Issue 134: Specification of Constraints There is no standard way of specifying constraints –Constraints in MDR metamodel OCL expressions can be provided for metaclass and its instance Target: Data Element Concept and Conceptual Domain, Value Domain and Data Element and so on. –Constraints of registered data elements (user should be defined) Target: Conceptual Domain or Value Domain Representation, Dimensionality and Classification are a kind of constraints User defined matadata should enable to be defined as extension mechanism, such as ebXML Registry and Repository Constraint should be described using such user defined slots Need formal description language such as OCL, CL We should allow OCL or other specification languages to be used by users of the registry

Data Element Concept (1) A Data Element Concept is a concept that can be represented in the form of a data element, described independently of any particular representation. (2) A Data Element Concept may have zero or one Object Class and zero or one Property. (3) The union of a Property and an Object Class provides significance beyond either that of the Property or the Object Class. (4) A Data Element Concept thus has a Definition independent from the Definition of the Object Class or the Property. (5) As an Administered Item, a Data Element Concept carries its own Administration Record information, allowing it to be identified, named, defined and optionally classified within a Classification Scheme. IdentifiedandOptionallyClassified (6) A Data Element Concept may be associated with other Data Element Concepts, via the Data Element Concept Relationship. (7) The nature of the relationship is described using the data element concept relationship type description. IsDescribedUsing (8) A Data Element Concept may be registered as an Administered Item without necessarily being associated with any Data Element, but a Data Element Concept shall be associated with exactly one Conceptual Domain, as represented by the "data element concept-conceptual domain relationship" in Figure 8. MustBeRegistered, ShallBeAssociatedWith (9) The Conceptual Domain specifies all valid Value Meanings of a Data Element Concept. The Conceptual Domain is described in MustBeContained Constraints in Data Element Concept

Examples of OCL expression MustBeContainedUnless…. ….AttributesCannotBeChanged ….CannotBeDeleted ….DependenciesCannotBeChanged ….NamesMustNotCollide ….MustNotBeSelf ….MustBeSame ….MustNotCollideWith…. ….RuleMustBeObeyed No….AllowedFor…..

Examples of Constraints (form MOF1.4) [A ModelElement that is not a Package must have a container. [C-1]] [The attribute values of a ModelElement which is frozen cannot be changed. [C-2]] [A frozen ModelElement which is in a frozen Namespace can only be deleted, by deleting the Namespace. [C-3]] [The link sets that express dependencies of a frozen Element on other Elements cannot be explicitly changed. [C-4]] [The names of the contents of a Namespace must not collide. [C-5]] [A Generalizable Element cannot be its own direct or indirect supertype. [C-6]] [A supertypes of a GeneralizableElement must be of the same kind as the GeneralizableElement itself. [C-7]] [The names of the contents of a GeneralizableElement should not collide with the names of the contents of any direct or indirect supertype. [C-8]] [Multiple inheritance must obey the “Diamond Rule.” [C-9]] [If a Generalizable Element is marked as a “root,” it cannot have any supertypes. [C-10]] [A GeneralizableElement’s immediate supertypes must all be visible to it. [C-11]] [A GeneralizableElement cannot inherit from a GeneralizableElement defined as a “leaf.” [C-12]]

[C-1] MustBeContainedUnlessPackage format1: MUST_BE_CONTAINED_UNLESS_PACKAGE format2: must_be_contained_unless_package evaluation policy: deferred description: A ModelElement that is not a Package must have a container. context ModelElement inv: not self.oclIsTypeOf(Package) implies self.container -> size = 1

format1: FROZEN_ATTRIBUTES_CANNOT_BE_CHANGED format2: frozen_attributes_cannot_be_changed evaluation policy: immediate description: The attribute values of a ModelElement which is frozen cannot be changed. [C-2] FrozenAttributesCannotBeChanged context ModelElement inv: self.isFrozen() implies let myTypes = self.oclType() -> allSupertypes() -> includes(self.oclType()) in let myAttrs : Set(Attribute) = self.RefBaseObject::refMetaObject() ->asOclType(Class) -> findElementsByTypeExtended(Attribute) in myAttrs -> forAll(a = self.RefObject::refValue(a))

[C-3] FrozenElementsCannotBeDeleted format1: FROZEN_ELEMENTS_CANNOT_BE_DELETED format2: frozen_elements_cannot_be_deleted evaluation policy: immediate description: A frozen ModelElement which is in a frozen Namespace can only be deleted, by deleting the Namespace. context ModelElement post: and -> notEmpty and implies (self.container.Object::non_existent() or not self.Object::non_existent())

[C-4] FrozenDependenciesCannotBeChanged format1: FROZEN_DEPENDENCIES_CANNOT_BE_CHANGED format2: frozen_dependencies_cannot_be_changed evaluation policy: immediate description: The link sets that express dependencies of a frozen Element on other Elements cannot be explicitly changed. context ModelElement post: self.isFrozen() implies let myClasses = self.oclType() -> allSupertypes() -> includes(self.oclType()) in let myRefs = Set(Reference) = self.RefBaseObject::refMetaObject() -> asOclType(Class) -> findElementsByTypeExtended(Reference) in let myDepRefs = myRefs -> select(r | Set{“contents”, “constraints”, “supertypes”, “type”, “referencedEnd”, “exceptions”, “importedNamespace”, “elements”} -> includes(r.name)) in myDepRefs -> forAll(r = self.RefObject::refValue(r))

[C-5] ContentNamesMustNotCollide format1: CONTENT_NAMES_MUST_NOT_COLLIDE format2: content_names_must_not_collide evaluation policy: immediate description: The names of the contents of a Namespace must not collide. context Namespace inv: self.contents.forAll( e1, e2 | e1.name = e2.name implies r1 = r2)

[C-6] SupertypeMustNotBeSelf format1: SUPERTYPE_MUST_NOT_BE_SELF format2: supertype_must_not_be_self evaluation policy: immediate description: A Generalizable Element cannot be its own direct or indirect supertype. context GeneralizableElement inv: self.allSupertypes() -> forAll(s | s <> self)

[C-7] SupertypeKindMustBeSame format1: SUPERTYPE_KIND_MUST_BE_SAME format2: supertype_kind_must_be_same evaluation policy: immediate description: A supertypes of a GeneralizableElement must be of the same kind as the GeneralizableElement itself. context GeneralizableElement inv: self.supertypes -> forAll(s | s.oclType() = self.oclType())

format1: CONTENTS_MUST_NOT_COLLIDE_WITH_SUPERTYPES format2: contents_must_not_collide_with_supertypes evaluation policy: immediate description: The names of the contents of a GeneralizableElement should not collide with the names of the contents of any direct or indirect supertype. context GeneralizableElement inv: let superContents = self.allSupertypes() -> collect(s | s.contents) in self.contents -> forAll(m1 | superContents -> forAll(m2 | m1.name = m2.name implies m1 = m2)) [C-8] ContentsMustNotCollideWithSupertypes

[C-9] DiamondRuleMustBeObeyed format1: DIAMOND_RULE_MUST_BE_OBEYED format2: diamond_rule_must_be_obeyed evaluation policy: immediate description: Multiple inheritance must obey the “Diamond Rule.” context GeneralizableElement inv: let superNamespaces = self.supertypes -> collect(s | s.extendedNamespace) in superNamespaces -> asSet -> isUnique(s | s.name)

[C-10] NoSupertypesAllowedForRoot format1: NO_SUPERTYPES_ALLOWED_FOR_ROOT format2: no_supertypes_allowed_for_root evaluation policy: immediate description: If a Generalizable Element is marked as a “root,” it cannot have any supertypes. context GeneralizableElement inv: self.isRoot implies self.supertypes -> isEmpty