Start with the topic guide.
Codebase analysis, dependency mapping, characterization tests, legacy integration, framework upgrades, database migrations, compatibility management, incremental replacement, deprecation, technical-debt reduction, and software retirement.
This is a learning outline. A complete worked tutorial has not been published for this topic yet.
Concept scope
Maintenance, Reverse Engineering & Modernization: 11 short lessons, one for each concept. Codebase analysis, dependency mapping, characterization tests, legacy integration, framework upgrades, database migrations, compatibility management, incremental replacement, deprecation, technical-debt reduct