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Part 2

Introduction to Unified Modeling Language UML

Levels of modelling Conceptual Model • Formally describes the content and structure of a data set • Describes the Universe of Discourse: a view on the real-world, depending on the aimed application(s) • Is software/platform independent • Is generally described using a graphical conceptual language (e.g. UML)

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Levels of modelling Logical Model • Closer to implementation, but still emphasis on information content and how it is structured, constraints, etc...

Physical storage Model • How it is actually stored/encoded (detailed instructions), also indexes, table spaces, binary compression methods, etc...

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Levels of modelling

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UML basics

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(acknowledgement goes to Julien Gaffuri – DG JRC)

• Purpose of slides: give basis to read INSPIRE UML class diagrams. • Notions: Class, Attribute, Operation, Association, Constraint, Package, Stereotype...

UML class diagram

INSPIRE UML class diagram for administrative units

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Class

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Definition: description of a set of objects that share the same attributes, operations, relationships, and semantics.

Class UML representation: Simple view

Full view

ClassName

ClassName

+ AttributeName : DataType ... + OperationName(parameter1Name : DataType) : outDataType ...

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Class: Attribute

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Definition: characteristic common to all the objects of a class. visibility name [multiplicity] : data-type = value • Visibility: + (public) or – (private) (always + in INSPIRE) • Multiplicity: number of values (optional) • Value: possible default values (optional)

Class: Operation

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Definition: An operation (or method) is a service that can be requested from an object. visibility name (parameters): outDataType • parameters: list of parameters (a parameter = a name + a data type)

Class

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Example: Car + seatNumber : int + color [1..*] : Col + repair(tool : Tool) : Bill + wash() : void

« A car is characterised by a seat number and one or several colours. » « A car can be repaired. This operation returns a bill to pay » « A car can be washed » …

Inheritage / generalisation

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Definition: taxonomic relationship between a more general element and a more specific element. Representation: ClassA

ClassB « A classB instance is also a classA instance » « classB instances share the same characteristics as class A instances » « classB specialises classA » « classA is more abstract / generalised than classB » ...

Inheritage / generalisation Example: Vehicule ownerName : String constructionDate : Date

Car

Boat draft : float

Bus passengerNb : int

« Cars, boats, and buses are vehicules » « All vehicules have a construction date » « A bus is a vehicule with a passenger number value » …

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Association

Definition: relationship between classes that specifies connections between their instances. roleA

ClassA

0..2

AssociationName

roleB ClassB *

Example: Company

employer 1..*

Employment employed Person 0..*

Multiplicity-Cardinality

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Definition: number of instances of a class that may be associated with a class at the other end of the association. Possible values: • • • •

Fixed: ‘1’, ‘2’, ‘n’, etc. Any: ‘*’ Several: ‘0,1’, ‘0,2,4’ Within an interval: ‘0..1’, ‘0..*’, ‘1..*’, etc.

Multiplicity-Cardinality

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Examples: Company

employer

Employment

employed Person 0..*

1..*

« Companies and persons are linked with an employment relation » « A person can be employed by several companies » « A compagny has to employ at least one person » parent

Kinship

2 Individual

0..* child

« There is a kinship relation between individuals » « All individuals have exactly 2 parents » « Each individual can have several children »

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Aggregation

Definition: Aggregation relationship between instances of a class and several instances of another class AggregateClass

AggregatedClass 0..2

*

« A classA instance is a an aggregate of instances of classB »

Example: Country

Region 1

*

« A country is an aggregation of regions »

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Composition

Definition: Composition relationship between instances of a class and several instances of another class (they cannot exist independently) CompositeClass

ComponantClass 0..2

*

« A classA instance is a a composite of instances of classB »

Example: Book

Page 0..1

2..*

« A book is composed of pages (at least two) »

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Navigability Definition: Indication on the navigation supported by an association ClassA

supplier 0..2

user ClassB *

« A classB instance knows the classA instances it is associated with » « It is not necessary to retrieve ClassB instances linked to a ClassA instance »

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Note

Definition: Comment or a constraint attached to a diagram element • Usually linked to the element it is related to (with dashed line) • In natural language

ClassA Comment on classA

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Constraint

Definition: condition or restriction to satisfy. • Can be represented in {…} or in a note • In natural language, or OCL (when possible) • OCL = Object Constraint Language ClassA ClassA objects should be like this

{ClassA objects should be like that}

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Package Definition: A package is a set of classes

• Defined according to some needs of decomposition of UML models. • UML representations: PackageX ClassA ClassB

PackageX ClassA

0..2 *

ClassB

PackageX

Package diagram

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Definition: representation of the relations between packages. • Provides a higher level of abstraction.

Package diagram

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INSPIRE package diagram for administrative units

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Stereotype Definition: Stereotypes extend the semantics, but not the structure of pre-existing UML elements (classes, attributes, operations, associations, roles, packages) UML representation:

> ClassName

> + AttributeName : DataType

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Stereotype Examples: : set of values without identity : data type with named literal values (ex: Boolean – TRUE, FALSE) : extendable enumeration

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Stereotype INSPIRE stereotypes: : for spatial object classes. : element that may not be present : class that will be specified in the future

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What is it ?

INSPIRE UML class diagram for administrative units

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Example CityModel Usage: string *

Owner Identification: string

Building Type: string

Name: string

Parcel Parcel ID: string

Adress: string *

Area: float

Private company Type: string NumberOfEmpl: integer

Private person IncomeTax: float

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Nesting vs normalisation • UML diagrams often explains nested structures (complex in XML) • Most databases are normalised – Simple structures (simple XML files) – Independent tables (more or less)

• The same conceptual model can be implemented in various ways • Can we transform a XML file from one schema to another?

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