Advanced UML Class Models

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1 Advanced UML Class Models Or: Love s Labors Lost Jonathan Sprinkle 1 University of Arizona Department of Electrical and Computer Engineering PO Box , Tucson, AZ 85721, USA August 27, 2012 Jonathan Sprinkle Advanced UML Class Models 1

2 Abstract Abstract This lecture continues discussion of Class Modeling and introduces object modeling. It then discusses special kinds of multiplicities, and has some in-class exercises relevant to critical thinking and design. Jonathan Sprinkle Advanced UML Class Models 2

3 Previously, on ECE There are 5 things you should remember about OO languages... 2 Class modeling is the modeling of the structure of software 3 Inheritance are IS-A relationships, that share properties 4 Associations permit... objects to be associated with one another Jonathan Sprinkle Advanced UML Class Models 3

4 Outline 1 Encapsulation Definitions 2 Object Diagrams How to show Objects Associations Multiplicity Association End Names In-Class Exercises 3 Advanced Class Diagram Concepts Stereotypes Enumerations and Numbers Scoping and Visibility Abstract classes Ordering Bags and Sequences Jonathan Sprinkle Advanced UML Class Models 4

5 Definitions Graphical Definition Encapsulation is a special kind of association, which is denoted using a diamond and extending line. Container attr : type oper : type * Class attr : type attr2 : type oper : type Figure: Encapsulation Jonathan Sprinkle Advanced UML Class Models 5

6 Definitions Kinds of Encapsulation There are two kinds of encapsulation: aggregation and composition. Roughly broken down, aggregation is containment through constructor creation (i.e., responsible for create/delete the memory), composition is containment without owning the memory. We will use aggregations notation exclusively, and rely on documentation to determine whether containment of object, or of pointer, is used in implementation. Encapsulation is a mechanism used for information hiding, where some data are hidden from either the user, or another class. Aggregation is denoted using a solid diamond (touching the containing class) with an extending line that touches the contained class. The extending line may contain multiplicities, which imply the cardinality of the relationship(s). Jonathan Sprinkle Advanced UML Class Models 6

7 Definitions Example 1 Example A Computer has a Processor Computer manufacturer : string * Processor manufacturer : string formfactor : string clock : long FSB_rate : long There are no semantics for whether the containment line is round, straight, angled, etc. Jonathan Sprinkle Advanced UML Class Models 7

8 Definitions Example 2 Example A bicycle has two wheels Bicycle manufacturer : string 2 Wheel diameter : double hasinnertube : bool Jonathan Sprinkle Advanced UML Class Models 8

9 Definitions Example 3 Example A square has four sides Square getarea( ) : double getperimeter( ): double 4 Side length : double Jonathan Sprinkle Advanced UML Class Models 9

10 Definitions Example 4 Example A staircase has one or more stairs Staircase getrise( ) : double getrun( ) : double 1..* Stair riser : double tread : double Jonathan Sprinkle Advanced UML Class Models 10

11 Definitions Example 5 Example A classroom has zero or more overhead projectors Room maxoccupancy : int buildingid : int roomnumber : string 0..* Projector manufacturer : string hasvga : bool hasdvi : bool Jonathan Sprinkle Advanced UML Class Models 11

12 Outline 1 Encapsulation Definitions 2 Object Diagrams How to show Objects Associations Multiplicity Association End Names In-Class Exercises 3 Advanced Class Diagram Concepts Stereotypes Enumerations and Numbers Scoping and Visibility Abstract classes Ordering Bags and Sequences Jonathan Sprinkle Advanced UML Class Models 12

13 How to show Objects Object diagrams are just like class diagrams, except they show instances/objects instead of types/classes. obj1 : Container attr : type = value oper : type = value obj2 : Class attr : type = value attr2 : type = value oper : type : Class attr : type = value attr2 : type = value oper : type Figure: A very simple object diagram. Names must be unique on a diagram, or two objects are considered unique. If no name is given to the object, its identity preserves uniqueness. Jonathan Sprinkle Advanced UML Class Models 13

14 How to show Objects Example A Person with two Jobs : Job title : str = "Junior Mint" salary : int = "1000" : Company name : string = "Century Theaters" address : string = "The Mall" dad : Person lastname : string = "Sprinkle" birthdate : date = "4/8/15" address : string = "1623 Lane" : Company name : string = "Sears" address : string = "The Mall" steady : Job title : str = "Senior Warden" salary : int = "10000" Note that multiplicities in object diagrams are not very meaningful. Jonathan Sprinkle Advanced UML Class Models 14

15 Associations Recall the definition of a link. Definition A link is a connection among objects (i.e., at runtime). An association is the design-time abstraction of links. Definition An association is a description of a group of links with common structure and common semantics. Jonathan Sprinkle Advanced UML Class Models 15

16 Multiplicity Definition Multiplicity specifies the number of instances of one class that may relate to a single instance of an associated class. Thus, multiplicity is a constraint on the number of related objects. In a UML diagram, multiplicity is explicitly listed at the ends of associations. A non-explicit listing is interpreted as 1, which although is a useful shorthand, should be made explicit when not used for aggregation associations. Jonathan Sprinkle Advanced UML Class Models 16

17 Multiplicity Example Consider a Team, which is associated with a HeadCoach. Each Team retains exactly one HeadCoach, and each HeadCoach is coaching exactly one Team. HeadCoach name : string Team name : string mascot : string Figure: HeadCoach and Team class diagram. Jonathan Sprinkle Advanced UML Class Models 17

18 Multiplicity phil: HeadCoach name : string = "Phillip Fulmer" ut: Team name : string = "UT" mascot : string = "Volunteers" Figure: HeadCoach and Team object diagram Jonathan Sprinkle Advanced UML Class Models 18

19 Multiplicity Example Consider a Laptop, which may or may not be associated with an ExternalKeyboard. The ExternalKeyboard may have only one Laptop associated with it, but the Laptop may, or may not, choose to participate in the association, since it has its own keyboard. Laptop manufacturer : string dnsname : string screensize : int ExternalKeyboard manufacturer : string numkeys : int Figure: Laptop and ExternalKeyboard class diagram. Jonathan Sprinkle Advanced UML Class Models 19

20 Multiplicity macphee : Laptop manufacturer : string = "Apple" dnsname : string = "macphee" screensize : int = 17 : ExternalKeyboard manufacturer : string = "Apple" numkeys : int = 88 home : ExternalKeyboard manufacturer : string = "Logitech" numkeys : int = 132 Figure: Laptop and ExternalKeyboard object diagram Jonathan Sprinkle Advanced UML Class Models 20

21 Association End Names Definition An association end is a named role which all objects participating in that role of the association may be referenced as. Association end names are extremely useful for describing roles of associations between objects of the same type, or when allowing multiple kinds of associations to take place between two types. Jonathan Sprinkle Advanced UML Class Models 21

22 Association End Names Example Consider a Person, which can be the parent of a child. Every child has 2 parents, and every parent can have 0.. child(ren). Person lastname : string birthdate : date child 0..* 2 parent Figure: Person with parent/child class diagram. Jonathan Sprinkle Advanced UML Class Models 22

23 Association End Names So, what is wrong with this object diagram? ken : Person lastname : string = "Sprinkle" birthdate : date = "Feb 30" teresa : Person lastname : string = "Sprinkle" birthdate : date = "June 31" jon : Person lastname : string = "Sprinkle" birthdate : date = "Jul 32" Figure: Person with parent/child object diagram. 1 There are no rolenames! 2 There are persons without 2 parents!!! Jonathan Sprinkle Advanced UML Class Models 23

24 Association End Names So, what is wrong with this object diagram? ken : Person lastname : string = "Sprinkle" birthdate : date = "Feb 30" teresa : Person lastname : string = "Sprinkle" birthdate : date = "June 31" jon : Person lastname : string = "Sprinkle" birthdate : date = "Jul 32" Figure: Person with parent/child object diagram. 1 There are no rolenames! 2 There are persons without 2 parents!!! Jonathan Sprinkle Advanced UML Class Models 24

25 Association End Names So, what is wrong with this object diagram? ken : Person lastname : string = "Sprinkle" birthdate : date = "Feb 30" teresa : Person lastname : string = "Sprinkle" birthdate : date = "June 31" jon : Person lastname : string = "Sprinkle" birthdate : date = "Jul 32" Figure: Person with parent/child object diagram. 1 There are no rolenames! 2 There are persons without 2 parents!!! Jonathan Sprinkle Advanced UML Class Models 25

26 Association End Names Revised Person/Parent Class Diagram Example (Updated) Consider a Person, which can be the parent of a child. Every child has 0..2 parents, and every parent can have 0.. child(ren). Person lastname : string birthdate : date child 0..* 0..2 parent Figure: Corrected class diagram Jonathan Sprinkle Advanced UML Class Models 26

27 Association End Names Revised Person/Parent Object Diagram ken : Person lastname : string = "Sprinkle" birthdate : date = "Feb 30" teresa : Person lastname : string = "Sprinkle" birthdate : date = "June 31" parent parent child jon : Person lastname : string = "Sprinkle" birthdate : date = "Jul 32" parent child mary : Person lastname : string = "Sprinkle" birthdate : date = "Nov 31" parent child george_andrew : Person lastname : string = "Sprinkle" birthdate : date = "Aug 15" child Figure: Revised object diagram Jonathan Sprinkle Advanced UML Class Models 27

28 In-Class Exercises In-Class Funtime Group together in fours, and get ready to draw some diagrams. Everyone draws a diagram, and then you choose one person to present your diagram on the projector. Jonathan Sprinkle Advanced UML Class Models 28

29 In-Class Exercises Example (Group A) Consider a SmartPhone which may or may not be associated with a Network. The Network may have many phones associated with it, but the SmartPhone may opt to not associate with a phone Network, but instead simply act as a handheld computer. Example (Group B) Consider a Professor, who may be associated with 1 or more University objects. The University has 1 or more Professor objects associated with it. Example (Group C) Consider a University which both hires, and teaches, Persons. While it is also possible to type the association in this case, by assigning roles it is a more lightweight design. Jonathan Sprinkle Advanced UML Class Models 29

30 In-Class Exercises Example (Group A) Consider a SmartPhone which may or may not be associated with a Network. The Network may have many phones associated with it, but the SmartPhone may opt to not associate with a phone Network, but instead simply act as a handheld computer. Example (Group B) Consider a Professor, who may be associated with 1 or more University objects. The University has 1 or more Professor objects associated with it. Example (Group C) Consider a University which both hires, and teaches, Persons. While it is also possible to type the association in this case, by assigning roles it is a more lightweight design. Jonathan Sprinkle Advanced UML Class Models 30

31 In-Class Exercises Example (Group A) Consider a SmartPhone which may or may not be associated with a Network. The Network may have many phones associated with it, but the SmartPhone may opt to not associate with a phone Network, but instead simply act as a handheld computer. Example (Group B) Consider a Professor, who may be associated with 1 or more University objects. The University has 1 or more Professor objects associated with it. Example (Group C) Consider a University which both hires, and teaches, Persons. While it is also possible to type the association in this case, by assigning roles it is a more lightweight design. Jonathan Sprinkle Advanced UML Class Models 31

32 Outline 1 Encapsulation Definitions 2 Object Diagrams How to show Objects Associations Multiplicity Association End Names In-Class Exercises 3 Advanced Class Diagram Concepts Stereotypes Enumerations and Numbers Scoping and Visibility Abstract classes Ordering Bags and Sequences Jonathan Sprinkle Advanced UML Class Models 32

33 Stereotypes A class may have a particular stereotype, which provides additional information about the class. Stereotypes are a special kind of inheritance, but on the language level (not the design level). The most useful kind of stereotype for you is the enumeration. Jonathan Sprinkle Advanced UML Class Models 33

34 Stereotypes Definition An enumeration is a (finite) set of values that make up a data type. Example enum ustimezones = ET, CT, MT, PT, AZ Jonathan Sprinkle Advanced UML Class Models 34

35 Stereotypes We refer to this enumeration as having cardinality 5, since ust imezones = 5 (i.e., the number of items in the enumeration is 5). An example of this representation in a class diagram can be seen in Figure 11. <<enumeration>> TimeZones ET CT MT PT AZ Figure: Enumeration as a stereotype. Jonathan Sprinkle Advanced UML Class Models 35

36 Scoping and Visibility Some features belong to the class, and not to an instantiated object. The concept of class features (rather than object features) is the most abstract of all scoping. Consequence: features in the class scope (denoted by the keyword static) do not require the class to be instantiated as an object before use. Example Using scoping at the class level. c l a s s C a l e n d a r { p u b l i c : s t a t i c short daysinweek ; i n t getnumevents ( ) ; } ; Jonathan Sprinkle Advanced UML Class Models 36

37 Scoping and Visibility Now, referring to Calendar::_daysInWeek should allow knowledge of the number of days in the week without having to query a Calendar object. Static scoping should only be applied to data members that are the same for all instances of a class. Changing this value for one instance would change for all instances. Example Checking how many instances there are of a class is knowledge at the class not object level. This usually requires that the constructor/destructor appropriately adds/subtracts a static variable each time they are called. Jonathan Sprinkle Advanced UML Class Models 37

38 Scoping and Visibility Syntax for Scoping Scoping is generally available through the :: operator in C++, allowing you to address objects in a namespace (std::cout), classes in a namespace (mynamespace::a) and various concatenations (mynamespace::a::staticmethodofa( )). Jonathan Sprinkle Advanced UML Class Models 38

39 Scoping and Visibility However, as a major point, there are two kinds of scope for design: class and object. We represent features with class scope as underlined in a class diagram. See the example in Figure 12 Calendar _daysinweek : short = 7 int getnumevents( ) Figure: Class scoping example. Jonathan Sprinkle Advanced UML Class Models 39

40 Scoping and Visibility Visibility refers to the access region of the features to other classes (including subclasses). We will cover visibility in more depth later, but you need to know the notation for regions. Example Using regions in class diagrams. c l a s s C a l e n d a r { p u b l i c : i n t getnumevents ( ) ; s t a t i c short getdaysinweek ( ) ; protected : s t d : : s t r i n g name ; p r i v a t e : s t a t i c short daysinweek ; } ; Jonathan Sprinkle Advanced UML Class Models 40

41 Scoping and Visibility We represent feature accessibility as shown in Figure 13, where + public access # protected access - private access Calendar -_daysinweek : short = 7 #_name : string +int getnumevents( ) +getdaysinweek( ) : short Figure: Jonathan Sprinkle Advanced UML Class Models 41

42 Abstract classes If a class is abstract, it is shown in italics when the classname is displayed. We will discuss abstract class implementation syntax later. Fundamentally, abstract classes cannot be instantiated. If a (non-abstract) class derived from an abstract is instantiated, then the IS-A concepts are still valid. Abstract classes are useful to use as interfaces, or to use in function signatures. Example (Look familiar?) Coin toss( ) : bool BiasedCoin bias : double = 0.6 result : bool toss( ) : bool Figure: An abstract class, from hw00 Jonathan Sprinkle Advanced UML Class Models 42

43 Ordering Sometimes it is convenient to consider that the many association end multiplicities can be ordered explicitly. Definition An ordering is an ordered set of objects; no duplicates are allowed. Example Consider that a Person may have an ordered association with EmergencyContact objects. Person lastname : string phonenumber : string emergencycontact 0..* {ordered} Figure: Person and EmergencyContact class diagram. Jonathan Sprinkle Advanced UML Class Models 43

44 Bags and Sequences You may explicitly allow duplicates, or ensure that duplicates are not ordered, by using the bag and sequence modifiers on an association end. Definition A bag is a collection of elements with duplicates allowed. Definition A sequence is an ordered collection of elements with duplicates allowed.. Jonathan Sprinkle Advanced UML Class Models 44

45 Bags and Sequences Example Consider a FrequentFlier who has flown several hundred segments in the previous year to numerous Airports. Since ordering is not important (the flights have already been taken) the association with Airports may contain duplicates. Jonathan Sprinkle Advanced UML Class Models 45

46 Bags and Sequences Example Consider an Itinerary which will visit multiple Airports. The multiplicity for each end is, but the Airport is a {sequence}, since the same airport may be visited multiple times. Jonathan Sprinkle Advanced UML Class Models 46

Advanced Class Diagrams and Intro to Interaction Modeling

Advanced Class Diagrams and Intro to Interaction Modeling Or: Advance to Illinois Avenue. Do not pass Go. Jonathan Sprinkle 1 University of Arizona Department of Electrical and Computer Engineering PO