Monolith vs Microservices: Architectural Schism

The software industry is gripped by a religious war. On one side: the microservice evangelists promising infinite scalability. On the other: battle-hardened engineers who know that a well-structured monolith can outperform a distributed mess.

The Microservice Promise

  • Independent deployments
  • Team autonomy
  • Technology diversity
  • Horizontal scaling per service

The Microservice Reality

  • Network is not reliable
  • Distributed transactions are a nightmare
  • Debugging across service boundaries requires tracing infrastructure
  • Data consistency requires eventual consistency patterns (sagas, CQRS)
  • DevOps overhead multiplied by number of services

The Monolith Advantage

A monolith with clean internal module boundaries provides:

my_app/
├── modules/
│   ├── auth/        # Authentication module
│   ├── billing/     # Payment processing
│   ├── inventory/   # Stock management
│   └── shipping/    # Order fulfillment
├── shared/
│   ├── database/    # Single, consistent data layer
│   └── events/      # In-process event bus
└── main.c           # Single deployment unit

One binary. One deployment. One database. Fast function calls instead of HTTP requests. Transactions instead of sagas.

When to Distribute

Split into services only when you have a concrete need:

  1. Different scaling requirements (e.g., video processing vs API serving)
  2. Different reliability requirements (e.g., payment processing isolation)
  3. Team size exceeds what can coordinate on a single codebase (100+ engineers)

Start with a monolith. Extract services when the pain is real, not imagined. Premature distribution is the root of all evil in modern architecture.