Modular Monolith Architecture: A Decade of Implementation Insights

Personal Journey in Software Development

I've had the privilege of developing frontend applications professionally since 2006. My journey in software development, however, began much earlier – at age 14 with Visual Basic 4. By 17, I had achieved national recognition for developing mathematical applications for high school students.

"My first real application, 'Wingraphic,' was born from a paradox – a mathematics-challenged student creating software to help others understand parabolas, circles, triangles, and their mathematical formulas. I learned mathematics and analytical geometry through programming, which seems counterintuitive but proved incredibly effective."

My professional evolution tracked the development of software patterns and architectures. Starting with MVVM (still used today with WPF and many frontend frameworks), I progressed to backend development with classic ASP.NET using MVC and later plugin architecture. Along the way, I studied and implemented various design patterns – Command, Mediator, Strategy, and others – all with the goal of creating maintainable, scalable applications.

The Reality of Industry Experience

Working with companies across the USA, UK, and Asia revealed a surprising truth:

"The vast majority of self-proclaimed 'Senior Engineers' I encountered had limited understanding of SOLID principles, let alone architectural or design patterns. Finding developers who correctly implement these patterns is rare, and when found, they often struggle with over-engineering."

This observation led me to realize that titles like Junior, Senior, or Architect are largely subjective. Many companies base these designations on years of experience rather than problem-solving capabilities.

This observation led me to realize that titles like Junior, Senior, or Architect are largely subjective. Many companies base these designations on years of experience rather than problem-solving capabilities.

"When someone claims 20 years of experience to justify their senior title, believe half of what they say. They might have spent those 20 years writing poor code in Visual Basic with Windows Forms."

The Modular Monolith Approach

In every project I lead, I implement design and architecture patterns to ensure team alignment. The Modular Monolith pattern has been particularly successful. Rather than explaining its mechanics, I'll share my conclusions about its benefits and drawbacks.

Key Benefits

1. Module Autonomy:

   • Each module's implementation is internal by default

   • Exposes only necessary contracts for other modules

   • Promotes separation of concerns and independence

2. Flexibility:

   • Modules can be removed or replaced without system-wide impact

   • Enables independent testing and development

3. Team Collaboration:

   • Multiple teams can work on the same solution with minimal conflicts

   • Clear boundaries reduce merge conflicts and integration issues

Challenges and Pitfalls

1. The Skill Issue:

"The biggest challenge in implementing any design pattern is what I call the 'skill issue' – when the engineer or project lead lacks the experience and expertise to execute it effectively."

2. Balance:

   • The line between appropriate implementation and over-engineering is thin

   • Developers often adopt new technologies without evaluating their necessity

3. Boundary Management:

   • Without clear module boundaries, unnecessary dependencies can develop

   • Poor boundary definition can complicate development and maintenance

Conclusion

The Modular Monolith pattern has proven invaluable for scaling projects efficiently without resorting to what I consider one of the industry's most problematic designs – microservices. It enables delivering final products to clients and businesses without the ceremonial complexity of production deployments.

"At the end of the day, it's simpler to maintain a well-structured monolithic executable deployed in the cloud (Azure, AWS, etc.) than to manage hundreds of micro(macro)-services that turn project work into a deployment nightmare."

The key to success with Modular Monolith architecture lies in understanding its principles, maintaining clear boundaries, and avoiding over-engineering. When implemented correctly, it provides a robust foundation for scalable, maintainable applications while keeping deployment and management complexity in check.

The pattern's success ultimately depends on the team's ability to maintain discipline in module boundaries and resist the temptation to create unnecessary dependencies. With proper implementation, it offers a practical middle ground between monolithic and microservice architectures.

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This article is based on over a decade of hands-on experience implementing and managing Modular Monolith architectures across various industries and project scales.