1 Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC Survol de Object Constraint Language & IDM À partir du cours Contracts, Patterns.

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

Survol de Object Constraint Language

& IDM

À partir du cours

Contracts, Patterns and Aspects within MDA De Jean-Marc Jézéquel

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

Un métamodèle

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

Conformité entre modèles et métamodele

• Un métamodele en UML contraint la structure d’un modèle : – typage des éléments

– Cardinalité des associations

• Ça ne suffit pas!

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

Un métamodèle : des contraintes

-- (C1) Error: the name of a Classifier must be unique within its package.context Classifier inv:not self.package.contents->exists(e | (e <> self) and (e.name = self.name))

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

Un métamodèle : des contraintes supplémentaires

-- (C2) Error: the name of a StructuralFeature must be unique within its Class --and its supertypes.

context StructuralFeature inv:not self.owner.allStructuralFeatures()-> exists(e |(e <> self) and (e.name = self.name))

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

Bank_Account{balance>=lowest}

balance: Moneylowest: Money

deposit (Money)withdraw(Money)

Invariants de classe en UML

• Contraintes ajoutées à un modèle UML – notation: between { }

• Invariant = expression booléenne – Vraie pour toutes les instances d’une classe dans un état stable …

– Exprimée en OCL (Object Constraint Language)• e.g. {balance >= lowest}

• Navigation au travers des associations

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

Precondition: De la responsabilité du client

• Spécification de ce qui doit être vraie pour être autorisé à appeler une méthode – example: amount > 0

• Notation en UML– {«precondition» OCL boolean expression}

– Abbreviation: {pre: OCL boolean expression}

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

Postcondition: De la responsabilité de l’implementeur

• Specification de ce qui doit être vraie à la fin de l’exécution réussie d’une méthode – example: balance = balance @pre + amount

• Notation en UML– {«postcondition» OCL boolean expression}

– Abbreviation: {post: OCL boolean expression}

– “Operator for previous value (idem old Eiffel):”• OCL expression @pre

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

To be Abstract and Precise with the UML

Bank_Account {balance>=lowest}

balance: Moneylowest: Money

deposit (amount: Money) {pre: amount> 0} {post: balance = balance @pre + amount}withdraw(amount: Money) {pre: amount> 0 and montant<=balance-lowest} {post: balance = balance @pre - amount}

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

Non-local contracts: navigating associations

• Each association is a navigation path– The context of an OCL expression is the starting point

– Rolenames are used to select which association is to be traversed (or target classname if only one)

Person Car1 owner ownings *ownership

Context Car inv:self.owner.age >= 18

Context Car inv:self.owner.age >= 18

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

Navigation of 0..* associations

• Through navigation, we no longer get a scalar but a collection of objects

• OCL defines 3 sub-types of collection– Set : when navigation of a 0..* association

• Context Person inv: ownings return a Set[Car]• Each element is in the Set at most once

– Bag : if more than one navigation step• An element can be present more than once in the Bag

– Sequence : navigation of an association {ordered}• It is an ordered Bag

• Many predefined operations on type collection

Syntaxe : Collection->operation

Syntaxe : Collection->operation

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

Basic operations on collections

• isEmpty– true if collection has no element

• notEmpty– true if collection has at least one element

• size– Number of elements in the collection

• count (elem)– Number of occurrences of element elem in the collection

Context Person inv: age<18 implies ownings->isEmpty

Context Person inv: age<18 implies ownings->isEmpty

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

select Operation

• possible syntax– collection->select(elem:T | expr)– collection->select(elem | expr) – collection->select(expr)

• Selects the subset of collection for which property expr holds

• e.g.

• shortcut:

context Person inv:ownings->select(v: Car | v.mileage<100000)->notEmpty

context Person inv:ownings->select(v: Car | v.mileage<100000)->notEmpty

context Person inv:ownings->select(mileage<100000)->notEmpty

context Person inv:ownings->select(mileage<100000)->notEmpty

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

forAll Operation

• possibles syntax– collection->forall(elem:T | expr)– collection->forall(elem | expr) – collection->forall(expr)

• True iff expr holds for each element of the collection • e.g.

• shortcut:

context Person inv:ownings->forall(v: Car | v.mileage<100000)

context Person inv:ownings->forall(v: Car | v.mileage<100000)

context Person inv:ownings->forall(mileage<100000)

context Person inv:ownings->forall(mileage<100000)

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Mireille Blay-Fornarino – 2007/2008 EPU département SI, Master STIC

forAll with two variables

• Considers each pair in the Cartesian product of employees

context Company inv:

self.employee->forAll( e1, e2 : Person |

e1 <> e2 implies e1.forename <> e2.forename)

This is the same as

self.employee->forAll(e1 | self.employee->

forAll (e2 | e1 <> e2 implies

e1.forename <> e2.forename)))