The progression from monolithic applications to composable architecture marks a significant leap in building highly scalable and maintainable software applications. This evolution crossed different milestones in its path.

The Era of Monolithic Applications

Historically, software systems were predominantly monolithic. In these systems, various components, including the user interface, business logic, and data access layers, are tightly integrated within a single codebase. While this approach was straightforward and productive initially, it inevitably led to challenges as applications grew in complexity.

Even a minor modification to the application could necessitate rebuilding, testing, and redeploying the entire application, introducing inefficiency. Additionally, developer efficiency decreases as many developers have to collaborate and handle a broader cognitive load to identify the areas of change and their impact.

The Modular Monolith

Before the widespread adoption of microservices and micro frontends, the modular monolith architectural style emerged as a middle ground between the traditional monolith and the fully distributed microservices.

This approach aims to retain the operational simplicity of the monolith while introducing a level of modularity and separation of concerns typically associated with Microservices. It draws clear boundaries around modules, making development and testing more granular, reducing the cognitive load for development, and thus improving overall productivity.

Yet, the fundamental challenges of a large code base still exist, impacting developer collaboration and efficient use of resources to run the application.

Shift Toward Microservices and Micro Frontends

The advent of Microservices marked a paradigm shift to address many challenges of monolithic architectures at scale. Microservices architecture enabled independent development, testing, and deployment by breaking down applications into smaller, loosely coupled services, each responsible for a specific function and communicating through well-defined interfaces.

Building on the principles of Microservices, the concept of Micro frontends emerged to address similar challenges in the frontend landscape. Microfrontends extend the Microservices paradigm to the frontend, breaking down monolithic frontend codebases into smaller, more manageable pieces.

However, there is a fundamental difference between Microservices and Microfrontends. Microservices are distributed systems where each service has an end-to-end lifecycle and complete autonomy in development and operations. Therefore, it is recommended that each Microservice run on its own process (runtime isolation) and databases (data isolation) and has its own codebase (code isolation), minimizing dependencies across development teams, resulting in less reuse and collaboration.

On the other hand, Micro frontends need a significant level of component reuse to keep UI consistent. It requires either run-time or build-time (preferred) integration before running in the browser.

Microservices and Micro frontends are not suitable for everyone. A startup or a small development team may find it difficult and counter-productive to adapt these architectural styles as they come with overheads in setting up projects and managing operations. Therefore, the cost of adapting these architectures makes sense beyond a certain scale.

Introducing Purely Composable Architecture

Composability involves creating software applications from independent, reusable components, each encapsulating its dependencies and distinct functionality. Then, these components (building blocks) can be combined to build complex applications. It’s a fundamental difference to the way we used to develop software applications.

Since components are smaller, reusable building blocks, the context of change becomes the scope of the components that can be modified and tested independently. The main gap in implementing composable architecture in the past is not having robust tooling to support it. And since some changes may cut across multiple components, robust tooling that aids in modifying components in bulk and testing the dependency chain is required.

The following diagram showcases how bit shows the dependency graph of modified components and their dependents.

And the beauty of this approach is that since it’s so fundamental, you can use it with other architectural styles to address some of their weaknesses. Following are some examples.

• You can use components to build your Microservices so that you can start collaborating between teams and share components.
• Use app as the shell component to build your Micro frontends, using a remote scope for each team.
• Create an Env for each Microservice so that the technology used in each Microservice is independent of one another.

And, since each component has its documentation, clear interfaces, tests, and previews and share these in bit.cloud, collaboration increases at scale across codebases and teams.

And there are many other benefits of implementing a composable architecture;

• Enhanced Flexibility: Architecture becomes flexible when adopting different styles and patterns.
• Scalability of the development team: Individual components can be scaled as needed, allowing for more efficient resource utilization.
• Maintainability: The modular nature of composable architectures simplifies maintenance and updates, as changes are localized to specific components.
• Innovation and Speed: Reusable components accelerate development cycles and foster innovation by enabling teams to leverage existing functionalities for new applications and collaborate better.
• Better dependency management: Consider a scenario where a UI component library is used across multiple projects within an organization. Bit can manage these components’ dependencies, ensuring that updates do not break functionality in any projects relying on the library.

Summary

The evolution from monolithic applications to composable architectures is redefining the standards for software development. With the support of advanced tools like Bit, the future of software development is set to be more flexible, efficient, and aligned with the dynamic needs of businesses.

As we move forward, composable architectures will undoubtedly continue to shape the future of software development, marking a significant shift towards more adaptable and resilient software systems.