Subscribing to Platform Events | Platform Events Developer Guide

Set Up Debug Logs for Event Subscriptions
Debug logs for platform event triggers, event processes, and resumed flow interviews are created by “Automated Process” and are separate from their corresponding Apex code logs. The debug logs aren’t available in the Developer Console’s Log tab. To collect logs for an event subscription, add a trace flag entry for the Automated Process entity in Setup.

Subscribe to Platform Event Notifications with Processes
Use processes to subscribe to events. You can receive event notifications in processes regardless of how they were published—through Apex, APIs, flows, or other processes. Processes provide an autosubscription mechanism.

Subscribe to Platform Event Notifications with Flows
Use flows to subscribe to events. You can receive event notifications in flows regardless of how they were published—through Apex, APIs, flows, or other processes. Flows provide an autosubscription mechanism.

Subscribe to Platform Event Notifications with Apex Triggers
Use Apex triggers to subscribe to events. You can receive event notifications in triggers regardless of how they were published—through Apex or APIs. Triggers provide an autosubscription mechanism. No need to explicitly create and listen to a channel in Apex.

Subscribe to Platform Event Notifications with CometD
Use CometD to subscribe to platform events in an external client. Implement your own CometD client or use EMP Connector, an open-source, community-supported tool that implements all the details of connecting to CometD and listening on a channel.

Obtain a Platform Event’s Subscribers
View a list of all triggers or processes that are subscribed to a platform event by using the Salesforce user interface or the API.