The document discusses strategies for dealing with legacy codebases, specifically rewriting the code completely versus incrementally redeveloping it. It outlines characteristics of software that lasts, such as the ability to evolve over time, separation of concerns, using standard languages, and fault tolerance. Best practices for developing lasting software are also presented, including coding standards, static analysis tools, defensive programming, testing, documentation, and leaving the codebase in a better state than when development started. The overall recommendation is for incremental redevelopment of legacy codebases rather than full rewrites.

1. Building Software
That Lasts
Agile India 2018
Kris Howard @web_goddess

12. LEGACY
CODEBASE
😱

13. Legacy software
🔥 Rewrite it completely 🔥
OR
⛵ Incremental redevelopment ⛵

15. Why to Rewrite
•The code is a mess.
•The application is slow.
•The code is ugly.
•We’ll get it right this time!
•We picked the wrong platform.

18. Characteristics
• Ability to evolve over time
• Separation of concerns

19. Characteristics
• Ability to evolve over time
• Separation of concerns
• Use of standard languages

20. Characteristics
• Ability to evolve over time
• Separation of concerns
• Use of standard languages
• Minimising of dependencies

21. Characteristics
• Ability to evolve over time
• Separation of concerns
• Use of standard languages
• Minimising of dependencies
• Simple, readable code

22. Characteristics
• Ability to evolve over time
• Separation of concerns
• Use of standard languages
• Minimising of dependencies
• Simple, readable code
• Fault-tolerance and fast recovery

24. Characteristics
• Ability to evolve over time
• Separation of concerns
• Use of standard languages
• Minimising of dependencies
• Simple, readable code
• Fault-tolerance and fast recovery

26. Best practices
• Coding standards and code reviews

27. Best practices
• Coding standards and code reviews
• Static analysis tools

28. Best practices
• Coding standards and code reviews
• Static analysis tools
• Defensive programming

30. Best practices
• Coding standards and code reviews
• Static analysis tools
• Defensive programming
• Property-based testing

32. Best practices
• Coding standards and code reviews
• Static analysis tools
• Defensive programming
• Property-based testing
• The Campsite Rule

33. Best practices
• Coding standards and code reviews
• Static analysis tools
• Defensive programming
• Property-based testing
• The Campsite Rule
• Documentation

34. Back to my story…

36. To recap…

37. Legacy software
🔥 Rewrite it completely 🔥
OR
⛵ Incremental redevelopment ⛵

38. Characteristics
• Ability to evolve over time
• Separation of concerns
• Use of standard languages
• Minimising of dependencies
• Simple, readable code
• Fault-tolerance and fast recovery

39. Best practices
• Coding standards and code reviews
• Static analysis tools
• Defensive programming
• Property-based testing
• The Campsite Rule
• Documentation

40. Thank you!
Agile India 2018
Kris Howard @web_goddess