Software Development is Upside Down
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5 management assumptions which are reversed when you develop software. Keynote at Agile Tour Lille, October 2016.
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Software Development is Upside Down
- 1. Allan Kelly @allankellynet allan@allankelly.net http://www.allankelly.net October 2016 is upside down SoftwareDevelopment
- 4. âAgile Allanâ Kelly⌠Agile Training & Consulting for Agile, adopting Agile, getting better Organizing teams Author â Little Book of Requirements & User Stories https://leanpub.com/userstories â Xanpan: Team Centric Agile Software Development https://leanpub.com/xanpan â Business Patterns for Software Developers â Changing Software Development: Learning to be Agile allan@allankelly.net http://www.allankelly.net @allankellynet (Twitter)
- 5. Upsidedown 1. Diseconomies of Scale 2. Higher quality is faster 3. Quickest way to learn is to do 4. Do it right, then do the right thing 5. Worse is better
- 7. Software development⌠⢠Does NOT have economies of Scale ⢠Development has DISECONOMIES of scale
- 8. Milk is cheapest in BIG cartons Software is cheapest in lots of small cartons And small cartons of software reduce risk
- 9. Consider a large project Against several small projects Project A: Risk = 30% Value at risk = £1m Therefore risk weighted value = £300,000 Prj B: Risk = 15% Value @ risk = £½m Therefore ⌠= £75,000 Prj C: Risk = 15% Value @risk = £½m Therefore ⌠= £75,000 E: Risk = 6% @risk = £200k Therefore = £12k F: Risk = 6% @risk = £200k Therefore = £12k G: Risk = 6% @risk = £200k Therefore = £12k H: Risk = 6% @risk = £200k Therefore = £12k I: Risk = 6% @risk = £200k Therefore = £12k
- 10. Software development⌠⢠Does NOT have economies of Scale ⢠Development has DISECONOMIES of scale Therefore ⢠Stop thinking BIG ⢠Start thinking SMALL
- 11. Higher quality is faster
- 12. Quality⌠makes all things possible Philip Crosby "Quality has much in common with sex. ⢠Everyone is for it. (Under certain conditions of, course) ⢠Everyone feels they understand it. (Even though they wouldn't want to explain it) ⢠Everyone thinks execution is only a matter of following natural inclinations. (After all, we do get along somehow) And, of course, most people feel that all problems in these areas are caused by other people."
- 13. public class RecentlyUsedList { private List<string> list; public RecentlyUsedList() { list = new List<string>(); } public string this[int index] { get { int position = 0; foreach (string value in list) { if (position == index) return value; ++position; } throw new ArgOutOfRngExcpt(); } public int Count { get { int size = list.Count; return size; } } public void Add(string newItem) { if (list.Contains(newItem)) { int position = list.IndexOf(newItem); string existingItem = list[position]; list.RemoveAt(position); list.Insert(0, existingItem); } else { list.Insert(0, newItem); } } } }
- 14. public class RecentlyUsedList { private List<string> list = new List<string>(); public void Add(string newItem) { list.Remove(newItem); list.Add(newItem); } public int Count { get { return list.Count; } } public string this[int index] { get { return list[Count - index - 1]; } } } Code & refactoring from Kevlin Henney â www.curbralan.com
- 15. Quality -> Quicker Capers Jones, 2008 Applied Software Measurement Projects with low defect potentials and high defect removal efficiency also have the shortest schedules, lowest costs and best customer satisfaction levels
- 16. Low Quality High Quality Faster!
- 17. Low Quality High Quality Faster!
- 18. How do you improve quality? T D D A T D D B D D
- 19. John Cage Defects are not free. Somebody makes them, and gets paid for making them
- 20. Quickest way to learn is to do "The world you perceive is drastically simplified model of the real world. â Herbert A. Simon
- 21. Planning is learning Planning is valuable ButâŚ
- 22. Time to estimate & plan 2 minutes of work? Average time to estimate: 6â minutes Average planning (inc. estimates): 11 minutes (total) Mean average (median slightly less) Data from 31 teams over 2 years
- 23. IBM 360 IBM 360 at Computer History Museum Dave Ross: CCL license via WikiMedia
- 24. 46 years ⌠1970 OS/360 model 195 ⢠10,000 KIPS (10 MIPS) ⢠4096kb (4Mb) ⢠COBOL on OS/360 ⢠IMS database ⢠Monthly rental $250,000 (Approx. $1.25m in 2016 prices) 2016 Raspberry Pi 2 ⢠4,744 MIPS ⢠1 Gb ⢠Linux ⢠Python, Scala, Ruby, ⌠⢠SQL, NoSQL ⢠Buy $35 CPU cycles âŹâŹâŹ-> Planning is cheap CPU cycles âŹâŹâŹ -> Planning is expensive
- 25. Valueofplanning Time Planning has rapidly diminishing returns
- 26. Planning is learning Planning is valuable But⌠Planning has rapidly diminishing returns
- 27. If you want to finish sooner Then Start building sooner
- 28. Do it right, then do the right thing
- 29. Humphrey's Law âUsers do not know what they want until they see working softwareâ Watts Humphrey
- 30. The Alignment Trap Less Effective More Effective Highly aligned Less aligned âAlignment trapâ 11% companies +13% IT spending -14% 3 year sales growth âMaintenance zoneâ 74% companies Avg IT spending -2% 3 year sales growth âIT Enabled growthâ 7% companies -6% IT spending +35% 3 year sales growth âWell-oiled ITâ 8% companies -15% IT spending +11% 3 year sales growth Source:Shpilberg,Berez,Puryear,Shah: MITSloanReview,Fall2007 1 2 Doingtherightthings Doing things right
- 31. He who learns fastest wins âWe understand that the only competitive advantage the company of the future will have is its managersâ ability to learn faster than then their competitors.â Arie de Geus, The Living Company 1988
- 32. 1) Do it right Build a machine which can iterate A learning machine 2) Do the right thing Iterate your way to the right thing
- 33. Worse is better
- 34. Worse is better in software making (and perhaps in other arenas as well) it is better to start with a minimal creation and grow it as needed Richard âDickâ Gabriel, 1989 https://www.dreamsongs.com/WorseIsBetter.html Piecemeal growth
- 35. Less is more
- 36. A complex system that works is invariably found to have evolved from a simple system that worked. A complex system designed from scratch never works and cannot be patched up to make it work. You have to start over with a working simple system. Gallâs law John Gall 1975 As a rule, software systems do not work well until they have been used, and have failed repeatedly, in real applications. Dave Parnas
- 37. Start small, grow⌠⢠Software ⢠Teams ⢠Processes ⢠Organization (Donât forget Conwayâs Law!)
- 38. Worse is better mode #2 Sometimestheupsidedownis upsidedown Sometimes the upside down is upside down
- 39. Complexity
- 40. In software development we are constantly battling complexity
- 42. Upside down thinking makes it all more complicated
- 43. Todayâs lesson: Think the other way around to make the world simpler 1. Diseconomies of Scale 2. Higher quality is faster 3. Quickest way to learn is to do 4. Do it right, then do the right thing 5. Worse is better
- 44. Questions? allan kelly allan@allankelly.net www.softwarestrategy.co.uk Twitter: @allankellynet Xanpan - Amazon or LeanPub https://leanpub.com/xanpan ½ price discount code: Lille Little Book https://leanpub.com/userstories