CommunicationD iagrams
Figure25.23 shows a communication diagram that models theATM executing a
BalanceInquiry. O bjects are m odeled in t heUML a s r ectanglescontainingnames i n t he
formobjectName: C lassName. I n t hisexample,which involves o nly o neobject o f e ach
type, we d isregardthe object n ame a ndlisto nly a colonfollowedb y t heclassname. [ Note:
Specifying thenameofeach object in a c ommunication diagramisrecommendedwhen
modelingmultiple objectsofthe s ame t ype.] Communicatingobjects arec onnected w ith
solid l ines, a nd messagesare p assed b etweenobjects a longthese l ines i n t he direction
shown b y arrows.The n ame o f themessage,whichappears n ext t o thearrow, i s t hename
ofanoperation (i.e.,a memberfunction) b elonging to thereceiving object—think ofthe
name asa s ervice that t hereceiving o bject p rovidestosendingobjects(its “ clients”).