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Basic Structural Modeling with UML2. Jacques Robin. Outline. UML2 x UML1 UML2 meta-model package structure UML2 Diagrams Classes Associations Objects and links Interfaces Packages Templates Active classes and objects. UML2: What is new?. New purposes: Model-driven development
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Basic Structural Modeling with UML2 Jacques Robin
Outline • UML2 x UML1 • UML2 meta-model package structure • UML2 Diagrams • Classes • Associations • Objects and links • Interfaces • Packages • Templates • Active classes and objects
UML2: What is new? • New purposes: • Model-driven development • Whole life-cycle component based development • Real-time systems engineering • Fully refined modeling with semi-formal notation (OCL) • New diagrams: • Component diagram • Composite structure diagram • Timing diagram • New design: • Separates: • Abstract syntax, a MOF meta-model • Visual syntax, the Diagram Interchange (DI) standard • Semantics • Decomposes each part for reuse in a hierarchy of MOF packages linked by embedding and merge relationships
UML2: New uses • UML2 is so comprehensive that it can be used for new purposes not initially envisioned by OMG • Agent-oriented software engineering and intelligent system development • Engineering semantic web ontologies and services • Teaching course in any field through modeling and meta-modeling the presented concepts to visually and precisely structure them
MOF2 EMOF CMOF Diagram Interchange Defines diagrams’ visual layout OCL2 • 6 Sub-packages defining: • Types • Expressions • Type value semantic domains • Expression evaluation semantic do mains • Type value semantic mapping • Expression value semantic mapping UML2: Internal Structure UML2 UML2 Infrastructure • Over 30 Sub-packages defining: • Classifiers (Classes, Interfaces, etc.) • Types • Associations • Packages • Properties • Constraints merge merge merge UML2 Superstructure • Over 50 Sub-packages defining: • Components • Composite structures • Deployments • Common behaviors • (Times, Durations, Events, Signals, etc.) • Actions • Activities • Interactions • State machines • Use cases • Profiles • Templates merge
UML2 Superstructure Structure Behavior Classes CommonBehaviors Interactions StateMachines UseCases CompositeStuctures Activities Actions Components Supplement Deployments AuxiliaryConstructs Profiles UML2: Internal Structure
Classes: Attributes • Common characteristics of the class members • Fields: • Base or derived (isDerived) • Visibility (public, protected, private, package) • Name • Type (Primitive Built-In or Used-Defined Enumerations) • Initial default value • Properties: • isReadOnly • Object attributes: different value for each object • Class attributes: same value for all objects • Attributes for MDA: as many fields as possible!
Classes: Operations • Common signature of services provided by the class members • Fields: • Visibility • Name • Return type • Properties: isQuery, isOrdered, isUnique • Input parameter • Direction • Name • Type • Multiplicity • Default value • Properties • Object operations: called on objects • Class operations: called to manipulate class attributes • Operations for MDA: as many fields as possible!
Associations • Association: • Generic relation between N classifiers • Fields: • One or two Names • Navigation direction • Two Ends, each with: • One Multiplicity Range (default = 1) • Zero to One role • Zero to one Qualifier • Qualifier: needed to distinguish different instances of a one-to-many or many-to-many association • Navigation: • Role if present • Otherwise destination class name • Associations for MDA: as many fields as possible!
Association Classes • Class connected to an association and not to any of its ends • Allows associating properties and behaviors to an association • One object of the association class for each link of the connected association • A one-to-many or many-to-many association class cannot be substituted by a simple class and a pair of simple associations • Example: • Ca has objects A1, A2, A3, A4 • Cb has objects B1, B2, B3, B4 • Extent of association class Cc between Ca and Cb with * multiplicity at both ends has necessarily 16 instances • Class Cc associated to Ca through association Aca and to Cb through association Acb could have only 4 instances Difference with: ? 4 Elevator control Queue Elevator
N-ary Associations • Single association between N classes • Different from N-1 binary associations • Example: • Ca has objects A1, A2 • Cb has objects B1, B2 • Cc has objects C1, C2 • No link in the ternary association Ca-Cb-Cc corresponding to pair of links A1-B1, B2-C1
Aggregation Associations • Association with “part-whole” semantics • Associate composite class to its building blocks • Static, definitional characteristic of the “whole” class • In contrast to composite structure diagrams that model dynamic, configuration characteristic of the containing class • Shared aggregation: • Many-to-many aggregation
Composition Associations • Special case of one-to-one or one-to-many aggregation where part(s) cannot exist(s) without the unique whole • Deletion of the whole must therefore always be followed by automatic deletion of the parts
Class generalizations • Taxonomic relation between a class and one of its more general direct super-class • Special case of generalization between any two classifiers • Several generalizations form a taxonomic tree free of generalization cycles • Sub-classifier inherits the features from all its direct super-classifiers • Private attributes and operations not accessible from sub-classes • Protected attributes and operations accessible from sub-classes but not from associated classes • UML generalizations allow multiple inheritanceand overriding • Instances of a sub-class must satisfy all the constraints on all its super-classes (principle of substituability)
Abstract Classes • Class that cannot be instantiated • Only purpose: factor gradual refinements of common and distinct structures and behaviors down a taxonomic hierarchy • Abstract operation: common signatures of distinct implementations specified in subclasses • Supports polymorphism: generic call signature to distinct operations, with automatic dispatch to the implementation appropriate to each specific call instance
Generalization Sets • Subclass set that can be labeled as: • complete or incomplete • overlapping or disjoint • Complete and disjoint generalization sets form a partition of the super-class • Sub-subclass can specialize members of two overlapping generalization sets
Power Types • Generalization set of a super-class defined in terms of a class associated to it • Subclasses of each power type inherits features from the associated class of the super-class that defines the power type • Allows separation of orthogonal concerns • Useful for MDA as a rich modeling element
Derived Attributes, Classes and Associations • Some class diagram elements can be entirely derived from other primitive ones • Derivation rules provided in { } near the derived element or as OCL constraint • Explicit derivable information key and rules for it are key for MDA
Constrained Associations • Properties and special graphical notation can express a limited set of constraints among associations • Other constraints expressed in OCL • Constraints key for MDA
Objects and Links • Object Diagram contains: • Specific (named) or generic (named after role, unnamed) instances of classes • Possibly several instances of the same class • Specific instances of associations (links) among objects • Possibly several instances of the same association • Illustrates specific instantiation patterns of associated class diagram
Interfaces • Classifier allowing to insulate classes, packages and components from one another for plug-and-play assembly and substitution • Concrete class: attributes + operation signatures + operation implementations + instances • Abstract class: attributes + operation signatures + partial implementations + (possibly but rarely) instances • Interface: attributes + operation signatures • A class realizes services specified in an interfaces, while it specializes the structure and behaviors whose signature they inherit from an abstract class • Other classifiers can use these services independently of how they are realized • Explicit, class-based notation more precise and thus preferred for MDA
Packages • Group of elements creating a namespace • A pure design-time entity, that might not be reflected at run-time • Model element can only belong to a single package and is deleted whenever its package is deleted • Relations between packages: • Generalization • Dependencies: nesting (sub-package), import, access (private import) and merge
Package Merge • Integrate elements of two packages into a resulting “merged” package, collapsing common elements into a single one • Redundancy-free cut and paste
Templates • Partially specified class, refined by instantiation of parameters • Alternative way to define derived class • Key for parametric patterns
Active Classes, Objects and Parts • Active classes are associated to a thread • Active objects have pro-active behavior, executing an operation not invoked by any other object • Active objects execute concurrently • Active classes/objects can be composite structures, containing both active and passive classes/objects as parts • What is an agent? • An active object that is also a component instance!
* BehavioralFeature Property Parameter StructuralFeature Operation Type TypedElement ValueSpecification Feature Classifier 1..* Relationship NamedElement RedefinableElement Element * * * InstanceSpecification Constraint Relationship Generalization Classifier * Class DataType Interface Association * * AssociationClass PrimitiveType Enumeration Simplified MOF Meta-Model of itself
<<enumeration>> enumType1 enumLit1 ... +attr4:enumType1 ... +attr2:type10[multi18] ... +/attr3:type11[multi19] ... +attr5:type12[multi17] ... +attr1:type9[multi16] ... AssoClass1 Class1 Class2 Class4 Class3 Property Association Property Constraint Association ExpressionInOCL Association Constraint ExpressionInOCL Enumeration Association EnumerationLiteral Constraint ExpressionInOCL Prototypical Class Diagram Example Class AssociationClass multi20 Property DataType part1 compos1 Generalization whole1 role1 assoc1 role2 multi21 multi22 multi23 context Class3::attr3 derived OCLExp3 multi24 whole2 multi26 whole3 aggreg2 context Class1 inv:inv2 OCLExp2 multi27 sharedPart3 multi25 /aggreg1 sharedPart1 context aggreg1 derived OCLExp4
