Quick Start

$ pip install --upgrade google-cloud-pubsub

Authentication

With google-cloud-python we try to make authentication as painless as possible. Check out the Authentication section in our documentation to learn more. You may also find the authentication document shared by all the google-cloud-* libraries to be helpful.

Using the API

Google Cloud Pub/Sub (Pub/Sub API docs) is designed to provide reliable, many-to-many, asynchronous messaging between applications. Publisher applications can send messages to a topic and other applications can subscribe to that topic to receive the messages. By decoupling senders and receivers, Google Cloud Pub/Sub allows developers to communicate between independently written applications.

See the google-cloud-python API Pub/Sub documentation to learn how to connect to Cloud Pub/Sub using this Client Library.

Publishing

To publish data to Cloud Pub/Sub you must create a topic, and then publish messages to it

import os
from google.cloud import pubsub

publisher = pubsub.PublisherClient()
topic = 'projects/{project_id}/topics/{topic}'.format(
    project_id=os.getenv('GOOGLE_CLOUD_PROJECT'),
    topic='MY_TOPIC_NAME',  # Set this to something appropriate.
)
publisher.create_topic()
publisher.publish(topic, b'My first message!', spam='eggs')

To learn more, consult the publishing documentation.

Subscribing

To subscribe to data in Cloud Pub/Sub, you create a subscription based on the topic, and subscribe to that.

import os
from google.cloud import pubsub

subscriber = pubsub.SubscriberClient()
topic = 'projects/{project_id}/topics/{topic}'.format(
    project_id=os.getenv('GOOGLE_CLOUD_PROJECT'),
    topic='MY_TOPIC_NAME',  # Set this to something appropriate.
)
subscription_name = 'projects/{project_id}/subscriptions/{sub}'.format(
    project_id=os.getenv('GOOGLE_CLOUD_PROJECT'),
    sub='MY_SUBSCRIPTION_NAME',  # Set this to something appropriate.
)
subscription = subscriber.create_subscription(topic, subscription)

The subscription is opened asychronously, and messages are processed by use of a callback.

def callback(message):
    print(message.data)
    message.ack()
subscription.open(callback)

To learn more, consult the subscriber documentation.