1. introductionto software engineering Prof. BerndBrueggeChapter 5 – Analysis: ObjectModelling Murat Hacioglu

2. Outline LastLecture : FunctionalModelling Now: ObjectModelling

3. ObjectModelling Activitiesduringobjectmodelling, ObjectIdentification, Abott’sTechnique Types: Entity, BoundaryandControlObjects,

4. scenario -> usecase -> object

5. steps of objectmodelling Classidentification Fundamentalassumtionsthatwe can findabstractions. Findingtheattributes Findingtheoperations Findingtheassociationsbetweenclasses Order of thesteps is secondary. Goal is gettingdesiredabstraction.

6. steps of objectmodelling Maingoal is findingtheimportantabstraction. Whenwefindthewrongabstractions : Iteratethenrenamethem. Revisethe model. Youwillneverfreezeyourrequirements. Youwillchangerequest. You can do an anotherreview.

7. classidentification Helpstoidentifytheimportantentities of a system ForwardEngineering Findtheclassesfor a new software system ReverseEngineering Identifytheclasses in an existingsystem.

8. CLASS IDENTIFICATION APPROACHES Application domain approach Syntacticapproach Analyzethetexttoidentifytheobjects Designpatternsapproach (nextweek) Identifyrelevantabstractions. Ex: Chessgame, bishop, queen.. like software pattern. Component – basedapproach Identifyexistingsolutionclasses.

9. Classidentificationproblems Definition of thesystemboundary Actorsareoutsidethesystem ClassesandObjectsare inside thesystem. Findingtheclassesandobjects Theapplciation domain has to be analyzed. Differentobjects has to be founddepending on systempurpose. Identifyingthepurpose is another problem.

10. Types of objects EntityObjects Representpersistentinformationtrackedbythesystem. Ex: Databases. BoundaryObjects Interactionbetweenuserandsystem. Ex: microfon (PC microphone, Lapelmicrophone) ControlObjects Controltasksto be performedbythesystem.

11. 2bwatch modelling Year <<Entity>> Button <<Boundary>> Month ChangeDate <<Control>> LCD Display Day Boundary Control Entity

12. icons can identifystereotype We can skipone of this 3 models. SystemBoundary

13. Graphicsforstereotype Developers can understand UML diagrams. Customer can understandgraphicseasily. Sowearepeelingoffgraphicstodiagrams. This is pros&cons of graphics. Weseethat UML is an extensiblelanguage.

14. Objecttypesdealwithdifferentchanges Having 3 types of objectleadsto model thatarestrongertochanges. Interface of a systemchangesmorethancontrol Controlchangesmorethanentities in application domain. Objecttypesoriginated in Objective C (MVC) Model -> EntityObject View -> BoundaryObject Controller -> ControlObject Observerpattern is a specialkind of MVC (willsee in nextweek)

15. Abbott’sTechnique Pick a usecaseandlook at flow of events Do textualanalysis  Nounsareobjects /classes Verbsareoperations Afterobject/classesarefoundidentfytheirtype. Real worldentities (FieldOfficer  EntityObject) Real worldprocedures (Emergency Plan  ControlObjects Interfaceartifacts (PoliceStation  BoundaryObjects) 50 yearsagoeveryvillage has a policestation but now not. Monopoly is a board game. Monopoly : subclass Board game: superclass is a / neithernor / eitherorshowsinheritance

17. Howtofindobject SyntacticalinvestigationwithAbbot’stechnique. Useothersources Applicationknowledge: Endusersandexpertsknow. Solutionknowledge: Abstraction in thesolution domain. General worldknowledge: Ourgenericknowledge.

18. Generatingclassdiagrams Classidentification Identification of attributesandoperations Identification of associationsbetweenclasses Identification of multiplicities Identification of roles Idenfication of inheritance.

19. whousesclassdiagrams Description of thestaticproperties of a system. Application domain expert: Usesclassdiagramto model theapplication domain. Developer: Usesclassdiagramsduringsystemdevelopment. Analysis, systemdesign, objectdesignandimplementation. Clientsandendusersareusually not interested in classdiagrams. Functionality of a system.

20. DynamicModelling– Wherearewe?