Process Modeling for Object Oriented Analysis using BORM Object Behavioral Analysis.

Transcription

1 Proce Modeling for Objec Oriened Analyi uing BORM Objec Behavioral Analyi. Roger P. Kno Ph.D., Compuer Science Dep, Loughborough Univeriy, U.K. 9RMW FKMerunka Ph.D., Dep. of Informaion Engineering, Czech Univeriy of Agriculure, Jiri Polak, Deloie & Touche Czech Republic. Abrac. BORM Objec Behavior Analyi (BOBA) i a fir age in a proce of objec modeling which ha proved ucceful in a wide number of applicaion. Thi paper dicue hi mehod and decribe a imple applicaion. One advanage of BOBA i he mall number of concep required combined wih coniderable expreivene. In hi way, BOBA i in he radiion eablihed over he pa few year by E-R modeling. 1. Inroducion Developmen of he BORM mehodology ared in A ha ime, here were in exience everal fir generaion objec or emi-objec-oriened analyi mehod (OMT, Marin-Odell, Booch, Coad-Yourdon, Jacobon, ec). Thee mehod were, and ill are, very ueful for he developmen of hybrid ofware yem. For example an objec/oriened clien alking o a number of relaional erver. owever he auhor fel ha hee mehodologie poeed wo fundamenal weaknee which made hem inappropriae for heir own developmen requiremen. Firly hee exiing mehod did no offer ufficien uppor for developmen uing a pure objec-oriened language like Smallalk. When developing yem in Smallalk he auhor ofen ued conruc of he language like polymorphim beween objec wihou any inheriance or objec dependency. Thee conruc were no uppored and could no be expreed in any of hee exiing developmen mehodologie. Addiionally, in he diagrammaic noaion, hey provided i wa impoible o repreen mo pure objec-oriened algorihm. Such algorihm may ofen be decribed a muual aynchronou communicaion (meage paing) beween objec, which a he reul of receiving meage invoke inernal mehod wih a conequenial change in heir ae. Secondly, hee exiing mehodologie iniially commenced wih he conrucion of a e of clae howing inheriance and aggregaion hierarchie. While hi i an effecive way of expreing he rucure required for ubequen coding in an objec-oriened language, i i no however effecive in illuraing he problem domain. Thi i becaue he objec oriened naure of hee diagram are difficul for domain exper, no educaed in compuer cience concep, o underand. Conequenly uch diagram canno be ued in decribing propoed oluion o clien. The iniial work on BORM wa carried ou under he uppor of he Czech Academic link program of he Briih Council, a par of he VAPPIENS reearch projec; furher developmen ha been carried ou wih he uppor of Deloie & Touche Czech Republic. (VAPPIENS wa funded by he Briih Governmen CZALP academic link programme, adminiered by he Briih Council. The auhor acknowledge he uppor hey received from hi ource, which enabled hem o mee and carry ou he iniial work, ou of which BORM grew.) BORM ha been ued for a number of large projec including he idenificaion of buine procee in Prague ciy hopial, he modeling of properie neceary for he general agriculural commodiie wholeale ecor in he Czech Republic, a a ool for buine proce reengineering in he elecriciy upply indury a a ool for buine proce reengineering for elecommunicaion nework managemen in he Czech Republic.

2 2. Developing Objec Oriened Syem Developing ofware yem i a complex aciviy fraugh wih many difficulie for ofware engineer a hey endeavor o enure ha he righ yem i buil. A righ yem being one ha mee he uer' need a a co hey can afford. On he urface hi would appear a raighforward ak, fir year univeriy uden udying yem deign, are ofen urpried when i i poined ou o hem ha incorrecly pecifying he required yem i one of he major caue of ofware yem failure. Such uden, however, have lile experience of he complexiy of he real world where ofware developer and exper from he uer domain appear o live in differen univere, each wih heir own jargon, which ac a a barrier o rue communicaion. I i in hi conex ha ofware developer face he fir and perhap major challenge of ofware developmen; o fully underand he uer domain and moreover, o convey heir underanding of ha domain o he uer. Adele Goldberg [1] ue he erm concep pace o decribe wha he uer/exper believe, aume or know o be he cae. The ariculaion pace i wha he exper/uer communicae in repone o he analy queion. The analy hen conruc a model o feed back o he uer/exper heir menal model of he concep pace, which hey conruc ou of he informaion preened in he ariculaion pace. The difference beween hi analy model and he uer pace i he concep gap. To a cerain exen, par of hi gap i unbridgeable; we canno eaily reduce he gap beween concep and ariculaion pace a hee exi in he uer/exper head. I i rue, however, ha he language, naural and graphical, ued by he analy in repreening hi model are a vial componen in he uer/exper abiliy o validae hi model again he uer own concep pace. The problem i o find a common language for he developer o expre heir underanding of he problem pace ha i boh ufficienly rich for he developer o fully ariculae heir idea, while alo being comprehenible o uer from all area of dicoure. Ue-Cae[2] ha become a well-acceped par of Objec Oriened analyi and in many cae ha proved a ueful mechanim for communicaion beween developer and domain exper. We do no inend o dicu i furher here. owever, Fowler[3] highligh ome deficiencie in he Ue-Cae approach, uggeing ha "aciviy diagram can be ueful in cae in which workflow procee are an imporan par of he uer world." Aciviie are a key componen of buine proce modeling [4], [5]. Eeele and Sim[6] define a buine proce a coniing of a number of elemen; aciviie, raniion, ae and deciion. They oo ae ha he UML aciviy-diagram can be a ueful modeling ool in capuring buine procee. 2.1 The BORM Approach BORM, like oher OOA&D mehodologie i baed on he piral model for he developmen life cycle [9]. One loop of he objec-oriened piral model conain age of raegic analyi, iniial analyi, advance analyi, iniial deign, advanced deign, implemenaion and eing. 1. The fir hree age are collecively referred o a he expanion age. Expanion end wih he finalizing of he deailed analyi concepual model, which fully decribe he oluion o he problem from he requiremen poin of view. 2. The remaining age are called conolidaion age. Thee are concerned wih he proce of developing from expanded idea o a working applicaion. During hee age, he concepual model i ep by ep, ranformed ino a ofware deign. BORM wa iniially developed a an objec-oriened mehod for he analyi and deign of objec-oriened ofware yem. The proce ar from an informal problem pecificaion and provide boh mehod and echnique, o enable hi informal pecificaion o be ranformed ino an iniial e of ineracing objec [7]. The ool and echnique developed for requiremen analyi and ued in he iniial phae of BORM, provide an independen mehod for buine proce modeling a par of buine proce reengineering. The auhor find ha hi independen mehod, referred o a BOBA (BORM Objec Behavior Analyi) i frequenly ued alone. One advanage of hi laer approach i ha i provide a cloe ineracive inerchange beween he developer and member of he uer' organizaion. A well a idenifying iniial objec, BOBA elici from he domain exper deailed decripion of heir requiremen which are fed back o hem via eaily underood decripion of he propoed yem' behavior, uing a number of able and graph. The problem pecificaion, from which he proce ar, are obained from relevan parie in he problem domain by inerviewing. Thi deermine a li of required yem funcion, which are eenially Ue Cae. From hi li, a e of yem cenario i formed. BOBA crip alway include a lea he four ecion hown in Table 1.

3 Table 1 1 Iniiaor A brief verbal decripion of he beginning of he cenario including any inpu or enry condiion. I alo decribe he fir even or fir aciviy of ome elemen wihin he proce. 2 Acion A verbal decripion of he proce ielf. 3 Paricipan The e of hoe elemen of he yem, which are required for he acion. I i ofen he cae ha he ame paricipan may be preen in everal procee of he modeled yem. 4 Reul A brief verbal decripion of he oucome and oupu of he cenario. A cuomer need o purchae good from a ore The Cahier can each iem a he erminal. The erminal read he bar code and he ock daabae i conuled o deermine he decripion of he iem and i price. Thi are hen diplayed on he erminal and added o he ale ranacion li. The Cuomer pay wih cah The Cuomer pay wih a cheque The Cuomer pay by credi card The cuomer wihe o pay for good purchaed Figure 1 Syem Funcion and Scenario Thee column repreen he four mo imporan aribue of each cenario. The complee e of cenario i capable of decribing yem behavior, a well a deermining he objec ha perform hee behavior. In addiion o hoe four aribue each cenario mu alo refer o he required yem funcion i realize. Currenly, he age of BOBA can be carried ou wih he aid of he METAEDIT cae ool developed by Meacae Ld(Meacae Ld., Jüväkyllä Finland, info@meacae.com, hp:// 3 A Cae Sudy We illurae he deail of he BOBA mehod hrough a cae udy. The yem i he familiar one of a EPOS (Elecronic POin of Sale) erminal in a upermarke. The main funcional requiremen of he yem o uppor uch erminal i o proce he good ha a upermarke cuomer bring o he erminal and o produce he oal co of hi ranacion. Figure 1 how wo required yem funcion, ogeher wih four aociaed cenario. We can click on each cenario o define and expand i decripion. If we

4 look a he decripion of he fir cenario we have he window how in figure 2: Objec Scenario x number imple diplay iniiaion A cuomer arrive a a erminal wih a number of iem o purchae paricipan cuomer cahier EPOS erminal ale ock li acion The Cahier can each iem a he erminal. The erminal read he bar code and he ock daabae i conuled o deermine he decripion of he iem and i price. Thi are hen diplayed on he erminal and added o he ale ranacion li. reul A cuomer arrive a a erminal wih a number of iem o purchae Open Cancel Info Figure 2 Properie of a Scenario Objec: Paricipan in Scenario x name viible properie diplay viible properie ale Toal Amoun Dae Time componen diplay componen Sale Line documenaion Open Cancel Info... Figure. 3. Objec Deail

5 Noe ha each of he column previouly idenified for a cenario decripion correpond o a pane of hi window. Thi able include a li of paricipan. Thi i he erm we ue for wha will probably become he objec in he yem. Thi form can be compleed wih he uer paricipaion and build up an iniial view of many apec of he required yem. In BOBA, a paricipan i any eniy ha ha a role in a cenario. Thee may evenually correpond o eiher yem objec or acor. A hi age we do no diinguih. If he ofware i o be releaed in a erie of incremenal ep, he yem boundary could be dynamic. Paricipan migh be exernal o he yem iniially, bu in laer releae be implemened a par of he yem. For each paricipan we can add deail a hown in figure 3. ere we are beginning o idenify relevan aribue of he candidae objec. 3.1 Modeling Procee One furher feaure of he BOBA approach, i he abiliy o model procee. We noed earlier ha Ue Cae ofen require he uppor of aciviy diagram o fully convey he deeper meaning of any yem. BOBA ue i own form of Buine Proce Modeling o achieve uch deep underanding. In BOBA proce diagram we diplay aciviie, ae, raniion and deciion. A proce diagram i a viual repreenaion of objec aociaion and communicaion in a paricular proce. The noaion i very imple and eaily underood by domain exper and i doe no conain repreenaion of unneceary objec oriened concep which will only be required a ubequen age in he developmen proce. In carrying ou he projec decribed earlier, we found ha o each he noaion and ynax o everyone in he conulaion eam, required a mo half a day. Thi ynergy of impliciy and poency, allow domain exper o become acive member of he modeling eam, working wih formal modeling ool and echnique. The BOBA Objec Relaion Diagram (ORD) alo called a proce diagram ue he graphical concep, hown in Table 2. Addiionally, he iniial ae and erminal ae are hown uing he andard ae raniion noaion. Table 3 give ome indicaion of he ize of he model we have conruced for ome of he projec we have underaken uing BOBA. BOBA proce model i ricly baed on he heory of finie auomaa. Previouly publihed work [9] and [10] uppor hi approach. I i our conenion ha he objecoriened daa and compuaional model i very imilar o he concep of finie-ae auomaa. We view an objec-oriened yem a a collecion of muually communicaing objec, where each objec behave a an auomaon. Oupu of ome auomaa (objec) in hi yem may be conneced o inpu of oher auomaa (objec). Thee connecion are called communicaion beween objec. In addiion, we adoped he Mealy-ype of auomaon for modeling objec behavior. Thi mean an objec i acive (receive inpu and generae oupu; i.e. communicae) during raniion among i ae. We aociaed he concep of objec mehod wih he concep of objec raniion ino a ingle concep of objec 'aciviy'. Conequenly, we pu aciviie on raniion among ae in our diagram. I i alo poible, of coure, o draw objec aciviy wihou any raniion beween ae. We may chooe o do hi if we do no require a deailed decripion of ome objec or when caaloguing an aciviy ha expree a raniion from a ae o ielf. From he formal viewpoin however, each aciviy perform ome change, which i modeled a he raniion from a ae o a ae, wihin he ame objec. Thu, we have a 'wo-dimenional' yle of eenial (buine) objec modeling: The fir dimenion i he equence of communicaion beween aciviie of he objec in he yem. Thi i very imilar o objec ineracion diagram of UML. The econd dimenion i hown inide each objec paricipaing in he yem. Thi i he equence of relaed ae and raniion of hi objec. Thi equence may be underood a he 'ubjecive' inerpreaion of he modeled proce from he viewpoin of an objec paricipaing in ha proce. Thi i very imilar o aeraniion diagram of UML. Figure 4 how he iniial proce model for he cuomer purchaing iem from he ore. Each proce diagram i relaed o a cenario from which i ha been exploded. Thee diagram have o be drawn, bu Meaedi doe uppor he drawing proce a all he neceary informaion, which ha been obained in previou age, can be impored from he repoiory. Many apec of he model under conrucion, can be repored a hml documen or a MS Acce daabae forma file. One uch repor i he e of model card for all he candidae objec a hown in figure 5. Thee are very imilar o CRC card wih he excepion ha hey do no how collaboraing objec. Collaboraion are however provided in one of he oher repor a hown in figure 6 below. From hee able, we can eaily conruc he iniial concepual model for he propoed yem uing he li of objec and aociaion. In fuure verion of he cae ool hi will be conruced auomaically. Table 2

6 Concep Symbol Decripion Objec A recangle wih name in op lef corner Objec are proce paricipan deermined from he collecion of modeling card. Sae A recangle wih ae decripion in ialic Expre he change in objec during heir life hiory, The ae of an objec i deermined by he value of i viible properie and i curren aciviy. Sae are drawn wihin he objec recangle. Aciviy An Oval The dynamic apec of an objec required o aify ome required yem funcionaliy. Aciviie are drawn wihin an objec or a ae or exernal o he objec bu conneced by a coninuou hin line. Communicaion A direcional arrow drawn beween aciviie Traniion Aociaion Projec An Arrow wih a large, open arrowhead, drawn beween ae and direcly aociaed wih an aciviy A hick line wih a large cloed arrowhead drawn beween ae or objec. Naional agrarian chamber (analyi and deign of ofware for frui marke public informaion yem) opial complex (BPR of organizaion rucure) TV and radio broadcaing company (BPR and company ranformaion for open marke) Regional elecriciy diribuion company (cuomer informaion yem analyi) Regional elecriciy diribuion company (failure handling informaion yem analyi and prooype implemenaion) Regional ga diribuion company (BPR of all company) Regional ga diribuion Number of yem funcion Thi expree he conrol flow beween aciviie. Communicaion may alo include ome daa flow in he ame way a in convenional objec collaboraion diagram. A mall arrow (objec) in he appropriae direcion repreen uch daa flow. Thi expree he dynamic of an objec life hiory. In BOBA, raniion are viewed a ariing from he objec having performed ome aciviy. Thi expree a aic relaionhip beween objec. The exience or naure of hi aociaion may change a he objec involved change ae. I can be viewed a a pecial ype of viible propery. Aociaion a hi age include boh i-a and ha-a hierarchie. Number of cenario Table 3 Number of proce diagram Number of objec* (paricipan) Average number of ae per objec Average number of aciviie* per objec company (BPR of all company) * excluive objec in communicaion daa flow ** in BPR projec, each objec aciviy conain approx addiional aribue like buine goal applicabiliy, required job poiion, ime requiremen ec

7 Cuomer Cahier Terminal Arrive wih good Receive good Good Received Wai for Toal Iniiae Terminal Iniiae new Tranacion awai erminal iniialiaion Iniialied Sar ranacion beep begin can awai inpu Scan Iem deermine uni price End Scan End Scan Obain bill Reque Toal Toal deermine oal Fig. 4. The Iniial Proce model

8 Fig. 5. Objec Card Figure. 6 Objec Communicaion Card 4 BOBA and UML Noe ha he BOBA proce diagram incorporae everal diagram from he UML. If we conrac he objec recangle unil hey become verical line, we obain a UML equence diagram howing he flow of meage beween objec. Likewie if we conrac he ae or he aciviie we can obain aciviy or ae diagram repecively. By having all hee feaure on a ingle diagram however, we believe a more comprehenive picure of he yem behavior i obained. 5 The Main advanage of BOBA Proce Modeling 5.1. Paricipan iory Diagram A Paricipan iory Diagram how he progre of he paricipan hrough i relevan aciviie and ae. Such a diagram can provide informaion on he proce from he viewpoin of each of i paricipan. Thu he collecion of hee diagram over all paricipan provide a complee view of he proce, from he perpecive of i paricipan. Thi i referred o a he Inernal View of he proce. The inernal view of a proce in a decripion of how he proce look from he inide. For paricipan from he uer domain, hee inernal view

9 hould cloely correpond wih heir concepion of how he propoed yem i expeced o behave. We can hu, early in he deign proce, validae our deign again uer expecaion Proce-Paricipan Ineracion Model We can diagram he hiory of all paricipan in a proce, ogeher wih all ineracion beween hoe hiorie. Each ineracion i a communicaion beween aciviie in he hiorie of collaboraing paricipan. The proce ielf i expreed by a equence of uch communicaion, flowing hrough everal paricipan hiorie. Thi flow i referred o a he procee aciviy race. The conideraion of he aciviy race of a proce, i a valuable way of idenifying all he aciviie and ae of paricipan neceary for he proce. Many of hee aciviie, eenial for he proce are exernal o he main proce flow. We can hu enure compleene of our deign a an early age..5.3 Self Correcing e of Aciviie BOBA' repreenaion of a proce aciviy race enable he developer o eaily idenify who i involved in each aciviy and heir paricular reponibiliy o ha aciviy. Thu he modeler i conrained by he developmen mehod and can only add aciviie o ome paricipan hiory and which are inernally conien wih aciviie and age already preen in he proce model. 5.4 Idenificaion of Objec A we aw above, BOBA conain in i repoiory a documen deailing each paricipan in he yem. Thoe paricipan who are no acor will become objec in he propoed yem. Thu we can eaily idenify an iniial e of objec. A ak which ofen prove o be exremely difficul o carry ou in oher developmen mehodologie. SockLi IemInformaion SaleLineIem Supermarke Iem Sale Epo ACuomer Paymen ACahier Fig 10. The Iniial Concepual Model

10 Cuomer Cahier epo Syem iem o purchae can bar code of iem reque paymen of oal amoun cheque + card * beep iem enry complee diplay oal wipe card reque auhoriaion confirm auhoriaion deermine iem price add o ale oal compue oal cheque Auhoriaion yem prin cheque cheque for ignaure igned cheque check ignaure confirm correc receip + card receip Prin receip Fig. 11. A UML Sequence Diagram 6 Concluion Our experience ince 1991, in proce modeling ugge ha claical concepual diagram are no uiable for fir age of analyi, where baic procee need o be recognized. Such diagram are oo complex for he uer from he problem domain communiy a hey ofen conain exceive deail concerning poenial ofware implemenaion (i.e. clae, inheriance, public/privae mehod, aribue, link clae, ec.) We believe ha he Objec Oriened Programming communiy need ome imple ye expreive ool for proce modeling; able o play an equivalen role o ha played by Eniy-Relaion Diagram and Daa-Flow Diagram over he pa decade. One of he rengh of hee diagram wa ha hey conained only a limied e of concep (approx 5) and were comprehenible by problem domain exper afer a few of minue of udy. Tha i why we developed he BOBA proce diagram. Our approach i o ar wih a limied e of high level concep which can ubequenly be ranformed ino more ofware-oriened concep neceary for he conrucion of a ofware oriened concepual model. Our experience over a number of projec, large and mall from many divere area, ugge ha he mall e of concep we eleced are ufficien for he ak of foering muual collaboraion beween ofware developer and problem domain exper. Thu we feel ha he BOBA approach in requiremen analyi and knowledge repreenaion i an advanageou pre-curor o ubequen objec-oriened modeling a he level of objec clae, inheriance,... uch a provided by variou mehodologie and uppored by UML. 7 Reference. [1] Goldberg A., Rubin K. S.: Succeeding wih Objec - Deciion Framework for Projec Managemen, Addion Weley, Reading Ma, [2] Jacobon, I., Chrieron, M., Jonon, P. and Overgaard, G., Objec-Oriened ofware Engineering- A ue Cae Driven Approach, Addion Weley, Reading Ma, [3] Fowler M, UML Diilled: Applying he Sandard Objec Modeling Language, Addion Weley, Reading Ma, 1997 [4] Taylor, D., A. Buine Engineering wih Objec Technology, John Wiley [5] Darnon, G., Darnon, M. Buine Proce Analyi, Inernaional Thomon Publihing 1997 [6] P. Eele P., Sim O., Building Buine Objec, John Wiley & Son, Inc., New York, [7] Sazinger J. W. and Orvik T. U. The Objec- Oriened Approach - Concep, Modeling and Syem Developmen, Boyd&Fraer [8] Bellin, D.; Simone, S.S.: The CRC Card Book Addion-Weley, Reading Ma, 1997 [9] Boehm, B. W.: Sofware Engineering Economic, Prenice-all, Englewood Cliff, NJ 1981