Component Communication

Component Communication is an important part of building production-ready Module Federation systems. This lesson explains what component communication means, how it works, and how to apply it with practical examples you can reuse.

Component Communication Overview

Component Communication lets you structure Module Federation work so it stays readable, testable, and easy to scale. Instead of ad-hoc code, you follow a clear pattern that other developers can recognise immediately.

The key is to keep component communication focused and predictable. Start from the minimal example here, then layer in only the complexity your feature actually needs.

const { ModuleFederationPlugin } = require('webpack').container;

module.exports = {
  plugins: [
    new ModuleFederationPlugin({
      name: 'shell',
      remotes: { catalog: 'catalog@http://localhost:3001/remoteEntry.js' },
      exposes: {},
      shared: { react: { singleton: true }, 'react-dom': { singleton: true } },
    }),
  ],
};

ModuleFederationPlugin configures which modules an app exposes, consumes, and shares.

Component Communication Example

new ModuleFederationPlugin({
  name: 'app',
  filename: 'remoteEntry.js',
  exposes: { './Widget': './src/Widget' },
  remotes: { other: 'other@http://host/remoteEntry.js' },
  shared: { react: { singleton: true } },
});

Start from a minimal Component Communication example and grow it only as needed.
Keep configuration explicit so Component Communication behaves the same in every environment.
Name things clearly so teammates understand your Component Communication at a glance.
Add tests around Component Communication early to lock in expected behaviour.

Module Federation Cheatsheet

Key Module Federation settings related to component communication.

Option	Example	Purpose
name	`name: 'shell'`	Unique container name
filename	`filename: 'remoteEntry.js'`	Remote entry manifest
exposes	`exposes: { './X': './src/X' }`	Modules a remote shares
remotes	`remotes: { app: 'app@url' }`	Remotes a host consumes
shared	`shared: { react: { singleton: true } }`	Deduplicate libraries
lazy load	`import('remote/Module')`	Load remotes on demand
Suspense	`<Suspense fallback={...}>`	Handle async loading

How Component Communication Works in Module Federation

Component Communication builds on Module Federation's ability to load code from another independently built and deployed application at runtime. Each app can be a host, a remote, or both.

ModuleFederationPlugin configures which modules an app exposes, consumes, and shares.

Remotes expose modules through a remoteEntry.js manifest.
Hosts declare remotes and import exposed modules dynamically.
Shared dependencies are deduplicated, ideally as singletons.
Each micro frontend builds and deploys on its own schedule.

Practical Guidance for Component Communication

In production, component communication needs careful version management and graceful failure handling. Align shared dependency versions and always render a fallback when a remote cannot load.

Concern	Recommendation
Shared versions	Use singletons with requiredVersion
Runtime errors	Wrap remotes in error boundaries and fallbacks
Deployment	Resolve remotes from a runtime manifest
Performance	Lazy-load remotes and cache remoteEntry.js

Common Mistakes

Copying component communication snippets without understanding what each line does.
Skipping error handling and edge cases when wiring up component communication.
Leaving component communication untested, so regressions slip into production.
Over-engineering component communication before you actually need the extra flexibility.

Key Takeaways

Component Communication is a core part of working effectively with Module Federation.
Start small and keep component communication focused on a single responsibility.
Apply consistent patterns so component communication scales across your project.
Test and document component communication to keep it maintainable over time.

Pro Tip

When you get stuck on component communication, reduce it to the smallest reproducible example first — most Module Federation issues become obvious once the noise is gone.