azure-messaging-webpubsubservice-py

Azure Web PubSub Service SDK for Python

Real-time messaging with WebSocket connections at scale.

Installation

# Service SDK (server-side)
pip install azure-messaging-webpubsubservice

# Client SDK (for Python WebSocket clients)
pip install azure-messaging-webpubsubclient

Environment Variables

AZURE_WEBPUBSUB_HUB=my-hub  # Required for all auth methods
AZURE_TOKEN_CREDENTIALS=prod # Required only if DefaultAzureCredential is used in production

Authentication & Lifecycle

🔑 Two rules apply to every code sample below:

1. Prefer DefaultAzureCredential. It works locally (Azure CLI / VS Code / Developer CLI) and in Azure (managed identity, workload identity) with no code change. Avoid connection strings, account/API keys — they bypass Entra audit and rotation.
   • Local dev: DefaultAzureCredential works as-is.
   • Production: set AZURE_TOKEN_CREDENTIALS=prod (or AZURE_TOKEN_CREDENTIALS=<specific_credential>) to constrain the credential chain to production-safe credentials.
2. Wrap every client in a context manager so HTTP transports, sockets, and token caches are released deterministically:
   • Sync: with <Client>(...) as client:
   • Async: async with <Client>(...) as client: and async with DefaultAzureCredential() as credential: (from azure.identity.aio)

Snippets may abbreviate this setup, but production code should always follow both rules.

Service Client (Server-Side)

Authentication

from azure.messaging.webpubsubservice import WebPubSubServiceClient
from azure.identity import DefaultAzureCredential, ManagedIdentityCredential

# Local dev: DefaultAzureCredential. Production: set AZURE_TOKEN_CREDENTIALS=prod or AZURE_TOKEN_CREDENTIALS=<specific_credential>
credential = DefaultAzureCredential(require_envvar=True)
# Or use a specific credential directly in production:
# See https://learn.microsoft.com/python/api/overview/azure/identity-readme?view=azure-python#credential-classes
# credential = ManagedIdentityCredential()

with WebPubSubServiceClient(
    endpoint="https://<name>.webpubsub.azure.com",
    hub="my-hub",
    credential=credential
) as client:
    # Use `client` for all subsequent operations (see examples below)
    ...

Generate Client Access Token

# Token for anonymous user
token = client.get_client_access_token()
print(f"URL: {token['url']}")

# Token with user ID
token = client.get_client_access_token(
    user_id="user123",
    roles=["webpubsub.sendToGroup", "webpubsub.joinLeaveGroup"]
)

# Token with groups
token = client.get_client_access_token(
    user_id="user123",
    groups=["group1", "group2"]
)

Send to All Clients

# Send text
client.send_to_all(message="Hello everyone!", content_type="text/plain")

# Send JSON
client.send_to_all(
    message={"type": "notification", "data": "Hello"},
    content_type="application/json"
)

Send to User

client.send_to_user(
    user_id="user123",
    message="Hello user!",
    content_type="text/plain"
)

Send to Group

client.send_to_group(
    group="my-group",
    message="Hello group!",
    content_type="text/plain"
)

Send to Connection

client.send_to_connection(
    connection_id="abc123",
    message="Hello connection!",
    content_type="text/plain"
)

Group Management

# Add user to group
client.add_user_to_group(group="my-group", user_id="user123")

# Remove user from group
client.remove_user_from_group(group="my-group", user_id="user123")

# Add connection to group
client.add_connection_to_group(group="my-group", connection_id="abc123")

# Remove connection from group
client.remove_connection_from_group(group="my-group", connection_id="abc123")

Connection Management

# Check if connection exists
exists = client.connection_exists(connection_id="abc123")

# Check if user has connections
exists = client.user_exists(user_id="user123")

# Check if group has connections
exists = client.group_exists(group="my-group")

# Close connection
client.close_connection(connection_id="abc123", reason="Session ended")

# Close all connections for user
client.close_all_connections(user_id="user123")

Grant/Revoke Permissions

from azure.messaging.webpubsubservice import WebPubSubServiceClient

# Grant permission
client.grant_permission(
    permission="joinLeaveGroup",
    connection_id="abc123",
    target_name="my-group"
)

# Revoke permission
client.revoke_permission(
    permission="joinLeaveGroup",
    connection_id="abc123",
    target_name="my-group"
)

# Check permission
has_permission = client.check_permission(
    permission="joinLeaveGroup",
    connection_id="abc123",
    target_name="my-group"
)

Client SDK (Python WebSocket Client)

from azure.messaging.webpubsubclient import WebPubSubClient

with WebPubSubClient(credential=token["url"]) as client:
    @client.on("connected")
    def on_connected(e):
        print(f"Connected: {e.connection_id}")

    @client.on("server-message")
    def on_message(e):
        print(f"Message: {e.data}")

    @client.on("group-message")
    def on_group_message(e):
        print(f"Group {e.group}: {e.data}")

    client.send_to_group("my-group", "Hello from Python!")

Async Service Client

from azure.messaging.webpubsubservice.aio import WebPubSubServiceClient
from azure.identity.aio import DefaultAzureCredential

async def broadcast():
    async with DefaultAzureCredential() as credential:
        async with WebPubSubServiceClient(
            endpoint="https://<name>.webpubsub.azure.com",
            hub="my-hub",
            credential=credential
        ) as client:
            await client.send_to_all("Hello async!", content_type="text/plain")

Client Operations

Best Practices

1. Pick sync OR async and stay consistent. Do not mix azure.xxx sync clients with azure.xxx.aio async clients in the same call path. Choose one mode per module.
2. Always use context managers for clients and async credentials. Wrap every client in with Client(...) as client: (sync) or async with Client(...) as client: (async). For async DefaultAzureCredential from azure.identity.aio, also use async with credential: so tokens and transports are cleaned up.
3. Use DefaultAzureCredential for portable auth across local dev and Azure (avoid connection strings / access keys when possible).
4. Use roles to limit client permissions
5. Use groups for targeted messaging
6. Generate short-lived tokens for security
7. Use user IDs to send to users across connections
8. Handle reconnection in client applications
9. Use JSON content type for structured data
10. Close connections gracefully with reasons

Reference Files