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Evolution or Intelligent Design?

Evolution or Intelligent Design?. an objective view of software development. Stephen Jenkins. In the beginning …. Snap prototyped in 1980 First commercial version in 1981 MS-Basic under CP/M Rewritten 1986/7 in C under MS-DOS First Windows version 1992/3 Now: C/C++

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Evolution or Intelligent Design?

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  1. Evolution or Intelligent Design? an objective view of software development Stephen Jenkins

  2. In the beginning … • Snap prototyped in 1980 • First commercial version in 1981 • MS-Basic under CP/M • Rewritten 1986/7 in C under MS-DOSFirst Windows version 1992/3 • Now: C/C++ • Utilities in VB, online scripting in Python

  3. Snap today … • multi-mode, multi-language questionnaires • paper, scanning, web, pda, tablet, kiosk • tables, charts, weights, filters, scores • descriptive stats, factor & cluster analysis • online management & real-time analysis • > 20,000 active users • > 500,000 web respondents/month • active forum with ~600 registered

  4. Snap users … • Snap user profile:- MR function in commercial organisation- Consultation in government / education- Smaller research agencies • Some full-time, many stop/start • Snap is a tool to get the job done

  5. Forces at work … Users and Prospects Changing Domain Requirements Systems Infrastructure Business Constraints

  6. Forces at work … Users and Prospects Changing Domain Requirements Systems Infrastructure Business Constraints

  7. Users and Prospects … • Not “programmers” • Snap treated more like a Word Processor than a Database system • Snap used as a guide and assistant • Sales demos are typically to new users

  8. Forces at work … Changing Domain Requirements Users and Prospects Systems Infrastructure Changes Business Constraints

  9. Changing Domain Requirements … • Multi-mode questionnaires- more respondent self-completion • More re-use of existing data- database links- other survey systems (Triple-s) • More coarse fragmentation- more “standardisation”- but in disparate areas

  10. Forces at work … Users and Prospects Changing Domain Requirements Systems Infrastructure Changes Business Constraints

  11. Systems Infrastructure … • Systems Configuration- Stand-alone desktop- LAN / WAN -connected desktop- Browser model • Memory / media etc.48k - 2Gb RAM (x42,000)80k - 100Gb disk (x1,250,000)

  12. Systems Infrastructure … • Language choice- Snap in C/C++, VB, Python- ?PL-1? / ?Pascal? / ?Ada?- very expensive to rewrite later • Avoid big black-box components- better control of update schedules- better control of licensing models

  13. Forces at work … Users and Prospects Changing Domain Requirements Business Constraints Systems Infrastructure Changes

  14. Business Constraints … • Commercial model- Standard package / optional modules- Desktop / server based- Perpetual licence- Free support & updates for 1 year- Optional annual support & updates • Updates every 12-18 months

  15. Developers … • “Ownership” of specific areas- Agreed macro-design- Do their own micro-designs • Systems / language expertise- Language and/or system focus • Dabbled in eXtreme Programming- pair-programming

  16. Architectural Design Users and Prospects Domain Requirements Systems Infrastructure Business Constraints

  17. Architecture … • Single C/C++ program- optional modules turned on- fewer option incompatibility issues- helps consistent, holistic view • No “special versions” etc. • Build VB apps to get features to market quickly (“SurveyPlus”)

  18. Architecture … • Object-oriented- Questions, Styles, Variables, Tables …- No overall navigable DOM- No user-accessible API • Files / persistence- Metadata file (object streams)- Raw data file (fixed-length records)- Processed data file (response streams)

  19. Abstract for re-use … • Filter expressions- tables, browse data, derive categories routing preconditions • Text substitution- answers from previous question(s)- headers, footers and report titles- dynamic multi-language

  20. Ongoing Development … • Domain-based extensibility • Patterns ...

  21. Patterns … as data cleaner Q1. How much did you spend? 4.56 raw data syntax & value checks variable 4.56 processed output

  22. Patterns … as data cleaner Q1. How much did you spend? £4.56 raw data syntax & value checks variable ERROR processed output

  23. Patterns … as data cleaner Q1. How much did you spend? £4.56 raw data syntactictransforms pattern 4.56 cleaned input syntax & value checks variable 4.56 processed output

  24. Patterns … as data cleaner Q2. How many children do you have? three raw data syntactictransforms pattern 3 cleaned input syntax & value checks variable 3 processed output

  25. Patterns … as sub-field prompt Q3. When did you arrive? raw data 25 / 01 / 2006 pattern day 25 matched input month 01 year 2006 variable Q3 Q3 25/01/2006 processed output

  26. Patterns … as sub-field selector Q3. When did you arrive? raw data 25 / 01 / 2006 pattern day 25 matched input month 01 year 2006 variable Q3 Q3 month 01 processed output

  27. Ongoing Development … • Domain-based extensibility • Patterns ... • Prototype-based object model ...

  28. Class-based Object Model declare & assignproperties& methods axis Rows; axis Cols; num Accumulate(cell) { cell = cell + 1; return cell } class Rows = Q2; Cols = Q10; ... instance assign properties

  29. Class-based Object Model Programmer declare & assignproperties & methods axis Rows; axis Cols; num Accumulate(cell) { cell = cell + 1; return cell } class User Rows = Q2; Cols = Q10; ... instance assign properties

  30. Class-based Object Model Programmer declare & assignproperties & methods axis Rows; axis Cols; num Accumulate(cell) { cell = cell + 1; return cell } class User Rows = Q2; Cols = Q10; ... instance assign properties

  31. Class-based Object Model Programmer declare & assignproperties & methods axis Rows; axis Cols; num Accumulate(cell) { cell = cell + 1; return cell } class User instance assign properties

  32. Prototype-based Object Model class prototype instance

  33. Prototype-based Object Model axis Rows; axis Cols; num Accumulate(cell) { cell = cell + 1; return cell } declare & assignproperties & methods prototype num Weight=1; num Accumulate(cell) { cell=cell+weight; return cell } declare & assignproperties & methods prototype / instance

  34. Prototype-based Object Model Programmer axis Rows; axis Cols; num Accumulate(cell) { cell = cell + 1; return cell } declare & assignproperties & methods prototype User num Weight=1; num Accumulate(cell) { cell=cell+weight; return cell } declare & assignproperties & methods prototype / instance

  35. Prototype-based Model Programmer axis Rows; axis Cols; num Accumulate(cell) { cell = cell + 1; return cell } declare & assignproperties & methods prototype User num Weight=1; num Accumulate(cell) { cell=cell+weight; return cell } declare & assignproperties & methods prototype / instance

  36. Prototype-based Model Programmer axis Rows; axis Cols; num Accumulate(cell) { cell = cell + 1; return cell } declare & assignproperties & methods prototype User-developer declare & assignproperties & methods prototype / instance

  37. User prototype / instance declare & assignproperties & methods Prototype-based Object Model User-developer declare & assignproperties & methods prototype / instance

  38. Ongoing Development … • Domain-based extensibility • Patterns ... • Prototype-based object model ... • Core wholly driven by metadata

  39. Snap development philosophy … • Know & understand intended users • Allow users to work in their domain • Don’t rely solely on software • Plan for evolution

  40. Evolution Intelligent Design and Evolution or Intelligent Design? Stephen Jenkins sjenkins@snapsurveys.com

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