Extension Manager Design

To define a common application interface for runtime extension in a Nuxt 3 application, you need a structured approach to ensure that your core application provides a flexible yet consistent API for external extensions to hook into. Below is a process for achieving this, focusing on modularity, consistency, and safety.

1. Define a Shared Interface or API Create a clear interface that describes the common methods, properties, and events that any extension can rely on. In Nuxt 3, this can be done using TypeScript interfaces and a well-defined structure within your application.

Example: Create an interface that defines what any extension can expect from the core application.

// types/ExtensionInterface.ts
export interface ExtensionInterface {
  register(): void; // Called when the extension is registered
  init(appContext: AppContext): void; // Called when the extension is initialized
  destroy?(): void; // Optional method for cleanup if necessary
}

export interface AppContext {
  logger: (message: string) => void;
  store: any; // Example store object
  router: any; // Example router object
}

This ExtensionInterface defines the basic lifecycle methods (register, init, destroy) and ensures that all extensions follow a common structure.

2. Create an Extension Manager A central service or module should handle the registration and management of extensions. This service will load the extensions dynamically during runtime and call their lifecycle methods, adhering to the common interface.

Example:

// composables/useExtensionManager.ts
import { ExtensionInterface, AppContext } from '~/types/ExtensionInterface';

const extensions: ExtensionInterface[] = [];

export const useExtensionManager = () => {
  const registerExtension = (extension: ExtensionInterface) => {
    extensions.push(extension);
  };

  const initializeExtensions = (appContext: AppContext) => {
    extensions.forEach((extension) => {
      extension.init(appContext);
    });
  };

  const destroyExtensions = () => {
    extensions.forEach((extension) => {
      if (extension.destroy) {
        extension.destroy();
      }
    });
  };

  return {
    registerExtension,
    initializeExtensions,
    destroyExtensions,
  };
};

In this example:

registerExtension: Adds an extension to the list of active extensions. initializeExtensions: Initializes all extensions by providing them with the necessary application context. destroyExtensions: Gracefully cleans up extensions if necessary. 3. Expose the Interface via Nuxt Plugins To ensure the extensions can hook into the application properly, you should expose the necessary application context (like router, store, etc.) through a Nuxt plugin.

Example Nuxt Plugin:

// plugins/extensionManager.ts
import { defineNuxtPlugin } from '#app';
import { useExtensionManager } from '~/composables/useExtensionManager';

export default defineNuxtPlugin((nuxtApp) => {
  const extensionManager = useExtensionManager();

  // Example app context to pass to extensions
  const appContext = {
    logger: (message: string) => {
      console.log(`[APP LOG]: ${message}`);
    },
    store: nuxtApp.$pinia, // Example store integration
    router: nuxtApp.$router, // Example router
  };

  // Initialize extensions after setup
  extensionManager.initializeExtensions(appContext);

  nuxtApp.hook('app:beforeClose', () => {
    extensionManager.destroyExtensions();
  });

  return {
    provide: {
      extensionManager,
    },
  };
});

This plugin makes the extensionManager available globally, and ensures that extensions are initialized with the proper application context. It also provides a cleanup hook when the app is closed.

4. Loading Extensions Dynamically Extensions can be loaded dynamically either by:

Installing them via an NPM package. Allowing external contributors to drop extension files into a specific folder that gets dynamically loaded during runtime. Example: Loading Extensions from a Folder You can configure the system to dynamically load extensions from a folder during application runtime.

// plugins/loadExtensions.ts
import { useExtensionManager } from '~/composables/useExtensionManager';

export default defineNuxtPlugin((nuxtApp) => {
  const extensionManager = useExtensionManager();

  // Assuming all extensions are defined in the ~/extensions folder
  const extensionFiles = import.meta.glob('../extensions/*.ts');

  Object.keys(extensionFiles).forEach(async (path) => {
    const extension = await extensionFiles[path]();
    extensionManager.registerExtension(extension.default);
  });
});

This example uses import.meta.glob to load all .ts files from the extensions/ folder dynamically.

5. Documentation for Extension Developers Create clear documentation that explains how developers can build and register their extensions. This includes:

How to implement the ExtensionInterface. Lifecycle methods like register, init, and destroy. How to access the application's context, like the router, store, or custom logger. 6. Security and Isolation Consider security best practices by sandboxing or limiting the scope of extensions if they come from third-party sources. This ensures that they can’t interfere with critical parts of your application.

Use Permissions: Allow extensions to request only the permissions they need. Namespace Extensions: Provide extensions with their own namespace within the global context to prevent conflicts. Conclusion By defining a clear extension interface in your Nuxt 3 application, along with a lifecycle and management system, you provide a robust foundation for extending the application at runtime. This process can handle dynamic installation, initialization, and cleanup of extensions while maintaining consistency across different parts of the application.

Key components include:

Defining a TypeScript interface. Creating an extension manager for lifecycle control. Dynamically loading extensions from a folder. Providing clear documentation for developers building extensions. This architecture ensures a clean, maintainable, and scalable approach to building a runtime-extensible application.