Dialogue Notations and Design zDialogue Notations yDiagrammatic xstate transition networks, JSD diagrams, flow charts yTextual xformal grammars, production rules, CSP zIssues yDialogue Analysis ySemantics and dialogue yProperties of dialogue yPresentation and lexical issue zExample - Digital watch

State transition networks (STN) zcircles - states zarcs - actions/events

State transition networks - events zarc labels a bit cramped because: ynotation is `state heavy‘ ythe events require most detail

State transition networks - states zlabels in circles a bit uninformative: ystates are hard to name ybut easier to visualise

Hierarchical STNs zmanaging complex dialogues znamed sub-dialogues

Flowcharts zfamiliar to programmers zboxes - process/event - not state zuse 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 read record C1 delete record C3 other NY

JSD diagrams zfor tree structured dialogues yless expressive ygreater clarity transactionlogin add employee record change employee record display employee record logout Personnel Record System delete employee record *

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

Concurrent dialogues - II three toggles - individual STNs bolditalicunderline NO bold click on ‘bold’ NO italic click on ‘italic’ NO u’line click on ‘underline’

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’

Concurrent dialogues - IV all together - combinatorial explosion ‘italic’ NO style bold only ‘bold’ italic only bold italic ‘bold’ ‘italic’ u’line only bold u’line ‘bold’ italic u’line bold italic u’line ‘bold’ ‘italic’ ‘underline’ Text Style bold italic underline example

Textual - Grammars zRegular expressions sel-line click click* dble-click zcompare with JSD xsame computational model xdifferent notation zBNF expr ::= empty | atom expr | '(' expr ')' expr zmore powerful than regular exp. or STNs zStill NO concurrent dialogue

Production rules zUnordered list of rules: if condition then action ycondition based on state or pending events yevery rule always potentially active zGood for concurrency zBad for sequence

Event based production rules Sel-line  first C-point first  rest C-point rest  rest D-point rest  zNote: yevents added to list of pending events  ‘ first ’ and ‘ rest ’ are internally generated events zBad at state!

Prepositional Production System zState based zAttributes: xMouse: { mouse-off, select-line, click-point, double-click } xLine-state: { menu, first, rest } zRules (feedback not shown): xselect-line  mouse-off first xclick-point first  mouse-off rest xclick-point rest  mouse-off xdouble-click rest  mouse-off menu zBad at events!

CSP and process algebras zused in Alexander's SPI, and Agent notation zgood for sequential dialogues Bold-tog = select-bold?  bold-on  select-bold?  bold-off  Bold-tog Italic-tog =... Under-tog =... zand concurrent dialogue Dialogue-box = Bold-tog || Italic-tog || Under-tog zbut causality unclear

Dialogue Notations - Summary zDiagrammatic xSTN, JSD, Flow charts zTextual xgrammars, production rules, CSP zIssues xevent base vs. state based xpower vs. clarity xmodel vs. notation xsequential vs. concurrent

Semantics - Alexander's SPI (i) zTwo part specication: xEventCSP - pure dialogue order xEventISL - target dependent semantics zdialogue description - centralised zsyntactic/semantic trade-off - tollerable

Semantics Alexander SPI (ii) zEventCSP Login = login-mess -> get-name -> Passwd Passwd = passwd-mess -> (invalid -> Login [] valid -> Session) zEventISL 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)

Semantics - raw code zevent loop for word processor zdialogue 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 */

Action properties zcompleteness xmissed arcs xunforeseen circumstances zdeterminism xseveral arcs for one action xdeliberate: application decision xaccident: production rules znested escapes zconsistency xsame action, same effect? xmodes and visibility

Checking properties (i) zcompleteness ydouble-click in circle states? double click ?

Checking properties (ii) zReversibility: yto reverse select `line'

Checking properties (ii) zReversibility: yto reverse select `line' yclick

Checking properties (ii) zReversibility: yto reverse select `line' yclick - double click

Checking properties (ii) zReversibility: yto reverse select `line' yclick - double click - select `graphics' y(3 actions) zN.B. not undo

State properties zreachability xcan you get anywhere from anywhere? xand how easily zreversibility xcan you get to the previous state? xbut NOT undo zdangerous states xsome states you don't want to get to

Dangerous States zword processor: two modes and exit F1- changes mode F2- exit (and save) Esc- no mode change but... Esc resets autosave edit exit menu F1F2 Esc

Dangerous States (ii) zexit with/without save  dangerous states zduplicate states - semantic distinction F1-F2 - exit with save F1-Esc-F2 - exit with no save edit exit menu F1F2 Esc edit exit menu F1F2 Esc any update

Lexical Issues zvisibility xdifferentiate modes and states xannotations to dialogue zstyle xcommand - verb noun xmouse based - noun verb zlayout xnot just appearance...

layout matters zword processor - dangerous states zold keyboard - OK Esc F1F2 F3... F tab... edit exit menu F1F2 Esc edit exit menu F1F2 Esc any update

layout matters znew keyboard layout intend F1-F2 (save) finger catches Esc EscF1F2F3... edit exit menu F1F2 Esc edit exit menu F1F2 Esc any update

layout matters znew keyboard layout intend F1-F2 (save) finger catches Esc F1-Esc-F2 - disaster! EscF1F2F3... edit exit menu F1F2 Esc edit exit menu F1F2 Esc any update

Dialogue Analysis - Summary zSemantics and dialogue xattaching semantics xdistributed/centralised dialogue description xmaximising syntactic description zProperties of dialogue xaction properties: completeness, determinism, consistency xstate properties: reachability, reversibility, dangerous states zPresentation and lexical issues xvisibility, style, layout xN.B. not independent of dialogue

Dialogue Analysis - Summary zSemantics and dialogue xattaching semantics xdistributed/centralised dialogue description xmaximising syntactic description zProperties of dialogue xaction properties: completeness, determinism, consistency xstate properties: reachability, reversibility, dangerous states zPresentation and lexical issues xvisibility, style, layout xN.B. not independent of dialogue

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

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?

Digital watch – Designers instructions and... that’s just one button