snapshot of https://github.com/ThreeDotsLabs/watermill.git (master, 2026-09-15; blobs > 131072B omitted)

docs/content/advanced/fanout.md

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+title = "FanOut (multiplying messages)"
+description = "FanOut is a component that receives messages from the subscriber and passes them to all publishers."
+date = 2024-10-09T02:47:30+01:00
+weight = -50
+draft = false
+bref = "FanOut is a component that receives messages from the subscriber and passes them to all publishers."
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+
+## FanOut component
+
+FanOut is a component that receives messages from a topic and passes them to all subscribers. In effect, messages are "multiplied".
+
+A typical use case for using FanOut is having one external subscription and multiple workers
+inside the process.
+
+### Configuring
+
+{{% load-snippet-partial file="src-link/pubsub/gochannel/fanout.go" first_line_contains="// NewFanOut" last_line_contains=")" padding_after="0" %}}
+
+You need to call AddSubscription method for all topics that you want to listen to.
+This needs to be done *before* starting the FanOut.
+
+{{% load-snippet-partial file="src-link/pubsub/gochannel/fanout.go" first_line_contains="// AddSubscription" last_line_contains=")" padding_after="0" %}}
+
+### Running
+
+{{% load-snippet-partial file="src-link/pubsub/gochannel/fanout.go" first_line_contains="// Run" last_line_contains=")" padding_after="0" %}}
+
+Then, use it as any other `message.Subscriber`.