Lecture 22: Meta-Modelling

Transcription

1 Software Design, Modelling and Analysis in UML Lecture 22: Meta-Modelling main Prof. Dr. Andreas Podelski, Dr. Bernd Westphal Albert-Ludwigs-Universität Freiburg, Germany

2 Contents & Goals Last Lecture: Inheritance in UML: concrete syntax Liskov Substitution Principle desired semantics This Lecture: Educational Objectives: Capabilities for following tasks/questions. What s the Liskov Substitution Principle? What is late/early binding? What is the subset, what the uplink semantics of inheritance? What s the effect of inheritance on LSCs, State Machines, System States? What s the idea of Meta-Modelling? Sprelim Content: The UML Meta Model Wrapup & Questions 2/63

3 Meta-Modelling: Idea and Example 3/ main

4 Meta-Modelling: Why and What Meta-Modelling is one major prerequisite for understanding the standard documents [OMG, 2007a, OMG, 2007b], and the MDA ideas of the OMG. The idea is simple: if a modelling language is about modelling things, and if UML models are and comprise things, then why not model those in a modelling language? Smm In other words: Why not have a model M U such that the set of legal instances of M U is the set of well-formed (!) UML models. 4/63

5 Meta-Modelling: Example For example, let s consider a class. A class has (on a superficial level) a name, any number of attributes, any number of behavioural features. Each of the latter two has a name and a visibility. Behavioural features in addition have Smm a boolean attribute isquery, any number of parameters, a return type. Can we model this (in UML, for a start)? 5/63

6 UML Meta-Model: Extract from UML 2.0 Standard Comment Element NamedElement name visibility type type Type 0..1 TypedElement RedefElement redefdelem Feature Namespace Classifier StructFeature BehavFeature Smm Class 0..1 Property Operation 0..1 Parameter 6/63

7 Meta-Modelling: Principle 7/ main

8 Modelling vs. Meta-Modelling Meta- Model (M2) Class name : Str Property name : Str Type name : Str Sprinciple Model (M1) Instance (M0) C v : Z :C v = 0 :Class name = C :Property name = v :Type name = Z So, if we have a meta model M U of UML, then the set of UML models is the set of instances of M U. A UML model M can be represented as an object instance-of diagram (or system state) wrt. the meta-model M U. Other view: An object diagram wrt. meta-model M U can (alternatively) be rendered as the UML model M. S = ({Z}, {C},{v}, {C v}), D Σ D S σ = {u {v 0}} 8/63

9 Well-Formedness as Constraints in the Meta-Model The set of well-formed UML models can be defined as the set of object diagrams satisfying all constraints of the meta-model. For example, [2] Generalization hierarchies must be directed and acyclical. A classifier cannot be both a transitively general and transitively specific classifier of the same classifier. not self. allparents()-> includes(self) [OMG, 2007b, 53] Sprinciple The other way round: Given a UML model M, unfold it into an object diagram O 1 wrt. M U. If O 1 is a valid object diagram of M U (i.e. satisfies all invariants from Inv(M U )), then M is a well-formed UML model. That is, if we have an object diagram validity checker for of the meta-modelling language, then we have a well-formedness checker for UML models. 9/63

10 The UML 2.x Standard Revisited 10/ main

11 Claim: Extract from UML 2.0 Standard Comment Element NamedElement name visibility type type Type 0..1 TypedElement RedefElement redefdelem Feature Namespace Classifier StructFeature BehavFeature Sumlmm Class 0..1 Property Operation 0..1 Parameter 11/63

12 Classes [OMG, 2007b, 32] StructuralFeature Relationship Classifier Classifier {redefines general} + /superclass Class * * {subsets classifier, subsets namespace, subsets featuringclassifier} + class subsettedproperty {subsets attribute, subsets ownedmember, ordered} +ownedattribute {subsets redefinedelement} + redefinedproperty * * * * * Property isderived : Boolean isreadonly : Boolean isderivedunion : Boolean /default : String aggregation : AggregationKind /IsComposite : Boolean +/opposite {subsets member, ordered} +memberend +association 2..* 0..1 {subsets memberend, subsets feature, subsets ownedmember, ordered} +ownedend * {subsets owner} +navigableownedend {subsets association, subsets namespace, subsets featuringclassifier} +owningassociation 0..1 * 0..1 {subsets owner} +owningproperty Association isderived : Boolean (subsets ownedelement} +defaultvalue ValueSpecification * Sumlmm {subsets namespace, subsets redefinitioncontext} +class 0..1 {subsets redefinitioncontext, subsets namespace, subsets featuringclassifier} +class 0..1 {subsets ownedmember, ordered} +nestedclassifier {subsets feature, subsets ownedmember, ordered} +ownedoperation Figure Classes diagram of the Kernel package * * Classifier Operation <<enumeration>> AggregationKind none shared composite {readonly, odered} +/endtype Type 1..* 12/63

13 Operations [OMG, 2007b, 31] Sumlmm Figure Operations diagram of the Kernel package 13/63

14 Operations [OMG, 2007b, 30] Sumlmm Figure Features diagram of the Kernel package 14/63

15 Classifiers [OMG, 2007b, 29] Sumlmm Figure Classifiers diagram of the Kernel package 15/63

16 Namespaces [OMG, 2007b, 26] Element NamedElement Name : String visibility : VisibilityKind /qualifiedname : String [0..1] [0..1] [0..1] <<enumeration>> VisibilityKind public private protected package {readonly, subsets member} PackageableElement visibility : VisibilityKind +importedmember * Namespace * {readonly, union, subsets owner} +/namespace {readonly, union} +/member NamedElement * * +/ownedmember {readonly, union, subsets member, subsets ownedelement} 0..1 DirectedRelationship Sumlmm Figure Namespaces diagram of the Kernel package {subsets source, subsets owner} + importingnamespace * ElementImport 1 +elementimport {subsets ownedelement} {subsets source, subsets owner} +importingnamespace 1 +packageimport {subsets ownedelement} visibility : VisibilityKind alias : String [0..1] * DirectedRelationship PackageImport visibility : VisibilityKind {subsets target} + importedelement 1 1 {subsets target} + importedpackage * 1 PackageableElement Package 16/63

17 Root Diagram [OMG, 2007b, 25] Sumlmm Figure Root diagram of the Kernel package 17/63

18 Interesting: Declaration/Definition [OMG, 2007b, 424] Sumlmm Figure Common Behavior 18/63

19 UML Architecture [OMG, 2003, 8] Meta-modelling has already been used for UML 1.x. Infrastructure (with semantics) Class, Object Action, Filmstrip Package, Snapshot For UML 2.0, the request for proposals (RFP) asked for a separation of concerns: Infrastructure and Superstructure. Superstructure (abstract syntax) Superstructure (concrete syntax) Class, State, Transition, Flow, ClassBox, StateBox, TransitionLine, One reason: sharing with MOF (see later) and, e.g., CWM. Diagram Interchange Node, Edge Figure 0-1 Overview of architecture Swhole UML MOF Core CWM Profiles 19/63

20 UML Superstructure Packages [OMG, 2007a, 15] CommonBehaviors Classes UseCases StateMachines Interactions Activities CompositeStructures AuxiliaryConstructs Actions Components Swhole Figure The top-level package structure of the UML Superstructure Deployments 20/63

21 Reading the Standard Table of Contents 1. Scope Conformance Language Units Compliance Levels Meaning and Types of Compliance Compliance Level Contents Normative References Terms and Definitions Symbols Additional Information Sreading 6.1 Changes to Adopted OMG Specifications Architectural Alignment and MDA Support On the Run-Time Semantics of UML The Basic Premises The Semantics Architecture The Basic Causality Model Semantics Descriptions in the Specification The UML Metamodel Models and What They Model Semantic Levels and Naming How to Read this Specification Specification format Diagram format Acknowledgements Part I - Structure Classes UML Superstructure Specification, v2.1.2 i 21/63

22 Reading the Standard Sreading Table of Contents 7.1 Overview Abstract Syntax Class Descriptions Abstraction (from Dependencies) AggregationKind (from Kernel) Association (from Kernel) Scope AssociationClass (from... AssociationClasses) BehavioralFeature (from Kernel) Conformance BehavioredClassifier (from... Interfaces) Class (from Kernel) Language Units Classifier......(from.... Kernel,..... Dependencies, PowerTypes) Comment (from Kernel) Compliance Levels Constraint (from.... Kernel) Meaning and Types of Compliance DataType (from.... Kernel) Dependency (from Dependencies) Compliance Level Contents DirectedRelationship (from.... Kernel) Element (from Kernel) Normative References ElementImport (from... Kernel) Enumeration (from Kernel) Terms and Definitions EnumerationLiteral (from... Kernel) Expression (from Kernel) Symbols Feature.....(from... Kernel) Generalization (from Kernel, PowerTypes) Additional Information GeneralizationSet (from.... PowerTypes) InstanceSpecification (from Kernel) Changes to Adopted OMG Specifications InstanceValue (from.... Kernel) Interface (from Interfaces) Architectural Alignment and MDA Support InterfaceRealization (from.... Interfaces) On the Run-Time Semantics of UML LiteralBoolean (from.... Kernel) LiteralInteger (from Kernel) The Basic Premises LiteralNull (from Kernel) The Semantics Architecture LiteralSpecification (from Kernel) The Basic Causality Model LiteralString (from Kernel) Semantics Descriptions in the Specification LiteralUnlimitedNatural... (from Kernel) The UML Metamodel MultiplicityElement (from.... Kernel) NamedElement (from Kernel, Dependencies) Models and What They Model Namespace (from Kernel) Semantic Levels and Naming OpaqueExpression (from Kernel) How to Read this Specification Operation (from.... Kernel,..... Interfaces) Package (from Kernel) Specification format PackageableElement (from Kernel) Diagram format PackageImport (from Kernel) Acknowledgements PackageMerge (from... Kernel) Parameter (from Kernel, AssociationClasses) ParameterDirectionKind (from Kernel) PrimitiveType (from Kernel) Part I - Structure Property (from Kernel, AssociationClasses) Realization (from Dependencies) RedefinableElement (from Kernel) Classes ii UML Superstructure Specification, v2.1.2 UML Superstructure Specification, v2.1.2 i 21/63

23 Sreading Reading the Standard Relationship (from Kernel) Slot (from Kernel) Overview StructuralFeature (from.... Kernel) Table of Contents 7.2 Abstract Syntax Substitution (from... Dependencies) Type (from Kernel) Class Descriptions TypedElement (from.... Kernel) Abstraction (from Dependencies) Usage (from Dependencies) AggregationKind (from Kernel) ValueSpecification (from Kernel) Association (from Kernel) VisibilityKind (from Kernel) Scope AssociationClass (from... AssociationClasses) Diagrams BehavioralFeature (from Kernel) Conformance BehavioredClassifier (from... Components Interfaces) Class (from Kernel) Language Units Classifier......(from.... Kernel,..... Dependencies, Overview... PowerTypes) Comment (from Kernel) Compliance Levels Constraint (from.... Kernel) Abstract syntax Meaning and Types of Compliance DataType (from.... Kernel) Class Descriptions Dependency (from Dependencies) Compliance Level Contents DirectedRelationship (from.... Kernel) Component (from BasicComponents, PackagingComponents) Element (from Kernel) Connector (from BasicComponents) Normative References ElementImport (from... Kernel) ConnectorKind (from BasicComponents) Enumeration (from Kernel) ComponentRealization (from BasicComponents) Terms and Definitions EnumerationLiteral (from... Kernel) Diagrams Expression (from Kernel) Symbols Feature.....(from... Kernel) Composite Structures Generalization (from Kernel, PowerTypes) Additional Information GeneralizationSet (from.... PowerTypes) Overview InstanceSpecification (from Kernel) Changes to Adopted OMG Specifications InstanceValue (from.... Kernel) Abstract syntax Interface (from Interfaces) Architectural Alignment and MDA Support InterfaceRealization (from Interfaces).... Class Descriptions On the Run-Time Semantics of UML LiteralBoolean (from.... Kernel) Class (from StructuredClasses) LiteralInteger (from Kernel) Classifier (from Collaborations) The Basic Premises LiteralNull (from Kernel) Collaboration (from Collaborations) The Semantics Architecture LiteralSpecification (from Kernel) CollaborationUse (from Collaborations) The Basic Causality Model LiteralString (from Kernel) ConnectableElement (from InternalStructures) Semantics Descriptions in the Specification LiteralUnlimitedNatural... (from Kernel) Connector (from InternalStructures) The UML Metamodel MultiplicityElement (from.... Kernel) ConnectorEnd (from InternalStructures, Ports) NamedElement (from Kernel, Dependencies) EncapsulatedClassifier... (from Ports) Models and What They Model Namespace (from Kernel) InvocationAction (from InvocationActions) Semantic Levels and Naming OpaqueExpression (from Kernel) Parameter (from Collaborations) How to Read this Specification Operation (from.... Kernel,..... Interfaces) Port (from Ports) Package (from Kernel) Property (from InternalStructures) Specification format PackageableElement (from Kernel) StructuredClassifier (from InternalStructures) Diagram format PackageImport (from Kernel) Trigger (from InvocationActions) Acknowledgements PackageMerge (from... Kernel) Variable (from StructuredActivities) Parameter (from Kernel, AssociationClasses) Diagrams ParameterDirectionKind (from Kernel) PrimitiveType (from Kernel) Part I - Structure Deployments Property (from Kernel, AssociationClasses) Realization (from Dependencies) RedefinableElement (from Kernel) Classes ii UML Superstructure Specification, v2.1.2 UML Superstructure Specification, v2.1.2 i UML Superstructure Specification, v2.1.2 iii 21/63

24 Reading the Standard Cont d Figure Class notation: attributes and operations grouped according to visibility Classifier (from Kernel, Dependencies, PowerTypes) A classifier is a classification of instances, it describes a set of instances that have features in common. Generalizations Namespace (from Kernel) on page 99 RedefinableElement (from Kernel) on page 130 Type (from Kernel) on page 135 Description A classifier is a namespace whose members can include features. Classifier is an abstract metaclass. A classifier is a type and can own generalizations, thereby making it possible to define generalization relationships to other classifiers. A classifier can specify a generalization hierarchy by referencing its general classifiers. A classifier is a redefinable element, meaning that it is possible to redefine nested classifiers. Attributes Window public size: Area = (100, 100) defaultsize: Rectangle protected visibility: Boolean = true private xwin: XWindow public display() hide() private attachx(xwin: XWindow) Sreading isabstract: Boolean If true, the Classifier does not provide a complete declaration and can typically not be instantiated. An abstract classifier is intended to be used by other classifiers (e.g., as the target of general metarelationships or generalization relationships). Default value is false. Associations /attribute: Property [*] Refers to all of the Properties that are direct (i.e., not inherited or imported) attributes of the classifier. Subsets Classifier::feature and is a derived union. / feature : Feature [*] Specifies each feature defined in the classifier. Subsets Namespace::member. This is a derived union. / general : Classifier[*] Specifies the general Classifiers for this Classifier. This is derived. 52 UML Superstructure Specification, v /63

25 Reading the Standard Cont d Sreading generalization: Generalization[*] Specifies the Generalization relationships for this Classifier. These Generalizations navigate to more general classifiers in the generalization hierarchy. Subsets Element::ownedElement Window / inheritedmember: NamedElement[*] public size: Area = (100, 100) Specifies all elements inherited by this classifier from the general classifiers. Subsets Namespace::member. This is defaultsize: Rectangle derived. protected visibility: Boolean = true redefinedclassifier: Classifier [*] private References the Classifiers that are redefined by this Classifier. Subsets RedefinableElement::redefinedElement xwin: XWindow public Package Dependencies display() hide() substitution : Substitution private attachx(xwin: XWindow) References the substitutions that are owned by this Classifier. Subsets Element::ownedElement and NamedElement::clientDependency.) Figure Class notation: attributes and operations grouped according to visibility Package PowerTypes Classifier powertypeextent (from Kernel, : Dependencies, GeneralizationSet PowerTypes) Designates the GeneralizationSet of which the associated Classifier is a power type. A classifier is a classification of instances, it describes a set of instances that have features in common. Constraints Generalizations [1] The general classifiers are the classifiers referenced by the generalization relationships. Namespace (from Kernel) on page 99 general = self.parents() RedefinableElement (from Kernel) on page 130 [2] Generalization hierarchies must be directed and acyclical. A classifier cannot be both a transitively general and Type (from Kernel) transitively on page specific 135 classifier of the same classifier. not self.allparents()->includes(self) Description [3] A classifier may only specialize classifiers of a valid type. A classifier is a namespace self.parents()->forall(c whose members can self.mayspecializetype(c)) include features. Classifier is an abstract metaclass. A classifier is a type [4] and The can inheritedmember own generalizations, association thereby is derived making by it inheriting possible the to define inheritable generalization members of relationships the parents. to other classifiers. A classifier self.inheritedmember->includesall(self.inherit(self.parents()->collect(p can specify a generalization hierarchy by referencing its general p.inheritablemembers(self))) classifiers. A classifier is a redefinable element, meaning that it is possible to redefine nested classifiers. Package PowerTypes Attributes [5] The Classifier that maps to a GeneralizationSet may neither be a specific nor a general Classifier in any of the isabstract: Boolean Generalization relationships defined for that GeneralizationSet. In other words, a power type may not be an instance of If true, the Classifier itself nor does may not its provide instances a complete also be its declaration subclasses. and can typically not be instantiated. An abstract classifier is intended to be used by other classifiers (e.g., as the target of general metarelationships or generalization relationships). Additional Default Operations value is false. [1] The query allfeatures() gives all of the features in the namespace of the classifier. In general, through mechanisms such as Associations inheritance, this will be a larger set than feature. /attribute: Property Classifier::allFeatures(): [*] Set(Feature); Refers to all of allfeatures the Properties = member->select(ocliskindof(feature)) that are direct (i.e., not inherited or imported) attributes of the classifier. Subsets Classifier::feature and is a derived union. [2] The query parents() gives all of the immediate ancestors of a generalized Classifier. / feature : Feature [*] Classifier::parents(): Set(Classifier); Specifies each feature defined in the classifier. Subsets Namespace::member. This is a derived union. parents = generalization.general / general : Classifier[*] Specifies the general Classifiers for this Classifier. This is derived. 52 UML Superstructure Specification, v2.1.2 UML Superstructure Specification, v /63

26 Sreading Reading the Standard Cont d [3] The query allparents() gives all of the direct and indirect ancestors of a generalized Classifier. generalization: Generalization[*] Classifier::allParents(): Set(Classifier); Specifies the Generalization allparents = self.parents()->union(self.parents()->collect(p relationships for this Classifier. These Generalizations p.allparents()) navigate to more general classifiers [4] in the The generalization query inheritablemembers() hierarchy. Subsets gives Element::ownedElement all of the members of a classifier that may be inherited in one of its descendants, Window / inheritedmember: subject NamedElement[*] to whatever visibility restrictions apply. public size: Area = (100, 100) Specifies all elements Classifier::inheritableMembers(c: inherited by this classifier Classifier): from the general Set(NamedElement); classifiers. Subsets Namespace::member. This is defaultsize: Rectangle derived. pre: c.allparents()->includes(self) protected visibility: Boolean = true redefinedclassifier: inheritablemembers Classifier [*] = member->select(m c.hasvisibilityof(m)) private References [5] the The Classifiers query hasvisibilityof() that are redefined determines by this Classifier. whether a Subsets named RedefinableElement::redefinedElement element is visible the classifier. By default all are visible. It is xwin: XWindow only called when the argument is something owned by a parent. public display() Package Dependencies Classifier::hasVisibilityOf(n: NamedElement) : Boolean; hide() substitution : Substitution pre: self.allparents()->collect(c c.member)->includes(n) private attachx(xwin: XWindow) References the substitutions if (self.inheritedmember->includes(n)) that are owned by this Classifier. thensubsets Element::ownedElement and NamedElement::clientDependency.) hasvisibilityof = (n.visibility <> #private) Figure Class notation: attributes and operations else grouped according to visibility Package PowerTypes hasvisibilityof = true Classifier powertypeextent (from Kernel, [6] : Dependencies, The GeneralizationSet query conformsto() PowerTypes) gives true for a classifier that defines a type that conforms to another. This is used, for example, Designates the in GeneralizationSet the specification of of which signature the conformance associated Classifier for operations. is a power type. A classifier is a classification of instances, Classifier::conformsTo(other: it describes a set of instances Classifier): that have Boolean; features in common. Constraints conformsto = (self=other) or (self.allparents()->includes(other)) Generalizations [1] The general classifiers [7] The are query the inherit() classifiers defines referenced how to by inherit the generalization a set of elements. relationships. Here the operation is defined to inherit them all. It is intended Namespace (from Kernel) on page to be 99 redefined in circumstances where inheritance is affected by redefinition. general = self.parents() RedefinableElement (from Kernel) Classifier::inherit(inhs: on page 130 Set(NamedElement)): Set(NamedElement); [2] Generalization hierarchies must be directed and acyclical. A classifier cannot be both a transitively general and Type (from Kernel) transitively on page specific 135inherit classifier = inhs of the same classifier. not self.allparents()->includes(self) [8] The query mayspecializetype() determines whether this classifier may have a generalization relationship to classifiers of Description the specified type. By default a classifier may specialize classifiers of the same or a more general type. It is intended to be [3] A classifier may only specialize classifiers of a valid type. redefined by classifiers that have different specialization constraints. A classifier is a namespace self.parents()->forall(c whose members can self.mayspecializetype(c)) include features. Classifier is an abstract metaclass. Classifier::maySpecializeType(c : Classifier) : Boolean; A classifier is a type [4] and The can inheritedmember own generalizations, association thereby is derived making by it inheriting possible the to define inheritable generalization members of relationships the parents. to mayspecializetype = self.ocliskindof(c.ocltype) other classifiers. A classifier self.inheritedmember->includesall(self.inherit(self.parents()->collect(p can specify a generalization hierarchy by referencing its general p.inheritablemembers(self))) classifiers. A classifier is a redefinable element, Semantics meaning that it is possible to redefine nested classifiers. Package PowerTypes Attributes A classifier is a classification of instances according to their features. [5] The Classifier that maps to a GeneralizationSet may neither be a specific nor a general Classifier in any of the isabstract: Boolean Generalization A relationships Classifier may defined participate for that in GeneralizationSet. generalization relationships In other words, with a other power Classifiers. type may not An be instance instance of a of specific Classifier is If true, the Classifier itself nor does may not also its provide instances (indirect) a complete also be instance its declaration subclasses. of each and of can the typically general Classifiers. not be instantiated. Therefore, An abstract features specified for instances of the general classifier is intended to be used classifier by other are classifiers implicitly (e.g., specified as the for target instances of general of the metarelationships specific classifier. or generalization Any constraint applying to instances of the relationships). Additional Default Operations value general is false. classifier also applies to instances of the specific classifier. [1] The query allfeatures() Associations The specific gives semantics all of the of features how generalization in the namespace affects of the each classifier. concrete In general, subtype through of Classifier mechanisms varies. such All instances as of a inheritance, this classifier will be a have larger values set than corresponding feature. to the classifier s attributes. /attribute: Property Classifier::allFeatures(): [*] Set(Feature); Refers to all of allfeatures the Properties = member->select(ocliskindof(feature)) A that Classifier are direct defines (i.e., not a type. inherited Type or conformance imported) attributes between of generalizable the classifier. Classifiers Subsets is defined so that a Classifier conforms Classifier::feature and is a derived to itself union. and to all of its ancestors in the generalization hierarchy. [2] The query parents() gives all of the immediate ancestors of a generalized Classifier. / feature : Feature [*] Classifier::parents(): Set(Classifier); Specifies each feature defined in the classifier. Subsets Namespace::member. This is a derived union. parents = generalization.general / general : Classifier[*] Specifies the general Classifiers for this Classifier. This is derived. 54 UML Superstructure Specification, v UML Superstructure Specification, v2.1.2 UML Superstructure Specification, v /63

27 Sreading Reading the Standard Cont d Package PowerTypes [3] The query allparents() The notion gives of all power of the type direct was and inspired indirect by ancestors the notion of of a generalized power set. Classifier. A power set is defined as a set whose instances are generalization: Generalization[*] Classifier::allParents(): subsets. In Set(Classifier); essence, then, a power type is a class whose instances are subclasses. The powertypeextent association relates Specifies the Generalization allparents = self.parents()->union(self.parents()->collect(p a relationships Classifier with for this a set Classifier. of generalizations These Generalizations that p.allparents()) a) have a navigate common to specific more general Classifier, and b) represent a collection of subsets classifiers [4] in the The generalization query inheritablemembers() for hierarchy. that class. Subsets gives Element::ownedElement all of the members of a classifier that may be inherited in one of its descendants, Window / inheritedmember: subject NamedElement[*] to whatever visibility restrictions apply. public Semantic Variation Points size: Area = (100, 100) Specifies all elements Classifier::inheritableMembers(c: inherited by this classifier Classifier): from the general Set(NamedElement); classifiers. Subsets Namespace::member. This is defaultsize: Rectangle derived. pre: c.allparents()->includes(self) The precise lifecycle semantics of aggregation is a semantic variation point. protected visibility: Boolean = true redefinedclassifier: inheritablemembers Classifier [*] = member->select(m c.hasvisibilityof(m)) Notation private References [5] the The Classifiers query hasvisibilityof() that are redefined determines by this Classifier. whether a Subsets named RedefinableElement::redefinedElement element is visible the classifier. By default all are visible. It is xwin: XWindow only called when Classifier the argument is an abstract is something model owned element, by a and parent. so properly speaking has no notation. It is nevertheless convenient to define public Package Dependencies display() Classifier::hasVisibilityOf(n: in one place a NamedElement) default notation : available Boolean; for any concrete subclass of Classifier for which this notation is suitable. The hide() substitution : Substitution pre: self.allparents()->collect(c default notation for c.member)->includes(n) a classifier is a solid-outline rectangle containing the classifier s name, and optionally with private attachx(xwin: XWindow) References the substitutions if (self.inheritedmember->includes(n)) compartments that are owned separated by this Classifier. by then horizontal Subsets lines Element::ownedElement containing features or and other members of the classifier. The specific type of NamedElement::clientDependency.) hasvisibilityof classifier can = (n.visibility be shown in <> guillemets #private)above the name. Some specializations of Classifier have their own distinct notations. Figure Class notation: attributes and operations else grouped according to visibility The name of an abstract Classifier is shown in italics. Package PowerTypes hasvisibilityof = true Classifier powertypeextent (from Kernel, [6] : Dependencies, The GeneralizationSet query conformsto() An attribute PowerTypes) gives can true be shown for a classifier a text that string. defines The a format type that of conforms this string to is another. specified This in is the used, Notation for example, sub clause of Property Designates the in GeneralizationSet the specification (from of of Kernel, which signature the AssociationClasses) conformance associated Classifier for operations. on is page a power 123. type. A classifier is a classification of instances, Classifier::conformsTo(other: it describes a set of instances Classifier): that have Boolean; features in common. Constraints conformsto = Presentation (self=other) or (self.allparents()->includes(other)) Options Generalizations [1] The general classifiers [7] The are query the inherit() classifiers Any compartment defines referenced how to may by inherit the be generalization suppressed. a set of elements. A relationships. separator Here the line operation is not drawn is defined for to a suppressed inherit them compartment. all. It is intended If a compartment is Namespace (from Kernel) on page to be 99 redefined general = self.parents() suppressed, in circumstances no inference where inheritance can be drawn is affected about the by presence redefinition. or absence of elements in it. Compartment names can be used RedefinableElement (from Kernel) Classifier::inherit(inhs: on page 130 to remove Set(NamedElement)): ambiguity, if necessary. Set(NamedElement); [2] Generalization hierarchies must be directed and acyclical. A classifier cannot be both a transitively general and Type (from Kernel) transitively on page specific 135inherit classifier = inhs of the An same abstract classifier. Classifier can be shown using the keyword {abstract} after or below the name of the Classifier. not self.allparents()->includes(self) [8] The query mayspecializetype() determines whether this classifier may have a generalization relationship to classifiers of Description the specified type. The type, By default visibility, a classifier default, may multiplicity, specialize property classifiers string of the may same be or suppressed a more general from type. being It displayed, intended even to be if there are values [3] A classifier may only specialize classifiers of a valid type. redefined by classifiers in the model. that have different specialization constraints. A classifier is a namespace self.parents()->forall(c whose members can self.mayspecializetype(c)) include features. Classifier is an abstract metaclass. Classifier::maySpecializeType(c : Classifier) : Boolean; A classifier is a type [4] and The can inheritedmember own generalizations, association thereby The is derived individual making by it inheriting properties possible the to of define inheritable an attribute generalization members can be shown of relationships the parents. in columns to rather than as a continuous string. mayspecializetype = self.ocliskindof(c.ocltype) other classifiers. A classifier self.inheritedmember->includesall(self.inherit(self.parents()->collect(p can specify a generalization hierarchy by referencing its general p.inheritablemembers(self))) classifiers. Style Guidelines A classifier is a redefinable element, Semantics meaning that it is possible to redefine nested classifiers. Package PowerTypes Attribute names typically begin with a lowercase letter. Multi-word names are often formed by concatenating the words Attributes A classifier is a classification of instances according to their features. [5] The Classifier that maps to a GeneralizationSet and using may lowercase neither be for a all specific letters nor except a general for upcasing Classifier the in first any letter of the of each word but the first. isabstract: Boolean Generalization A relationships Classifier may defined participate for Center that in GeneralizationSet. generalization the name of the relationships classifier In other words, in boldface. with a other power Classifiers. type may not An be instance instance of a of specific Classifier is If true, the Classifier itself nor does may not also its provide instances (indirect) a complete also be instance its declaration subclasses. Center of each keyword and of can the typically (including general Classifiers. not stereotype be instantiated. Therefore, names) An in abstract plain features face specified within guillemets for instances above of the classifier general name. classifier is intended to be used classifier by other are classifiers implicitly (e.g., specified For as those the for target languages instances of general that of distinguish the metarelationships specific between classifier. or uppercase generalization Any constraint and lowercase applying characters, to instances capitalize of the names (i.e, begin them relationships). Additional Default Operations value general is false. classifier also applies with an to uppercase instances of character). the specific classifier. [1] The query allfeatures() gives all of the features in the namespace of the classifier. In general, through mechanisms such as Associations The specific semantics of Left how justify generalization attributes and affects operations each concrete in plain subtype face. of Classifier varies. All instances of a inheritance, this classifier will be a have larger values set than corresponding feature. Begin attribute to the and classifier s operation names attributes. with a lowercase letter. /attribute: Property Classifier::allFeatures(): [*] Set(Feature); Show full attributes and operations when needed and suppress them in other contexts or references. Refers to all of allfeatures the Properties = member->select(ocliskindof(feature)) A that Classifier are direct defines (i.e., not a type. inherited Type or conformance imported) attributes between of generalizable the classifier. Classifiers Subsets is defined so that a Classifier conforms Classifier::feature and is a derived to itself union. and to all of its ancestors in the generalization hierarchy. [2] The query parents() gives all of the immediate ancestors of a generalized Classifier. / feature : Feature [*] Classifier::parents(): Set(Classifier); Specifies each feature defined in the classifier. Subsets Namespace::member. This is a derived union. parents = generalization.general / general : Classifier[*] Specifies the general Classifiers for this Classifier. UML This Superstructure is derived. Specification, v UML Superstructure Specification, v UML Superstructure Specification, v2.1.2 UML Superstructure Specification, v /63

28 Sreading Examples Reading the Standard Cont d Package PowerTypes [3] The query allparents() The notion gives of all power of the type direct was and inspired indirect by ancestors the notion of of a generalized power set. Classifier. A power set is defined as a set whose instances are generalization: Generalization[*] Classifier::allParents(): subsets. In Set(Classifier); essence, then, a power ClassAtype is a class whose instances are subclasses. The powertypeextent association relates Specifies the Generalization allparents = self.parents()->union(self.parents()->collect(p a relationships Classifier with for this a set name: Classifier. of generalizations StringThese Generalizations that p.allparents()) a) have a navigate common to specific more general Classifier, and b) represent a collection of subsets classifiers [4] in the The generalization query inheritablemembers() for hierarchy. that class. shape: Rectangle Subsets gives + Element::ownedElement size: all Integer of the [0..1] members of a classifier that may be inherited in one of its descendants, Window / inheritedmember: subject NamedElement[*] to whatever visibility restrictions / area: apply. Integer {readonly} public Semantic Variation height: Points Integer= 5 size: Area = (100, 100) Specifies all elements Classifier::inheritableMembers(c: inherited by this classifier Classifier): from the general Set(NamedElement); width: Integer classifiers. Subsets Namespace::member. This is defaultsize: Rectangle derived. pre: c.allparents()->includes(self) The precise lifecycle semantics of aggregation is a semantic variation point. protected visibility: Boolean = true redefinedclassifier: inheritablemembers Classifier [*] = member->select(m c.hasvisibilityof(m)) Notation private References [5] the The Classifiers query hasvisibilityof() that are redefined determines by this Classifier. whether a Subsets named RedefinableElement::redefinedElement element is visible the classifier. By default all are visible. It is xwin: XWindow only called when Classifier the argument is an abstract is something model ClassB owned element, by a and parent. so properly speaking has no notation. It is nevertheless convenient to define public Package Dependencies display() Classifier::hasVisibilityOf(n: in one place a NamedElement) default id notation {redefines: available name} Boolean; for any concrete subclass of Classifier for which this notation is suitable. The hide() substitution : Substitution pre: self.allparents()->collect(c default notation for c.member)->includes(n) a shape: classifier Square is a solid-outline rectangle containing the classifier s name, and optionally with private height = 7 attachx(xwin: XWindow) References the substitutions if (self.inheritedmember->includes(n)) compartments that are owned separated by this Classifier. by then horizontal Subsets lines Element::ownedElement containing features or and other members of the classifier. The specific type of / width NamedElement::clientDependency.) hasvisibilityof classifier can = (n.visibility be shown in <> guillemets #private)above the name. Some specializations of Classifier have their own distinct notations. Figure Class notation: attributes and operations else grouped according to visibility The name of an abstract Classifier is shown in italics. Package PowerTypes hasvisibilityof = true Figure Examples of attributes Classifier powertypeextent (from Kernel, [6] : Dependencies, The GeneralizationSet query conformsto() An attribute PowerTypes) gives can true be shown for a classifier a text that string. defines The a format type that of conforms this string to is another. specified This in is the used, Notation for example, sub clause of Property The attributes in Figure 7.30 are explained below. Designates the in GeneralizationSet the specification (from of of Kernel, which signature the AssociationClasses) conformance associated Classifier for operations. on is page a power 123. type. A classifier is a classification of instances, it describes a set of instances that have ClassA::name features in is common. an attribute with type String. Classifier::conformsTo(other: Classifier): Boolean; Constraints conformsto = Presentation (self=other) or (self.allparents()->includes(other)) Options ClassA::shape is an attribute with type Rectangle. Generalizations [1] The general classifiers [7] The are query the inherit() classifiers defines referenced how to by inherit ClassA::size the generalization a set of elements. is a public relationships. Here attribute the operation of type is Integer defined with to inherit multiplicity them all Any compartment may be suppressed. A separator line is not drawn for a suppressed compartment. It is intended If a compartment is Namespace (from Kernel) on page to be 99 redefined general = self.parents() suppressed, in circumstances no inference where inheritance ClassA::area can be drawn is is affected about a derived the by presence redefinition. attribute with or absence type Integer. of elements It is marked in it. Compartment as read-only. names can be used RedefinableElement (from Kernel) Classifier::inherit(inhs: on page 130 to remove Set(NamedElement)): ambiguity, if necessary. ClassA::height Set(NamedElement); is an attribute of type Integer with a default initial value of 5. [2] Generalization hierarchies must be directed and acyclical. A classifier cannot be both a transitively general and Type (from Kernel) transitively on page specific 135inherit classifier = inhs of the same classifier. ClassA::width is an attribute of type Integer. An abstract Classifier can be shown using the keyword {abstract} after or below the name of the Classifier. not self.allparents()->includes(self) [8] The query mayspecializetype() determines ClassB::id whether is this an attribute classifier that may redefines have a generalization ClassA::name. relationship to classifiers of Description the specified type. The type, By default visibility, a classifier default, may specialize classifiers of the same or a more general type. It intended to be [3] A classifier may only specialize classifiers of a valid type. ClassB::shape multiplicity, is property an attribute string that may redefines be suppressed ClassA::shape. from being It has displayed, type Square, even a specialization if there are values of Rectangle. redefined by classifiers in the model. that have different specialization constraints. A classifier is a namespace self.parents()->forall(c whose members can self.mayspecializetype(c)) include features. Classifier is an ClassB::height abstract metaclass. is an attribute that redefines ClassA::height. It has a default of 7 for ClassB instances that overrides the Classifier::maySpecializeType(c : Classifier) : Boolean; A classifier is a type [4] and The can inheritedmember own generalizations, association thereby The is derived individual making by it inheriting properties possible the to ClassA of define inheritable an attribute default generalization of members can 5. be shown of relationships the parents. in columns to rather than as a continuous string. mayspecializetype = self.ocliskindof(c.ocltype) other classifiers. A classifier self.inheritedmember->includesall(self.inherit(self.parents()->collect(p can specify a generalization hierarchy by referencing ClassB::width its general is p.inheritablemembers(self))) classifiers. a derived attribute that redefines ClassA::width, which is not derived. Style Guidelines A classifier is a redefinable element, Semantics meaning that it is possible to redefine An attribute nested classifiers. may also be shown using association notation, with no adornments at the tail of the arrow as shown in Figure Package PowerTypes Attribute names typically begin with a lowercase letter. Multi-word names are often formed by concatenating the words Attributes A classifier is a classification of instances according to their features. [5] The Classifier that maps to a GeneralizationSet and using may lowercase neither be for a all specific letters nor except a general for upcasing Classifier the in first any letter of the of each word but the first. isabstract: Boolean Generalization A relationships Classifier may defined participate for Center that in GeneralizationSet. generalization the name of the relationships classifier In other words, in boldface. with a other power Classifiers. type may not An be instance instance of a of specific Classifier is If true, the Classifier itself nor does may not also its provide instances (indirect) a complete also be instance its declaration subclasses. Center of each keyword and of can the typically (including general Classifiers. not stereotype be instantiated. Therefore, names) size An in abstract plain features face specified within guillemets for instances above of the classifier general name. classifier is intended to be used classifier by other are classifiers implicitly (e.g., specified For as those the for target languages instances Window of general that of distinguish the metarelationships specific between classifier. or uppercase generalization Any Area constraint and lowercase applying characters, to instances capitalize of the names (i.e, begin them relationships). Additional Default Operations value general is false. classifier also applies with an to uppercase instances of character). the specific classifier. 1 [1] The query allfeatures() gives all of the features in the namespace of the classifier. In general, through mechanisms such as Associations The specific semantics of Left how justify generalization attributes and affects operations each concrete in plain subtype face. of Classifier varies. All instances of a inheritance, this classifier will be a have larger values set than corresponding feature. Begin attribute Figure to the and 7.31 classifier s operation - Association-like names attributes. with a notation lowercase for letter. attribute /attribute: Property Classifier::allFeatures(): [*] Set(Feature); Show full attributes and operations when needed and suppress them in other contexts or references. Refers to all of allfeatures the Properties = member->select(ocliskindof(feature)) A that Classifier are direct defines (i.e., not a type. inherited Type or conformance imported) attributes between of generalizable the classifier. Classifiers Subsets is defined so that a Classifier conforms Classifier::feature and is a derived to itself union. and to all of its ancestors in the generalization hierarchy. [2] The query parents() gives all of the immediate ancestors of a generalized Classifier. / feature : Feature [*] Classifier::parents(): Set(Classifier); Specifies each feature defined in the classifier. Subsets Namespace::member. This is a derived union. parents = generalization.general 56 UML Superstructure Specification, v2.1.2 / general : Classifier[*] Specifies the general Classifiers for this Classifier. UML This Superstructure is derived. Specification, v UML Superstructure Specification, v UML Superstructure Specification, v2.1.2 UML Superstructure Specification, v /63