Cognitive Metrics for the Management of Model-based

Software Development

Reuven Gallant, Yehuda Badihi, Hagai Sugarman

Jerusalem College of Technology-Machon Lev

JCT

Why are managers afraid of model-based development?

It sounds good

notation

method/process tool

Why are managers afraid of model-based development?

actor

• They like pictures

Why sw engineers do/don’t like models (1)

• They don’t like tools– Or are lacking motivation to use them

• They don’t have patience for semantics

NST: (US) (US) : (s, s') s – s'+ s' – s

• They like pictures• They like pictures

Is a picture worth 1000 words?

“To set the alarm , the key must be inserted into the lock , turned anti clockwise , and held for at least half a second.

  “To reset the alarm , the key must be inserted

into the lock and turned clockwise. The alarm will be deactivated immediately.”

Automobile Alarm

Why sw engineers do/don’t like models (2)

Key Characteristics of Engineering Models

• Abstraction

• Understandability

• Accuracy

• Predictiveness

• InexpensiveBrian Selic, “The Pragmatics of Model-Driven Development,” IEEE

Software, Sept./Oct. 2003.

Where measurements can help us manage model-based development

• Tool Evaluation

• People Evaluation

• Training Evaluation

• Model Evaluation

Metrics must be simple and easy to automate

Fenton N. and Neil M. (2000). Software Metrics: a Roadmap. Future of Software

Engineering. Anthony Finkelstein Ed., ACM, 359-370.

Bottom Up Tool Evaluation

Gestalt Approach to Tool Evaluation

R. Gallant, M. Winokur, and J. Kudish, "Tool and Method Reciprocity: A Case Study in Requirements Management," Proceedings of The Seventh Israel Conference on Computer Systems and Software Engineerinתg 1996.

“…attempt to produce the most aesthetic, and therefore comprehensible, layouts.”

Harel’s Aesthetics

• “An Algorithm for Blob Hierarchy Layout", Proc. Working Conf. on Advanced Visual Interfaces (AVI’2000), Palermo, Italy, ACM Press, New York, May 1999, pp. 29-40.

Automobile Alarm-unaesthetic?

Statechart Complexity Metrics (1)

“The aim of the experiment was to investigate the relationship between the complexity of UML statechart diagrams and their understandability (one maintainability subcharacteristic).

Defining and Validating Metrics for UML Statechart Diagrams

Marcela Genero, David Miranda and Mario Piattini, QAOOSE2002

Statechart Complexity Metrics (2)

•

Automobile Alarm-too many of something?

Statechart Complexity Metrics:economy vs. explicity

idle

running

spraying pulsing

evJ etPulseevJ etOffevJ etSprayevJetOff

idle

running

spraying pulsing

evJ etPulseevJ etOffevJetSpray

How Do We Measure Understandability? (2)Cognitive Dimensions (CDs)

• Viscosity• Visibility• Premature

commitment• Hidden dependencies• Role expressiveness• Error-proneness• Abstraction

• Secondary notation• Closeness of mapping• Consistency• Diffuseness• Hard mental

operations• Provisionality• Progressive evaluation

Proposed by Greene in 1989, who has developed it since then with Petre, Blackwell, et al.

Automobile Alarm-CD deficiency?

Patterns to the rescue!

resetting

setOrNeutral

setOrSetting

set

setting neutral

[settingCondition]

[neutralCondition]

tm(setTime)]IS_IN(setting)[/setAction

[resettingCondition/]resetAction

[neutralCondition/]neutralAction

/setup()

Cognitive “Measures”• Automatization

– Automatized vs. controlled tasks

• Types of knowledge– Declarative, Conceptual, Procedural

• Expertise– From novice to expert

• Learning hierarchy– Associations and chains; Discriminations Concepts; Rules ; Higher

order rules

• Knowledge structuring – Surface features task specific features abstract/hierarchical features

• Mental workload – single resource pool, multiple-resource

Automatization(1)Please enter OMTracer Command>> go idle

OMTracer (0:00:00.200) Display[0[ Sent to itself Event tm(200) at ROOT.active

OMTracer (0:00:00.200) Display[0[ Received from itself Event tm(200) at ROOT.active

OMTracer (0:00:00.200) main() Invoked Display[0[->Take Event Timeout

OMTracer (0:00:00.200) Display[0[ Invoked isDone()

OMTracer (0:00:00.200) Display[0[->isDone() Returned

OMTracer (0:00:00.200) Display[0[ Exited State ROOT.active

OMTracer (0:00:00.200) Display[0[ Invoked print(n = 1)

OMTracer (0:00:00.200) Display[0[->print(n = 1) Returned

OMTracer (0:00:00.200) Display[0[ Entered State ROOT.active

OMTracer (0:00:00.200) Display[0[ set tm(200) at ROOT.active

OMTracer (0:00:00.200) Display[0[->Take Event Timeout Returned

Automatization(2)topState

leftStates rightStates

topState

A

B

C

D

evBtoAevAtoB evDtoC/GEN(evAtoB)

evCtoD

Automatization(3)

full>

draining

empty>

filling

tm(4000)/itsDishwasher->GEN(evFull);

tm(4000)/itsDishwasher->GEN(evEmpty); evTankDrain

evTankFill

off filling rinsing

evStart/

itsTank->GEN(evTankFill)

evFull

Statechart of Dishwasher

Statechart of Tank

Any questions?

actor

Why engineers won’t use tools

Enter Professor Harel

More than one way to skin a cat!(1)Please enter OMTracer Command>> go idle

OMTracer (0:00:00.200) Display[0[ Sent to itself Event tm(200) at ROOT.active

OMTracer (0:00:00.200) Display[0[ Received from itself Event tm(200) at ROOT.active

OMTracer (0:00:00.200) main() Invoked Display[0[->Take Event Timeout

OMTracer (0:00:00.200) Display[0[ Invoked isDone()

OMTracer (0:00:00.200) Display[0[->isDone() Returned

OMTracer (0:00:00.200) Display[0[ Exited State ROOT.active

OMTracer (0:00:00.200) Display[0[ Invoked print(n = 1)

OMTracer (0:00:00.200) Display[0[->print(n = 1) Returned

OMTracer (0:00:00.200) Display[0[ Entered State ROOT.active

OMTracer (0:00:00.200) Display[0[ set tm(200) at ROOT.active

OMTracer (0:00:00.200) Display[0[->Take Event Timeout Returned

Automatization • Shiffrin et al. [9[ [10[ distinguish between

controlled and automatic processes. Whereas “automatized” processes require little or no cognitive resources, “controlled” processes are resource intensive. Abilities are important for mastering repetitive tasks, but not for performing them once mastered. In contrast, abilities continue to be important in the performance of controlled processes.

Level of Detail

Diagram Type

Application Type

How did the SHADOW get its name?????

• 2 Theories

Theory I

•Sikorsky Helicopter Advanced

Demonstrator of Operator Workload

Theory II

• Jimmy Durante’s radio program and nose!

The SHADOW was top top secret!!!!

• Not members of the U.S. House of Representatives…

• Not even Senators…– Got to see the SHADOW

The SHADOW was top top secret!!!!

•But the King got to fly in it!

4 Helicopters were sent to fetch the King from Boston

It was raining, and the King decided that discretion was the better part of

valour

How Do We Measure Understandability? (2)

Cognitive Dimensions (CDs)• Viscosity: resistance to change• Visibility• Greene, T. R. G. (1989). Cognitive Dimensions of Notations. In People and

Computers V. A. Sutcliffe and L. Macaulay, (Ed.). Cambridge: Cambridge University Press, 443-460.

• For non-specialists (no expertise in cognitive science or HFE required)• Broad-brush• Quick to apply, no lengthy analysis• Check list approach:

– abstraction, hidden dependencies, premature commitment, secondary notation, viscosity, visibility, closeness of mapping, diffuseness, error-proneness, hard mental operations, progressive evaluation, provisionality, role-expressiveness

Bottom Up Tool Evaluation