Lightning Aura Components Developer Guide

Introducing Aura Components
Quick Start
Creating Components
Using Components
Communicating with Events
Communicating Across the DOM with Lightning Message Service
Create a Message Channel
Publish on a Message Channel
Subscribe to a Message Channel
Lightning Message Service Limitations
Creating Apps
Styling Apps
Developing Secure Code
Using JavaScript
Working with Salesforce Data
Testing Components
Debugging
Performance
Reference
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Subscribe to a Message Channel

To subscribe to a message channel, create a handler method to run when it receives a message.

Example

The lmsSubscriberAuraComponent from the github.com/trailheadapps/lwc-recipes repo shows how to subscribe and unsubscribe from a message channel.

In this example, we define an Aura component called myNewComponent that contains the custom message channel, SampleMessageChannel__c. The lightning:messageChannel component's onMessage attribute calls the handleChanged method in the client-side controller.

By default, communication over a message channel can occur only between components in an active navigation tab, an active navigation item, or a utility item. Utility items are always active. A navigation tab or item is active when it’s selected. Navigation tabs and items include:
  • Standard navigation tabs
  • Console navigation workspace tabs
  • Console navigations subtabs
  • Console navigation items
To receive messages on a message channel from anywhere in the application, use lightning:messageChannel's optional parameter, scope. Set scope to the value "APPLICATION".

The component myNewComponent detects a new message and updates the display value.

Write the handler in your component's client-side controller. The handleChanged method fires when there is a new message. It checks whether there is a payload in the message, and if so, assigns the new data to the v.recordValue attribute. The lightning:formattedText element updates to display the new value.