Designing Microservices for Small-Scale E-Commerce Systems: An Empirically Evaluated Domain-Driven Refactoring Approach Using Event-Driven Architecture

Purpose: This study proposes a practical, domain-driven design (DDD)-based refactoring approach to guide small-scale e-commerce systems transitioning from a monolithic to an event-driven microservices architecture. Design/methodology/approach – The research combines an applied case study with a controlled experimental evaluation using k6 load testing under a low-traffic, single virtual user scenario. The approach is built around clearly identified bounded contexts, a database-per-service pattern, independently deployable services, and asynchronous communication via Apache Kafka. Structural maintainability was assessed using a Change Impact Scope (CIS) metric, while latency and deployment time were measured for the monolithic baseline and refactored architecture, centred on the Order and Payment services. Findings: The refactored architecture reduced the estimated change impact scope from 100% to 50%, indicating a narrower potential scope of change. Under low-traffic conditions, the microservices architecture showed modestly higher latency than the monolithic baseline, at 10.81 ms against 9.21 ms for the order operation, converging at the 95th percentile, while the initial deployment time differed by more than an order of magnitude. Therefore, maintainability gains are not automatically accompanied by better performance or lower operational costs at low concurrency. Research limitations/implications – The evaluation covered only Order and Payment under a single-user load; fault isolation and reliability were not measured and remain open for future work under concurrent workloads. Originality/value – Unlike most literature, which focuses on enterprise-scale or cloud-native environments and assumes uniform performance gains, this study reports both the structural benefits and performance trade-offs of a DDD-based migration in a small-scale case study.