Overview
Lightning Message Service (LMS) is a Salesforce framework for cross-component communication across the Lightning Platform. LMS enables components built with Lightning Web Components (LWC), Aura components, and Visualforce to publish and subscribe to messages using a centralized message channel. It is designed for reliable, secure, and decoupled messaging within a single Lightning Experience page, App Builder page, or Lightning Console.
Why LMS matters
LMS solves common component communication challenges — it replaces custom pub-sub implementations and provides a supported, scalable approach for sending lightweight messages between components that may not share a direct parent-child relationship. LMS is especially useful in complex pages or apps where multiple components need to react to the same event (for example: record selection, search filters, or global refresh triggers).
Key features and benefits
– Cross-framework: works with Lightning Web Components (LWC), Aura components, and Visualforce.
– Centralized message channels: message channels are defined as metadata (XML) making them reusable and manageable.
– Scoped delivery: messages can be scoped to the page or the entire Lightning Experience app when needed.
– Secure: uses Salesforce security model and permissions; only components with access to the message channel can interact with it.
How it works (basic flow)
1. Create a Message Channel (an XML metadata file) to define the message schema.r>
2. Import and use LMS primitives in LWC or Aura: import publish, subscribe, MessageContext, and APPLICATION_SCOPE when required.r>
3. Components publish messages to the channel; subscribers receive messages and act accordingly.
Example: LWC Publisher
In a Lightning Web Component, you typically import the message channel and LMS utilities and then call publish:
import { LightningElement } from 'lwc';
import { publish, MessageContext } from 'lightning/messageService';
import SAMPLE_CHANNEL from '@salesforce/messageChannel/SampleMessageChannel__c';
export default class PublisherComponent extends LightningElement {
@wire(MessageContext)
messageContext;
handleClick() {
const message = { recordId: '001xx000003DGb9AAG', action: 'refresh' };
publish(this.messageContext, SAMPLE_CHANNEL, message);
}
}
Example: LWC Subscriber
Subscribers use subscribe and the wired MessageContext to receive messages:
import { LightningElement, wire } from 'lwc';
import { subscribe, MessageContext } from 'lightning/messageService';
import SAMPLE_CHANNEL from '@salesforce/messageChannel/SampleMessageChannel__c';
export default class SubscriberComponent extends LightningElement {
subscription = null;
@wire(MessageContext)
messageContext;
connectedCallback() {
if (!this.subscription) {
this.subscription = subscribe(this.messageContext, SAMPLE_CHANNEL, (message) => {
// handle the incoming message
console.log('Received message', message);
});
}
}
}
When to use LMS vs alternatives
Use LMS when you need cross-component communication across frameworks or when components are not in a direct parent-child relationship. For simpler parent-child communication within a component tree, use properties and events (LWC @api and custom events). Avoid LMS for very large payloads or high-frequency data streaming; LMS is meant for lightweight messages (signals, IDs, small objects).
Best practices
– Define clear message schemas in the Message Channel metadata.r>
– Keep messages small and focused (IDs, action types, small state changes).r>
– Manage subscription lifecycle properly (subscribe in connectedCallback and unsubscribe in disconnectedCallback if using manual handlers).r>
– Use application scope only when truly needed to broadcast across apps; prefer default page scope for isolation.
Conclusion
Lightning Message Service is a powerful, supported mechanism for decoupled communication across the Salesforce Lightning stack. It simplifies cross-framework messaging, increases maintainability over custom pub-sub solutions, and should be part of any Salesforce developer’s toolkit for building modular, event-driven interfaces.