Modelling Enterprise Requirements

Transcription

1 Computr Sin Program, Th Univrsity of Txas, Dallas Modlling Entrpris Rquirmnts Why Entrpris Modlling? SADT IDEF0 Why Entrpris Modlling? "... Rquirmnts dfinition is a arful assssmnt of th nds that a systm is to fulfill. It must say why a systm is ndd, basd on urrnt and and forsn onditions, whih may b intrnal oprations or an xtrnal markt It must say what systm faturs will srv and satisfy this ontxt. And it must say how th systm is to b onstrutd..." [Ross77] Entrpris rquirmnts for "ontxt analysis" - th rasons why th systm is to b ratd...g, why IS for BPR, organizational strutur, agnts, goals) onstraints on th nvironmnt in whih th systm is to funtion..g, airplan running byond runway, AT&T Intrnt srvi) th maning of systm rquirmnts symbols, rlationships, ontology, voabulary) Systm) funtional rquirmnts a dsription of what th systm is to do; what information nds to b maintaind? what nds to b prosss? {f: I -> O} Systm) non-funtional rquirmnts global) onstraints on how th systm is to b onstrutd and funtion. E.g., -ilitis and -itis {bfhf: I -> O)}

2 Why Entrpris Modlling? Ordr Prossing loan rqust Buyr Dalr ordr Customr Support initial paymnt Invoi Shipmnt Transportation Fatory Ordr Prossing Aounting Finaning Loan Offir) ys/no/mor info, rat, priod Prson powr: svral hundrds Prossing tim: long nough to invit omplaints Errors: annoying and signifiant Why should a systm b ratd? goals/objtivs Whos work would th systm support? agnts, ativitis/oprations How would th info. in th systm hlp run th ntrpris? What s th rol of th systm for ross-funtional ativitis? information flow workflow SADT Struturd Analysis and Dsign Thniqu) d d d Bakground tradmark of Softh, In. Ross) in us sin th mid-svntis inspiration for many ommrial tools DFD?) Viw d "Systm" rfrs to any ntrpris/organization, physial, manufaturing, and sw systm => systm FRs! => Cours Projt Contxt Analysis should involv d d d thnial assssmnt: fasibility of systm arhittur Ar th omponnts and intr-rlationships thnially ralizabl? oprational assssmnt: systm prforman in a working nvironmnt Can th systm prform task X in lss than a wk of tim? onomi assssmnt: osts & impats of systm implmntation & us Can th systm b built with $20M, 1000 SErs, in 2 yrs?

3 SADT Struturd Analysis and Dsign Thniqu) Rquirmnts dfinition nompasss all aspts of systm dvlopmnt prior to atual systm dsign Currnt or Forsn Conditions similar ustomr bas similar dalrships+ similar intrst rats Managmnt Objtivs ordr prossing max. 1 wk rror rat 0.1% low fatory invntory lvl Oprational Conpts Dfin systm funtions and alloat Prsonal Funtions loan valuation Softwar Funtions warning of low invntory lvl loan rqust dat + 7 days < now.dat Hardwar Funtions dstroy onfidntial info. SADT Primitivs Diagrammati! SADT Struturd Analysis and Dsign Thniqu) Control Input Labl Output Mhanism Boxs "omposd" into a diagram and intronntd through arrows Eah diagram is domposd into up to "six" othr diagrams Informal doumntation as with DFDs) Two typs of diagrams h Atigrams h boxs: happnings - ativitis, oprations, prossing, vnts box labl: start with a vrb Datagrams boxs: things - ntitis, objts, data, information, substans box labl: noun

4 SADT Primitivs Diagrammati! SADT Struturd Analysis and Dsign Thniqu) Control Input Labl A26 Output Mhanism Box annotation: rprsnts a tra of stpwis rfinmnt/domposition h h Atigrams start with an A, suffix it with domposition squn h Datagrams Box numbr: optional, usually lvl of nsting Smantis of Arrows In an atigram j Inputs ar data that ar onsumd by th ativity j Outputs ar produd by th ativity j Controls influn th xution of an ativity but ar not onsumd j Mhanism is a prossor mahin, omputr, prson) whih maks th ativity happn SADT Struturd Analysis and Dsign Thniqu) Exampl: Modlling Softwar Pross for th dvlopmnt world Controls influn th xution of an ativity but ar not onsumd Dsign Rquirmnts Inputs ar data that ar onsumd by th ativity Prliminary Dsign Data A0 Prform Dtaild Dsign Rommndd Dtaild Data Outputs ar produd by th ativity Dsign Enginr Mhanism is a prossor mahin, omputr, prson) whih maks th ativity happn

5 SADT Struturd Analysis and Dsign Thniqu) Exampl: Modlling Softwar Pross for th dvlopmnt world Dsign Rquirmnts Prliminary Dsign Data Sparat Data Strutur From Prform Algorithm 1 Data Strutur PDS PA Dsign 2 DS Prform Algorithm Dsign Rommndd Dtaild Dsign A0 1 Dsign Enginr SADT Struturd Analysis and Dsign Thniqu) Exampl: Modlling Softwar Pross for th dvlopmnt world Dsign Rquirmnts Prliminary Dsign Data Sparat Data Strutur From Prform Algorithm 1 PDS Data Strutur Dsign PA 2 DS Prform Algorithm Dsign Rommndd Dtaild Dsign A0 1 Dsign Enginr PA DS Handl Normal Cass Dsign Rquirmnts 1 Dsign Enginr DD for Normal Handl Rommndd Dtaild Dsign Ex. 2 A 2 A2????

6 SADT Primitivs Diagrammati! SADT Struturd Analysis and Dsign Thniqu) Control Input D2 Labl Prliminary Dsign Prform Data Dtaild D0 0 Dsign Rpository disk Mhanism Smantis of Arrows h In an atigram j Inputs ar data that ar onsumd by th ativity j Outputs ar produd by th ativity j Controls influn th xution of an ativity but ar not onsumd j Mhanism is a prossor mahin, omputr, prson) whih maks th ativity happn h In a datagram j Inputs ar ativitis that produ th data j Outputs onsum th data j Controls influn th intrnal stat of th data j Mhanism is a dvi for storag, rprsntation, impl., t. Modify status Prform Prliminary Dsign Output h Bakground IDEF0 Intgration Dfinition for Funtion Modlling) rlasd in D., 199 th "rfrn modl" for systm/ntrpris funtion modlling also in us for softwar pross modlling Fdral Information Prossing Standard maintaind by Dpt. of Commr, NIST National Institut of Standards and Thnology) & Computr Systms Laboratory basd on ICAM Intgratd Computr-Aidd Manufaturing) from th US Air For Wright Aronautial Laboratoris supportd by Composr for ntrpris modlling losly rsmbls "atigrams" of SADT Information Modlling IDEF1X) uss ERD + gnralization/spialization Stringnt ruls E.g., Boxs shall b suffiint to insrt box nams rtangular in shap with squar ornrs drawn with solid lins Arrows that bnd shall b urvd using only 90 dgr ars shall b drawn in solid lin sqmnts vrtially or horizontally, not diagonally

7 IDEF0 Intgration Dfinition for Funtion Modlling) ICOM ods variations of arrows) E.g., tunnld arrows: provid information at a spifi lvl of domposition that is not rquird for undrstanding at som othr lvls I1, O1,, M1 ar not shown on hild diagram I1, O1,, M1 ar not shown on parnt diagram IDEF0 Intgration Dfinition for Funtion Modlling) Diagram syntax ruls E.g., ontrol fdbaks shall b shown as "up and ovr" 1 2 input fdbaks shall b shown as "down and undr" 1 2 mhanism fdbaks shall b shown as "down and undr" 1 2

8 Dfiinis Diagrammati! Control Input Labl Output Mhanism Ambiguitis h Informal doumntation as with DFDs) h Boxs insid a box may rprsnt spializations, instans, aggrgations h tmporal rlationships not lar Whn ar inputs produd? as a hunk or in a pi-mal mannr Whn ar outputs produd? on riving inputs, anytim aftrwards, instantanously How ar ativitis rlatd? squntial, onurrnt, ovrlap, during h ardinality, mandatory/optional h attributs of data h onstraints on arrows SADT/IDEF0 for a high-lvl systm funtional modl