Platform Events Developer Guide

Platform Events Developer Guide
Delivering Custom Notifications with Platform Events
Defining Your Custom Platform Event
Publishing Platform Events
Subscribing to Platform Events
Set Up Debug Logs
Flows
Processes
Apex Triggers
Lightning Components
Pub/Sub API
CometD
Group Your Event Streams
Create a Custom Channel and Channel Members Using the API
Subscribe to the Channel
List Custom Channels and Channel Members
Filter Your Event Streams
Obtain a Platform Event’s Subscribers
Identify and Match Event Messages with the EventUuid Field
Testing Your Platform Event in Apex
Encrypting Platform Event Messages at Rest in the Event Bus
Monitor Platform Event Publishing and Delivery Usage
Considerations
Examples
Reference
PDF

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Subscribe to the Channel

After creating the custom channel and its members, subscribe to the channel using a CometD client, and receive event messages. Only CometD clients support custom channels. Other subscribers, such as Apex triggers, flows, and processes, don’t support custom channels.
  1. To set up EMP Connector, follow the steps in Example: Subscribe to Events Using a CometD Client (EMP Connector). For the channel argument, provide the custom channel that you created: /event/Order_Channel__chn. The channel name is format /event/ChannelName__chn.

    To receive the EventApiName field, ensure that the client is subscribed with the Streaming API endpoint of API version 55.0 or later. See API Version in the Streaming API Endpoint in the EMP Connector GitHub repo.

    Note

  2. Now that you’re subscribed to the custom channel, publish event messages of both events, Order_NorthAmer__e and Order_EMEA__e, in the Developer Console using Apex.
    1. In Salesforce Classic, select your name | Developer Console.
    2. In Lightning Experience, click the quick access menu, and select Developer Console.
    3. Select Debug | Open Execute Anonymous Window.
    4. In the new window, replace the contents with this Apex code snippet, and click Execute.

      Notice that the eventList variable is declared with the SObject type and not the event type (for example, Order_NorthAmer__e). Using SObject enables this list variable to hold any event type, for example, Order_NorthAmer__e and Order_EMEA__e.

      Note

    Because Order_Channel__chn includes both the Order_NorthAmer__e and Order_EMEA__e event types, you receive the event messages of both events. This example shows the two received event messages after subscribing to the filtered channel, /event/Order_Channel__chn.