Model-Driven Legacy System Modernization at Scale

TL;DR

The paper tackles the challenge of modernizing large-scale, business-critical legacy systems by introducing a four-stage, model-driven migration approach that places a technology-agnostic intermediate abstraction between the legacy codebase and the target platform. It couples systematic analysis, semantic enrichment, and transformation-rule-driven synthesis to generate modern artifacts while preserving behavior and key non-functional qualities, demonstrated on a real industrial .NET/ASP.NET MVC web application migrating to Next.js. The contributions include an end-to-end process, an enriched intermediate abstraction capturing structure, dependencies, and semantics, declarative transformation rules, and an industrial evaluation detailing automation boundaries and maintainability benefits. Practically, this approach reduces risk and manual effort, enables scalable and traceable modernization, and provides reusable patterns applicable to comparable legacy contexts, with future work aimed at broader coverage and quantitative evaluation.

Abstract

This experience report presents a model-driven approach to legacy system modernization that inserts an enriched, technology-agnostic intermediate model between the legacy codebase and the modern target platform, and reports on its application and evaluation. The four-stage process of analysis, enrichment, synthesis, and transition systematically extracts, abstracts, and transforms system artifacts. We apply our approach to a large industrial application built on legacy versions of the .NET Framework and ASP.NET MVC and show that core user interface components and page structures can be migrated semi-automatically to a modern web stack while preserving functional behavior and essential non-functional qualities. By consolidating architectural knowledge into explicit model representations, the resulting codebase exhibits higher maintainability and extensibility, thereby improving developer experience. Although automation is effective for standard patterns, migration of bespoke layout composites remains challenging and requires targeted manual adaptation. Our contributions are: (i) an end-to-end model-driven process, (ii) an enriched intermediate model that captures structure, dependencies, and semantic metadata, (iii) transformation rules that preserve functional behavior and essential non-functional qualities, and (iv) application and evaluation of the approach in an industrial setting. Overall, model-based abstractions reduce risk and effort while supporting scalable, traceable modernization of legacy applications. Our approach generalizes to comparable modernization contexts and promotes reuse of migration patterns.

Figures (4)

• Figure 1: Four-stage model-driven migration pipeline
• Figure 2: Core layers and architectural components
• Figure 3: ASP.NET Web Forms markup, code excerpt (.aspx)
• Figure 4: Migrated Next.js page content, code excerpt (.tsx)