Model Oriented Programming: An Empirical Study of

Comprehension

Omar Badreddin

Andrew Forward

Timothy C. Lethbridge

try.umple.org

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Technology TrendL

evel

s o

f A

bst

ract

ion

Assembly

Pascal

Java, C++

Alf, Umple

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What is Umple?

• Model Oriented Programming• Add modeling abstractions to code

– Class diagram– State machines

• Model-Code Duality

• State-of-the-art code generation

• Open source (Google Code)

• Available online (try.umple.org) as well as on the command line and in Eclipse

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Examples of Umple code

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Associations

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State Machines

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What else can you model in Umple

• Composite state machine.– Nested– Concurrent

• Do Activities in state machines

• Tracing directives

• Aspect-oriented concepts– Code injection (Before, After)

• Certain patterns (e.g. singleton, immutable)

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Umple online (try.umple.org)

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Development Approaches

• Model-Only

• Code-Only

• A mix of Code and Model (Complete running systems)

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Technology trend revisited

main

mov cx,3

loopstart: do

mov dh,10 ;row 10

mov dl,20 ;column 20

call Gotoxy ;locate cursor

PromptForIntegers

ArraySum

DisplaySum ENDP

END main

for (int i = 0; i < 3; i++)

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JavaJava

AssemblyAssembly

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Technology trend revisited

public boolean e() {

boolean wasEventProcessed = false;

Status aStatus = status;

switch (aStatus) {

case On:

setStatus(Status.Off);

wasEventProcessed = true;

break;

case Off:

setStatus(Status.Off);

wasEventProcessed = true;

break; }

return wasEventProcessed; }

status { On { e -> Off;} Off{ e -> Off;}}

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UmpleUmple

JavaJava

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Experiment Hypotheses & Design

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Hypothesis

• H1: A system written in Umple is more comprehensible than an equivalent Java implementation of the system

– H10: Umple and Java do not differ in comprehensibility

• H2: A system written in Umple has a different comprehensibility level than an equivalent UML diagram of the system

– H20: Umple and UML diagrams do not differ in comprehensibility

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Experiment Design

Umple UML

Java

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Experiment Design

Umple UML

Java

C

MM

C

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Umple UML

Java

C

MM

C

T V

T

Experiment Design

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Umple

Java

C

M

C

T

T

Comparing Umple & Java

Common to both:Textual syntaxComplete system

Natural advantage to Java:Familiarity

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Umple UMLC

MM

T V

Comparing Umple and UML

Common to both:Modeling notation

Natural advantage to UML:FamiliarityModel only (fewer details)

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Experiment Procedure

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Experiment Procedure

System Example

Analyze

9 Participants3 system examples represented in 3

notations (Umple, UML, Java)

12 Questions per example

Measure time, count number

of incorrect responses

Mix of students and professionals

Questions reflect comprehension and

some require tracing

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Experiment Results

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Average Response Time

Participants

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Box Plot of Response Time

Notation

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Statistical tests

• Examining Data for Umple and Java– Mann-Whitney test ((p = 8.9x10-9)– Two Tailed t-test: Umple was faster for users than Java

(p=1.5x10-8)

• Examining Data for Umple and UML– Mann-Whitney test (p = 0.2)– Two Tailed t-test: Umple ~ UML (p=0.9)

• Number of errors

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Threats of Validity

• Number of Participants and their experience• Will users interpret questions consistently?

• Fairness of comparing Umple, UML, and Java– Umple & Java / Umple and UML

• Examples could be too simple, not realistic/representative, not ‘the same’ as each other

• Time for response is very small.

• External validity (can it scale to real systems?)

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Conclusion

• Modeling abstractions embedded in code enhances comprehensibility.

• Such abstractions retain comprehensibility benefits as evident in UML.

• Replication of experiment

• Experimenting with larger, more complex system examples and tasks.

Future Work

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