Originally published on my medium page

Hey there, folks! Get ready for a super cool tech showdown! 

In this story, our web developers as superheroes, just like the Avengers. They've got a new trick up their sleeves called Micro-Frontends. It's like breaking big stuff into smaller, easier-to-handle pieces. Think of it like the Avengers splitting up to handle different tasks separately. Our developers can do the same with the front-end of websites! 

It's similar to using special ways to break down old, outdated web elements.

And the best part? Each part can be worked on, put out there, and made bigger all by itself. It's like each hero can do their thing without waiting for the others. 

So, let's watch these web-building Avengers go wild with their Micro-Frontends powers! 🦸‍♂️🚀

What are Micro-Frontends?

In the age of monoliths, developers faced countless challenges. As applications grew in complexity, making even the smallest update felt like an epic battle. Teams struggled to collaborate. Deploying changes felt very risky, like trying to walk on a thin rope over a sea full of sharks.

But here comes the solution - Micro-Frontends!

Micro-Frontends, in simple terms, refers to a modern architectural approach for building web applications by breaking down the frontend into smaller, independent, and self-contained modules. 
The main goal of Micro-Frontends is to improve the scalability, maintainability, and flexibility of large and complex web applications.

In this article, we will delve into the concept of Micro-Frontends. We will explore its key characteristics and illustrate its implementation through an example of an e-commerce site. The article also sheds light on three types of integrations for Micro Frontends.

So..

Let's understand with an Example

Let's consider a hypothetical example of an e-commerce website that uses a micro-frontend architecture. In this example, the e-commerce website is composed of four main micro-frontends:

1. Product Catalog: This micro-frontend is responsible for displaying the list of products available on the site. It includes features like product search, filtering, and sorting. 
2. Shopping Cart: This micro-frontend handles the user's shopping cart functionality. It allows users to add products to their cart, update quantities, and proceed to checkout. 
3. User Account: This micro-frontend deals with user authentication and account-related features. Users can log in, view their orders, and update their account information.

Each of these micro-frontends is developed as an independent project with its own codebase, build, and deployment process. They can be maintained by separate teams, allowing for parallel development and faster iterations.

Key Characteristics of Micro-Frontends

1. Decentralization: Since the e-commerce application functionality is broken into three independent units, each micro-frontend is typically owned and maintained by a separate team, which fosters decentralization and allows teams to work independently.
2. Loose Coupling: The loose coupling between these micro-frontends enables different teams to add new features or enhancements or bug/hot fixes to their micro-frontend without directly affecting other parts of the application.
3. Parallel Development: All the teams can work simultaneously on different features or modules, speeding up the development process.
4. Autonomous Deployment: These teams can deploy new features, updates or bug fixes without affecting other parts of the application.
5. Scalability: These micro-frontends can be scaled independently based on the specific requirements of each module, optimizing resource usage and performance.
6. Technology Diversity: Each team can the use of different technologies and frameworks for each of their module. 
7. Improved Codebase Organization: In large codebases, it can be challenging to navigate and maintain code. Micro-frontends can improve codebase organization by breaking down the application into smaller, more manageable parts, making it easier to understand and maintain the code.
8. Improved QA Process: Micro-frontends can facilitate more focused and efficient testing, as teams can isolate and test individual modules independently.

Container

• To orchestrate the communication and rendering of these micro-frontends, there is a central shell application, which acts as the Container for all these micro-frontends. 
• It provides the overall layout and navigation for the website.

Integration

• Integration in the context of micro-frontends refers to the process of combining individual micro-frontend modules into a cohesive and functional web application. 
• As Micro-Frontends are designed as independent and autonomous units, integration becomes a crucial step to assemble these modules into a single user interface that provides a seamless and unified experience to the end-users.

Types of Integrations in Micro-Frontends

In Micro-Frontend architectures, there are three major types of integration to combine the individual micro-frontends into a cohesive web application.

1. Build-Time Integration

• Build-time integration involves combining the micro-frontends during the build process before deploying the application. 
• In this approach, the various micro-frontends are built separately, and then they are bundled together into a single application during the build step.
• In the context of our e-commerce website, in Build-time integration, team responsible for developing Product Catalog can publish it as an NPM package. Then the Container team will install/update the Product Catalog package and builds their app. After completing the build, the resulting bundle is then deployed as a complete e-commerce website.
• Pros: Easy to set and understand
• Cons: Container App has to be deployed every time one of the micro-frontends is updated.

2. Run-time Integration

• Run-time integration (sometimes referred as Client-Side Integration) involves combining the micro-frontends on the client-side, usually within a Container.
• The Container is responsible for loading and rendering the micro-frontends. 
• The Micro-Frontends can be loaded asynchronously at runtime, allowing for a more dynamic and flexible integration.
• In the context of our e-commerce website, in Run-time Integration, the team responsible for developing Product Catalog can build their project and deploy the bundle as a static resource at https://my-web-app.com/productlist.js. Assuming the Container team has included the path of this file path into their code, when user navigates to https://my-web-app.com, container app fetches this resource at run-time whenever required and executes it. 
• In simple terms, the corresponding micro-frontends are dynamically loaded as and when needed.
• Pros: Individual micro-frontends can be deployed independently at any point of time. Re-deployment of Container App is not required.
• Cons: Setup can be complicated.

3. Server-Side Integration

• Server-side integration involves combining the micro-frontends on the server-side before delivering the final HTML to the client. 
• In this approach, the server takes care of assembling the various micro-frontends into a complete HTML page, which is then sent to the client for rendering.
• In the context of our e-commerce website, in Server-side integration, the server-side code (e.g. using server-side rendering or server templates) fetches data from the respective micro-frontends (Product Catalog, Shopping Cart, User Account) and generates a complete HTML page that includes the necessary components from each micro-frontend. The assembled HTML page is then sent to the client, where it can be further enhanced with client-side interactions.
• Pros: Good for SEO; Initial load time is less
• Cons: Not be suitable for highly dynamic applications or when the server load and tight coupling concerns need to be minimized

In summary, Micro-Frontends can be integrated through Run-time , Server-side, or build-time integration. Each integration type has its own advantages and disadvantages, and the choice depends on factors such as project requirements, tech stack, and the team's mindset.

Conclusion 
In conclusion, Micro-Frontends offer a compelling solution for building scalable and maintainable web applications. Through the example of an e-commerce site, we witnessed how this approach can be helpful in the frontend development, unlocking agility and fostering continuous innovation. 

By understanding and implementing the various integration options, developers can fully leverage the potential of Micro-Frontends to deliver seamless user experiences and stay ahead in today's dynamic digital landscape.