Pulse: Real-Time Applications with Prisma's Pulse CDC Service in Nest.js

Pulse is a highly efficient managed Change Data Capture (CDC) service provided by Prisma, designed to simplify the development of real-time applications. With Pulse, you can capture change events from your database and deliver them instantly to your applications in a type-safe manner using Prisma Client.

Using Pulse in Nest.js

To use Pulse in Nest.js, you must first install the @prisma/client package in your Nest.js project. You can do this by running the following command:

npm install @prisma/client

Once the @prisma/client package is installed, you need to create a Prisma schema file. This file will define your database's tables and their relationships. You can create a Prisma schema file by running the following command:

prisma init

Once you have created a Prisma schema file, you must generate the Prisma Client code. You can do this by running the following command:

prisma generate

This will generate a PrismaClient class that you can use to interact with your database and consume CDC events.

To consume CDC events in your Nest.js application, you can use the PrismaClient class to subscribe to CDC events for a particular table. Once you have subscribed to CDC events, you can start listening for CDC events using the subscribe() method.

When a CDC event is received, the subscribe() method will return a type-safe event object. You can then use this event object to respond to the change in the database.

How to create a real-time chat application using Pulse in Nest.js:

Prerequisites

You will need to have the following installed:

• Node.js
• Nest.js CLI
• Pulse

Creating a new Nest.js project

To create a new Nest.js project, run the following command:

nest new real-time-chat-app

This will create a new Nest.js project called real-time-chat-app.

Installing Pulse

To install Pulse, run the following command:

npm install @nestjs-pulse/core --save

This will install the Pulse core package.

Creating a WebSocket gateway

Next, we must create a WebSocket gateway to handle our real-time chat messages. To do this, run the following command:

nest generate gateway chat

This will generate a new WebSocket gateway called chat.gateway.ts.

Updating the chat gateway

Open the chat.gateway.ts file and update it as follows:

import { WebSocketGateway, WebSocketServer } from '@nestjs/websockets';
import { Server } from 'socket.io';
import { PulseGateway } from '@nestjs-pulse/core';

@WebSocketGateway()
export class ChatGateway extends PulseGateway {
  @WebSocketServer()
  server: Server;

  constructor() {
    super();
    this.subscribeTo('chat-messages', (message) => {
      this.emitToAll('chat-messages', message);
    });
  }
}

This code defines a WebSocket gateway called ChatGateway that extends the PulseGateway class. This gives us access to the Pulse API for sending and receiving messages.

In the constructor, we subscribe to the chat-messages channel. This means that whenever a message is sent to this channel, we will receive it in the subscribeTo() callback function.

We simply emit the message to all connected clients in the callback function.

Updating the app module

Next, we need to update the app module to import the ChatGateway module. Open the app.module.ts file and update it as follows:

import { Module } from '@nestjs/common';
import { ChatGateway } from './chat.gateway';
import { PulseModule } from '@nestjs-pulse/core';

@Module({
  imports: [PulseModule],
  providers: [ChatGateway],
})
export class AppModule {}

Creating a client

To create a client for our real-time chat application, we can use the Socket.IO client library. Install the Socket.IO client library by running the following command:

npm install socket.io-client --save

Once the Socket.IO client library is installed, we can create a new client as follows:

import { io } from 'socket.io-client';

const socket = io('http://localhost:3000');

This will create a new Socket.IO client connected to our Nest.js server.

Sending and receiving messages

To send a message, we can use the socket.emit() method. For example, to send a message to the chat-messages channel, we would use the following code:

socket.emit('chat-messages', 'Hello world!');

To receive messages, we can use the socket.on() method. For example, to receive messages from the chat-messages channel, we would use the following code:

socket.on('chat-messages', (message) => {
  console.log(message);
});

This is just a simple example of how to use Pulse to build a real-time chat application in Nest.js. Pulse can be used to build other real-time applications, such as dashboards, financial applications, etc.

Benefits of using Pulse in Nest.js

There are several benefits to using Pulse in Nest.js, including:

• Easy to use: Pulse is a managed CDC service, so there is no need to implement CDC from scratch. You can start using Pulse in minutes by simply connecting your database to Pulse.
• Type-safe: Pulse uses Prisma Client to generate type-safe code for your Nest.js application. This makes it easy to consume CDC events in your Nest.js application without the risk of errors.
• Scalable and reliable: Pulse is built on Prisma's proven infrastructure, so you can be confident that your CDC events will be delivered reliably and at scale.
• Well-integrated with Nest.js: Pulse is well-integrated with Nest.js, so you can easily use Pulse in your Nest.js applications.

Use cases for Pulse in Nest.js

Pulse can be used to build a variety of real-time applications in Nest.js, including:

• Real-time dashboards: Pulse can be used to build real-time dashboards that display data from a database in real-time. This can be useful for monitoring business metrics, such as sales or website traffic.
• Real-time chat applications: Pulse can be used to build real-time chat applications that allow users to communicate with each other in real-time. This can be useful for customer support applications or team collaboration applications.
• Real-time financial applications: Pulse can be used to build real-time financial applications that display stock prices or other financial data in real-time. This can be useful for trading applications or investments.

Conclusion

Pulse is an efficient and user-friendly Change Data Capture (CDC) service well-suited for constructing real-time applications within the Nest.js framework. Pulse is a highly attractive choice if you're searching for a solution to create real-time applications using Nest.js.

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