# Legacy Modernization Published articles for Legacy Modernization. This is one page of public article previews, not the complete archive. Follow Next page to continue. Summaries are not the original full articles. ## How to Use Differential Testing During a Legacy Migration DevFeed: [How to Use Differential Testing During a Legacy Migration]() Original publisher: [Read original article]() Author: Hugo Teijiz Published: 2026-09-14T16:25:50Z Content type: tutorial Language: en Sources: [freeCodeCamp Programming Tutorials: Python, JavaScript, Git & More]() Topics: [migration](), [Testing](), [TypeScript](), [Integration testing](), [API](), [observability](), [Artificial Intelligence]() Tags: [ai](), [api](), [architecture](), [artificial-intelligence](), [code](), [how-to](), [integration](), [legacy-code](), [legacy-modernization](), [migration](), [modernization](), [observability](), [software-architecture](), [software-testing](), [testing](), [tests](), [tutorial](), [typescript]() ### AI overview This tutorial explains how to use differential testing during a legacy migration by running old and new implementations with identical inputs and comparing their behavior. It covers equivalence rules, output normalization, nondeterministic values, errors, side effects, automated testing, mismatch analysis, production shadow traffic, and using AI to classify divergences without allowing it to determine correctness. ### Source excerpt The most dangerous moment in a legacy migration isn't necessarily when you start writing the new implementation. It's when the new implementation looks finished. The code compiles, the tests pass, the ## Modernizing a Legacy Java 1.5 Codebase with Evidence-Grounded AI and Docker DevFeed: [Modernizing a Legacy Java 1.5 Codebase with Evidence-Grounded AI and Docker]() Original publisher: [Read original article]() Author: Martin Fowler (martin@martinfowler.com) Published: 2026-07-16T13:25:00Z Content type: article Language: en Sources: [Martin Fowler]() Topics: [Legacy Modernization](), [Java](), [Large Language Model](), [Refactoring](), [Docker]() Tags: [docker](), [java](), [legacy-modernization](), [llms](), [refactoring](), [tests]() ### AI overview The article describes modernizing a Java 1.5 codebase for current hardware. It finds that LLM output was unreliable when used without repository evidence, while progress came from evidence-based analysis, Docker validation, and gradual refactoring protected by tests. ### Source excerpt When people think of legacy modernization, most folks aren't imagining the target environment will be Java 8. But this was the challenge facing Nik Malykhin when he needed to run a Java 1.5 codebase on today's hardware. His early use of LLMs gave plausible answers that did not hold up in the codebase. Progress came when he grounded the process in evidence, using AI to support analysis, validation in a stable Docker environment, and gradual refactoring protected by tests. The main takeaway is practical: AI was most useful when constrained by evidence, clear roles, and a step-by-step modernization strategy. more... ## Using Gherkin to Document Behavioral Equivalence in RPG Migrations DevFeed: [Using Gherkin to Document Behavioral Equivalence in RPG Migrations]() Original publisher: [Read original article]() Author: Federico Tomassetti Published: 2026-07-14T06:24:03Z Content type: article Language: en Sources: [Federico Tomassetti]() Topics: [migration](), [Testing](), [Mainframe]() Tags: [legacy-modernization](), [mainframe](), [migration](), [rpg](), [specifications](), [testing]() ### AI overview The article argues that Gherkin can make RPG migration testing auditable to business stakeholders by expressing undocumented business rules in a readable form. It presents behavioral equivalence and stakeholder sign-off as more important migration outcomes than test coverage alone. ### Source excerpt Everyone benchmarks RPG migration test suites on coverage. That's the wrong metric -- the real deliverable is behavioral equivalence a non-programmer will sign off on, and Gherkin is the only format the people who actually know the rules can read. The post Why Gherkin Is the Right Testing Tool for RPG Migration -- And It Has Nothing to Do With BDD appeared first on Federico Tomassetti. ## AI RPG Migration Can Compile and Still Break Business Logic DevFeed: [AI RPG Migration Can Compile and Still Break Business Logic]() Original publisher: [Read original article]() Author: Federico Tomassetti Published: 2026-06-30T08:00:00Z Content type: opinion Language: en Sources: [Federico Tomassetti]() Topics: [migration](), [AI-assisted coding](), [Benchmark](), [Code]() Tags: [ai](), [benchmarks](), [business-logic](), [compilation](), [legacy-modernization](), [migration](), [rpg](), [tests]() ### AI overview The article argues that AI-assisted RPG migration tools should be evaluated on behavioral equivalence, not only compilation and generated test-pass rates. It cites the AgentModernize study, where the best reported result reached 19.4% behavioral equivalence, and describes gaps between extracting business rules and implementing them faithfully. ### Source excerpt AI-assisted RPG migration tools report high compilation success rates while silently failing on behavioral equivalence -- packed decimal truncation, activation group persistence, and cycle logic. The benchmarks show why, and what a real accuracy test looks like. The post AI RPG Migration Can Compile and Still Break Business Logic appeared first on Federico Tomassetti. ## Joining forces to modernize legacy software DevFeed: [Joining forces to modernize legacy software]() Original publisher: [Read original article]() Author: Mary Louise Stewart Published: 2026-05-14T08:00:00Z Content type: release Language: en Sources: [Federico Tomassetti]() Topics: [Software](), [Reverse Engineering](), [Refactoring](), [Code generation](), [interoperability](), [AI-assisted coding]() Tags: [code-generation](), [interoperability](), [legacy-code](), [legacy-modernization](), [migration](), [model-driven-development](), [modernization](), [parsing](), [refactoring](), [reverse-engineering](), [software](), [transpilers]() ### AI overview Strumenta and Metadev announced a collaboration to modernize legacy software. Strumenta contributes code analysis, extraction, and transformation capabilities, while Metadev contributes modeling, AI integration, and code generation. Their approach uses LionWeb models as an intermediate representation between legacy code and modernized systems. ### Source excerpt Strumenta and Metadev Join Forces to Modernize Legacy Software A collaboration combining Strumenta's expertise in code analysis, extraction, and transformation with Metadev's capabilities in modeling, artificial intelligence, and code generation from models. Torino/Seville, May 14, 2026 -- Strumenta S.r.l. and Metadev S.L. have reached a collaboration agreement to offer a joint approach to Modernizing Legacy [...] The post Joining forces to modernize legacy software appeared first on Federico Tomassetti. ## 7 steps in a Legacy Modernization Project DevFeed: [7 steps in a Legacy Modernization Project]() Original publisher: [Read original article]() Author: Federico Tomassetti Published: 2026-02-25T06:55:00Z Content type: tutorial Language: en Sources: [Federico Tomassetti]() Topics: [Agile](), [Code quality](), [Code](), [modules]() Tags: [automated](), [business-value](), [code-quality](), [legacy-modernization](), [modernization](), [modules](), [project](), [rpg](), [technical]() ### AI overview This tutorial outlines seven steps for modernizing an RPG-based ERP/MRP system: assess the legacy landscape, define a roadmap, secure buy-in and budget, build the right team and partnerships, execute iterative value-driven increments, manage change, and measure and adapt the modernization effort. ### Source excerpt Embarking on an RPG-based ERP/MRP system modernization is undeniably complex. But it's also highly rewarding when aligned with your business's long-term success. By addressing both the technical and strategic facets, you turn an aging system from a liability into a competitive asset. Let's outline the 7 steps in a legacy modernization project: Step 1: Assess [...] The post 7 steps in a Legacy Modernization Project appeared first on Federico Tomassetti. ## 7 Reasons Why CEOs Should Modernize their Software DevFeed: [7 Reasons Why CEOs Should Modernize their Software]() Original publisher: [Read original article]() Author: Aisling Foley Published: 2026-02-18T07:23:00Z Content type: opinion Language: en Sources: [Federico Tomassetti]() Topics: [Software](), [cobol](), [Visual Basic](), [SAS]() Tags: [cobol](), [financial-services](), [growth](), [integration](), [leadership](), [legacy](), [legacy-modernization](), [manufacturing](), [security](), [software]() ### AI overview This commentary argues that CEOs should modernize legacy software because systems that remain stable can still create strategic, regulatory, security, integration, and knowledge-retention risks. It discusses legacy systems used in manufacturing and financial services, including COBOL, RPG, Visual Basic 6, and SAS. ### Source excerpt Key Takeaways Legacy software is tolerated because, let's face it, it works, and works well. But that's no longer good enough. Nowadays, it limits an organisation's strategic options. Legacy software can slow down, or make strategic plans more expensive or complicated than they need to be. Whilst legacy software is considered stable, the real risk [...] The post 7 Reasons Why CEOs Should Modernize their Software appeared first on Federico Tomassetti.