02291: System Integration

Transcription

1 02291: System Integration Week 5 Hubert Baumeister huba@dtu.dk DTU Compute Technical University of Denmark Spring 2018

2 Contents Components (part Ia) Class Diagrams Important Concepts Class Diagrams

3 Software architecture Software architecture building blocks: components glue: connectors ports: interfaces to the outside Components: replacable piece of software Resuable Pluggable Well-defined interfaces: provided and required Similar to classes: better encapsulation Component = set of collaborating classes Microservices are components

4 Example Bank ATM: UML 2.0 Component Diagram BankATM Clearing Bank ATM Company CB BC BA AB Note: Cannot be expressed in Topcased and MagicDraw (cf. note on the home page)

5 Showing interfaces Required Interface by port BA Provided Interface by port AB Port AB Clearing Company Bank ATM Port BC Port BA Provided Interface by port BA Required Interface by port AB

6 Component Meta-Model Conceptual meta-model (not actual UML 2.0 meta-model) 1 Assembly * * Component CompositeComponent * SimpleComponent * Connector * Port Protocol 1 1 required * * Interface provided

7 Realizing components No runtime representation (usually) No programming language support (usually) Different types of component concepts EJB, CORBA, COM/DCOM,.NET, JavaBeans,... Java Messaging, Web Services, Docker Images, Virtual Machines,... (Microservices)

8 Bank component with Implementation Bank component seen from the outside Bank component seen from the inside ClearingCompanyToBank BankToClearingCompany Bank «delegate» «delegate» BankToATMPort * Bank «delegate» «delegate» * BankToAtm AtmToBank Account Customer

9 Detailed Class Diagram for the Bank Component «interface» BankToAtm verifypin(a,p): bool withdraw(a,m): bool «interface» AtmToBank pinok pinnotok withdrawok withdrawnotok 1 atm BankToATMPort verifypin(a,p): bool withdraw(a,m): bool pinok pinnotok * Account number : IBAN balance : int withdraw(amount:int): bool * «interface» BankToClearingCompany pinok pinnotok «interface» ClearingCompanyToBank verifypin(a,p) 1 cc Bank name: String... pinok pinnotok accountfor(a): Account... 1 b * c * 1..* Customer name address... Rules for classes implementing components Provided interfaces must to be implemented by some class Required interfaces must to be used by one or serveral classes No access to and from classes of other components (exception: common datatypes) Use packages to indicate classes belonging to a component

10 Contents Components (part Ia) Class Diagrams Important Concepts Associations and Attributes Aggregation and Composition Constraints and Stereotypes Class Diagrams

11 Associations: Role names vs association names Role names: Default is the class name of the association end public Person { private List<Car> cars; } public Car { private Person owner; } Association names

12 Wrong 1 Person company: Company name: String address: Address * employee employs 0..1 Company employees: List<Peson> address: Address * * 1 Address street: String city: String house_number: int 1

13 Wrong 1 Person company: Company name: String address: Address * employee employs 0..1 Company employees: List<Peson> address: Address * * 1 Address street: String city: String house_number: int 1 Don t use attributes and associations in the same diagram Use associations if the class of the attribute is in the class diagram

14 Attributes and Associations public class Order { public Date date; public boolean isprepaid = false; public List<OrderLine> lineitems = new ArrayList<OrderLine)();... }

15 Wrong 2 Person person_id: int company_id: int name: String address_id: int * employee employs 0..1 Company company_id: int employees: int[*] (employees: List<int>) address_id: int * * 1 Address address_id: int street: String city: String house_number: int 1

16 Wrong 2 Person person_id: int company_id: int name: String address_id: int * employee employs 0..1 Company company_id: int employees: int[*] (employees: List<int>) address_id: int * * 1 Address address_id: int street: String city: String house_number: int 1 Don t use object identifiers: Each object in UML has an implicit unique identifier (its reference) like in Java This is different if you want to show database schema using class diagrams

17 Java: Public attributes Person age : int {read only} public class Person { public int age; } for (Person p : persons) { System.out.println("age = ",p.age); } Person birthyear : int /age : int { result = currentyear - birthyear } public class Person { public int birthyear; public int age; } for (Person p : persons) { System.out.println("age = ",p.age); }

18 for (Person p : persons) { System.out.println("age = ",p.getage()); } Java: Private attributes and getter and setter Person age : int {read only} public class Person { private int age; public int getage() { return age; } } for (Person p : persons) { System.out.println("age = ",p.getage()); } Person birthyear : int /age : int { result = currentyear - birthyear } public class Person { private int birthyear; private int age; public int getage() { return... ; } }

19 Class Diagram and Program Code What is the class diagram for the following program? public class C { private int a; public int geta() { return a; } public void seta(int a) { this.a = a; } }

20 Class Diagram and Program Code What is the class diagram for the following program? public class C { private int a; public int geta() { return a; } public void seta(int a) { this.a = a; } } a) b) C -a: int seta(a: int) geta(): int C a: int

21 Class With Read-Only Attributes C a: int {read only} public class C { private int a = 3; public int geta() { return a; } public C(int a) { this.a = a; } }

22 Part of relationship Special type of associations aggregation composition Use part of instead of has a A car has an engine = an engine is part of the car But Peter has a house!= the house is part of Peter

23 Composite Aggregation 1. A part can only be part of one object 2. The life of the part object is tied to the life of the containing object

24 Composite Aggregation 1. A part can only be part of one object 2. The life of the part object is tied to the life of the containing object

25 Composite Aggregation The life of the part object is tied to the life of the containing object

26 Composite Aggregation

27 Keywords 1. Constraints e.g. {ordered}, {abstract} Constraint on a metaclass attribute 2. Stereotypes e.g. interface, component Subclass in the metamodel

28 Constraint

29 Constraint Abstract Class {isabstract = true} Alternative notation: {abstract}

30 (Standard) Stereotype Interface interface Subclass Interface of class Classifier

31 Contents Components (part Ia) Class Diagrams Important Concepts Class Diagrams Introduction Classes Attributes and Operations Notes and Comments Dependencies Interfaces Generalisation Reference Objects and Value Objects Association Classes Qualified Associations Three-way association Derived Properties / Associations

32 Overview Class Diagram

33 Classes Classes corresponds to one concept

34 General correspondence between classes and programs ClassName +attr1: String[1]="def" -attr2: int[*] #attr3: boolean -F1(a1: int, a2: Sring[]): float +f2(x1: String, x2: boolean): void #f3(y: int): String public class ClassName { private String attr1 = "def"; public String getattr1() {... }; public String setattr1(string a) {... }; private Set<int> attr2 = new HashSet<int>(); protected static boolean attr3; private static float F1(int a1, String[] a2); public void f2(string x1, boolean x2); protected String f3(int y); }

35 General correspondence between classes and programs Person employs * employee CEO of ceo 0..1 Company public class Person { private Company company; public void setcompany(company c) {...}; public Company getcompany() {...}; }

36 General correspondence between classes and programs Person employs * employee CEO of ceo 0..1 Company public class Company { private Set<Person> employees = new HashSet<Person>(); private Person ceo; public Company(Person p) {ceo = p;}; public Person getceo() {...}; public void setceo(person p) {...}; public void employ(person person) {employees.add(p);}; public void fire(person person) {employees.remove(p);}; public boolean worksatcompany(person p) {employees.contains(p);}; public void setemployees(set<person> ps) { employees = new HashSet<Person>(ps); } public Set<Person> getemployees() { return Collection.unmodifiableSet(employees); } }

37 Referential Integrity p1: Person c1: Company c2: Company

38 Notes and Comments

39 Dependencies

40 Dependencies UML defines keywords for special dependencies e.g. for classes call The source calls an operation in the target create The source creates instances of the target derive The source is derived from the target instantiate The source is an instance of the target permit The target allows the source to access the targets private features realize The source is an implementation of a specification or interface defined by the target refine Refinement indicates a relationship between different semantic levels substitute The source is substitutable for the target trace Used to track such things as requirements to classes or how changes in one model link to changes elsewhere use The requires the target for its implementation but also for, e.g., use cases include A use case includes another use case extend A use case extends another use case

41 Interfaces

42 Requires and implements interface dependency As dependencies Lollipop notation

43 Generalisation Example {abstract} Medium String signature String title String author Calendar borrowdate int fine int maxborrowindays boolean isoverdue boolean isborrowed fine and maxborrowindays are abstract in Medium and defined differently in Book and Cd. For Book we have 20 DKK and 28 days, while for CD we have 40 DKK fine and max days for borrowing is 7. Book Book(String,String,String) int fine int maxborrowindays Cd Cd(String,String,String) int fine int maxborrowindays Liskov-Wing Substitution Principle If S is a subtype of T, then objects of type T in a program may be replaced with objects of type S without altering any of the desirable properties of that program (e.g., correctness).

44 Generalisation Sets

45 Keywords

46 Generalisation Set: Notations (II)

47 Types Reference Objects: Customer, Person, Company,... Identity is important Attributes can change Datatypes I: boolean, integer,... Value is important No identity datatype Datatypes II: Value Objects: Date, Point,... Value is important Have Identity Attributes cannot change datatype ( value suggested by Martin Fowler)

48 Reference Object vs Datatype (Value Object) Class Diagram Objects

49 Association classes

50 Implementing Association Classes

51 Implementing Association Classes (II) Allowed or not?

52 Qualified Associations public class Order { private Map<Product,OrderLine> lineitems = new HashMap<Product,OrderLine>(); // private Set<OrderLine> lineitem = new Set<OrderLine>(); }

53 Ternary association

54 Derived attributes

55 Derived associations

56 Template class Parametric polymorphism public class Set<T> {... public void insert(t e) {...} ; public void remove(t e) {...};... } Set<Employee> employees; for(employee employee : employees)... }