Putting legacy to REST with middleware
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Adam Culp discusses the challenges and methods of refactoring legacy code using middleware, emphasizing the importance of iteration and modernization. He highlights various strategies such as total rewrites and RESTful APIs, while also addressing potential pitfalls and benefits. The talk concludes with an emphasis on teamwork, testing, and the significance of middleware in modern application development.
Putting legacy to REST with middleware
- 1. Putting Legacy to REST with Middleware By: Adam Culp Twitter: @adamculp
- 2. 2 Putting Legacy to REST with Middleware ● About me – DevRel and Tech Lead at Nexmo – OSS Contributor – PHP-Fig voting member (IBM i Toolkit) – Organizer SoFloPHP (South Florida) – Organizer SunshinePHP (Miami) – Long distance (ultra) runner – Judo Black Belt Instructor
- 3. 3 Putting Legacy to REST with Middleware ● About me – DevRel and Tech Lead at Nexmo – OSS Contributor – PHP-Fig voting member (IBM i Toolkit) – Organizer SoFloPHP (South Florida) – Organizer SunshinePHP (Miami) – Long distance (ultra) runner – Judo Black Belt Instructor I am the PHP Ninja!!!
- 4. 4 Putting Legacy to REST with Middleware ● Fan of iteration – Pretty much everything requires iteration to do well: ● Long distance running ● Judo ● Development ● Evading project managers ● Refactoring!
- 5. 5 Refactoring Legacy Code ● What is “Legacy Code”? – Is there a coding standard for your project?
- 6. 6 Refactoring Legacy Code ● What is “Legacy Code”? – Is there a coding standard for your project? – Is code using OOP?
- 7. 7 Refactoring Legacy Code ● What is “Legacy Code”? – Is there a coding standard for your project? – Is code using OOP? – Is Composer used in your project?
- 8. 8 Refactoring Legacy Code ● What is “Legacy Code”? – Is there a coding standard for your project? – Is code using OOP? – Is Composer used in your project? – Is the project using a framework?
- 9. 9 Refactoring Legacy Code ● What is “Legacy Code”? – Is there a coding standard for your project? – Is code using OOP? – Is Composer used in your project? – Is the project using a framework? – Are you unit testing?
- 10. 10 Refactoring Legacy Code ● What is “Legacy Code”? – Is there a coding standard for your project? – Is code using OOP? – Is Composer used in your project? – Is the project using a framework? – Are you unit testing? – Does your project avoid NIH?
- 11. 11 Refactoring Legacy Code ● What is “Legacy Code”? – Is there a coding standard for your project? – Is code using OOP? – Is Composer used in your project? – Is the project using a framework? – Are you unit testing? – Does your project avoid NIH? If you can answer “No” to any of these, you may be creating “Legacy Code”!!!
- 12. 12 Refactoring Legacy Code ● What is “legacy” really? – According to https://en.wikipedia.org/wiki/Legacy_code ● “...no longer supported or manufactured...” ● “...code inserted into modern software for the purpose of maintaining an older or previously supported feature...” ● “...supporting older file formats...” ● “...code may no longer work without changes...” ● “...code that no longer runs on a later version of a system, or requires a compatibility layer to do so...”
- 13. 13 Putting Legacy to REST with Middleware ● Why Rewrite? – Change technology (PHP to Javascript, Python, etc.) – Code is REALLY bad – If less expensive to rewrite versus refactor – Little to no chance to lose business logic – Desire a “different” application
- 14. 14 Putting Legacy to REST with Middleware ● API First! – API is first class citizen
- 15. 15 Putting Legacy to REST with Middleware ● API First! – API is first class citizen – API comes first, then implementation
- 16. 16 Putting Legacy to REST with Middleware ● API First! – API is first class citizen – API comes first, then implementation – Development teams can work in parallel
- 17. 17 Putting Legacy to REST with Middleware ● API First! – API is first class citizen – API comes first, then implementation – Development teams can work in parallel – Reduces cost of developing apps ● Through re-use of business logic
- 18. 18 Putting Legacy to REST with Middleware ● API First! – API is first class citizen – API comes first, then implementation – Development teams can work in parallel – Reduces cost of developing apps ● Through re-use of business logic – Faster time to market
- 19. 19 Putting Legacy to REST with Middleware ● API First! – API is first class citizen – API comes first, then implementation – Development teams can work in parallel – Reduces cost of developing apps ● Through re-use of business logic – Faster time to market – OpenAPI
- 20. 20 Putting Legacy to REST with Middleware ● API First! – API is first class citizen – API comes first, then implementation – Development teams can work in parallel – Reduces cost of developing apps ● Through re-use of business logic – Faster time to market – OpenAPI – Reduces risk of failure
- 21. 21 Putting Legacy to REST with Middleware ● Modernization Methods
- 22. 22 Putting Legacy to REST with Middleware ● Modernization Methods – #1 Total Rewrite ● Create entirely new app ● Build until complete ● Big BANG!
- 23. 23 Putting Legacy to REST with Middleware ● Modernization Methods – #1 Total Rewrite ● Create entirely new app ● Build until complete ● Big BANG!
- 24. 24 Putting Legacy to REST with Middleware ● Modernization Methods – #1 Total Rewrite ● Create entirely new app ● Build until complete ● Big BANG! ● Pitfalls – Constant “scope creep” – Maintain 2 apps – Expensive!
- 25. 25 Putting Legacy to REST with Middleware ● Modernization Methods – #1 Total Rewrite ● Create entirely new app ● Build until complete ● Big BANG! ● Pitfalls – Constant “scope creep” – Maintain 2 apps – Expensive! ● Benefits – Clean slate – Energy/Excitement – Less business disruption
- 26. 26 Putting Legacy to REST with Middleware ● Modernization Methods (cont’d) – #2 REST API Backend ● Build an API ● Use the API to drive logic and data
- 27. 27 Putting Legacy to REST with Middleware ● Modernization Methods (cont’d) – #2 REST API Backend ● Build an API ● Use the API to drive logic and data ● Pitfalls – Requires cleanup of objects first – Longer time to get productive – Very difficult for spaghetti apps
- 28. 28 Putting Legacy to REST with Middleware ● Modernization Methods (cont’d) – #2 REST API Backend ● Build an API ● Use the API to drive logic and data ● Pitfalls – Requires cleanup of objects first – Longer time to get productive – Very difficult for spaghetti apps ● Benefits – Cleans up data/business logic – Shorter time to completion
- 29. 29 Putting Legacy to REST with Middleware ● Modernization Methods #2 (How-To) – Create standalone REST API ● Add one module at a time
- 30. 30 Putting Legacy to REST with Middleware ● Modernization Methods #2 (How-To) – Create standalone REST API ● Add one module at a time – Refactor the Legacy application to use API as Service/Model
- 31. 31 Putting Legacy to REST with Middleware ● Modernization Methods #2 (How-To) – Create standalone REST API ● Add one module at a time – Refactor the Legacy application to use API as Service/Model – Eventually API First, w/ frontend application
- 32. 32 Putting Legacy to REST with Middleware ● Modernization Methods (cont’d) – #3 Legacy Middleware ● New application (as with rewrite) ● In stages
- 33. 33 Putting Legacy to REST with Middleware ● Modernization Methods (cont’d) – #3 Legacy Middleware ● New application (as with rewrite) ● In stages ● Pitfalls – Takes upfront planning – Takes longer – Overall, still creating 2 new apps – Not API first until the end
- 34. 34 Putting Legacy to REST with Middleware ● Modernization Methods (cont’d) – #3 Legacy Middleware ● New application (as with rewrite) ● In stages ● Pitfalls – Takes more planning – Takes longer – Overall, still creating 2 new apps – Not API first until the end ● Benefits – Can update/implement new frontend faster (duplicated) – Spaghetti app easier to manage – Less business impact – Marketing “new” features regularly
- 35. 35 Putting Legacy to REST with Middleware ● Modernization Methods #3 (How-To) – New sub-directory for new app
- 36. 36 Putting Legacy to REST with Middleware ● Modernization Methods #3 (How-To) – New sub-directory for new app – Create LegacyMiddleware, add it before FinalMiddleware
- 37. 37 Putting Legacy to REST with Middleware ● Modernization Methods #3 (How-To) – New sub-directory for new app – Create LegacyMiddleware, add it before FinalMiddleware – Fix issues with routing and includes
- 38. 38 Putting Legacy to REST with Middleware ● Modernization Methods #3 (How-To) – New sub-directory for new app – Create LegacyMiddleware, add it before FinalMiddleware – Fix issues with routing and includes – Update doc_root to be new location ● Site working as it used to
- 39. 39 Putting Legacy to REST with Middleware ● Modernization Methods #3 (How-To) – New sub-directory for new app – Create LegacyMiddleware, add it before FinalMiddleware – Fix issues with routing and includes – Update doc_root to be new location ● Site working as it used to – Start creating new modules in new app
- 40. 40 Putting Legacy to REST with Middleware ● Modernization Methods #3 (How-To) – New sub-directory for new app – Create LegacyMiddleware, add it before FinalMiddleware – Fix issues with routing and includes – Update doc_root to be new location ● Site working as it used to – Start creating new modules in new app – LegacyMiddleware called less and less
- 41. 41 Putting Legacy to REST with Middleware ● Modernization Methods #3 (How-To) – New sub-directory for new app – Create LegacyMiddleware, add it before FinalMiddleware – Fix issues with routing and includes – Update doc_root to be new location ● Site working as it used to – Start creating new modules in new app – LegacyMiddleware called less and less – Remove legacy app once all endpoints satisfied
- 42. 42 Putting Legacy to REST with Middleware ● What is “Middleware”? – NEW? way to build multi-layers as tiered approach to execution – “Software glue” - wikipedia ● Implement communication and input/output ● Popular in ‘80s to link newer applications to legacy systems
- 43. 43 Putting Legacy to REST with Middleware ● Frameworks! – Expressive (Laminas Project, formerly Zend Framework) – Slim PHP – Most others: ● Laravel ● Symfony ● Etc.
- 44. 44 Putting Legacy to REST with Middleware ● Testing – Always test prior to refactoring – Then refactor – Then test again – Refactor tests as needed – Repeat
- 45. 45 Putting Legacy to REST with Middleware ● Tools – Source Control ● Allows easier rollback ● Allows collaboration ● Git makes branching easier
- 46. 46 Putting Legacy to REST with Middleware ● Tools (cont’d) – CI/CD ● Makes updates across team seamless
- 47. 47 Putting Legacy to REST with Middleware ● Conclusion – Middleware makes modernization easier – Do it in stages – Test all the things...often – Teamwork – Love iteration!
- 48. 48 Putting Legacy to REST with Middleware ● Go! – Your turn!
- 49. ● Thank you! – Code: https://github.com/adamculp/ Adam Culp https://beachcasts.com https://geekyboy.com https://rungeekradio.com Twitter @adamculp Questions?