This example illustrates building a Microfrontend (MFE) application with a shared session store using Express.js and MongoDB. This setup allows a front-end application and a separate API service to share user session data seamlessly.

The project consists of two main parts:

• Web Server (app.js): Serves the frontend content, manages user sessions, and communicates with the API.
• API Server (api.js): Provides a protected API that only serves requests with a valid session.

These components use MongoDB as a shared session store to ensure session continuity across the services.

Session management is critical for modern web applications. Here, we use express-session with a MongoDB store provided by connect-mongo. Sessions are created on the first visit to the web server and are then shared with the API server via cookies.

Security in session management is achieved through:

• Signing session IDs using a secret to prevent session hijacking.
• Configuring cookies securely to avoid XSS and CSRF vulnerabilities.

The routing in routes/index.js is set up to demonstrate session tracking. Each time the main page is visited, the session view count is incremented.

The views/index.hbs file is a Handlebars template to display session data on the front end.

Docker is used to containerize the MongoDB instance for session storage, ensuring that our application can be run consistently across different environments.

To follow this tutorial, you should have the following installed on your machine:

• Node.js
• npm (comes with Node.js)
• Docker (for containerization of MongoDB)

Follow these steps to set up the environment:

1. Clone the repository:

   git clone https://github.com/your-repo/mfe-api-shared-session-store.git
   cd mfe-api-shared-session-store

2. Install dependencies:

   npm install

3. Start MongoDB with Docker Compose:

   docker-compose up -d

4. Run the web server:

   npm start

5. Run the API server:

   npm run start:api

The config.js file contains the session cookie settings and MongoDB connection details. Review this file to understand how sessions are configured.

Open app.js and follow the code to see how the Express server is set up, how sessions are initiated, and how the view engine is configured.

In api.js, notice how we protect the API routes with the withSession middleware from utils.js, ensuring only requests with a valid session can access them.

To test session sharing:

• Visit http://localhost:3000 in your browser to initiate a session and increment the view count.
• Access http://localhost:3001/api using a REST client like Postman with the session cookie from the browser to see if the session persists.

Understand how Docker is used to run MongoDB, which stores the session data, by reviewing the docker-compose.yml file.

This section can outline steps for extending the application, such as adding new routes or integrating other Microfrontend services.

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