When it comes to structuring and developing frontend web applications, there are two main approaches: monolithic and micro-frontend. A monolithic frontend application is built as a single, large codebase where all the application code is contained in one place. A micro-frontend application, on the other hand, is composed of several independent micro-applications or microservices that can be developed, deployed, and scaled independently.

Background.

As already briefly explained in the preface, the above image is a pictorial representation to help us understand what monolithic architecture and micro-frontend architecture look like. Further along in the course of this blog, the key differences, features, advantages, and disadvantages will be satisfactorily explained.

Imagine the Twitter homepage as portrayed in the image below, with several UI fragments or components such as the search bar, news feed, nav bar, user profile etc.

Now imagine different teams working on different fragments/components on the frontend of the Twitter homepage. There is an obvious and apparent need to break or move away from a monolithic application structure so as to allow for better speed and efficiency and also to enable a natural decoupling for these teams. The proposed solution must allow teams to manage their code repositories and build processes independently. This is where micro-frontend architecture steps in as the new kid on the block that’s taking the frontend world by storm.

Differences between Monolithic and Micro-frontends.

Pros of Monolithic Architecture

Organizations can still gain from a monolithic architecture despite the shift in the trend toward micro-frontend development since its main advantage is quick development speed because it is straightforward to have an application based on a single code base. Other benefits include;

1. Easy deployment – One executable file or directory makes deployment easier.

2. Development – When an application is built with one code base, it is easier to develop.

3. Performance – In a centralized code base and repository, one API can often perform the same function that numerous APIs perform with microservices.

4. Simplified testing – Since a monolithic application is a single, centralized unit, end-to-end testing can be performed faster than with a distributed application.

5. Easy debugging – With all code located in one place, it’s easier to follow a request and find an issue.

6. Low cost in early stages of the application – All source code is located in one place, packaged in a single deployment unit and deployed. What can be easier? There is no overhead either in infrastructure cost or development cost.

Cons of Monolithic Architecture

Monolithic applications can be quite effective until they grow too large and scaling becomes a challenge. Making a small change in a single function requires compiling and testing the entire platform, which goes against the agile approach today’s developers favor, below are the problems with a monolithic architecture;

1. Slower development speed – A large, monolithic application makes development more complex and slower.

2. Scalability – You can’t scale individual components.

3. Reliability – If there’s an error in any module, it could affect the entire application’s availability.

4. A barrier to technology adoption – Any changes in the framework or language affects the entire application, making changes often expensive and time-consuming.

5. Lack of flexibility – A monolith is constrained by the technologies or stacks already used in the monolith.

6. Deployment – A small change to a monolithic application requires the redeployment of the entire monolith.

7. Testing becomes harder – Even a small change can negatively affect the system. As a result, regression toward full monolithic service is required.

Pros of Micro-frontend Architecture

Microservices are by no means a walk in the park, but they solve a number of problems for growing software and companies. Since a microservices architecture consists of units that run independently, each service can be developed, updated, deployed, and scaled without affecting the others. Software updates can be performed more frequently, with improved reliability, uptime, and performance. In short, the many advantages of microservices include but are not limited to:

1. Agility – Promote agile ways of working with small teams that deploy frequently.

2. Flexible scaling – If a microservice reaches its load capacity, new instances of that service can rapidly be deployed to the accompanying cluster to help relieve pressure. We are now multi-tenant and stateless with customers spread across multiple instances. Now we can support much larger instance sizes.

3. Continuous deployment – We now have frequent and faster release cycles. Before we would push out updates once a week and now we can do so about two to three times a day.

4. Highly maintainable and testable – Teams can experiment with new features and roll back if something doesn’t work. This makes it easier to update code and accelerates time-to-market for new features. Plus, it is easy to isolate and fix faults and bugs in individual services.

5. Independently deployable – Since microservices are individual units they allow for the fast and easy independent deployment of individual features.

6. Technology flexibility – Microservice architectures allow teams the freedom to select the tools they desire.

7. High reliability – You can deploy changes for a specific service, without the threat of bringing down the entire application.

8. Happier teams – The teams who work with microservices are a lot happier since they are more autonomous and can build and deploy themselves without waiting weeks for a pull request to be approved.

Cons of Micro-frontend Architecture

Microservices can add increased complexity that leads to "development sprawl," or rapid and unmanaged growth. It can be challenging to determine how different components relate to each other, who owns a particular software component, or how to avoid interfering with dependent components. Therefore, if you are a single-product company, then microservices may not be necessary.

1. Development sprawl – Microservices add more complexity compared to a monolith architecture since there are more services in more places created by multiple teams. If development sprawl isn’t properly managed, it results in slower development speed and poor operational performance.

2. Exponential infrastructure costs – Each new microservice can have its own cost for the test suite, deployment playbooks, hosting infrastructure, monitoring tools, and more.

3. Added organizational overhead – Teams need to add another level of communication and collaboration to coordinate updates and interfaces.

4. Debugging challenges – Each microservice has its own set of logs, which makes debugging more complicated. Plus, a single business process can run across multiple machines, further complicating debugging.

5. Lack of standardization – Without a common platform, there can be a proliferation of languages, logging standards, and monitoring.

6. Lack of clear ownership – As more services are introduced, so are the number of teams running those services. Over time it becomes difficult to know the available services a team can leverage and who to contact for support.

Summary and Conclusion

Monolithic frontend and micro-frontend are two different approaches to developing a web application. A monolithic frontend is a single codebase that is responsible for all the frontend components of the application. This approach is simpler to develop and maintain, but it can become difficult to scale and update. A micro-frontend is an approach that breaks down the frontend into smaller components, each with its own codebase. This approach is more complex to develop, but it makes it easier to scale and update the application. It also allows different teams to work on different components in parallel. In conclusion, the monolithic frontend is simpler to develop and maintain, but the micro-frontend makes it easier to scale and update the application.

Overall, while both monolithic and micro-frontend architectures have their pros and cons, micro-frontend architecture offers more flexibility, scalability, and maintainability. However, it may require more effort in terms of coordination and planning to ensure that the micro-applications work seamlessly together.

Click here to see my blog post on the basics, whys and hows of Micro-frontend architecture.