Three different kinds of object diagram

CO817 2008 25 Three different kinds of object diagram Class diagrams – show static relationships between classes. Communication diagrams – show communication patterns between objects. Sequence diagrams – use the vertical dimension to represent time and show detailed communication between small numbers of objects. CO817 2008 26 Class Diagrams Used to model static objects and the relationships between them. Feature in just about every OO software design methodology. Show objects as boxes and relationships as lines with annotations and possible arrow heads. CO817 2008 27 A typical class diagram (from Fowler)‫‏‬ CO817 2008 28 Perspectives There are three perspectives that can be used in class diagrams. Conceptual – represents the problem domain and is created in order to analyse and understand it. (also called a domain model)‫‏‬ Specification – boxes in the diagram represent software objects but not to the level of programming language implementation Implementation – shows real classes in the implementation language (e.g. Java)‫‏‬ Can start off with a domain model and refine it into an design model. CO817 2008 29 Kinds of relationship Associations an order has a customer who initiated it and will take delivery Subtypes A corporate customer is a kind of customer CO817 2008 30 Associations Represent relationships between instances of classes. Can be annotated with multiplicities a customer can have zero or more orders but each order is associated with just one customer. An association can have an optional role, describing what the relationship is. for example: sales rep in the example diagram Arrows showing navigability CO817 2008 31 Multiplicities * 1..* T zero or more; "many" T one or more 1..40 T one to 40 5 T exactly 5 3, 5, 8 T exactly 3, 5, or 8 CO817 2008 32 Navigability Open arrow heads are used to show that an association is navigable. For example, a sales order can be interrogated to determine the customer but not the other way round. CO817 2008 33 Subclasses These are shown using a large, open arrow head. In the specification or implementation perspectives, represent class subtyping. In a domain model, show a subtype relationship between concepts. CO817 2008 34 Domain Model Described using class diagrams with a conceptual perspective. Part of the requirements-capture part of a project. understandable by the user classes can be developed into classes in a design model (with a specification or implementation perspective)‫‏‬ CO817 2008 35 Example Domain Model Diagram co ce t n p o d m in r o a o je b ct S le a s L e m in Ite q a tity un 1* .. S cke -in to d a cia n sso tio C n in d o ta e -in 1 S le a a u s ttrib te d te a tim e 1 P id y a -b 1 P ym n a et a on mu t S re to a d ss d re nm a e 1 Hu s o se 1* .. Rg r e iste C p re -o  a tu d n 1 1 0 ..1 R co s-sa -o e rd le f 1 Ite m * 0 ..1 CO817 2008 36 Domain Model to Design Model U D m inM d l P o a oe S k h ld r'sv wo th n te o yc n e tsinth d m in ta e o e ie f e o w rth o c p e o a . AP y e t inth D m inM d l a mn e o a oe isac n e t, b t aP y e t in ocp u a mn th D s nM d l isas ftw re e e ig o e o a c s . T e a n t th s m la s h y re o e a e th g b t th fo e in p dth in , u e rm r s ire e n m ga dd fin no th a in n e itio f e la r. tte T isre u e th re re e ta n l h d c s e p s n tio a gp a. T isiso eo th b id a in h n f e ig e s o je t te h o g . b c c n lo y Py et a mn a o n Mn y m u t: o e g tB la c (): M n y e a ne oe 1 P y -fo as r 1 d te D te a : a s rtT e T e ta im : im g tT ta M n y e o l(): o e ... Py et a mn a on mu t in p s s ire o je ts b c ad n n m sin a e S le a S le a 1 P y -fo as r 1 d te a tim e U D s nM d l P e ig o e T eo je t-o n dd v lo e h sta e in p tio fro th re l w rldd m in h b c rie te e e p r a k n s ira n m e a o o a inc a gs ftw rec s e . re tin o a la s s T e fo , th re re e ta n l g pb tw e h ws k h ld rsc n e eth h re re e p s n tio a a e e n o ta e o e o c iv e d m in a ditsre re e ta nins ftw re h sb e lo e d o a , n p s n tio o a , a e n w re . CO817 2008 37 Finding Domain-model Classes Reuse or modify existing models Books of existing domain models exist. Use a category list containing categories of things that are good candidates to be classes e.g. roles of people, physical objects, containers of things. Identify nouns and noun phrases in a description of the domain. Verbs are good candidates for methods. CO817 2008 38 A problem description The cinema booking system should store seat bookings for multiple theatres. Each theatre has seats arranged in rows. Customers can reserve seats and are given a row number and seat number. They may request bookings of several adjoining seats. Each booking is for a particular show (i.e., the screening of a given movie at a certain time). Shows are at an assigned date and time, and scheduled in a theatre where they are screened. The‫‏‬system‫‏‬stores‫‏‬the‫‏‬customers’‫‏‬telephone number. CO817 2008 39 Nouns and verbs Cinema booking system Stores (seat bookings)‫‏‬ Stores (telephone number)‫‏‬ Theatre Has (seats)‫‏‬ Movie Customer Reserves (seats)‫‏‬ Is given (row number, seat number)‫‏‬ Requests (seat booking)‫‏‬ Show Is scheduled (in theatre)‫‏‬ Telephone number Time Date Seat booking Seat Row Seat number Row number CO817 2008 40 Communication diagrams Lines between objects represent communications paths and are annotated with numbered messages. 1 aP e c h nrd : k a n aTde m y t s ee ) e m ( 2o :o f : e tr Rs ge i 2b .: a 1 r :a S l e lke i l ni n CO817 2008 41 Message sequence numbers fir t s scn eo d th d ir mg s1 1 mg : s2 :A :B 1 : mg .1 s 3 2 : mg .1 s 5 2 mg : s4 :C fo r uth 2 : mg .2 s 6 fifth s th ix :D CO817 2008 42 Sequence Diagrams Show sequences of input and output events Can show events for a system component or for the whole system. System Sequence Diagrams (SSDs) are used to show use case scenarios in a diagrammatic form. CO817 2008 43 Example SSD Po e sS leS e aio r cs a cnr : C s ie ah r mk N w a a e e S le S p c s - n Po e sS les e aio imle a ho ly r c s a c n r : 1 C s mr ar e a aP Sc e k u . u to e r iv s t O hcot w g o sa d r s r ic stop r h s . ith o d n /o ev e uc a e 2 C s ie s r an w a . . a h r tats e s le 3 C s ie e tesite id n r . ah r n r m e tifie. 4 S s m e od s lelin ite a d . y te r c r s a e mn pe e tsite d s r tio , pic , a d r sn m e cip n r e n r n in to l. u n g ta C s ie r p a s p 34u til in ic te a h r e e ts te s - n d a s dn. oe 5 S s m r s n to l w ta e . y te pe e ts ta ith x s c lc la d a u te . 6 C s ie te C s mr th to l, a d . a h r lls u to e e ta n a k fo p y e t. s s r a mn 7 C s mr p y a dS s m a d s . u to e a s n y te h n le p y e t. a mn ... lo p o [ mr ite s] oe m e teIte ( m , q a tity n r m ite ID u n ) :S s m y te d s r tio , to l e cip n ta ed a n S le to l w ta e ta ith x s mk P y e t( mu t) a e a mn a o n c a g d e r c ip h n e u , ee t CO817 2008 44 Sequence diagram notation Each participating object is shown as a veritcal line (called a lifeline) with a box at the top. The lifeline is usually drawn dashed though it can be solid. Time always goes downwards. A lifelines can also contain vertical boxes called activation bars or execution specification bars, showing when the code in that object is active CO817 2008 45 Example activation boxes life eb xr pe e tin a lin o e r s n g n u n m din ta c o c s S le n a e s n e f la s a life eb xr pe e tin a lin o e r s n g n m din ta c a e s ne life eb xr pe e tin th c s lin o e r s n g e la s F n o m r pe is ly th t F n is o t, r oe r c e , a o t a in ta c o c s C s –a n s n e f la s la s n in ta c o am ta la s s ne f e c s : a S le s : S le 1 a « ea la s mt c s » Fn ot L t isa in r c is n tefa e life eb xr pe e tin a lin o e r s n g n in ta c o a Ar y is c s , s n e f n r a L t la s p r m teiz d( m la e ) to aa e r e te p tiz d h ldS leo je ts o a b c life eb xr pe e tin lin o e r s n g o ein ta c o c s S le n s n e f la s a , s le te fr m es le e c d o th a s Ar y is < a >c lle tio r a L t S le o c n inU L1 w c u n t u ea M .x e o ld o s n in r c h r , b t inU L2 th ( r tefa e ee u M , is o a a s a t c s ) isle a n b tr c la s gl s le : a s Ar y is S le r a L t< a > s le [ i ] : S le a s a x: L t is r la d e te ea p x m le CO817 2008 46 Messages : R g te e is r dX o dA o dB o dC o dD o : S le a afo n m s a e ud esg w o es n e w n t h s e d r ill o b s e ifie e pc d e e u ns e ific tio x c tio p c a n b r in ic te fo u o a d a s cs f cn l o tro ty ic l s c r n u m s a e p a y ho o s e s g s o nw afille -a wlin h w ith d rro e CO817 2008 47 Object Construction :R i t r es ge :Sl a e nt t anw c a d o ht e l r t e y ee oj c a p cd tt e b t r l e a hi es e a r c ao " e h r t n hi t ei g" m e am t csTne d a Py e ( ahedr ) k n e c a ( ahedr d r t csTne ) ee e :Py et am n at oz u re hi CO817 2008 48 Diagram Frames Show conditional or looping constructs :A m NS a e a k wl e e aM o U l p L o fae ih rm t a ,w b l ag r oe ud on a e rso xei n p s o tm r e ] l o [m ies o p :B eee(eI ,q ny nr m m u t ) t I t i t D ai t d c t nol e r i ,t t si o a p eS na dl e