Subscribe to Platform Event Notifications in a Lightning Component

The empApi component uses a shared CometD-based Streaming API connection, enabling you to run multiple streaming apps in the browser for one user. The connection isn’t shared across user sessions.

The concurrent CometD client limit applies to the empApi component. Each logged-in user using empApi counts as one concurrent client. The empApi component isn’t recommended for apps or sites that are used by a large number of users, such as Experience Cloud sites, because the limit can be reached. This limit is shared with other CometD clients. For more information, see Platform Event Allocations.

Subscribe in a Lightning Web Component

To use the empApi methods in your Lightning web component, import the methods from the lightning/empApi module as follows.

1import { subscribe, unsubscribe, onError, setDebugFlag, isEmpEnabled } 
2    from 'lightning/empApi';

Then call the imported methods in your JavaScript code.

For an example of how to use the lightning/empApi module and a complete reference, see the lightning-emp-api documentation in the Lightning Component Library.

Subscribe in an Aura Component