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# http://www.apache.org/licenses/LICENSE-2.0
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#
# pytype: skip-file
from __future__ import absolute_import
import typing
from past.builtins import unicode
import apache_beam as beam
from apache_beam.io.gcp import pubsub
from apache_beam.transforms import Map
from apache_beam.transforms.external import ExternalTransform
from apache_beam.transforms.external import NamedTupleBasedPayloadBuilder
ReadFromPubsubSchema = typing.NamedTuple(
'ReadFromPubsubSchema',
[
('topic', typing.Optional[unicode]),
('subscription', typing.Optional[unicode]),
('id_label', typing.Optional[unicode]),
('with_attributes', bool),
('timestamp_attribute', typing.Optional[unicode]),
]
)
[docs]class ReadFromPubSub(beam.PTransform):
"""An external ``PTransform`` for reading from Cloud Pub/Sub.
Experimental; no backwards compatibility guarantees. It requires special
preparation of the Java SDK. See BEAM-7870.
"""
URN = 'beam:external:java:pubsub:read:v1'
def __init__(self, topic=None, subscription=None, id_label=None,
with_attributes=False, timestamp_attribute=None,
expansion_service=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:`~apache_beam.io.gcp.pubsub.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.
"""
self.params = ReadFromPubsubSchema(
topic=topic,
subscription=subscription,
id_label=id_label,
with_attributes=with_attributes,
timestamp_attribute=timestamp_attribute)
self.expansion_service = expansion_service
[docs] def expand(self, pbegin):
pcoll = pbegin.apply(
ExternalTransform(
self.URN, NamedTupleBasedPayloadBuilder(self.params),
self.expansion_service))
if self.params.with_attributes:
pcoll = pcoll | 'FromProto' >> Map(pubsub.PubsubMessage._from_proto_str)
pcoll.element_type = pubsub.PubsubMessage
else:
pcoll.element_type = bytes
return pcoll
WriteToPubsubSchema = typing.NamedTuple(
'WriteToPubsubSchema',
[
('topic', unicode),
('id_label', typing.Optional[unicode]),
# this is not implemented yet on the Java side:
# ('with_attributes', bool),
('timestamp_attribute', typing.Optional[unicode]),
]
)
[docs]class WriteToPubSub(beam.PTransform):
"""An external ``PTransform`` for writing messages to Cloud Pub/Sub.
Experimental; no backwards compatibility guarantees. It requires special
preparation of the Java SDK. See BEAM-7870.
"""
URN = 'beam:external:java:pubsub:write:v1'
def __init__(self, topic, with_attributes=False, id_label=None,
timestamp_attribute=None, expansion_service=None):
"""Initializes ``WriteToPubSub``.
Args:
topic: Cloud Pub/Sub topic in the form "/topics/<project>/<topic>".
with_attributes:
True - input elements will be
:class:`~apache_beam.io.gcp.pubsub.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.
"""
self.params = WriteToPubsubSchema(
topic=topic,
id_label=id_label,
# with_attributes=with_attributes,
timestamp_attribute=timestamp_attribute)
self.expansion_service = expansion_service
self.with_attributes = with_attributes
[docs] def expand(self, pvalue):
if self.with_attributes:
pcoll = pvalue | 'ToProto' >> Map(pubsub.WriteToPubSub.to_proto_str)
else:
pcoll = pvalue | 'ToProto' >> Map(
lambda x: pubsub.PubsubMessage(x, {})._to_proto_str())
pcoll.element_type = bytes
return pcoll.apply(
ExternalTransform(
self.URN,
NamedTupleBasedPayloadBuilder(self.params),
self.expansion_service)
)