The Architecture Decision That Shapes Everything

Choosing between microservices and a monolithic architecture is one of the most consequential technical decisions a team will make. The choice affects development speed, deployment complexity, operational cost, and team structure for years to come. At Nexis Limited, we have built production systems using both patterns — monoliths for our Digital Menu platform and microservices for Bondorix — and the lessons have been pragmatic rather than dogmatic.

Understanding Monolithic Architecture

A monolith is a single deployable unit that contains the entire application logic. The codebase lives in one repository, compiles into one artifact, and runs as one process. Despite the negative connotation the term has acquired, monoliths remain the right choice for most early-stage and mid-scale applications.

Advantages of Monoliths

  • Simplicity: One codebase, one deployment pipeline, one database. Developers can trace a request from HTTP handler to database query without crossing service boundaries.
  • Performance: In-process function calls are orders of magnitude faster than inter-service HTTP or gRPC calls. No serialization overhead, no network latency.
  • Transactional integrity: ACID transactions across the full domain are straightforward. No need for sagas, eventual consistency, or distributed transaction coordinators.
  • Easier debugging: A single stack trace captures the full call chain. Distributed tracing tools are unnecessary.

When Monoliths Struggle

Monoliths become painful when the team grows beyond 8–12 engineers working on the same codebase, when different parts of the system have drastically different scaling requirements, or when deployment risk grows because every change redeploys the entire application.

Understanding Microservices Architecture

Microservices decompose an application into independently deployable services, each owning its own data and business logic. Communication happens over the network via REST, gRPC, or message queues.

Advantages of Microservices

  • Independent deployment: Teams can ship changes to one service without coordinating releases across the organization.
  • Technology heterogeneity: Each service can use the language and database best suited to its problem. Bondorix uses Go for its bidding engine and Python for its analytics pipeline.
  • Granular scaling: Scale only the services under load. A CPU-intensive image processing service can scale independently from a lightweight metadata API.
  • Fault isolation: A crash in one service does not bring down the entire system if circuit breakers and bulkheads are in place.

The Hidden Costs

Microservices introduce distributed systems complexity: network failures, data consistency challenges, service discovery, distributed tracing, and significantly more infrastructure to manage. Teams that adopt microservices prematurely often spend more time on infrastructure plumbing than on business logic.

Our Decision Framework

At Nexis Limited, we apply a simple heuristic:

  • Start with a well-structured monolith (modular monolith).
  • Extract services only when there is a concrete scaling, deployment, or team-autonomy reason.
  • Each extraction should solve a problem you are actively experiencing, not one you anticipate.

The Modular Monolith: Best of Both Worlds

A modular monolith enforces strong module boundaries within a single deployable unit. Each module has its own internal data access layer and communicates with other modules through well-defined interfaces. This gives you the organizational clarity of microservices without the operational complexity. When a module genuinely needs to become a separate service, the extraction is straightforward because the boundaries are already clean.

Conclusion

There is no universally correct architecture. Monoliths are faster to build and simpler to operate for most applications. Microservices shine when scale, team size, or deployment frequency demands them. The best teams start simple and evolve their architecture in response to real constraints.

Need help designing the right architecture for your project? Talk to our engineering team for a free consultation.