Send client events to Event Hubs

Note

Event listener feature is in preview.

Overview

If you want to listen to your client events without exposing a publicly accessible endpoint, you can configure an "event listener" rule with an event hub endpoint, and a filter to specify which kinds of events it concerns. You can configure multiple event listeners at the same time. Web PubSub service notifies all concerning event listeners in parallel when a client event comes.

This tutorial shows you how to authorize your Web PubSub service to connect to Event Hubs and how to add an event listener rule to your service settings.

Web PubSub service uses Azure Active Directory (Azure AD) authentication with managed identity to connect to Event Hubs. Therefore, you should enable the managed identity of the service and make sure it has proper permissions to connect to Event Hubs. You can grant the built-in Azure Event Hubs Data sender role to the managed identity so that it has enough permissions.

To configure an Event Hubs listener, you need to:

  1. Add a managed identity to your Web PubSub service
  2. Grant the managed identity an Azure Event Hubs Data sender role
  3. Add an event listener rule to your service settings

Configure an event listener

Add a managed identity to your Web PubSub service

Find your Azure Web PubSub service from Azure portal. Navigate to Identity. To add a system-assigned identity, on the System assigned tab, switch Status to On. Select Save. For more information about managed identities, see Managed identities in Azure Web PubSub.

Screenshot of adding a system-assigned identity in the portal

Grant the managed identity an Azure Event Hubs Data sender role

  1. Find your Azure Event Hubs resource in Azure portal. You could choose to grant the role in the Event Hubs namespace level or entity level. The following steps choose the namespace level.

  2. Navigate to Access Control. Select Add role assignment. Screenshot of granting access to Event Hubs namespace

  3. Select Azure Event Hubs Data Sender role in the Role tab. Then select Next. Screenshot of selecting Azure EventHubs Data Sender role

  4. In the Members tab, choose to assign access to Managed identity. Select Select members to select your Web PubSub service. Then you can Review + assign your role assignment. Screenshot of selecting your Web PubSub service identity

Add an event listener rule to your service settings

  1. Find your service from Azure portal. Navigate to Settings. Then select Add to configure your event listener. For an existing hub configuration, select ... on right side will navigate to the same editing page. Screenshot of Web PubSub settings

  2. Then in the below editing page, you'd need to configure hub name, and select Add to add an event listener. Screenshot of configuring hub settings

  3. On the Configure Event Listener page, first configure an event hub endpoint. You can select Select Event Hub from your subscription to select, or directly input the fully qualified namespace and the event hub name. Then select user and system events you'd like to listen to. Finally select Confirm when everything is done. Screenshot of configuring Event Hubs Listener

Test your configuration with live demo

  1. Open this Event Hubs Consumer Client web app, input the Event Hubs connection string to connect to an event hub as a consumer. If you get the Event Hubs connection string from an Event Hubs namespace resource instead of an event hub instance, then you need to specify the event hub name. This event hub consumer client is connected with the mode that only reads new events; the events published before aren't seen here. You can change the consumer client connection mode to read all the available events in the production environment.

  2. Use this WebSocket Client web app to generate client events. If you've configured to send system event connected to that event hub, you should be able to see a printed connected event in the Event Hubs consumer client after connecting to Web PubSub service successfully. You can also generate a user event with the app. Screenshot of a printed connected event in the Event Hubs consumer client app The area of the WebSocket client app to generate a user event

Next steps

In this article, you learned how event listeners work and how to configure an event listener with an event hub endpoint. To learn the data format sent to Event Hubs, read the following specification.