timestamp is optional, and digits beyond the first three (i.e., time
           units smaller than milliseconds) may be ignored.
     """
     super(ReadFromPubSub, self).__init__()
     self.with_attributes = with_attributes
     self._source = _PubSubSource(
         topic=topic,
         subscription=subscription,
         id_label=id_label,
         with_attributes=self.with_attributes,
         timestamp_attribute=timestamp_attribute)

   def expand(self, pvalue):
     pcoll = pvalue.pipeline | Read(self._source)
     pcoll.element_type = bytes
     if self.with_attributes:
       pcoll = pcoll | Map(PubsubMessage._from_proto_str)
       pcoll.element_type = PubsubMessage
     return pcoll

   def to_runner_api_parameter(self, context):
     # Required as this is identified by type in PTransformOverrides.
     # TODO(BEAM-3812): Use an actual URN here.
     return self.to_runner_api_pickled(context)


 @deprecated(since='2.7.0', extra_message='Use ReadFromPubSub instead.')
 def ReadStringsFromPubSub(topic=None, subscription=None, id_label=None):
   return _ReadStringsFromPubSub(topic, subscription, id_label)


 class _ReadStringsFromPubSub(PTransform):
   """This class is deprecated. Use ``ReadFromPubSub`` instead."""

   def __init__(self, topic=None, subscription=None, id_label=None):
     super(_ReadStringsFromPubSub, self).__init__()
     self.topic = topic
     self.subscription = subscription
     self.id_label = id_label

   def expand(self, pvalue):
     p = (pvalue.pipeline
          | ReadFromPubSub(self.topic, self.subscription, self.id_label,
                           with_attributes=False)
          | 'DecodeString' >> Map(lambda b: b.decode('utf-8')))
     p.element_type = unicode
     return p


 @deprecated(since='2.7.0', extra_message='Use WriteToPubSub instead.')
 def WriteStringsToPubSub(topic):
   return _WriteStringsToPubSub(topic)


 class _WriteStringsToPubSub(PTransform):
   """This class is deprecated. Use ``WriteToPubSub`` instead."""

   def __init__(self, topic):
     """Initializes ``_WriteStringsToPubSub``.

     Attributes:
       topic: Cloud Pub/Sub topic in the form "/topics/<project>/<topic>".
     """
     super(_WriteStringsToPubSub, self).__init__()
     self._sink = _PubSubSink(topic, id_label=None, with_attributes=False,
                              timestamp_attribute=None)

   def expand(self, pcoll):
     pcoll = pcoll | 'EncodeString' >> Map(lambda s: s.encode('utf-8'))
     pcoll.element_type = bytes
     return pcoll | Write(self._sink)


 class WriteToPubSub(PTransform):
   """A ``PTransform`` for writing messages to Cloud Pub/Sub."""
   # Implementation note: This ``PTransform`` is overridden by Directrunner.

   def __init__(self, topic, with_attributes=False, id_label=None,
                timestamp_attribute=None):
     """Initializes ``WriteToPubSub``.

     Args:
       topic: Cloud Pub/Sub topic in the form "/topics/<project>/<topic>".
       with_attributes:
         True - input elements will be :class:`~PubsubMessage` objects.
         False - input elements will be of type ``bytes`` (message
         data only).
       id_label: If set, will set an attribute for each Cloud Pub/Sub message
         with the given name and a unique value. This attribute can then be used
         in a ReadFromPubSub PTransform to deduplicate messages.
       timestamp_attribute: If set, will set an attribute for each Cloud Pub/Sub
         message with the given name and the message's publish time as the value.
     """
     super(WriteToPubSub, self).__init__()
     self.with_attributes = with_attributes
     self.id_label = id_label
     self.timestamp_attribute = timestamp_attribute
     self._sink = _PubSubSink(topic, id_label, with_attributes,
                              timestamp_attribute)

   @staticmethod
   def to_proto_str(element):
     if not isinstance(element, PubsubMessage):
       raise TypeError('Unexpected element. Type: %s (expected: PubsubMessage), '
                       'value: %r' % (type(element), element))
     return element._to_proto_str()

   def expand(self, pcoll):
     if self.with_attributes:
       pcoll = pcoll | 'ToProtobuf' >> Map(self.to_proto_str)

     # Without attributes, message data is written as-is. With attributes,
     # message data + attributes are passed as a serialized protobuf string (see
     # ``PubsubMessage._to_proto_str`` for exact protobuf message type).
     pcoll.element_type = bytes
     return pcoll | Write(self._sink)

   def to_runner_api_parameter(self, context):
     # Required as this is identified by type in PTransformOverrides.
     # TODO(BEAM-3812): Use an actual URN here.
     return self.to_runner_api_pickled(context)


 PROJECT_ID_REGEXP = '[a-z][-a-z0-9:.]{4,61}[a-z0-9]'
 SUBSCRIPTION_REGEXP = 'projects/([^/]+)/subscriptions/(.+)'
 TOPIC_REGEXP = 'projects/([^/]+)/topics/(.+)'


 def parse_topic(full_topic):
   match = re.match(TOPIC_REGEXP, full_topic)
   if not match:
     raise ValueError(
         'PubSub topic must be in the form "projects/<project>/topics'
         '/<topic>" (got %r).' % full_topic)
   project, topic_name = match.group(1), match.group(2)
   if not re.match(PROJECT_ID_REGEXP, project):
     raise ValueError('Invalid PubSub project name: %r.' % project)
   return project, topic_name


 def parse_subscription(full_subscription):
   match = re.match(SUBSCRIPTION_REGEXP, full_subscription)
   if not match:
     raise ValueError(
         'PubSub subscription must be in the form "projects/<project>'
         '/subscriptions/<subscription>" (got %r).' % full_subscription)
   project, subscription_name = match.group(1), match.group(2)
   if not re.match(PROJECT_ID_REGEXP, project):
     raise ValueError('Invalid PubSub project name: %r.' % project)
   return project, subscription_name


 class _PubSubSource(dataflow_io.NativeSource):
   """Source for a Cloud Pub/Sub topic or subscription.

   This ``NativeSource`` is overridden by a native Pubsub implementation.

   Attributes:
     with_attributes: If False, will fetch just message data. Otherwise,
       fetches ``PubsubMessage`` protobufs.
   """

   def __init__(self, topic=None, subscription=None, id_label=None,
                with_attributes=False, timestamp_attribute=None):
     self.coder = coders.BytesCoder()
     self.full_topic = topic
     self.full_subscription = subscription
     self.topic_name = None
     self.subscription_name = None
     self.id_label = id_label
     self.with_attributes = with_attributes
     self.timestamp_attribute = timestamp_attribute

     # Perform some validation on the topic and subscription.
     if not (topic or subscription):
       raise ValueError('Either a topic or subscription must be provided.')
     if topic and subscription:
       raise ValueError('Only one of topic or subscription should be provided.')

     if topic:
       self.project, self.topic_name = parse_topic(topic)
     if subscription:
       self.project, self.subscription_name = parse_subscription(subscription)

   @property
   def format(self):
     """Source format name required for remote execution."""
     return 'pubsub'

   def display_data(self):
     return {'id_label':
             DisplayDataItem(self.id_label,
                             label='ID Label Attribute').drop_if_none(),
             'topic':
             DisplayDataItem(self.full_topic,
                             label='Pubsub Topic').drop_if_none(),
             'subscription':
             DisplayDataItem(self.full_subscription,
                             label='Pubsub Subscription').drop_if_none(),
             'with_attributes':
             DisplayDataItem(self.with_attributes,
                             label='With Attributes').drop_if_none(),
             'timestamp_attribute':
             DisplayDataItem(self.timestamp_attribute,
                             label='Timestamp Attribute').drop_if_none(),
            }

   def reader(self):
     raise NotImplementedError

   def is_bounded(self):
     return False


 class _PubSubSink(dataflow_io.NativeSink):
   """Sink for a Cloud Pub/Sub topic.

   This ``NativeSource`` is overridden by a native Pubsub implementation.
   """

   def __init__(self, topic, id_label, with_attributes, timestamp_attribute):
     self.coder = coders.BytesCoder()
     self.full_topic = topic
     self.id_label = id_label
     self.with_attributes = with_attributes
     self.timestamp_attribute = timestamp_attribute

     self.project, self.topic_name = parse_topic(topic)

   @property
   def format(self):
     """Sink format name required for remote execution."""
     return 'pubsub'

   def display_data(self):
     return {
         'topic': DisplayDataItem(self.full_topic, label='Pubsub Topic'),
         'id_label': DisplayDataItem(self.id_label, label='ID Label Attribute'),
         'with_attributes': DisplayDataItem(
             self.with_attributes, label='With Attributes').drop_if_none(),
         'timestamp_attribute': DisplayDataItem(
             self.timestamp_attribute, label='Timestamp Attribute'),
     }

   def writer(self):
     raise NotImplementedError
	#
	# Licensed to the Apache Software Foundation (ASF) under one or more
	# contributor license agreements. See the NOTICE file distributed with
	# this work for additional information regarding copyright ownership.
	# The ASF licenses this file to You 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.
	#
	"""Google Cloud PubSub sources and sinks.

	Cloud Pub/Sub sources and sinks are currently supported only in streaming
	pipelines, during remote execution.

	This API is currently under development and is subject to change.
	"""

	from __future__ import absolute_import

	import re
	from builtins import object

	from past.builtins import unicode

	from apache_beam import coders
	from apache_beam.io.iobase import Read
	from apache_beam.io.iobase import Write
	from apache_beam.runners.dataflow.native_io import iobase as dataflow_io
	from apache_beam.transforms import Map
	from apache_beam.transforms import PTransform
	from apache_beam.transforms.display import DisplayDataItem
	from apache_beam.utils.annotations import deprecated

	try:
	from google.cloud import pubsub
	except ImportError:
	pubsub = None

	__all__ = ['PubsubMessage', 'ReadFromPubSub', 'ReadStringsFromPubSub',
	'WriteStringsToPubSub', 'WriteToPubSub']


	class PubsubMessage(object):
	"""Represents a Cloud Pub/Sub message.

	Message payload includes the data and attributes fields. For the payload to be
	valid, at least one of its fields must be non-empty.

	This interface is experimental. No backwards compatibility guarantees.

	Attributes:
	data: (bytes) Message data. May be None.
	attributes: (dict) Key-value map of str to str, containing both user-defined
	and service generated attributes (such as id_label and
	timestamp_attribute). May be None.
	"""

	def __init__(self, data, attributes):
	if data is None and not attributes:
	raise ValueError('Either data (%r) or attributes (%r) must be set.',
	data, attributes)
	self.data = data
	self.attributes = attributes

	def __hash__(self):
	return hash((self.data, frozenset(self.attributes.items())))

	def __eq__(self, other):
	return isinstance(other, PubsubMessage) and (
	self.data == other.data and
	self.attributes == other.attributes)

	def __repr__(self):
	return 'PubsubMessage(%s, %s)' % (self.data, self.attributes)

	@staticmethod
	def _from_proto_str(proto_msg):
	"""Construct from serialized form of ``PubsubMessage``.

	Args:
	proto_msg: String containing a serialized protobuf of type
	https://cloud.google.com/pubsub/docs/reference/rpc/google.pubsub.v1#google.pubsub.v1.PubsubMessage

	Returns:
	A new PubsubMessage object.
	"""
	msg = pubsub.types.pubsub_pb2.PubsubMessage()
	msg.ParseFromString(proto_msg)
	# Convert ScalarMapContainer to dict.
	attributes = dict((key, msg.attributes[key]) for key in msg.attributes)
	return PubsubMessage(msg.data, attributes)

	def _to_proto_str(self):
	"""Get serialized form of ``PubsubMessage``.

	Args:
	proto_msg: str containing a serialized protobuf.

	Returns:
	A str containing a serialized protobuf of type
	https://cloud.google.com/pubsub/docs/reference/rpc/google.pubsub.v1#google.pubsub.v1.PubsubMessage
	containing the payload of this object.
	"""
	msg = pubsub.types.pubsub_pb2.PubsubMessage()
	msg.data = self.data
	for key, value in self.attributes.iteritems():
	msg.attributes[key] = value
	return msg.SerializeToString()

	@staticmethod
	def _from_message(msg):
	"""Construct from ``google.cloud.pubsub_v1.subscriber.message.Message``.

	https://googleapis.github.io/google-cloud-python/latest/pubsub/subscriber/api/message.html
	"""
	# Convert ScalarMapContainer to dict.
	attributes = dict((key, msg.attributes[key]) for key in msg.attributes)
	return PubsubMessage(msg.data, attributes)


	class ReadFromPubSub(PTransform):
	"""A ``PTransform`` for reading from Cloud Pub/Sub."""
	# Implementation note: This ``PTransform`` is overridden by Directrunner.

	def __init__(self, topic=None, subscription=None, id_label=None,
	with_attributes=False, timestamp_attribute=None):
	"""Initializes ``ReadFromPubSub``.

	Args:
	topic: Cloud Pub/Sub topic in the form
	"projects/<project>/topics/<topic>". If provided, subscription must be
	None.
	subscription: Existing Cloud Pub/Sub subscription to use in the
	form "projects/<project>/subscriptions/<subscription>". If not
	specified, a temporary subscription will be created from the specified
	topic. If provided, topic must be None.
	id_label: The attribute on incoming Pub/Sub messages to use as a unique
	record identifier. When specified, the value of this attribute (which
	can be any string that uniquely identifies the record) will be used for
	deduplication of messages. If not provided, we cannot guarantee
	that no duplicate data will be delivered on the Pub/Sub stream. In this
	case, deduplication of the stream will be strictly best effort.
	with_attributes:
	True - output elements will be :class:`~PubsubMessage` objects.
	False - output elements will be of type ``bytes`` (message
	data only).
	timestamp_attribute: Message value to use as element timestamp. If None,
	uses message publishing time as the timestamp.

	Timestamp values should be in one of two formats:

	- A numerical value representing the number of milliseconds since the
	Unix epoch.
	- A string in RFC 3339 format, UTC timezone. Example:
	``2015-10-29T23:41:41.123Z``. The sub-second component of the
	timestamp is optional, and digits beyond the first three (i.e., time
	units smaller than milliseconds) may be ignored.
	"""
	super(ReadFromPubSub, self).__init__()
	self.with_attributes = with_attributes
	self._source = _PubSubSource(
	topic=topic,
	subscription=subscription,
	id_label=id_label,
	with_attributes=self.with_attributes,
	timestamp_attribute=timestamp_attribute)

	def expand(self, pvalue):
	pcoll = pvalue.pipeline \| Read(self._source)
	pcoll.element_type = bytes
	if self.with_attributes:
	pcoll = pcoll \| Map(PubsubMessage._from_proto_str)
	pcoll.element_type = PubsubMessage
	return pcoll

	def to_runner_api_parameter(self, context):
	# Required as this is identified by type in PTransformOverrides.
	# TODO(BEAM-3812): Use an actual URN here.
	return self.to_runner_api_pickled(context)


	@deprecated(since='2.7.0', extra_message='Use ReadFromPubSub instead.')
	def ReadStringsFromPubSub(topic=None, subscription=None, id_label=None):
	return _ReadStringsFromPubSub(topic, subscription, id_label)


	class _ReadStringsFromPubSub(PTransform):
	"""This class is deprecated. Use ``ReadFromPubSub`` instead."""

	def __init__(self, topic=None, subscription=None, id_label=None):
	super(_ReadStringsFromPubSub, self).__init__()
	self.topic = topic
	self.subscription = subscription
	self.id_label = id_label

	def expand(self, pvalue):
	p = (pvalue.pipeline
	\| ReadFromPubSub(self.topic, self.subscription, self.id_label,
	with_attributes=False)
	\| 'DecodeString' >> Map(lambda b: b.decode('utf-8')))
	p.element_type = unicode
	return p


	@deprecated(since='2.7.0', extra_message='Use WriteToPubSub instead.')
	def WriteStringsToPubSub(topic):
	return _WriteStringsToPubSub(topic)


	class _WriteStringsToPubSub(PTransform):
	"""This class is deprecated. Use ``WriteToPubSub`` instead."""

	def __init__(self, topic):
	"""Initializes ``_WriteStringsToPubSub``.

	Attributes:
	topic: Cloud Pub/Sub topic in the form "/topics/<project>/<topic>".
	"""
	super(_WriteStringsToPubSub, self).__init__()
	self._sink = _PubSubSink(topic, id_label=None, with_attributes=False,
	timestamp_attribute=None)

	def expand(self, pcoll):
	pcoll = pcoll \| 'EncodeString' >> Map(lambda s: s.encode('utf-8'))
	pcoll.element_type = bytes
	return pcoll \| Write(self._sink)


	class WriteToPubSub(PTransform):
	"""A ``PTransform`` for writing messages to Cloud Pub/Sub."""
	# Implementation note: This ``PTransform`` is overridden by Directrunner.

	def __init__(self, topic, with_attributes=False, id_label=None,
	timestamp_attribute=None):
	"""Initializes ``WriteToPubSub``.

	Args:
	topic: Cloud Pub/Sub topic in the form "/topics/<project>/<topic>".
	with_attributes:
	True - input elements will be :class:`~PubsubMessage` objects.
	False - input elements will be of type ``bytes`` (message
	data only).
	id_label: If set, will set an attribute for each Cloud Pub/Sub message
	with the given name and a unique value. This attribute can then be used
	in a ReadFromPubSub PTransform to deduplicate messages.
	timestamp_attribute: If set, will set an attribute for each Cloud Pub/Sub
	message with the given name and the message's publish time as the value.
	"""
	super(WriteToPubSub, self).__init__()
	self.with_attributes = with_attributes
	self.id_label = id_label
	self.timestamp_attribute = timestamp_attribute
	self._sink = _PubSubSink(topic, id_label, with_attributes,
	timestamp_attribute)

	@staticmethod
	def to_proto_str(element):
	if not isinstance(element, PubsubMessage):
	raise TypeError('Unexpected element. Type: %s (expected: PubsubMessage), '
	'value: %r' % (type(element), element))
	return element._to_proto_str()

	def expand(self, pcoll):
	if self.with_attributes:
	pcoll = pcoll \| 'ToProtobuf' >> Map(self.to_proto_str)

	# Without attributes, message data is written as-is. With attributes,
	# message data + attributes are passed as a serialized protobuf string (see
	# ``PubsubMessage._to_proto_str`` for exact protobuf message type).
	pcoll.element_type = bytes
	return pcoll \| Write(self._sink)

	def to_runner_api_parameter(self, context):
	# Required as this is identified by type in PTransformOverrides.
	# TODO(BEAM-3812): Use an actual URN here.
	return self.to_runner_api_pickled(context)


	PROJECT_ID_REGEXP = '[a-z][-a-z0-9:.]{4,61}[a-z0-9]'
	SUBSCRIPTION_REGEXP = 'projects/([^/]+)/subscriptions/(.+)'
	TOPIC_REGEXP = 'projects/([^/]+)/topics/(.+)'


	def parse_topic(full_topic):
	match = re.match(TOPIC_REGEXP, full_topic)
	if not match:
	raise ValueError(
	'PubSub topic must be in the form "projects/<project>/topics'
	'/<topic>" (got %r).' % full_topic)
	project, topic_name = match.group(1), match.group(2)
	if not re.match(PROJECT_ID_REGEXP, project):
	raise ValueError('Invalid PubSub project name: %r.' % project)
	return project, topic_name


	def parse_subscription(full_subscription):
	match = re.match(SUBSCRIPTION_REGEXP, full_subscription)
	if not match:
	raise ValueError(
	'PubSub subscription must be in the form "projects/<project>'
	'/subscriptions/<subscription>" (got %r).' % full_subscription)
	project, subscription_name = match.group(1), match.group(2)
	if not re.match(PROJECT_ID_REGEXP, project):
	raise ValueError('Invalid PubSub project name: %r.' % project)
	return project, subscription_name


	class _PubSubSource(dataflow_io.NativeSource):
	"""Source for a Cloud Pub/Sub topic or subscription.

	This ``NativeSource`` is overridden by a native Pubsub implementation.

	Attributes:
	with_attributes: If False, will fetch just message data. Otherwise,
	fetches ``PubsubMessage`` protobufs.
	"""

	def __init__(self, topic=None, subscription=None, id_label=None,
	with_attributes=False, timestamp_attribute=None):
	self.coder = coders.BytesCoder()
	self.full_topic = topic
	self.full_subscription = subscription
	self.topic_name = None
	self.subscription_name = None
	self.id_label = id_label
	self.with_attributes = with_attributes
	self.timestamp_attribute = timestamp_attribute

	# Perform some validation on the topic and subscription.
	if not (topic or subscription):
	raise ValueError('Either a topic or subscription must be provided.')
	if topic and subscription:
	raise ValueError('Only one of topic or subscription should be provided.')

	if topic:
	self.project, self.topic_name = parse_topic(topic)
	if subscription:
	self.project, self.subscription_name = parse_subscription(subscription)

	@property
	def format(self):
	"""Source format name required for remote execution."""
	return 'pubsub'

	def display_data(self):
	return {'id_label':
	DisplayDataItem(self.id_label,
	label='ID Label Attribute').drop_if_none(),
	'topic':
	DisplayDataItem(self.full_topic,
	label='Pubsub Topic').drop_if_none(),
	'subscription':
	DisplayDataItem(self.full_subscription,
	label='Pubsub Subscription').drop_if_none(),
	'with_attributes':
	DisplayDataItem(self.with_attributes,
	label='With Attributes').drop_if_none(),
	'timestamp_attribute':
	DisplayDataItem(self.timestamp_attribute,
	label='Timestamp Attribute').drop_if_none(),
	}

	def reader(self):
	raise NotImplementedError

	def is_bounded(self):
	return False


	class _PubSubSink(dataflow_io.NativeSink):
	"""Sink for a Cloud Pub/Sub topic.

	This ``NativeSource`` is overridden by a native Pubsub implementation.
	"""

	def __init__(self, topic, id_label, with_attributes, timestamp_attribute):
	self.coder = coders.BytesCoder()
	self.full_topic = topic
	self.id_label = id_label
	self.with_attributes = with_attributes
	self.timestamp_attribute = timestamp_attribute

	self.project, self.topic_name = parse_topic(topic)

	@property
	def format(self):
	"""Sink format name required for remote execution."""
	return 'pubsub'

	def display_data(self):
	return {
	'topic': DisplayDataItem(self.full_topic, label='Pubsub Topic'),
	'id_label': DisplayDataItem(self.id_label, label='ID Label Attribute'),
	'with_attributes': DisplayDataItem(
	self.with_attributes, label='With Attributes').drop_if_none(),
	'timestamp_attribute': DisplayDataItem(
	self.timestamp_attribute, label='Timestamp Attribute'),
	}

	def writer(self):
	raise NotImplementedError