This Level 3 documentation and implementation diagram shows an example of the fanout pattern. It depicts an event being published and written to a single queue when a record is modified via a user interaction, flow, or batch job. The subscriber system has multiple services that receive the same event from the message queue.

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Pattern Overview

With the fanout pattern, messages are delivered to one or multiple destinations (that is, listening clients or subscribers) through a single message queue. Subscribers retrieve the same message from the queue, rather than their own unique copy. While this can improve performance, it also makes it more difficult to verify whether or not a subscriber received a message.

This is a Level 3 Documentation and Implementation diagram according to the Salesforce diagram framework.

Learn more by reading the Architect's Guide to Event-Driven Architecture with Salesforce.