02291: System Integration

Transcription

1 02291: System Integration Week 4 Hubert Baumeister huba@dtu.dk DTU Compute Technical University of Denmark Spring 2018

2 Contents From Requirements to Design CRC Cards Components (part Ia) Object-orientation: Centralized vs Decentralized Control/Computation Summary

3 From Requirements to Design Problem Given a requirements model consisting of: 1 use case diagram 2 detailed use case descriptions 3 glossary 4 non functional requirements how do I get a system design consisting of a component diagram b class diagram c behaviour design

4 From Requirements to Design: Solution Design process 1 Define the basic architecture of the system 2 The terms in the glossary give first candidates for classes, attributes, and operations 3 Realize one use case scenario / user story at a time simulate execution CRC cards

5 Contents From Requirements to Design CRC Cards Components (part Ia) Object-orientation: Centralized vs Decentralized Control/Computation Summary

6 Introduction CRC Cards Class Responsibility Collaboration Developed in the 80 s Used to Analyse a problem domain Discover object-oriented design Teach object-oriented design Object-oriented design Objects have state and behaviour Think objects

7 CRC Card Template A larger example

8 Process Basic: Simulate the execution of use case scenarios / user stories Steps 1. Brainstorm classes/objects/components 2. Assign classes/objects/components to persons (group up to 6 peopel) 4. Execute the scenarios one by one a) add new classes/objects/components as needed b) add new responsibilities c) delegate to other classes / persons

9 Library Example: Problem Description and Glossary Problem Description Library system for checking out, returning, and searching for books. No more than 5 books can be loaned by one borrower at a time. And if a book is returned after its overdue date, a fine has to be paid.

10 Library Example: Problem Description and Glossary Problem Description Library system for checking out, returning, and searching for books. No more than 5 books can be loaned by one borrower at a time. And if a book is returned after its overdue date, a fine has to be paid. Glossary Librarien The object in the system that fulfills User requests to check out, check in, and search for library materials Book The set of objects that represent Users who borrow items from the library Borrower The set of objects that represent Users who borrow items from the library...

11 Library Example: Use Case Diagram Use Cases LibrarySystem borrow book return book User search for book

12 Library Example: Detailed Use Case Check Out Book Name: Check Out Book Description: The user checks out a book from the library Actor: User Main scenario: 1 A user presents a book for check-out at the check-out counter 2 The system registers the loan Alternative scenarios: The user already has 5 books borrowed 2a The system denies the loan The user has one overdue book 2b The system denies the loan

13 Example II Set of initial CRC cards Librarien The object in the system that fulfills User requests to check out, check in, and search for library materials Borrower The set of objects that represent Users who borrow items from the library Book The set of objects that represent items to be borrowed from the library Use case Check out book main scenario What happens when Barbara Stewart, who has no accrued fines and one outstanding book, not overdue, checks out a book entitled Effective C++ Strategies+?

14 Library Example: CRC cards

15 Library Example: CRC cards

16 Library Example: CRC cards

17 Library Example: CRC cards

18 Library Example: CRC cards

19 Library Example: CRC cards

20 Library Example: CRC cards

21 Library Example: CRC cards

22 Library Example: CRC cards

23 Library Example: CRC cards

24 Library Example: CRC cards

25 Library Example: CRC cards

26 Library Example: CRC cards

27 Library Example: CRC cards

28 Library Example: CRC cards

29 Library Example: All CRC cards

30 Process: Next Steps Repeat the process with other scenarios completes the design Review the result Group cards Check cards Refactor Transfer the result UML class diagram UML interaction diagrams

31 Example: Class Diagram (so far) Librarien checkoutbook(b:book) * Borrower canborrow 0..1 * Book isoverdue checkout(b:borrower) calculateduedate * Date compare(d:date) 0..1 duedate

32 Example: Sequence Diagram for Check-out book Check Out Book Realization

33 Summary Process Further scenarios give more detail Repeat CRC process on a more detailed level e.g. to design database interaction, or user interface Choose your level of abstraction and stay there Alternative: Build sequence and class diagrams directly (the modern way) Danger: talk about the system instead of being part of the system Possible when object-oriented principles have been learned CRC cards help with object-oriented thinking

34 Contents From Requirements to Design CRC Cards Components (part Ia) Object-orientation: Centralized vs Decentralized Control/Computation Summary

35 Software architecture Software architecture building blocks: components glue: connectors ports: interfaces to the outside Decompose the system into smaller components and their interconnection E.g. browser, Web server, database E.g. presentation layer, application layer, domain layer

36 Components Components: replacable piece of software Resuable Pluggable Well-defined interfaces: provided and required ports connectors Similar to classes: better encapsulation Component = set of collaborating classes Microservices are components

37 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)

38 Example Bank ATM: UML 2.0 Component Diagram BankATM verifypin verifypin withdraw Clearing Bank ATM Company CB BC BA AB pinok pinnotok pinok pinnotok withdrawok withdrawnotok

39 Example Bank ATM: Configuration (composite structure diagram) :BankATM atm 0 :ATM c:clearing Company :CB :BC b:bank :BA :BA :AB atm 1 :ATM :AB

40 Strong encapsulation of components Strong encapsulation What is provided to others What is needed of others Ports define a portal to a component Have interfaces: provided / required Connect to other components

41 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

42 Port BA Bank <<interface>> BankToAtm verifypin(iban:iban, pin:int) withdraw(iban, amount:money) <<interface>> AtmToBank pinok pinnotok withdrawok withdrawnotok ATM C1 «interface» I1 m1 m2 m3 «refine» «interface» I2 m1 m3 C2

43 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

44 Component Notation Component as a stereotype

45 Realizing components No runtime representation (usually) No programming language support (usually) Different types of component concepts EJB, CORBA, COM/DCOM,.NET, JavaBeans,... Microservices

46 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

47 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

48 Contents From Requirements to Design CRC Cards Components (part Ia) Object-orientation: Centralized vs Decentralized Control/Computation Summary

49 Marriage Agency: How to implement? MarriageAgency matchcustomer(c):customer[*] * Customer sex:string birthyear:int interests:string[*] public class MarriageAgency{ private List<Customer> customers = new ArrayList<Customer>(); public List<Customer> matchcustomer(c) { List<Customer> matches = new ArrayList<Customer>(); for (Customer candidate : customers) {... // if customer matches candidate add to variable matches } return candidate; } }

50 Marriage Agency: centralized control MarriageAgency matchcustomer(c):customer[*] match(c,p) : boolean * Customer sex:string birthyear:int interests:string[*] public class MarriageAgency{ private List<Customer> customers = new ArrayList<Customer>(); public List<Customer> matchcustomer(c) { List<Customer> matches = new ArrayList<Customer>(); for (Customer candidate : customers) { // if customer matches candidate add to variable matches if (match(c,candidate)) { matches.add(candidate); } return candidate; } } public bool match(customer customer, Customer candidate) {... } }

51 Marriage Agency: centralized control sd match centralized loop [for all customers p]

52 Marriage Agency: decentralized/distributed control sd match decentralized loop [for all customers]

53 Marriage Agency: decentralized/distributed control MarriageAgency matchcustomer(c):customer[*] * Customer sex:string birthyear:int interests:string[*] match(c:customer) hasoppositesex(c) hasappropriateagedifference(c) hasoneinterestincommon(c) public class MarriageAgency{ private List<Customer> customers = new ArrayList<Customer>(); public List<Customer> matchcustomer(c) { List<Customer> matches = new ArrayList<Customer>(); for (Customer candidate : customers) { if (c.match(candidate)) { matches.add(candidate); } return candidate; } } } public class Customer {... public bool match(customer candidate) {... } }

54 Design for change: centralized control MarriageAgency matchcustomer(c):customer[*] matchcustomertypea(c):boolean matchcustomertypeb(c):boolean * Customer sex:string birthyear:int interests:string[*] CustomerTypeA CustomerTypeB public List<Customer> matchcustomer(customer c) { List<Customer> r = new ArrayList<Customer>(); for (Customer p : customers) { if (c instanceof CustomerA) { if (matchcustomertypea(p)) { r.add(p); } continue; } if (c instanceof CustomerB) { if (matchcustomertypeb(p)) { r.add(p); } continue; } } return r; }

55 Design for change: centralized control sd match centralized loop [for all customers] alt [c instanceof CustomerTypeA]

56 Design for change: decentralized control sd match decentralized loop [for all customers] alt

57 Design for change: decentralized control MarriageAgency matchcustomer(c):customer[*] * Customer sex:string birthyear:int interests:string[*] match(c:customer) CustomerTypeA match(c:customer) CustomerTypeB match(c:customer) public List<Customer> matchcustomer(customer c) { List<Customer> matches = new ArrayList<Customer>(); for (Customer candidate : customers) { if (c.match(candidate)) { matches.add(p); } } return matches; }

58 Centralised control

59 Centralized control Order calculate price calculate base price calculate discounts 1 Customer name discount info * OrderLine quantity 1 name price Product

60 Distributed control

61 Class diagram

62 Distributed control

63 Distributed Control: Class diagram Order calculate price calculate base price calculate discounts 1 Customer name discount info calculate discount * OrderLine quantity calculate price 1 Product name price get price for quantity

64 Centralized vs Distributed control Centralized control One method Data objects procedural programming language Distributed control Objects collaborate Objects = data and behaviour Object-orientation Advantage Easy to adapt Design for change CRC cards lead to distributed control

65 Contents From Requirements to Design CRC Cards Components (part Ia) Object-orientation: Centralized vs Decentralized Control/Computation Summary

66 Next Week: UML Class Diagrams Read/Skim the lectures notes and the UML user manual on classes and class diagrams Send me questions and UML class diagrams for discussion by Monday 26.2 What is unclear to you? What would you like to hear more about? Why is this feature used in this digram? What does this notation in this diagram mean?... I am going to answer the questions and discuss your class diagrams in the lecture Your questions and diagrams determine the lecture