Exploring a Model-Oriented and Executable Syntax for UML Attributes

SERA 2013 (August 7, 2013 in Prague, Czech Republic)

Omar Badreddin, Andrew Forward, Timothy C. Lethbridge1 University of Ottawaobadr024@uottawa.ca / oobahy@gmail.com aforward@site.uottawa.ca / aforward@gmail.comtcl@site.uottawa.cahttp://umple.org

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Overview• Model Oriented Programming• Umple Overview• Attributes in Practice• Umple Attribute Syntax• Attribute Code Generation

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The philosophy of Model-Oriented Programming (MOP)

MOP

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Embed Models In Code

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Unify programs and models

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Supports Modeller and Programmer workflows

Model-First Incremental Re-Engineering

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Text Diagram Duality

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Reduce Need to Round-Trip

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Easily Integrate with Text-Based Tooling

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A MOP technology and language family

Umple

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Why call it Umple?

UML Programming LanguageAmpleSimple

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What does Umple support?• Modeling abstractions

• Associations, Attributes, State machines (both simple and composite), model based tracing, and simple debugging.

• Supported languages• Java, C++, Ruby, PhP

• Integration support• XMI for model exchange, Ecore, textUML, Yuml,

GraphViz, SQL

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Attributes In PracticeGoogle Code:• fizzbuzz• ExcelLibrary• Ndependencyinjection• Java Bug Reporting SourceForge:• jEdit• FreemakerFreecode:• Java Financial Library

• 1831 variables• 620 static• 1211 instance

• 469 classes

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Variable Distribution

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Static (Class) Variables

Member (Object) Variables

E.g. avoiding magic numbers and state symbols (i.e. LEFT_NODE, RIGHT_NODE)

Mostly counts, names and booleans (51%)

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A lot of other object types

Attribute Identification

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About 33% had attribute-like methods implementations

Surprising that 35% had no external access at all

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Attribute Code Generation

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Over half were simple boiler-plate implementations

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Observations• Many simple set and get methods

• Drastic reduction in boiler-plate code

• Few truly immutable attributes• Few attributes set in constructor• Immutability needed for proper hash code (Java)

• Attribute multiplicities typically ‘one’• Basic multiplicity (0..1, 1, 0..*) available for attributes

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Umple Attributesclass Student{ // defaults to String studentNumber; String grade; Integer entryAverage;}

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Umple Data Types

Umple treats the following attribute types as specialString (always the default if unspecified)IntegerDoubleBooleanDate, Time

• Code generation from the above will generate suitable types in the underlying language (Java, PHP, etc.)

• Umple classes can be used as types, but consider associations instead 19

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Initializing Attributesclass Student{ // Initial value set to “Unknown”, // not required in class constructor name = "Unknown";

// Initialized, but can also be reset defaulted type = “FullTime”; // Name initialized to null in // constructor lazy program;}

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Immutable Attributesclass Student{ // Cannot be changed after set in constructor immutable idNumber;

// Can be set once, right after construction, // and is immutable after that // Useful for frameworks where objects are // created without initializing values lazy immutable barcode;}

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Derived Attributesclass Rectangle{ Integer l; Integer w; // Derived Attributes Integer perimeter = { 2*getL() + 2*getW() } Integer area = { getL() * getW() }}

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Additional Attribute Optionsclass Student{ // Umple assigns the next // available number autounique id; // Creates a constant value const Integer MAX_NUM_COURSES = 8;} class Address{ // An address has many lines String[] lines;}

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Attribute Code Generation (1)

class Rectangle{ name = "Rectangle"; Integer length; Integer width; Integer area = {getLenth() * getWidth()} }

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Attribute Code Generation (2)// line 2 "model.ump"public class Rectangle{ @java.lang.annotation.Retention(java.lang.annotation.RetentionPolicy.RUNTIME) public @interface umplesourcefile{int[] line();String[] file();int[] javaline();int[] length();}

//------------------------ // MEMBER VARIABLES //------------------------

//Rectangle Attributes private String name; private int length; private int width;

//------------------------ // CONSTRUCTOR //------------------------

public Rectangle(int aLength, int aWidth) { name = "Rectangle"; length = aLength; width = aWidth; }

//------------------------ // INTERFACE //------------------------

public boolean setName(String aName) { boolean wasSet = false; name = aName; wasSet = true; return wasSet; } public boolean setLength(int aLength) { boolean wasSet = false; length = aLength; wasSet = true; return wasSet; }

public boolean setWidth(int aWidth) { boolean wasSet = false; width = aWidth; wasSet = true; return wasSet; }

public String getName() { return name; }

public int getLength() { return length; }

public int getWidth() { return width; }

@umplesourcefile(line={7},file={"model.ump"},javaline={79},length={2}) public int getArea() { return getLenth() * getWidth(); }

public void delete() {}

public String toString() { String outputString = ""; return super.toString() + "["+ "name" + ":" + getName()+ "," + "length" + ":" + getLength()+ "," + "width" + ":" + getWidth()+ "," + "area" + ":" + getArea()+ "]" + outputString; }} 25

Constructor based on attributes missing an initial value

Set method returns a boolean (was it “set” or not)

Simple get method

Derived methods do not have internal members

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http://try.umple.org

Try It Yourself

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Summary

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Umple features can be created and viewed diagrammatically or textually

Umple extends a base language in a minimally invasive way

Intermediate generated code should not be edited

=Modeling is programming and vice versa

No round-trip engineering required

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Getting involved• Open source project: https://code.google.com/p/umple/• Teaching

• Use Umple to introduce UML and MDE.• Umplification

• Incrementally replace boilerplate code with modeling abstractions

• Lightweight Modeling and Analysis• Visualize Umple source as UML diagrams to analyze it

• Model driven development• Generate code in one of the supported base languages

Comments and feedback: tcl@site.uottawa.ca 28

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More information

• Publications on Umple:

https://code.google.com/p/umple/wiki/Publications

• The User Manual:

http://cruise.eecs.uottawa.ca/umple/GettingStarted.html

• Umple Home page: http://cruise.eecs.uottawa.ca/umple/

• Download Umple:

http://cruise.eecs.uottawa.ca/umpleonline/download_eclipse

_umple_plugin.html

• Report an issue:

https://code.google.com/p/umple/issues/entry

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