Interviewing Domain Experts - Heuristics From the Trenches (DDD Europe 2016 Morning Keynote on day 2)
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Deep conversations with domain experts and careful attention to the language are central in software development and in particular in Domain-Driven Design (DDD). However it takes many years and many failures to get better at this game. Still, over time it is possible to extract a growing set of techniques and heuristics that can boost the effectiveness of the interviews with domain experts, to learn faster and converge quickly to better models. There are techniques and heuristics for asking better questions, listening carefully to words and other signals, and for managing credibility as a developer facing business experts. If you think all the above is important, then these interviewing techniques will improve your skills, step up the quality of your collaboration with your domain experts, and will provide benefits for better domain models. And if you find all that boring, then perhaps you could focus your career on Java EE instead.
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Interviewing Domain Experts - Heuristics From the Trenches (DDD Europe 2016 Morning Keynote on day 2)
- 1. @cyriux CyrilleMartraire Interviewing Domain Experts: heuristics from the trenches 1
- 2. Osmo Wiio
- 3. “Communications usually fails, except by accident.” Wiio’s law
- 4. Perhaps he didn’t mean that… Or perhaps he did mean that… https://en.wikipedia.org/wiki/Wiio%27s_laws
- 5. Imagine
- 7. Tell us what I need to know to build the software
- 8. Hi kids, I don’t have time for that. I’ve already sent you what I want by email.
- 9. #FAIL SCARY
- 10. Could be worse
- 11. Tell us what I need to know to build the software
- 12. Sure, I want a red button to save data in table T_DEAL_2
- 16. A while ago In a large French bank
- 18. Weekly DDD Book Club What? Talking to experts is a thing now?
- 19. Weekly DDD Book Club You can learn that?
- 29. “We don’t talk the same language.”
- 30. “They don’t have time for us.”
- 34. Don’t go naked
- 35. Teach Yourself some Domain Knowledge!
- 36. It all starts with curiosity 36
- 37. It all starts with curiosity 37 genuine
- 40. Do your homework
- 42. Civil Case Type <FiduciaryTypeCode>* <JurisdictionalGroundsCode> <ReliefTypeCode> Domestic Case Type <NoContactCode>* <RequestToVacateCode> Common Types <AliasAlternateNameTypeCode>* <CaseAssociationTypeCode>* <CaseOfficialRoleText>* <CaseParticipantRoleCode>* <CauseOfActionCode> <CourtEventTypeCode> <EntityAssociationTypeCode> <ErrorCode>* Juvenile Case Type <DelinquentActApplicabilityCode> <DelinquentActDegreeCode> <DelinquentActSeverityCode> <DelinquentActSpecialAllegationCode> <DependencyAllegationCode> <GuardianAssociationTypeCode>* <PlacementTypeCode> ... http://docs.oasis-open.org/legalxml-courtfiling/specs/ecf/v4.01/ecf-v4.01-spec/os/ecf-v4.01-spec-os.pdf Electronic Court Filing Ver OASIS Standard 23 May 2013 Specification URIs This version: http://docs.oasis-open.org/legalxml-courtfiling/specs/ecf/v4 os.doc (Authoritative) http://docs.oasis-open.org/legalxml-courtfiling/specs/ecf/v4 os.html http://docs.oasis-open.org/legalxml-courtfiling/specs/ecf/v4 os.pdf Previous version: http://www.oasis-open.org/committees/download.php/4564 Latest version: http://docs.oasis-open.org/legalxml-courtfiling/specs/ecf/v4 (Authoritative) http://docs.oasis-open.org/legalxml-courtfiling/specs/ecf/v4 http://docs.oasis-open.org/legalxml-courtfiling/specs/ecf/v4 Technical Committee: OASIS LegalXML Electronic Court Filing TC Chairs: James Cabral (jcabral@mtgmc.com), MTG Management C Jim Harris (jharris@ncsc.org), National Center for State Co Editors: Adam Angione (aangione@courthousenews.com), Courtho James Cabral (jcabral@mtgmc.com), MTG Management C Additional artifacts: This prose specification is one component of a Work Produ XML schemas: http://docs.oasis-open.org/legalxml-courtfiling/specs/ec
- 43. 3.3 Outline This high-level process model i experience For clarity, the whole process c election, election, post election; processes. • Pre election • Election (100) • Candidates (200) • Options (600) • Voters (300) • Election • Voting (400) • Post election • Results (500) • Audit • Analysis Some functions belong to the w • Administration Interface • Help Desk http://docs.oasis-open.org/election/eml/v5.0/os/EML-Process-Data-Requirements-v5.0.html Election Markup Language
- 45. OK Domain Overview Checklist of potential questions Corpus of vocabulary NOT OK Ready-made solutions Features list The Truth (TM)
- 47. First I’d like to better understand how an insurance policy works
- 48. Ok, so basically it starts with a contract… <useful stuff here>
- 49. Now we have a conversation #WIN
- 53. ”The visitor requests an insurance quote”
- 54. “The user asks a quote”
- 55. Not what he said!
- 56. LOST knowledge
- 58. “The user asks a quote” visitor
- 59. “The user asks a quote” requests
- 60. “The user asks a quote” insurance
- 62. ACTIVE LiSTENING
- 63. Harder than you’d think Turn it into a game
- 64. WORD SAFARI
- 65. The trader makes a deal …
- 66. the trader makes a deal
- 67. the trader makes a deal new word
- 69. …
- 70. Then the trade is booked in a particular portfolio.
- 71. So the trader makes a deal. Then the trade is booked in a particular portfolio.
- 72. So the trader makes a deal. Then the trade is booked in a particular portfolio. synonyms?
- 73. You talked about ”deal” and ”trade” as if they were the same thing…
- 75. Now we’re talking! And learning some real useful stuff. #WIN
- 76. 76 Meh. it’s just a simple trick…
- 78. *This* is DDD
- 79. Let’s move on…
- 80. On execution the remaining order fill is reduced by its size.
- 81. On execution the remaining order fill is reduced by its size. new word
- 82. You’re talking about ”order” and ”execution”.
- 83. I know that an order is like a request to trade, what about the execution?
- 84. I know that an order is like a request to trade, what about the execution?
- 85. Showing interest and some amount of knowledge here
- 88. Show your genuine curiosity Ask better questions Challenge respectfully 88
- 89. Talking to people is hard 89 But there’s an antidote…
- 91. 91 Interactive Conversations You have control
- 93. Don’t interrupt. Write questions for later.
- 94. Then the trade is saved in a particular portfolio” My note-taking syntax new word
- 95. Then the trade is saved in a particular portfolio” [Check Wikipedia on trading] My note-taking syntax *MY* remarks not clear
- 96. Then the trade is saved in a particular portfolio” My note-taking syntax Q: When is this done? question for later
- 98. Scan your notes while listening to decide on next questions.
- 100. Our map of concepts http://www.infoq.com/articles/conversation-patterns-3 invoice paper e-invoice partner chasing
- 101. invoice paper e-invoice partner chasing depth Vs breadth http://www.infoq.com/articles/conversation-patterns-3 Conversation Patterns for Software Professionals Michał Bartyzel
- 102. paper e-invoice partner chasinginvoice Summarizing + intent http://www.infoq.com/articles/conversation-patterns-3
- 103. Image Found on Google Images; Credited to www.s-curiosity.com
- 104. We need a print button on this screen.
- 105. WHY?
- 106. Let me check to the users…
- 107. …
- 108. They need to give printouts to another department.
- 109. WHY?
- 110. Because they need to type the data into their system.
- 111. WTF!
- 112. Start with ”what’s the goal?”
- 113. Reverse-engineer the true need from the expressed solution
- 115. But don’t go too far…
- 118. I think we agree, but to be sure we should have an example
- 119. BDD: your best friend to interview domain experts
- 121. Asking for concrete examples Why is it so hard?
- 123. Is it faster when we’re wrong or missing stuff that matters?
- 124. http://www.hometalkusa.com/Tips/sample_construction_contract.htm Ask for genuine sample documents / data
- 125. Ask for genuine sample documents / data
- 126. Ask for genuine sample documents / data Ask! Insist!
- 128. bla bla bla shopping cart…
- 129. And by the way this is not the case for the marketplace
- 130. And by the way this is not the case for the marketplace
- 131. bla bla bla shopping cart… Q: marketplace???
- 132. Take note of side remarks
- 134. In real life…
- 136. THE ALMIGHTY EXPERT
- 137. DOES NOT EXIST
- 140. The worst domain expert is the one whose expertise was built from the intricacies of the existing systems
- 142. We can help.
- 143. EMPATHYput yourself in their shoes
- 144. EMPATHYput yourself in their shoes Figuratively
- 145. EMPATHYput yourself in their shoes Figuratively & Literally
- 150. "The best way to get the right answer on the Internet is not to ask a question, it's to post the wrong answer.” — Cunningham’s Law
- 151. PROPOSEas-a-tactic
- 153. Propose something. 153 Doesn’t have to be right / complete But do your best anyway
- 154. "Given a shopping basket which is over the free shipping limit, when I go to checkout the basket, what should I see on the screen?" Liz Keogh: http://www.infoq.com/articles/pulling-power
- 155. "Oh… Shipping is FREE with this order!" Liz Keogh: http://www.infoq.com/articles/pulling-power
- 156. Got it! Given a shopping basket which is over the free shipping limit When I go to checkout the basket Then I am notified that "shipping is FREE with this order"
- 157. The interview is over for today. Next is tomorrow.
- 158. SPIKE
- 160. Kitten kitty = new Kitten(Attitude.ROCK_STAR); Microphone mike = new Microphone(); kitty.sing(mike); system.out.println(mike.playBack()); //”mew mew meeew”
- 162. Code ☛ Issues + Questions Perfect for better questions for the next interview! #WIN Greg Young codeanalysis http://skillsmatter.com/podcast/design-architecture/mystery-ddd/js-4401
- 163. Teach Yourself Active Listening Code leading to new questions Learn Together Propose WITH the EXPERT WITHOUT the EXPERT
- 168. The Complexity of the Domain is there http://www.leunig.com.au
- 169. You can ignore the domain complexity, but it won’t ignore you
- 172. The obligatory exercise for the audience
- 173. You’re all domain experts too!
- 174. Pants!
- 175. Pants! Give a clear definition 2mn
- 176. Tacit Mental Models
- 177. What would happen if <change something>?
- 178. Need more examples.
- 180. ”You idiot! It’s to cover the ass of course!”
- 181. Ooops!
- 182. It’s to cover the ass?
- 183. Cover the ass: fixed!
- 184. No ass, no pants?
- 185. ”It’s easy! It’s to cover the legs of course!”
- 187. To cover legs, really?
- 189. A deep definition would answer this question
- 190. (I don’t have the answer)
- 193. A Good Investment
- 194. Learn some maths (monoids…) 194 A Good Investment
- 195. Could we say that? HotelBooking Jan26to27 HotelBooking Jan27to29 HotelBooking Jan26to29 + =
- 196. Past work experience, from any domain. 196 A Good Investment
- 197. Knowledge of other domains often introduces surprising insights into a project […] […] things like core accounting patterns crop up in places that don't look like accounting on the surface. http://lizkeogh.com/2015/12/14/bdd-a-three-headed-monster/ - Liz Keogh
- 198. Businesses don’t want all powers concentrated into the same hands 198
- 199. Astonishment as-a-tool 199 I’m surprised, I was expecting a segregation of duties here
- 200. Assume + Probe 200 Oops, you’re right! My bad.
- 201. Businesses don’t usually like ”hard delete” 201
- 202. Probe 202 Can we *really* delete the entry?
- 203. No no. We add another entry to compensate it.
- 204. Faster Discovery 204
- 205. INVARIANTS
- 206. “Is there any other outcome that’s important?” Liz Keogh
- 207. So the budget is the sum of all the tickets, right?
- 208. Yes.
- 209. Is it always true? Is there a case where it would not be true?
- 210. Well, yes. Some attendees do not pay, and some donate more.
- 211. And we have sponsors too…
- 212. Tickets: OK Donations Non paying attendees Sponsors New concepts
- 213. Tickets: OK Donations Non paying attendees Sponsors #WIN
- 216. The plural of domain expert is ”confusion”
- 218. Scalar / Record List Tree Graph Different Shape Different Bounded Context
- 219. 219 What happens if there’s a cycle?
- 220. I don’t get it; there can’t be any cycle…
- 221. Different shapes -> Bounded Contexts 221
- 222. BONUS TIPS
- 224. Shall we sort by date or by price?
- 225. Um… Err… I’d say by date…
- 226. ”Sort by date” [Not convincing]
- 227. Expect change ➔ Design with a Comparator Little bit of speculation here!
- 228. Hesitation -> Design Expect change ➔ Design with a Comparator
- 229. MIND THE LOGISTICS
- 230. Important screenshots / diagrams close to hands ”I mean HERE”
- 233. This place is magic
- 234. All on the same side
- 235. Can sketch together!
- 238. Music
- 244. In closing
- 246. In closing
- 247. Just examples. Live your own life. Build your own toolbox. 247
- 249. just tell me what I need to code!
- 250. I'm an architect, I will impress you with my technical brilliance
- 251. I'm smarter than the business guys!
- 252. THE RULE Make it clear they are safe with you. e.g. you have no plan to steal their job.
- 253. THE RULE ALWAYS ask for validation of everything (even if you’re sure).
- 254. Talking to Domain Experts is a thing now!
- 255. I have to tell you a secret
- 256. I choose projects based on their potential for applying DDD 256 Rich Business Domain Software as a differentiator
- 257. I choose projects based on the people too. 257 Clear Vision Collaborative mindset
- 258. "Dude, you are just a programmer." But I don't think that's true @JefClaes at #BuildStuffLT — @selketjah
- 259. Proposing ideas not just as a tactic, but also suggesting genuinely valuable business ideas 259
- 260. 260 Good models have Predictive Power
- 262. 262 DDD: Software to support the domain DDD: Software- augmented domain
- 263. “If one group of people does market research and makes product decisions, and another group that develops the software, we have less integrated understanding.” — Symbiosis - A Provocation About Organizations Michael Feathers, R7K Research & Conveyance https://drive.google.com/file/d/0B8ZX1RoWHuiJRnppcERLNjdSV00/view
- 264. #WIN!
- 270. Follow me @cyriux Slides: slideshare.net/cyriux Blog: cyrille.martraire.com In Paris? Join ! We offer training, coaching & consulting on DDD, BDD, TDD