From OCL to JMLOn the Relationship between The Object Constraint

Language (OCL) and The Java Modeling Language(JML)

Translating the Object Constraint Language into the Java Modeling Language

Ali HamieSchool of Computing, Mathematical and Information Sciences

University of BrightonBa.a.hamie@brighton.ac.uk

By Karen Richart

The Object Constraint Language (OCL)

Formal specification language that could be used for constraining the model elements that occur in a UML diagram.

The Object Constraint Language (OCL)

Formal specification language that could be used for constraining the model elements that occur in a UML diagram.

The Java Modeling Language (JML)

Design for specifying java classes and interfaces.

Motivation

To be able to map UML object oriented designs with OCL constraints to Java classes annotated with JML specifications

WHY?

Map object oriented design models expressed in UML and OCL to Java classes annotated with JML specifications

Development of Java application using UML/OCL, JML for later stages

Can use tools that support JML to reason about specifications, testing and verification

JML same notation as Java

Basic Types

OCL

Boolean Integer Real String

JML (Java)

Boolean int float/double String

Boolean Operators

μ(b1 and b2) = μ(b1) && μ(b2)

μ(b1 or b2) = μ(b1) || μ(b2)

μ(b1 implies b2) = μ(b1) ==> μ(b2)

μ(not b1) = !μ(b1)

and - &&or - ||

implies - ==>not - !

Collection Operators

OCL

Collection(T) Set(T) Bag(T) Sequence(T)

JML

Object VS value collections

JMLObjectSet/JMLValueSet

JMLObjectBag/JMLValueBag

JMLObjectSequence/JMLValueSequence

JMLValueSet VS

JMLObjectSet JMLValueSet (\forall JMLType e;

μ(s).has(e);e instanceof JMLLong)

JMLObjectSet (\forall Object e;

μ(s).has(e);e instanceof T)

Set(Person)

(\forall Object p; μ(s).has(p);p instanceof Person)

Common Operators

μ(c->size()) = μ(c).size() μ(c->includes(e)) = μ(c).has(μ(e)) μ(c->excludes(e)) = !μ(c).has(μ(e)).

What about excludesAll()?

c1->excludesAll(c2) μ(c1->excludesAll(c2)) = (\forAll T e;μ(c2).has(e);!μ(c1).has(e))

Other operators

μ(s->union(s1)) = μ(s).union(μ(s1)) μ(s->intersection(s1)) =

μ(s).intersection(μ(s1))

μ(s->union(b)) = μ(s).toBag().union(μ(b))

Iterator Expressions

μ(c->exists(e : T | p(e))) = (\exists T e;μ(c).has(e);μ(p))

μ(c->select(e : T | p(e))) = new JMLObjectSet{T e | μ(c).has(e) &&

μ(p)}

Operations not defined in Java

Library for OCL type that facilitates mapping Including classes for the collection types

along with their operations s->op(..) To s.op(.. )

max()class OclIntegerOperations {

static public int max(int i1, int i2){

if (i1 > i2) {return i1;}

else {return i2;}}

static public int min(int i1, int i2){

if (i1 < i2) {return i1;}

else {return i2;}}

}

i1.max(i2)μ(i1.max(i2)) =

OclIntegerOperations.max(i1,i2)

Collections

public class OclObjectSet extends JMLObjectSet{ public boolean includes(Object e) {this.has(e);}//@ is the argument ‘==’ to one of the objects in the

setpublic int size() {this.size()};//@ number of elements in the setpublic boolean notEmpty() {!isEmpty(); }//@ is the set not empty? }

context TitleInv: availableCopies > 0 = copies->exists(isAvailable)

availableCopies >0 <==>(\exists Copy c; copies.includes(c); c.isAvailable)

Exercise

Translate the following OCL constraint to JML

Solution ?

/*@ requires question->excludes(q) = !question.has(q); @ ensures question == \old(question.union(q)); @*/

Thank You