Background

This project was written at Morgan Stanley to provide an internal messaging system for large scale UI systems. The project was later Open Sourced so others could benefit from it.

Use cases

Here is an example of a usecase in which the Message Broker could be useful.

Notification system

Let’s say you have some document uploading functionality in your UI. The uploading may take up to a minute and you don’t want the user to have to wait, so once the upload is complete you want to have a pop-up notification appear which tells the user that their upload was successful.

The code for your pop-up notification can live anywhere in your codebase, and can “listen” for a “document_uploaded” message using the MessageBroker. Now all that needs to happen is for the document upload service to publish that message when the upload completes.

Note: that with this model, our document uploading service doesn’t even have to know about the existence of the notification service, so everything is nice and decoupled.

Mediator Pattern

More generically, the Message Broker essentially acts as a Mediator for your components. Any time you would apply the Mediator pattern, the Message Broker is the perfect solution to avoid you some boilerplate coding.

Alternatives

List of alternatives to the Message Broker.

• BullMQ
  • Relies on Redis
• @node-ts/bus

Both of these alternatives lack the same level of type safety that the Message Broker provides.

Getting Started

npm install @morgan-stanley/message-broker

import {
    messagebroker,
    IMessageBroker
} from '@morgan-stanley/message-broker'

interface IContracts {
    myChannel: {
        payload: string
    }
}

const broker: IMessageBroker<IContracts>
    = messagebroker<IContracts>();

broker.get('myChannel').subscribe(message => {
    console.log(message.payload)
});

broker.create('myChannel').publish({
    payload: 'My first message using the MessageBroker!'
});