Azure WebPubSub Service Client Library for Python

Warnings

• breaking Support for Python 2.7 has officially ended as of January 1, 2022. Users on Python 2.7 will not receive updates and should migrate to Python 3.6+ (or preferably 3.8+ as per current PyPI requirements).
  Fix: Upgrade your Python environment to version 3.8 or higher.
• gotcha When using Azure Active Directory (AAD) for authentication with `DefaultAzureCredential`, you must install the `azure-identity` package separately (`pip install azure-identity`) and enable AAD authentication on your Azure Web PubSub resource. Direct use of connection strings is simpler for initial setup but less secure for production.
  Fix: Install `azure-identity` and configure AAD on your Web PubSub resource, or use connection string/access key for simpler authentication.
• gotcha The SDK provides both synchronous (`WebPubSubServiceClient`) and asynchronous (`WebPubSubServiceAsyncClient` from `azure.messaging.webpubsubservice.aio`) clients. Mixing sync and async operations without proper `asyncio` context can lead to unexpected behavior or deadlocks. Choose the appropriate client for your application's concurrency model.
  Fix: For asynchronous applications, use `WebPubSubServiceAsyncClient` and ensure all calls are awaited within an `asyncio` event loop. For synchronous applications, stick to `WebPubSubServiceClient`.
• gotcha Error handling for server-side issues will often involve `azure.core.exceptions.HttpResponseError` rather than client-side `ValidationError`. This means you need to catch these exceptions for robust error handling, especially for issues like malformed requests or service-side failures.
  Fix: Implement `try-except HttpResponseError` blocks around API calls to handle potential server-side validation or other HTTP errors.

Install

• pip install azure-messaging-webpubsubservice Install stable version

Imports

• WebPubSubServiceClient

  from azure.messaging.webpubsubservice import WebPubSubServiceClient

• WebPubSubServiceAsyncClient

  from azure.messaging.webpubsubservice.aio import WebPubSubServiceClient

  The async client is found in the `.aio` submodule and typically aliased for clarity, or used directly if you prefer the original name from `aio`.

Quickstart

This quickstart demonstrates how to instantiate `WebPubSubServiceClient` using a connection string from an environment variable and send a plain text message to all connected clients within a specified hub. Ensure `AZURE_WEBPUBSUB_CONNECTION_STRING` and `AZURE_WEBPUBSUB_HUB` environment variables are set for authentication and hub selection, respectively.

import os
from azure.messaging.webpubsubservice import WebPubSubServiceClient

# --- Authentication --- 
# Option 1: Connection string (recommended for quickstart/dev)
# Set environment variable AZURE_WEBPUBSUB_CONNECTION_STRING
connection_string = os.environ.get('AZURE_WEBPUBSUB_CONNECTION_STRING', 'Endpoint=https://<your-service>.webpubsub.azure.com;AccessKey=<your-access-key>;Version=1.0;')
# Set environment variable AZURE_WEBPUBSUB_HUB
hub_name = os.environ.get('AZURE_WEBPUBSUB_HUB', 'myHub')

if not connection_string or 'Endpoint=' not in connection_string:
    print("Please set the AZURE_WEBPUBSUB_CONNECTION_STRING environment variable or provide a valid connection string.")
    exit(1)
if not hub_name or hub_name == 'myHub':
    print("Please set the AZURE_WEBPUBSUB_HUB environment variable or provide a valid hub name.")
    exit(1)

# Create a WebPubSubServiceClient instance
service_client = WebPubSubServiceClient.from_connection_string(connection_string, hub=hub_name)

# --- Send a message to all clients in the hub ---
try:
    print(f"Sending 'Hello World' to all clients in hub '{hub_name}'...")
    response = service_client.send_to_all("Hello World", content_type='text/plain')
    print(f"Message sent. Response: {response}")

    # Example: Send a JSON message
    # response = service_client.send_to_all({'message': 'Hello from Python!', 'type': 'greeting'}, content_type='application/json')
    # print(f"JSON message sent. Response: {response}")

except Exception as e:
    print(f"An error occurred: {e}")