Choosing the Right Architecture

Thinking “Now, Next, and Later”

When designing software architecture for a business, one of the most important decisions you make is choosing the type of architecture that aligns with the current needs, supports upcoming growth, and adapts to future scalability.

It is not just about solving the immediate problem. Choosing the right architecture is the most important decision we will face as a software architect or engineering leader. The choice between monolith, modular monolith, distributed monolith, and microservices depends on the business’s current state, future plans, and non-functional requirements (NFRs) like cost, scalability, and maintainability.

In this article, I will explore how to approach architecture decisions for the “Now,” “Next,” and “Later” stages of a business.

1. Monolith Architecture

A monolith is a single codebase where all application components (frontend, backend, database access, multiple modules, etc.) are tightly coupled and deployed.

When to Choose Monolith

• You are building an MVP or starting a new business.
• The team size is small, and you want to reduce development complexity.
• You need to prioritize time to market and cost efficiency.
• Your application has low traffic and simple use cases.

Advantages

• Simplicity — Easy to develop, test, and deploy (depends on the scope).
• Cost-effective — Lower infrastructure and operational costs.
• Faster Development — No need for complex orchestration.

Disadvantages

• Scalability — Difficult to scale individual components independently.
• Maintainability — As the application grows, the codebase becomes harder to manage.
• Deployment Risks — A single bug can crash the entire system.

2. Modular Monolith

A modular monolith is a single codebase like a monolith but organized into well-defined modules with strict boundaries. Each module is responsible for a specific domain or feature.

When to Choose Modular Monolith

• You want to improve maintainability and separation of concerns without introducing the complexity of microservices.
• You foresee the need to scale specific features in the future.
• The team size is medium, and responsibilities can be divided among teams working on individual modules.

Advantages

• Better Maintainability — Modular design ensures clean separation of concerns.
• Easier Testing — Individual modules can be tested independently.
  Simpler Deployment — A single deployment pipeline with well-organized modules.
• Future-Proofing — Modules can later be extracted as microservices.

Disadvantages

• Single Deployment — Modules are still deployed together, so scaling is limited.
• Initial Overhead — Requires careful design to define module boundaries.
• Interdependencies — Modules might still depend on each other, causing potential tight coupling.

3. Distributed Monolith

A distributed monolith is an anti-pattern that occurs when applications are split into multiple services, but they are tightly coupled, leading to challenges in deployment and communication.

When to Choose Distributed Monolith

Ideally, you should not choose this architecture. It is often an accidental result of transitioning from a monolith to microservices without properly decoupling components.

Challenges

• Tightly Coupled Services — Each service depends on others to function, reducing independence.
• Complex Deployments — A change in one service may require coordinated deployments across all services.
• Latency Issues — Communication between tightly coupled services adds unnecessary overhead.

How to Avoid It

• Clearly define bounded contexts using Domain-Driven Design (DDD).
• Use asynchronous communication (e.g., message queues) to reduce coupling.
• Prioritize independence when splitting services.

4. Microservices Architecture

Microservices consist of small, independent services, each responsible for a specific business capability. These services communicate via APIs or messaging systems.

When to Choose Microservices

• You are scaling a mature business or application.
• The team size is large, and responsibilities can be split across multiple teams.
• Your business needs high scalability, global availability, or real-time performance.
• Your application has diverse and complex requirements.

Advantages

• Scalability — Scale services independently based on traffic.
• Flexibility — Use different tech stacks for different services.
• Fault Isolation — Failure in one service doesn’t affect others.
• Continuous Deployment — Services can be deployed independently.

Disadvantages

• Operational Complexity — Requires infrastructure for service discovery, orchestration, monitoring, and logging.
• Cost — Higher infrastructure costs compared to monoliths.
• Team Skills — Requires a team skilled in distributed systems.
• Data Consistency — Managing distributed transactions is challenging.

How to Decide?

Here is a simple framework to help you decide based on the stage of the business and requirements.

1. For Startups or MVPs
   Start with a monolith. It is simple, cost-effective, and allows you to focus on delivering value quickly.
2. For Growing Businesses
   Use a modular monolith to introduce clear boundaries within your application. This helps prepare for future scalability without introducing operational complexity.
3. For Mature Enterprises
   Opt for microservices when you need to scale globally, handle large traffic volumes, and offer independent deployments.
4. Avoid Distributed Monoliths
   If transitioning from a monolith, do it carefully with well-defined service boundaries and independent deployment pipelines.

Balancing NFRs

Non-functional requirements (NFRs) like cost, scalability, and availability should guide your architectural decisions. Here is how.

• Cost — Monoliths are cheaper initially but become expensive to scale. Microservices cost more upfront but pay off in the long run.
• Scalability — Microservices allow fine-grained scaling, while monoliths require scaling the entire application.
• Availability — Microservices enable fault isolation, ensuring one service failure does not take down the entire system.
• Maintainability — Modular monoliths and microservices shine here, as they provide a clear separation of concerns.

It is About Trade-offs and Evolution

Choosing an architecture is not a one-time decision. it is an evolutionary process. Start simple, align with the current business needs, and keep your future growth in mind.

• Start with a monolith for simplicity.
• Transition to a modular monolith as you grow.
• Evolve into microservices for global scalability and resilience.

Remember, it is all about balancing trade-offs with the business goals and non-functional requirements. What works for a startup may not work for a global enterprise — and that is okay.

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