Evolution of Software Architecture: Monolithic, Distributed, Microservices, and Serverless

1. Monolithic Architecture

Monolithic architecture is a basic three‑tier structure (frontend + business logic + database) commonly implemented with Java Spring MVC or Python Django. It is easy to deploy and test at early project stages, but as codebase grows it becomes complex, hard to maintain, and incurs high deployment costs.

High complexity and tangled modules.

Accumulating technical debt.

Low deployment frequency due to full‑application redeployment.

Poor reliability—one bug can crash the whole system.

Limited scalability; resources must be provisioned for the whole app.

Inhibits adoption of new technologies.

2. Distributed Applications

Distributed architecture splits the system into multiple business modules deployed on separate servers, with distributed databases (e.g., Redis, Elasticsearch). Load balancers such as LVS/Nginx distribute requests. This reduces coupling, clarifies responsibilities, eases scaling, and improves code reuse, though remote communication adds development overhead.

Lower coupling via interface‑based communication.

Clear responsibility boundaries for different teams.

Easy to add new modules.

Flexible deployment across servers.

Improved code reuse across platforms.

Increased effort for remote API development.

3. Microservice Architecture

Microservices further decompose the middle layer into many small, independently deployable services (e.g., Spring Cloud, Dubbo). Each service focuses on a single business capability, allowing fast development, quick startup, isolated deployments, and technology‑stack flexibility, but introduces operational complexity, distributed‑system challenges, and higher interface‑change costs.

Easy development and maintenance of small, focused services.

Fast startup for individual services.

Isolated deployment reduces impact of changes.

Freedom to choose different tech stacks per service.

Higher operational overhead for many services.

Inherent distributed system complexity (fault tolerance, latency, transactions).

High cost of API adjustments.

Potential code duplication across services.

4. Serverless Architecture

Serverless (e.g., AWS Lambda, Google Firebase, Parse) abstracts away server management, charging only for actual execution time. It offers low operational cost, simplified maintenance, improved maintainability through third‑party services, and rapid development, but can lock developers into a vendor ecosystem and lacks mature standards for large‑scale applications.

Low operating cost with pay‑as‑you‑go pricing.

Reduced infrastructure maintenance for developers.

Enhanced maintainability via managed services.

Accelerated development using ready‑made backend services.

Vendor lock‑in and migration challenges.

Few proven large‑scale use cases and limited industry standards.

Currently, microservices dominate the industry, while serverless is emerging as a future trend. The article encourages readers to follow the author for deeper tutorials on building microservices with Spring Cloud and Docker.

Original source: https://www.jianshu.com/p/e7b992a82dc0