Designing Dialogues Using Dialogue Notations and State Transition Networks

1. Dialogue Notations and Design z Dialogue Notations y Diagrammatic x state transition networks, JSD diagrams, flow charts y Textual x formal grammars, production rules, CS P z Issues y Dialogue Analysis y Semantics and dialogue y Properties of dialogue y Presentation and lexical issue z Example - Digital watch

2. State transition networks (STN) z circles - states z arcs - actions/events

3. State transition networks - events z arc labels a bit cramped because: y notation is `state heavy y the events require most detail

4. State transition networks - states z labels in circles a bit uninformative: y states are hard to name y but easier to visualise

5. Hierarchical STNs z managing complex dialogues z named sub-dialogues

6. Flowcharts z familiar to programmers z boxes - process/event - not state z use for dialogue (not internal algorithm) Delete D1 Please enter employee no.: ____ Delete D3 Name: Alan Dix Dept: Computing delete? (Y/N): _ Please enter Y or N Delete D2 Name: Alan Dix Dept: Computing delete? (Y/N): _ answer? C2 Finish Finish read record C1 delete record C3 other N Y

7. JSD diagrams z for tree structured dialogues y less expressive y greater clarity transaction login add employee record change employee record display employee record logout Personnel Record System delete employee record *

8. Concurrent dialogues - I simple dialogue box Text Style bold italic underline example

9. Concurrent dialogues - II three toggles - individual STNs bold italic underline NO bold bold click on bold NO italic italic click on italic NO uline uline click on underline

10. Concurrent dialogues - III bold and italic combined Text Style bold italic underline example NO style bold only click on bold click on italic italic only bold italic click on bold click on italic

11. Concurrent dialogues - IV all together - combinatorial explosion italic NO style bold only bold italic only bold italic bold italic uline only bold uline bold italic uline bold italic uline bold italic italic underline underline underline underline Text Style bold italic underline example

12. Textual - Grammars z Regular expressions sel-line click click* dble-click z compare with JSD x same computational model x different notation z BNF expr ::= empty | atom expr | '(' expr ')' expr z more powerful than regular exp. or STNs z Still NO concurrent dialogue

13. Production rules z Unordered list of rules: if condition then action y condition based on state or pending events y every rule always potentially active z Good for concurrency z Bad for sequence

14. Event based production rules Sel-line first C-point first rest C-point rest rest D-point rest < draw line > z Note: y events added to list of pending events first and rest are internally generated events z Bad at state!

15. Prepositional Production System z State based z Attributes: x Mouse: { mouse-off, select-line, click-point, double-click } x Line-state: { menu, first, rest } z Rules (feedback not shown): x select-line mouse-off first x click-point first mouse-off rest x click-point rest mouse-off x double-click rest mouse-off menu z Bad at events!

16. CSP and process algebras z used in Alexander's SPI, and Agent notation z good for sequential dialogues Bold-tog = select-bold? bold-on select-bold? bold-off Bold-tog Italic-tog = . . . Under-tog = . . . z and concurrent dialogue Dialogue-box = Bold-tog || Italic-tog || Under-tog z but causality unclear

17. Dialogue Notations - Summary z Diagrammatic x STN, JSD, Flow charts z Textual x grammars, production rules, CSP z Issues x event base vs. state based x power vs. clarity x model vs. notation x sequential vs. concurrent

18. Semantics - Alexander's SPI (i) z Two part specication: x EventCSP - pure dialogue order x EventISL - target dependent semantics z dialogue description - centralised z syntactic/semantic trade-off - tollerable

19. Semantics Alexander SPI (ii) z EventCSP Login = login-mess -> get-name -> Passwd Passwd = passwd-mess -> (invalid -> Login [] valid -> Session) z EventISL event: login-mess prompt: true out: Login: event: get-name uses: input set: user-id = input event: valid uses: input, user-id, passwd-db wgen: passwd-id = passwd-db(user-id)

20. Semantics - raw code z event loop for word processor z dialogue description - very distributed syntactic/semantic trade-off - terrible! switch ( ev.type ) { case button_down: if ( in_text ( ev.pos ) ) { mode = selecting; mark_selection_start(ev.pos); } ... case button_up: if ( in_text ( ev.pos ) && mode == selecting ) { mode = normal; mark_selection_end(ev.pos); } ... case mouse_move: if (mode == selecting ) { extend_selection(ev.pos); } ... } /* end of switch */

21. Action properties z completeness x missed arcs x unforeseen circumstances z determinism x several arcs for one action x deliberate: application decision x accident: production rules z nested escapes z consistency x same action, same effect? x modes and visibility

22. Checking properties (i) z completeness y double-click in circle states? double click ?

23. Checking properties (ii) z Reversibility: y to reverse select `line'

24. Checking properties (ii) z Reversibility: y to reverse select `line' y click

25. Checking properties (ii) z Reversibility: y to reverse select `line' y click - double click

26. Checking properties (ii) z Reversibility: y to reverse select `line' y click - double click - select `graphics' y (3 actions) z N.B. not undo

27. State properties z reachability x can you get anywhere from anywhere? x and how easily z reversibility x can you get to the previous state? x but NOT undo z dangerous states x some states you don't want to get to

28. Dangerous States z word processor: two modes and exit F1 - changes mode F2 - exit (and save) Esc - no mode change but ... Esc resets autosave edit exit menu F1 F2 Esc

29. Dangerous States (ii) z exit with/without save dangerous states z duplicate states - semantic distinction F1-F2 - exit with save F1-Esc-F2 - exit with no save edit exit menu F1 F2 Esc edit exit menu F1 F2 Esc any update

30. Lexical Issues z visibility x differentiate modes and states x annotations to dialogue z style x command - verb noun x mouse based - noun verb z layout x not just appearance ...

31. layout matters z word processor - dangerous states z old keyboard - OK Esc F1 F2 F3 ... F4 ... 1 tab ... ... edit exit menu F1 F2 Esc edit exit menu F1 F2 Esc any update

32. layout matters z new keyboard layout intend F1-F2 (save) finger catches Esc Esc F1 F2 F3 ... edit exit menu F1 F2 Esc edit exit menu F1 F2 Esc any update

33. layout matters z new keyboard layout intend F1-F2 (save) finger catches Esc F1-Esc-F2 - disaster! Esc F1 F2 F3 ... edit exit menu F1 F2 Esc edit exit menu F1 F2 Esc any update

34. Dialogue Analysis - Summary z Semantics and dialogue x attaching semantics x distributed/centralised dialogue description x maximising syntactic description z Properties of dialogue x action properties: completeness, determinism, consistency x state properties: reachability, reversibility, dangerous states z Presentation and lexical issues x visibility , style , layout x N.B. not independent of dialogue

35. Dialogue Analysis - Summary z Semantics and dialogue x attaching semantics x distributed/centralised dialogue description x maximising syntactic description z Properties of dialogue x action properties: completeness, determinism, consistency x state properties: reachability, reversibility, dangerous states z Presentation and lexical issues x visibility , style , layout x N.B. not independent of dialogue

36. Digital watch User Instructions two main modes limited interface - 3 buttons button A changes mode

37. Digital watch User Instructions dangerous states guarded by two second hold completeness distinguish depress A and release A what do they do in all modes?

38. Digital watch Designers instructions and ... thats just one button