NestJS Framework

Nest is a progressive Node.js framework designed for building efficient, scalable, and maintainable server-side applications. It is built with TypeScript (while maintaining compatibility with pure JavaScript) and leverages principles from Object-Oriented Programming (OOP), Functional Programming (FP), and Functional Reactive Programming (FRP).

Key architectural features:

• Architecture-First: Unlike many Node.js libraries that focus on individual utilities, Nest provides a complete application architecture out of the box, heavily inspired by Angular.
• Underlying Engine: By default, Nest uses Express, but it is designed to be platform-agnostic and can easily switch to other libraries like Fastify.
• Scalability: The framework is designed to help developers create highly testable, loosely coupled, and easily maintainable applications.

NestJS is a progressive Node.js framework designed for building efficient and scalable server-side applications. It is heavily inspired by Angular and leverages modern JavaScript or TypeScript.

Key characteristics include:

• Programming Paradigms: Combines elements of Object-Oriented Programming (OOP), Functional Programming (FP), and Functional Reactive Programming (FRP).
• Underlying HTTP Engine: By default, Nest uses Express, but it is designed to be platform-agnostic and provides compatibility with other libraries like Fastify, allowing you to easily use various third-party plugins.

NestJS aims to enable the immediate construction of practical architectures. The framework is designed to help developers build applications that are:

• Test-friendly
• Scalable
• Loosely coupled
• Easy to operate

The architecture is inspired by Angular.

Nest aims to solve the architectural challenges often found in Node.js development. Its primary goal is to provide an application architecture that is:

• Test-friendly
• Scalable
• Loosely coupled
• Easy to maintain

The architecture is heavily inspired by Angular.

While many Node.js libraries and tools exist, they often fail to address the core issue of application architecture.

Nest's primary goal is to provide an out-of-the-box application architecture. This architecture enables developers to easily create applications that are:

• Highly testable
• Scalable
• Loosely coupled
• Easy to maintain

To set up the local environment for this sample application, use npm to install the necessary dependencies.

$ npm install

Use the following npm scripts to run the application in different environments:

• Development: Standard execution.
• Watch mode: Automatically restarts the application when files change.
• Production mode: Optimized execution for production environments.

# development
$ npm run start

# watch mode
$ npm run start:dev

# production mode
$ npm run start:prod

This sample project demonstrates a schema-first GraphQL implementation using NestJS and Prisma with a SQLite database.

To get the project running, follow these steps:

1. Install dependencies: Run npm install to install all required packages.
2. Generate GraphQL typings: Run npm run generate:typings to create the TypeScript type definitions based on your GraphQL schema.
3. Initialize the database: Run npx prisma db push to create the SQLite database and sync the schema with the database tables.
4. Start the development server: Run npm run start:dev to launch the application.

Note: This sample uses SQLite. If you wish to use a different database provider, refer to the Prisma documentation.

To run this GraphQL Federation example using the Schema First approach, you must start the sub-graph applications before starting the gateway. This ensures the gateway can successfully fetch the schemas from the sub-graphs during startup.

Follow these steps in order:

1. Start the users-application sub-graph.
2. Start the posts-application sub-graph.
3. Start the gateway application.

# 1. Start users sub-graph
cd users-application && npm run start

# 2. Start posts sub-graph
cd posts-application && npm run start

# 3. Start gateway
cd gateway && npm run start

To begin building with NestJS, refer to the official documentation for comprehensive guides and tutorials.

• Official Documentation: docs.nestjs.com
• Chinese Documentation: docs.nestjs.cn
• Korean Documentation: docs.nestjs.com
• Japanese Documentation: docs.nestjs.com

The Sequelize sample requires a MySQL database. You can use Docker for an automated setup or a local MySQL installation.

Using Docker

Use the provided docker-compose.yml file to start the database container:

docker-compose up

To stop the container, run:

docker-compose down

Using a local MySQL installation

If you are using a local MySQL instance instead of Docker, you must manually configure the database credentials. Check app.module.ts in the source code to find the required credentials and ensure they match your local database configuration.

Once the services are running, the federated gateway is accessible at the following endpoint:

http://localhost:3002/graphql