Micro frontends and its principles like module federation.

 

Micro Frontends and Module Federation

Micro Frontends is an architectural style where a single frontend application is decomposed into multiple smaller, loosely coupled, and independently deployable parts (called "micro frontends"). Each part of the frontend is responsible for a specific domain or feature and can be developed, tested, deployed, and scaled independently. This approach is similar to microservices but applied to the frontend.

Module Federation is a feature introduced by Webpack 5 that allows multiple, independently built and deployed frontend applications to share code and resources dynamically at runtime. It's one of the most powerful tools to implement the Micro Frontends architecture.

Let's dive deeper into Micro Frontends and Module Federation:

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Key Principles of Micro Frontends

1. Independent Development and Deployment:

   • Each micro frontend is a separate module that can be developed by different teams.
   • Teams can choose their own technologies, frameworks, or libraries.
   • Each micro frontend can be independently deployed, meaning updates to one part of the app don't affect the rest of the system.

2. Decentralized Teams:

   • Different teams manage different parts of the user interface (UI), allowing them to work autonomously.
   • Micro frontends can be split based on business domains, for example, a shopping cart, user profile, or payments might each be handled by different teams.

3. Loosely Coupled:

   • Micro frontends should have minimal dependencies between them, making them decoupled. They interact with each other through well-defined APIs or shared state management solutions.

4. Unified User Experience:

   • Even though the micro frontends are independent, the end user should experience a seamless UI. This is done through consistent design patterns, shared styles, and common components, ensuring the user doesn’t feel like they are interacting with multiple applications.

5. Isolation:

   • Each micro frontend should be isolated so that it does not interfere with the functioning of other parts of the application. For example, a micro frontend should not directly manipulate the state or UI of another micro frontend.

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Benefits of Micro Frontends:

• Scalability: Since different teams can work on different parts of the application simultaneously, the development process is scalable.
• Flexibility: Teams can choose their tech stack independently, enabling experimentation and innovation.
• Independent Deployment: Each micro frontend can be deployed without needing to deploy the entire application, leading to quicker updates and faster bug fixes.
• Technology Agnostic: Teams can use different technologies for each part of the frontend (e.g., React, Angular, Vue.js) and integrate them seamlessly into one application.

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Challenges of Micro Frontends:

• Coordination: Coordinating multiple teams working on different micro frontends can be complex, especially in larger organizations.
• Performance: If not managed well, loading multiple micro frontends can impact performance, particularly if each micro frontend brings its own dependencies and libraries.
• Consistency: Ensuring consistency in design, state management, and shared logic across different micro frontends can be challenging.
• Cross-cutting concerns: Handling global concerns like authentication, routing, and data management across multiple micro frontends requires careful planning.

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What is Webpack Module Federation?

Webpack Module Federation is a feature in Webpack 5 that allows different JavaScript applications to share and consume modules (code) with each other at runtime. It’s specifically designed to make the integration of micro frontends easier by enabling dynamic code sharing between different frontend applications.

Before Module Federation, sharing code between multiple frontend apps was difficult because each app had its own separate build and dependency tree. Module Federation allows you to share dependencies, components, and other assets at runtime, meaning you don’t need to include the same libraries multiple times in each micro frontend.

Core Concepts of Module Federation:

1. Host and Remote:

   • Host: The application that consumes modules from other applications.
   • Remote: The application that exposes modules to be consumed by the host.

2. Exposing and Consuming Modules:

   • A remote app exposes specific modules (like React components, utility functions, or even entire libraries).
   • A host app consumes those exposed modules without needing to know about their implementation details.

3. Dynamic Loading:

   • The modules are loaded dynamically at runtime, which means the host app doesn’t need to include all the dependencies upfront. This can significantly reduce the size of the application bundle.

4. Shared Dependencies:

   • Module Federation enables shared dependencies between different applications, which means common libraries (e.g., React, Vue, etc.) can be loaded once and shared across multiple applications. This minimizes duplication and improves performance.

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How Module Federation Works:

1. Expose Modules in Webpack:

   • In the webpack configuration of a micro frontend, you use the ModuleFederationPlugin to expose specific modules.

   Example of exposing a component (HeaderComponent):

   js
   // webpack.config.js for the remote application
   const { ModuleFederationPlugin } = require('webpack').container;
   
   module.exports = {
     plugins: [
       new ModuleFederationPlugin({
         name: 'remoteApp', // Name of this micro frontend
         filename: 'remoteEntry.js', // Exposed entry file
         exposes: {
           './HeaderComponent': './src/HeaderComponent', // Exposing a component
         },
       }),
     ],
   };
   

2. Consume Exposed Modules in Another App:

   • In the host application, you can use the ModuleFederationPlugin to load the exposed module from the remote app.

   Example of consuming the HeaderComponent from the remote app:

   js
   // webpack.config.js for the host application
   const { ModuleFederationPlugin } = require('webpack').container;
   
   module.exports = {
     plugins: [
       new ModuleFederationPlugin({
         name: 'hostApp',
         remotes: {
           remoteApp: 'remoteApp@http://localhost:3001/remoteEntry.js', // Point to the remote app's entry file
         },
       }),
     ],
   };
   

3. Using the Exposed Component:

   • In the host app, you can dynamically import the HeaderComponent and use it in your application.

   js
   // In the host application (React example)
   import React, { Suspense, lazy } from 'react';
   
   const HeaderComponent = lazy(() => import('remoteApp/HeaderComponent'));
   
   function App() {
     return (
       <Suspense fallback={<div>Loading...</div>}>
         <HeaderComponent />
       </Suspense>
     );
   }
   
   export default App;
   

4. Handling Shared Dependencies:

   • If both the host and remote apps use common libraries like React or Lodash, you can share these dependencies across apps to prevent multiple copies of the same library.

   Example of sharing React:

   js
   new ModuleFederationPlugin({
     name: 'hostApp',
     shared: {
       react: { singleton: true, requiredVersion: '^17.0.0' },
       'react-dom': { singleton: true, requiredVersion: '^17.0.0' },
     },
   });
   

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Advantages of Using Module Federation for Micro Frontends:

1. Independent Deployment: Micro frontends can be deployed independently, and you can update just one micro frontend without impacting others.
2. Performance: By sharing common libraries (like React, Angular, etc.), Module Federation ensures that the same dependencies are not loaded multiple times.
3. Seamless Integration: Different micro frontends can use different frameworks (e.g., React, Angular, Vue), and Module Federation enables them to work together seamlessly.
4. Reduced Bundle Size: You only load the modules that are required, which helps in reducing the initial load time of the application.

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Conclusion:

• Micro Frontends break down large, monolithic applications into smaller, more manageable units, enabling different teams to work on different parts of the app independently.
• Webpack Module Federation is a powerful feature that enables the sharing of modules (such as components, libraries, or utilities) between different frontend applications at runtime. This allows micro frontends to be developed and deployed independently while ensuring a seamless user experience.

By combining Micro Frontends with Module Federation, you can build scalable, maintainable, and performant frontend architectures that are easier to manage and evolve over time.