Decision-Making Framework for Modular Monoliths and Microservices

Abstract

Choosing between a modular monolith and microservices is a impactful architectural decision, yet the literature offers no empirically grounded, structured approach to guide it. This thesis develops and validates a decision-making framework that integrates technical and business considerations. Following a design-science methodology, a systematic literature review first establishes the research gap. Next, 55 Key Decision Factors (KDFs) are consolidated from academic sources, industry documentation, and expert interviews, organized into seven themes via thematic analysis, and prioritized using a weighted-frequency scheme that reflects evidence across sources. These actors are operationalized as unambiguous yes/no questions and implemented in a lightweight, portable spreadsheet tool that aggregates responses, supports optional theme weightings, and reports a five-point recommendation ranging from “strongly modular monolith” to “strongly microservices.” Validation with two expert sessions on realistic software cases indicates strong face validity: the framework’s recommendations align with architects’ initial judgements and make the underlying rationale transparent. The contribution is a practical, context-sensitive decision aid that makes trade-offs explicit, improves stakeholder dialogue, and can be adopted immediately by software teams, while providing a reproducible basis for further academic evaluation.