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DFDcombinedwithObjectOriented - DESIGN PROGRAM How to...

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PROGRAM DESIGN How to Integrate Object Orientation with Structured Analysis Ohjechriented languees are populah but many developers mistakenly believe that to use them Paul T. Ward, Software Development Concepts angiiages that permit ohjcct<)iient- cd programmiiig havc received in- L creasing attention in the last'fcw years. The hest know1 of thcsc languages is Ada because of thc influence ofthc US Dcfcnsc Ilcpt. iis its sponsot-ing orpiim- tion. In addition, ohiccti)ricntetl exteii- aHic/e shows that , Several software ciigiiicws, including there is no Connict. ~ to create optimal ohjecti)ricntcd iinplc- Rooch' and Mcy? have contendcd that, niciitatiotis, a systciii~lc\.clopmcnt para- digni based on the siiiiic abstl-actions used in the programming must bc tiscd. This paradigin is called ohjcct<)ricntcd design or, soiiietimes, object-oriented develop These developments pose ii potential tors bvho will bc mandated to use Ad;i and fix other org;inizations that ai-c atti-acted by the IICW langriage's perceived kiiefirs. 111c111. problc1~i both for lkfi.Iisc Ijcpt. cotltl'iic- Developers in tiiany of these organimtions have been using the system-de\.elopmcnt method called structured analysis/struc- turcti design; some arc using CfiE tools that support this inethod. These devcl- opcrs arc being wged replace the well- understood str~ict~it-ed-desigti nicthod with the urifatniliar object-oricnted meth- od. Furthermore, the change will require either ligkiring out how translate str-tic- tui-cd-analysis specifications into object- oriented designs or, in the cxtrctiic' c;isc, replacing structured analysis as a specifica- tion method. Iti an attempt clarify sonic of the is- sues involved, I will address hvo questions: Mliat m-c the diff'erenccs txt\vecti the ;ihstr;ictions embodied in objcct-oriented design ;tiid the ahstl-actions rmhodied in sti-~ict~ircd an;ilysis/sti-ucturcd design? At-c object-oricnred design and struc- tured ;iiiaIysis/str~ictul.cd design liiii- damentiilly incompatible, or can they bc integrated? 74 07J0-7J~Y/XY~l7~X)/01 OUO IYXY Ikk t. IEEE Software
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Objectdented abstractions There are two major themes in object- oriented design: the closely related ideasofobject, class, and abstract data type and the idea of inheritance. Object, class, and abstract data type. Consider a simple software system for in- dustrial process control, which controls the filling and emptying of a tank by moni- toring the liquid level in the tank and by opening and closing a discrete-state inlet valve and a discrete-state outlet valve. The inlet valve is always controlled by the sys tem. The outlet valve may be controlled by the system in automatic mode or be manu- ally operated. The system obtains the auto/manual and on/off valve statuses by monitoring the valves. The system will dis play the maximum fill level for the tank on request, it will accept and store a desired liquid level, and it will accept commands to fill the tank to thedesired level, toempty the tank, and to reset (close both valves) after a valve error. The system will report
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DFDcombinedwithObjectOriented - DESIGN PROGRAM How to...

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