Lightning Message Service (LMS)

by Sakthivel Madesh October 18, 2020

Lightning Message Service (LMS) is generally available from Summer ’20 onwards, In this post & video to sharing how we can leverage it to communicate between Visualforce and Lightning Components (Aura & LWC) anywhere on a Lightning Page & utility bar.

Lightning Message Service (LMS) is a standard publish-subscribe library in the UI, enabling components in any part of the DOM to communicate.

All interactions have to originate from the same Lightning Experience Application (Example Same browser tab).

Lightning message service is available in Lightning Experience only.

Lightning Message Service (LMS) is a simple API to publish messages throughout Lightning Experience and subscribe to messages that originated from anywhere within Lightning Experience.

Lightning Message Service is based on a new type of metadata called Lightning Message Channels. its a lightweight, packageable components.

Its represents a secure channel to communicate across Salesforce UI technologies i.e Visualforce and Lightning Components (AURA/LWC).

Lightning Message Service (LMS)

Lightning Message Service is based on a new metadata type: Lightning Message Channels.

In Visualforce, use to access from global variable $MessageChannel
In Aura, use to access from lightning:messageChannel
In LWC, use to access from Lightning Message Channel with the scoped module @salesforce/messageChannel

Create a Lightning Message Channel

Salesforce UI doesn’t support creating the message channel directly
Create LMC and deploy using ANT, Workbench or VS Code, or any IDE
Create a folder called “messageChannels” under force-app/main/default folder.
Create a file & structure should be MessageChannelName.messageChannel-meta.xml

<?xml version=”1.0″ encoding=”UTF-8″ ?>
<LightningMessageChannel xmlns=”http://soap.sforce.com/2006/04/metadata”>
<masterLabel>Account Message Channel</masterLabel>
<isExposed>true</isExposed>
<description>Message Channel to pass a Account Record Id</description>
<lightningMessageFields>
<fieldName>recordId</fieldName>
<description>This is the account Record Id</description>
</lightningMessageFields>
<lightningMessageFields>
<fieldName>recordData</fieldName>
<description>This is the account recordData</description>
</lightningMessageFields>
</LightningMessageChannel>

Demo

Demo – Lightning Message Service with VF Page
Demo – Lightning Message Service with AURA
Demo – Lightning Message Service with LWC
Demo – Lightning Message Service with b/w VF Page, AURA & LWC
Demo – Lightning Message Services with b/w VF Page, AURA & LWC (Utility-bar)

Session Video

Limitations/Consideration for LMS

LMS doesn’t currently support these Salesforce experiences and tools: Salesforce Mobile app, AppExchange, Lightning Out and Lightning Communities
LMS unsupported module for the LWC Local Development
Salesforce UI currently doesn’t support creating the message channel directly

Resources: