So You Just Inherited a $Legacy Application… NomadPHP July 2016
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The document discusses the challenges and processes involved in inheriting and modernizing legacy applications, emphasizing that there are no perfect solutions, only trade-offs. It outlines a series of emotional stages developers may go through, practical strategies for assessment, and methods to consolidate and refactor code effectively. Tools and resources for PHP development, such as coding standards and local development environments, are also provided to assist in the modernization process.
So You Just Inherited a $Legacy Application… NomadPHP July 2016
- 1. So You Just Inherited a $Legacy Application... https://legacy.joind.in/18603 Joe Ferguson
- 2. Who Am I? Joe Ferguson PHP Developer Engineer @ Aol. Twitter: @JoePFerguson Organizer of @MemphisPHP @NomadPHP Lightning Talks Passionate about Community
- 6. “There are no solutions, only trade offs” - Joe Ferguson - Paul M. Jones - Thomas Sowell
- 7. What is a "Legacy" application
- 8. Legacy is often used for an older production application that was written before, or without regard for modern technologies or practices.
- 9. If you ask Wikipedia… "... no-longer supported …" "... maintained by an administrator that did not develop the code …" "... supporting older file formats ..." https://en.wikipedia.org/wiki/Legacy_code
- 10. Modern Interpretation "... source code inherited from someone else …" "... source code inherited from an older version of the software ..."
- 11. Some people say… "Any code in production is not legacy” "Any code written X years ago is legacy"
- 12. Legacy is all these things As we talk about Legacy code here, we're really talking about all of these definitions
- 13. This process is not Legacy Specific…
- 14. Inheriting a Legacy App Precontemplation or Shock/Disbelief Contemplation and/or Anger Determination and Bargaining Action and Reconstruction Maintenance and Acceptance
- 16. This is the initial "what is this?!"
- 17. That’s now how this works!
- 18. Precontemplation Not ready for change (project, code base, etc) Usually you don’t know the depths of issues Can sometimes lead to assuming the worst Usually this is the shortest phase due to business needs
- 19. Shock/Disbelief This is where the WTFs and the WTHs should be left Try to work through any negativity here Be positive about the previous developer’s intentions
- 21. This is the planning phase
- 22. Try to get all of your ager at the code base out during this phase, it will help you see the path forward.
- 23. Taking stock of what we’re working with
- 24. Initial Project Overview Is there a framework? Is there a coding standard? Is there any autoloading? How are dependencies behind handled? Is there an ORM or how is the database being utilized? Is there a development environment?
- 25. Is there a framework?
- 26. Is there a coding standard?
- 27. No Standard? No problem!
- 28. Is there any autoloading?
- 29. There is a PSR for that…
- 30. How are dependencies behind handled?
- 31. Is there an ORM or how is the database being utilized?
- 32. Is there a development environment?
- 33. Tools to help
- 34. PHP Coding Standards Fixer http://cs.sensiolabs.org/
- 35. PHP Coding Standards Fixer php-cs-fixer fix app --dry-run
- 37. PHP Mess Detector https://phpmd.org $ phpmd app html cleancode --reportfile report.html
- 38. Warning about Automating Code Changes
- 42. Local Dev Environments Physical Hardware Vagrant (Virtual Machines) Docker (Containers)
- 44. Vagrant
- 45. PuPHPet.com
- 48. Determination and Bargaining Decision making and triage time
- 49. Triage Address any critical things found in Contemplation phase PHP version issues Fixing critical vulnerabilities
- 50. You have a plan and now you need to estimate this plan.
- 51. I hate estimating nomadphp.com/2016/04/06/stop- multiplying-4/ Lightning talk by Chuck Reeves (@manchuck) Short and sweet talk about how to do better estimating
- 52. No Question Left Behind! The application has no framework, We’re going to use a micro framework as we refactor. The application has no autoloading, But we’re using Composer Dependencies are checked into version control, But we’re using Composer There is no ORM, but we’re going to use Propel We have no dev environment but we’re going to use Vagrant
- 53. Proof of Concept Any new things introduced should be tested to ensure functionality Build out a small example of an area you or the team doesn't fully comprehend so you can address any questions that may arise
- 54. Bargaining Getting stakeholders on board with your estimates Do the decisions made thus far make business sense? Are there any doubts in the plan?
- 55. “We should just rewrite the app”
- 56. "This would be so much easier in framework _____________”
- 57. Why not rewrite? Progress halts entirely Business logic is rarely reused Most of the time is getting back to current functionality
- 58. Why you should refactor Progress continues Business logic reused Modernizing functionality instead of recreating
- 59. Make Decisions Build Proof of Concept(s) Ensure stakeholder buy in Avoid the allure of green fields** ** in some cases a rewrite is warranted
- 61. Existing Tests This is great! Review the tests to get an idea of coverage Passing tests become your control for any upcoming changes Confidence++
- 62. No Existing Tests Not the end of the world! Inspect the code base, was it written to be easily testable? Could you easily mock dependencies?
- 63. Untestable Code Not all code is testable If you can’t easily unit test the code base, consider alternatives Functional testing and Acceptance testing are valid options
- 64. Acceptance Testing NOT a replacement for Unit Testing Test large parts of your application at a time Can be harder to pinpoint error location Gives large code coverage in short amount of time
- 65. Digging into the Code Code Consolidation
- 66. Digging into the Code Code Consolidation Replace globals with DI
- 67. Digging into the Code Code Consolidation Replace globals with Dependency Injection Write tests
- 68. Digging into the Code Code Consolidation Replace globals with Dependency Injection Write tests Extract SQL (to ORM or other)
- 69. Digging into the Code Code Consolidation Replace globals with Dependency Injection Write tests Extract SQL (to ORM or other) Extract Business Logic (To domain logic)
- 70. Digging into the Code Code Consolidation Replace globals with Dependency Injection Write tests Extract SQL (to ORM or other) Extract Business Logic (To domain logic) Extract Presentation Logic to Views (Twig, Blade, etc)
- 71. Digging into the Code Code Consolidation Replace globals with Dependency Injection Write tests Extract SQL (to ORM or other) Extract Business Logic (To domain logic) Extract Presentation Logic to Views (Twig, Blade, etc) Extract Action Logic (To Controllers)
- 72. Digging into the Code Code Consolidation Replace globals with Dependency Injection Write tests Extract SQL (to ORM or other) Extract Business Logic (To domain logic) Extract Presentation Logic to Views (Twig, Blade, etc) Extract Action Logic (To Controllers) Write (more) tests
- 74. Maintenance and Acceptance Code Consolidation Replace globals with Dependency Injection Write tests Extract SQL (to ORM or other) Extract Business Logic (To domain logic) Extract Presentation Logic to Views (Twig, Blade, etc) Extract Action Logic (To Controllers) Write (more) tests
- 75. Maintenance and Acceptance Adding Features More New Code Less Refactoring Maintain your processes
- 78. Resources / Q & A Modernizing Legacy Applications In PHP - Paul M. Jones https://leanpub.com/mlaphp Minimum Viable Tests - Chris Hartjes https://leanpub.com/minimumviabletests Code Style https://github.com/FriendsOfPHP/PHP-CS-Fixer, http://editorconfig.org php mess detector https://phpmd.org Autoloading PSR-4 https://getcomposer.org/doc/01-basic-usage.md ORMs http://www.doctrine-project.org http://propelorm.org Docker https://leanpub.com/dockerfordevs, Vagrant https://puphpet.com
- 79. Feedback! https://legacy.joind.in/18603 Joe Ferguson Twitter: @JoePFerguson Email: joe@joeferguson.me Freenode: joepferguson Contact Info: