Do you know the Modular Monolithic architecture?

A Modular Monolith is a software architecture pattern that combines elements of both monolithic and modular architectures. In this approach, the application is built as a single, unified codebase like a traditional monolith, but it is designed and organized in a modular manner, allowing for logical separation of different components or modules within the codebase.
> The Modular Monolith architecture is the “goldilocks” approach that combines the modularity of microservices with the simplicity of traditional Monoliths
>
> * Steve “Ardalis” Smith

## Modular Monolith characteristics


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* Single Host/Process
* Single Deployment
* Loosely coupled modules that each have their own
  * Domain
  * Application
  * Infrastructure
  * Presentation (API or UI)
* Each module represents a business capability or domain
* Each module should be as highly cohesive and loosely coupled with other modules
* Each module manages it's own data and persistence

### ✅ Advantages

* **Simplicity in Deployment** - Since it's a monolith, the deployment is typically simpler than distributed systems like microservices
* **Ease of Development** - Developers can work on separate modules without significantly affecting other parts of the application
* **Performance** - Inter-module communication is often faster and more reliable than inter-service communication in distributed architectures

### ❌ Challenges

* **Scalability** - While more scalable than a traditional monolith, it may not scale as effectively as microservices
* **Modular Discipline** - Maintaining strict modularity can be challenging as the application grows and evolves

A Modular Monolith offers a balance between the simplicity and coherence of a monolith and the modularity and maintainability of more distributed architectures. It is particularly useful for certain kinds of applications and organizational contexts.

### Modular Monolith compared to other architectures

| Trade-Offs  | Layered / CA | Microservices | Modular Monolith |
| ----------- | ------------ | ------------- | ---------------- |
| Modularity  | ❌           | ✅            | ✅               |
| Cost        | $            | $$$           | $                |
| Scalability | ❌           | ✅            | ❌               |
| Simplicity  | ✅           | ❌            | ✅               |