![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); }
}
} }](https://image.slidesharecdn.com/upsidedown-170512144533/85/Software-Development-is-Upside-Down-13-320.jpg)
![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 – www.curbralan.com](https://image.slidesharecdn.com/upsidedown-170512144533/85/Software-Development-is-Upside-Down-14-320.jpg)
Uploaded byallan kelly
Software Development is Upside Down
This document discusses key principles in agile software development, emphasizing the importance of small projects to reduce risks and achieve higher quality at a faster pace. It advocates for iterative learning and minimal initial designs, highlighting that complexity in software can often hinder effective development. The author, Allan Kelly, shares insights on optimizing software processes and promoting effective team organization.
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Software Development is Upside Down
- 1. Allan Kelly @allankellynet allan@allankelly.net http://www.allankelly.net October 2016 isupside down SoftwareDevelopment
- 2.
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- 4. “Agile Allan” Kelly… AgileTraining & Consulting for Agile, adopting Agile, getting better Organizing teams Author – Little Book of Requirements & User Stories https://leanpub.com/userstories – Xanpan: Team Centric Agile Software Development https://leanpub.com/xanpan – Business Patterns for Software Developers – Changing Software Development: Learning to be Agile allan@allankelly.net http://www.allankelly.net @allankellynet (Twitter)
- 5. Upsidedown 1. Diseconomies ofScale 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
- 6.
- 7. Software development… • DoesNOT have economies of Scale • Development has DISECONOMIES of scale
- 8. Milk is cheapest inBIG cartons Software is cheapest in lots of small cartons And small cartons of software reduce risk
- 9. Consider a largeproject 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… • DoesNOT have economies of Scale • Development has DISECONOMIES of scale Therefore • Stop thinking BIG • Start thinking SMALL
- 11. Higher quality isfaster
- 12. Quality… makes allthings 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 – www.curbralan.com
- 15. Quality -> Quicker CapersJones, 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 HighQuality Faster!
- 17. Low Quality HighQuality Faster!
- 18. How do youimprove quality? T D D A T D D B D D
- 19. John Cage Defects arenot free. Somebody makes them, and gets paid for making them
- 20. Quickest way tolearn is to do "The world you perceive is drastically simplified model of the real world. ” Herbert A. Simon
- 21. Planning is learning Planningis valuable But…
- 22. Time to estimate& plan 2 minutes of work? Average time to estimate: 6⅓ minutes Average planning (inc. estimates): 11 minutes (total) Mean average (median slightly less) Data from 31 teams over 2 years
- 23. IBM 360 IBM 360at Computer History Museum Dave Ross: CCL license via WikiMedia
- 24. 46 years … 1970OS/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 €€€-> Planning is cheap CPU cycles €€€ -> Planning is expensive
- 25. Valueofplanning Time Planning has rapidlydiminishing returns
- 26. Planning is learning Planningis valuable But… Planning has rapidly diminishing returns
- 27. If you wantto finish sooner Then Start building sooner
- 28. Do it right, thendo the right thing
- 29. Humphrey's Law “Users donot know what they want until they see working software” Watts Humphrey
- 30. The Alignment Trap Less Effective More Effective Highlyaligned Less aligned ‘Alignment trap’ 11% companies +13% IT spending -14% 3 year sales growth ‘Maintenance zone’ 74% companies Avg IT spending -2% 3 year sales growth ‘IT Enabled growth’ 7% companies -6% IT spending +35% 3 year sales growth ‘Well-oiled IT’ 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 learnsfastest wins “We understand that the only competitive advantage the company of the future will have is its managers’ ability to learn faster than then their competitors.” Arie de Geus, The Living Company 1988
- 32. 1) Do itright Build a machine which can iterate A learning machine 2) Do the right thing Iterate your way to the right thing
- 33.
- 34. Worse is better insoftware making (and perhaps in other arenas as well) it is better to start with a minimal creation and grow it as needed Richard “Dick” Gabriel, 1989 https://www.dreamsongs.com/WorseIsBetter.html Piecemeal growth
- 35.
- 36. A complex systemthat 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. Gall’s 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 (Don’t forget Conway’s Law!)
- 38. Worse is bettermode #2 Sometimestheupsidedownis upsidedown Sometimes the upside down is upside down
- 39.
- 40. In software developmentwe are constantly battling complexity
- 41.
- 42. Upside down thinkingmakes it all more complicated
- 43. Today’s lesson: Think theother 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