Impact of Micro Services Architecture Design Patterns on Software Maintenance Cost

Microservices Architecture (MSA) has become a prevalent approach for developing scalable and maintainable software systems. However, practitioners often lack quantified expectations for the maintenance cost improvements achievable through MSA design patterns. This study proposes an integrated framework combining maintainability metrics assessment, cost prediction formulas, and design pattern application to evaluate maintenance cost reduction in microservices-based systems. Using a real-world Student Registration System (PPDB module) with 21 classes as a case study, we applied five MSA design patterns: Service Decomposition, Anti-Corruption Layer, Event-Driven Architecture, Database Per Service, and API Gateway. The results demonstrate a 23.1% reduction in Architectural Maintenance Effort (AME) and an estimated 25% annual maintenance cost reduction ($15,000 savings). The findings validate that MSA design patterns significantly reduce predicted maintenance costs, with Service Decomposition achieving the highest individual impact (41.8% AME reduction). This research contributes a practical framework for quantifying the return on investment of architectural refactoring decisions.