Architectural Comparison & Trade-offs:
1. Modular Monolith:
- Architecture: A single unified codebase and deployment artifact partitioned internally into strictly encapsulated domain modules with clean interface boundaries.
- Advantages: Zero network latency between modules, trivial local debugging, ACID transactional consistency across domains, simplified CI/CD, and lower infrastructure cost.
- Disadvantages: Entire application must be redeployed together; tight coupling can accumulate if boundary enforcement becomes undisciplined.
2. Microservices Architecture:
- Architecture: Distributed independent services organized around business domains, each with its own datastore and deployment pipeline, communicating over HTTP/gRPC or message queues.
- Advantages: Independent deployability and scaling per domain, team autonomy for large engineering organizations (Conway's Law), and freedom to select specialized tech stacks.
- Disadvantages: Extreme operational complexity, distributed transaction hurdles (eventual consistency, Saga pattern), network latency, partial failures, and complex distributed tracing/monitoring.
3. Pragmatic Decision:
- Start with a modular monolith until team scale (>50 engineers) or distinct scaling bottlenecks justify distributed operational complexity.