#!/usr/bin/env python

# Copyright 2019 Google LLC

#

# 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.

# [START pubsub_quickstart_pub_all]

import argparse

import time

# [START pubsub_quickstart_pub_deps]

from google.cloud import pubsub_v1

# [END pubsub_quickstart_pub_deps]

def get_callback(api_future, data):

"""Wrap message data in the context of the callback function."""

def callback(api_future):

try:

print("Published message {} now has message ID {}".format(

data, api_future.result()))

except Exception:

print("A problem occurred when publishing {}: {}\n".format(

data, api_future.exception()))

raise

return callback

def pub(project_id, topic_name):

"""Publishes a message to a Pub/Sub topic."""

# [START pubsub_quickstart_pub_client]

# Initialize a Publisher client

client = pubsub_v1.PublisherClient()

# [END pubsub_quickstart_pub_client]

# Create a fully qualified identifier in the form of

# `projects/{project_id}/topics/{topic_name}`

topic_path = client.topic_path(project_id, topic_name)

# Data sent to Cloud Pub/Sub must be a bytestring

data = b"Hello, World!"

# When you publish a message, the client returns a future.

api_future = client.publish(topic_path, data=data)

api_future.add_done_callback(get_callback(api_future, data))

# Keep the main thread from exiting until background message

# is processed.

while api_future.running():

time.sleep(0.1)

if __name__ == '__main__':

parser = argparse.ArgumentParser(

description=__doc__,

formatter_class=argparse.RawDescriptionHelpFormatter

)

parser.add_argument('project_id', help='Google Cloud project ID')

parser.add_argument('topic_name', help='Pub/Sub topic name')

args = parser.parse_args()

pub(args.project_id, args.topic_name)

# [END pubsub_quickstart_pub_all]