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#!/usr/bin/env python
# Copyright 2016 Google Inc. All Rights Reserved.
#
# 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.
"""This application demonstrates how to perform basic operations on
subscriptions with the Cloud Pub/Sub API.
For more information, see the README.md under /pubsub and the documentation
at https://cloud.google.com/pubsub/docs.
"""
import argparse
import time
from google.cloud import pubsub_v1
def list_subscriptions_in_topic(project, topic_name):
"""Lists all subscriptions for a given topic."""
subscriber = pubsub_v1.PublisherClient()
topic_path = subscriber.topic_path(project, topic_name)
for subscription in subscriber.list_topic_subscriptions(topic_path):
print(subscription)
def list_subscriptions_in_project(project):
"""Lists all subscriptions in the current project."""
subscriber = pubsub_v1.SubscriberClient()
project_path = subscriber.project_path(project)
for subscription in subscriber.list_subscriptions(project_path):
print(subscription.name)
def create_subscription(project, topic_name, subscription_name):
"""Create a new pull subscription on the given topic."""
subscriber = pubsub_v1.SubscriberClient()
topic_path = subscriber.topic_path(project, topic_name)
subscription_path = subscriber.subscription_path(
project, subscription_name)
subscription = subscriber.create_subscription(
subscription_path, topic_path)
print('Subscription created: {}'.format(subscription))
def create_push_subscription(project,
topic_name,
subscription_name,
endpoint):
"""Create a new push subscription on the given topic.
For example, endpoint is
"https://my-test-project.appspot.com/push".
"""
subscriber = pubsub_v1.SubscriberClient()
topic_path = subscriber.topic_path(project, topic_name)
subscription_path = subscriber.subscription_path(
project, subscription_name)
push_config = pubsub_v1.types.PushConfig(
push_endpoint=endpoint)
subscription = subscriber.create_subscription(
subscription_path, topic_path, push_config)
print('Push subscription created: {}'.format(subscription))
print('Endpoint for subscription is: {}'.format(endpoint))
def delete_subscription(project, subscription_name):
"""Deletes an existing Pub/Sub topic."""
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project, subscription_name)
subscriber.delete_subscription(subscription_path)
print('Subscription deleted: {}'.format(subscription_path))
def update_subscription(project, subscription_name, endpoint):
"""
Updates an existing Pub/Sub subscription's push endpoint URL.
Note that certain properties of a subscription, such as
its topic, are not modifiable. For example, endpoint is
"https://my-test-project.appspot.com/push".
"""
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project, subscription_name)
push_config = pubsub_v1.types.PushConfig(
push_endpoint=endpoint)
subscription = pubsub_v1.types.Subscription(
name=subscription_path,
push_config=push_config)
update_mask = {
'paths': {
'push_config',
}
}
subscriber.update_subscription(subscription, update_mask)
result = subscriber.get_subscription(subscription_path)
print('Subscription updated: {}'.format(subscription_path))
print('New endpoint for subscription is: {}'.format(
result.push_config))
def receive_messages(project, subscription_name):
"""Receives messages from a pull subscription."""
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project, subscription_name)
def callback(message):
print('Received message: {}'.format(message))
message.ack()
subscriber.subscribe(subscription_path, callback=callback)
# The subscriber is non-blocking, so we must keep the main thread from
# exiting to allow it to process messages in the background.
print('Listening for messages on {}'.format(subscription_path))
while True:
time.sleep(60)
def receive_messages_with_custom_attributes(project, subscription_name):
"""Receives messages from a pull subscription."""
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project, subscription_name)
def callback(message):
print('Received message: {}'.format(message.data))
if message.attributes:
print('Attributes:')
for key in message.attributes:
value = message.attributes.get(key)
print('{}: {}'.format(key, value))
message.ack()
subscriber.subscribe(subscription_path, callback=callback)
# The subscriber is non-blocking, so we must keep the main thread from
# exiting to allow it to process messages in the background.
print('Listening for messages on {}'.format(subscription_path))
while True:
time.sleep(60)
def receive_messages_with_flow_control(project, subscription_name):
"""Receives messages from a pull subscription with flow control."""
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project, subscription_name)
def callback(message):
print('Received message: {}'.format(message))
message.ack()
# Limit the subscriber to only have ten outstanding messages at a time.
flow_control = pubsub_v1.types.FlowControl(max_messages=10)
subscriber.subscribe(
subscription_path, callback=callback, flow_control=flow_control)
# The subscriber is non-blocking, so we must keep the main thread from
# exiting to allow it to process messages in the background.
print('Listening for messages on {}'.format(subscription_path))
while True:
time.sleep(60)
def listen_for_errors(project, subscription_name):
"""Receives messages and catches errors from a pull subscription."""
subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(
project, subscription_name)
def callback(message):
print('Received message: {}'.format(message))
message.ack()
subscription = subscriber.subscribe(subscription_path, callback=callback)
# Blocks the thread while messages are coming in through the stream. Any
# exceptions that crop up on the thread will be set on the future.
try:
subscription.future.result()
except Exception as e:
print(
'Listening for messages on {} threw an Exception: {}.'.format(
subscription_name, e))
raise
if __name__ == '__main__':
parser = argparse.ArgumentParser(
description=__doc__,
formatter_class=argparse.RawDescriptionHelpFormatter
)
parser.add_argument('project', help='Your Google Cloud project ID')
subparsers = parser.add_subparsers(dest='command')
list_in_topic_parser = subparsers.add_parser(
'list_in_topic', help=list_subscriptions_in_topic.__doc__)
list_in_topic_parser.add_argument('topic_name')
list_in_project_parser = subparsers.add_parser(
'list_in_project', help=list_subscriptions_in_project.__doc__)
create_parser = subparsers.add_parser(
'create', help=create_subscription.__doc__)
create_parser.add_argument('topic_name')
create_parser.add_argument('subscription_name')
create_push_parser = subparsers.add_parser(
'create-push', help=create_push_subscription.__doc__)
create_push_parser.add_argument('topic_name')
create_push_parser.add_argument('subscription_name')
create_push_parser.add_argument('endpoint')
delete_parser = subparsers.add_parser(
'delete', help=delete_subscription.__doc__)
delete_parser.add_argument('subscription_name')
update_parser = subparsers.add_parser(
'update', help=update_subscription.__doc__)
update_parser.add_argument('subscription_name')
update_parser.add_argument('endpoint')
receive_parser = subparsers.add_parser(
'receive', help=receive_messages.__doc__)
receive_parser.add_argument('subscription_name')
receive_with_custom_attributes_parser = subparsers.add_parser(
'receive-custom-attributes',
help=receive_messages_with_custom_attributes.__doc__)
receive_with_custom_attributes_parser.add_argument('subscription_name')
receive_with_flow_control_parser = subparsers.add_parser(
'receive-flow-control',
help=receive_messages_with_flow_control.__doc__)
receive_with_flow_control_parser.add_argument('subscription_name')
listen_for_errors_parser = subparsers.add_parser(
'listen_for_errors', help=listen_for_errors.__doc__)
listen_for_errors_parser.add_argument('subscription_name')
args = parser.parse_args()
if args.command == 'list_in_topic':
list_subscriptions_in_topic(args.project, args.topic_name)
elif args.command == 'list_in_project':
list_subscriptions_in_project(args.project)
elif args.command == 'create':
create_subscription(
args.project, args.topic_name, args.subscription_name)
elif args.command == 'create-push':
create_push_subscription(
args.project,
args.topic_name,
args.subscription_name,
args.endpoint)
elif args.command == 'delete':
delete_subscription(
args.project, args.subscription_name)
elif args.command == 'update':
update_subscription(
args.project, args.subscription_name, args.endpoint)
elif args.command == 'receive':
receive_messages(args.project, args.subscription_name)
elif args.command == 'receive-custom-attributes':
receive_messages_with_custom_attributes(
args.project, args.subscription_name)
elif args.command == 'receive-flow-control':
receive_messages_with_flow_control(
args.project, args.subscription_name)
elif args.command == 'listen_for_errors':
listen_for_errors(args.project, args.subscription_name)
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