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NRWConf, DE: Defensive programming, resilience patterns & antifragility
The document discusses defensive programming and resilience patterns in software development, emphasizing the importance of robustness and antifragility. It outlines various programming tactics, such as input validation and resilience patterns like circuit breakers and leader elections, to enhance system reliability. The author shares personal insights from years of experience in the field, stressing that overcoming failures leads to stronger, more efficient code and teams.
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NRWConf, DE: Defensive programming, resilience patterns & antifragility
- 1. danielfisher.com Defensive Programming, Daniel Fisher ResiliencePatterns & Antifragility
- 2. danielfisher.com I’m a technician& always concerned about bandwidth So I ask you to send one packet instead of two DANIEL My name is Any further questions? Just Ask!
- 3. danielfisher.com software I design, develop,deploy, teach, train, coach and speak HTML5 & WEB, DATA ACCESS & PERFORMANCE, SCALABLE & TESTABLE DESIGN, DISTRIBUTED SYSTEMS & SERVICES, SECURITY & TRUST lennybacon.com my blog url @lennybacon my twitter handle info@danielfisher.com my smtp find my services at danielfisher.com
- 4. danielfisher.com THAT IS ALLTHAT I DEEPLY BELEVE IN D I S C L A I M E R IT FITS MY SHOES IT MIGHT NOT FIT YOURS THIS PRESENTATION CONTAINS MY PERSONAL VIEW ON THE WORLD IT IS BASED ON MY EXPERIENCE IN SOFTWARE DEVELOPMENT PROJECTS SINCE 1996 MOST THINGS I LEARNED FROM PAIN OTHERS FROM MOMENTS OF GRACEFULNESS, BRAVENESS & SUCCESS
- 5. danielfisher.com CHAPTER 1 Software Development:A world of fear
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- 10. danielfisher.com “Office Space” byMike Judge / Twentieth Century Fox Film Corporation
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- 16. danielfisher.com “Fight Club” byDavid Fincher / Twentieth Century Fox Film Corporation
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- 19. danielfisher.com I have notfailed! I've just found 10,000 ways that won't work …Thomas Edison
- 20. danielfisher.com CHAPTER 2 Paranoia basics:Defensive programming
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- 22. danielfisher.com Yoda Conditions if (variable.Equals("literal")) { ... } if("literal".Equals(variable)) { ... }
- 23. danielfisher.com Check Collections forNull var files = SomeApi.GetFileList(); if (files != null) { for (var i = 0; i < files.length; i++) { ... } }
- 24. danielfisher.com All classes aresealed by default public class Class1 { ... } internal sealed class Class1 { ... }
- 25. danielfisher.com DDD Value ObjectInput Validation public sealed class ZipCode : IValueObject { public ZipCode(int value) { // Input validation!!! Value = value; } public int Value { get; private set;} }
- 26. danielfisher.com CHAPTER 3 Advanced paranoiatactics: Robustness
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- 28. danielfisher.com Finding Bugs is goodand mustn’t be punished! It makes code less buggy!
- 29. danielfisher.com Finding Bugs in testsis even better! No customer will even face them!
- 30. danielfisher.com Try to break,burn, shoot and drown it together! I call it Breakstorming!
- 31. danielfisher.com CHAPTER 4 Professional Paranoia:Resilience patterns
- 32. danielfisher.com A distributed system isone in which the failure of a computer you didn't even know existed can render your computer unusable http://research.microsoft.com/en-us/um/people/lamport/pubs/distributed-system.txt
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- 34. danielfisher.com Topology changes Networks fail Latencyvaries by location Bandwidth differs by location Things get hacked
- 35. danielfisher.com Servers get rebooted Codehas bugs Other users might use it different Failover means offline Processing time varies by amount of data Environments differ File system is not always available
- 36. danielfisher.com Life is nota walk in the park. neither is software!
- 37. danielfisher.com Success is theability to go from one failure to another with no loss of enthusiasm. WinstonChurchill
- 38. danielfisher.com Scale like aboss Asynchronicity No one waiting for an error Bulkheads & Replays Loose coupling for the win But dare you forget the dead letters No cascading failures and stack trace
- 39. danielfisher.com BASE OVER ACID Atomic,Consistent, Isolated and Durable solutions are not a silver bullet. Basic Availability, Soft-state and Eventual consistency work better in most distributed scenarios. BUT YOU MUST THINK DIFFERENT FOR BASE Use a more relaxed consistency model to reduce coupling Queues are as transactional as databases
- 40. danielfisher.com Idempotency Non-idempotency is complicatedto handle and increases coupling between participants. stateless stateless stateless THIS ALSO REQUIRES YOU TO THINK DIFFERENT But in the end it is nothing more than divide and conquer with an eye on the results Functional programming and immutable types for the win.
- 41. danielfisher.com Monitor & Audit Measureto gain latency control and detect non- timely responses before they time out. Learn more about the life of your system to predict its behavior. If you can’t debug, log is your friend Respond to detected failures. 20% - 40% logging code Auditing and Logging can even be party of your architecture
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- 46. danielfisher.com CHAPTER 5 Things thatgain from disorder: Antifragility
- 47. danielfisher.com Nassim Nicholas Talebwrote two interesting books about how economical systems behave. He focusses on what happens under stress and on unexpected occurrences of events. The black swan Antifragility
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- 49. danielfisher.com What Doesn't KillYou Makes You Stronger Every time something catastrophic happens that you take on and survive… … your team and you code becomes Stronger, Better, Faster, More
- 50. danielfisher.com Asymmetric information &options An opportunity to cope with the lack of knowledge ST R AT E GY Business, Architecture & Code Long Term vs Short Term Sustainability vs Reward
- 51. danielfisher.com Thank you! danielfisher.com mycompany lennybacon.com my blog url @lennybacon my twitter handle info@danielfisher.com my smtp
Editor's Notes
- #24 No NullReferenceException No accidential assignment
- #27 No duplicate validation Trust that values are correct
- #44 https://msdn.microsoft.com/en-us/library/dn589788.aspx
- #45 https://msdn.microsoft.com/en-us/library/dn589784.aspx
- #46 https://msdn.microsoft.com/en-us/library/dn568104.aspx
- #47 https://msdn.microsoft.com/en-us/library/dn589804.aspx
- #52 Thales of Milet and the olive press