Software Reengineering of Monolithic Applications into Layered Architecture

Abstract

Software reengineering of monolithic applications into layered architecture is important for improving maintainability, scalability, testability, and long-term system evolution. Monolithic applications often contain tightly coupled business logic, user interface code, database access routines, shared utilities, and hard-coded dependencies within the same codebase, making modification and testing difficult. Traditional maintenance may correct defects or add features, but it may not remove architectural rigidity that causes slow development, regression risk, and integration problems. This article focuses on software reengineering of monolithic applications into layered architecture by examining code analysis, responsibility separation, presentation-layer extraction, business-logic restructuring, data-access isolation, interface definition, and incremental migration. The study discusses how layered architecture can improve separation of concerns, reduce dependency complexity, support easier testing, and enable controlled modernization without disrupting existing business functions. The article concludes that structured reengineering from monolithic to layered architecture can reduce maintenance effort, improve software quality, support future scalability, and extend the operational life of legacy applications.