Identifying and Modelling Complex Workflow Requirements in Web Applications

Iden i ying and Modelling Complex Wo k low Requi emen s in Web Applica ions Ma io Ma ias U bie a1,2, Gus a o Rossi1,2, Sil ia Go dillo1,3, Wieland Schwinge 4, We ne Re schi zegge 4, and Ma ía José Escalona5 1 LIFIA, Facul ad de In o má ica, UNLP, La Pla a, A gen ina {mu bie a,gus a o,go dillo}@li ia.in o.unlp.edu.a 2 Conice 3 CiCPBA 4 Depa men o Coope a i e In o ma ion Sys ems, Johannes Keple Uni e si y Linz {wieland.schwinge ,we ne . e schi zegge }@jku.a 5 IWT2 G oup. Uni e si y o Se ille, Spain [email p o ec ed] Abs ac . Wo k low plays a majo ole in nowadays business and he e o e i s equi emen elici a ion mus be accu a e and clea o achie ing he solu ion closes o business’s needs. Due o Web applica ions popula i y, he Web is be- coming he s anda d pla o m o implemen ing business wo k lows. In his con ex , Web applica ions and hei wo k lows mus be adap ed o ma ke de- mands in such a way ha ime and e o a e minimize. As hey ge mo e popu- la , hey mus gi e suppo o di e en unc ional equi emen s bu also hey con ain angled and sca e ed beha iou . In his wo k we p esen a model-d i en app oach o modelling wo k lows using a Domain Speci ic Language o Web applica ion equi emen called WebSpec. We p esen an ex ension o WebSpec based on Pa e n Speci ica ions o modelling c osscu ing wo k low equi e- men s iden i ying angled and sca e ed beha iou and educing inconsis encies ea ly in he cycle. Keywo ds: Requi emen s, Wo k low, C osscu ing, Model-d i en pa adigm, Web applica ion. 1 In oduc ion Nowadays business mus adap o global ends in o de o keep use s engaged; un- planned ma ke ing campaigns, season p omo ions ( inal season sales), c isis manage- men , among o he s business equi emen s a e examples o unexpec ed equi emen s ha s ess he whole applica ions’ in as uc u e. We will ocus on he p oblem p oduced by hose equi emen s ha demand busi- ness p ocesses change acco ding o he use s’ con ex . Depending on con ex a i- ables like cu en day, paymen me hod, ac i e ma ke campaign, accessing de ice, e c. he sys em may modi y he unde lying wo k low model; his may imply execu - ing a sligh ly di e en wo k low p o iding adap a ions which suppo new equi e- men s like discoun s and ee-shipping, o in oduces new wo k low s eps like new o ms o be illed, e c. Un o una ely, hese changes may a ec di e en applica ion´s ea u es. In Web Applica ions hese changes comp omise se e al applica ions’ ie s (model, na iga ion, and in e ace). When he unde lying wo k low changes, use in- e aces may, o example, in oduce a new o m ha will demand new iew con ol- le s ha o ches a es alida ion and na iga ion, and inally he business model mus be modi ied o suppo ing new en i ies’ o ms and ields. To make ma e wo s , when new conce ns a e un o eseen and unp edic able like C isis Managemen [7] o Vola ile equi emen s[8], hese equi emen s a e usually in oduced in an ad-hoc way. The inadequa e implemen a ion o hese changes may lead o a decay o so wa e quali y comp omising applica ion main enance, s abili y, and complexi y, and inally he applica ion’s budge . In his pape we p esen a model-d i en app oach o analysing and modelling wo k low changes in Web adap a ions in he ea ly s age o equi emen ga he ing. The main con ibu ion is a model-d i en app oach o dealing wi h base and adap a- ion equi emen s. I is based on a clea sepa a ion o conce ns applied in he ea ly phase o he so wa e de elopmen p ocess. The app oach allows de ining symme i- cally bo h base and adap a ion equi emen s; la e hese models a e used o imple- men ing es sui es ha assess he inal applica ion beha iou . The es o he pape is s uc u ed as ollows: in Sec ion 2 he p oblem will be mo- i a ed wi h simple bu illus a i e examples; in Sec ion 3, we discuss some ela ed wo k; in Sec ion 4, we p esen some backg ound hemes; in Sec ion 5, we in oduce an ex ension o WebSpec ha uses Pa e n Speci ica ion; and in Sec ion 6 we p e- sen ou model-d i en app oach o modelling wo k low changes in Web Applica ion and in Sec ion 7, a unning example is p esen ed; inally in sec ion 8 we conclude and discuss some u he wo k we a e pu suing. 2 Mo i a ing Example We mo i a e ou esea ch wi h an example in he e-comme ce domain. In he check- ou p ocess o buying selec ed i ems, he use mus ollow a simple wo k low p e- sen ing se e al s eps such as choosing he w apping con igu a ion ( egula o special o bi hday), selec ing he shipping add ess, and he paymen me hod, e c. Suppose an un o eseen e en such as a ca as ophe ha leads o a dona ion campaign. We may equi e he in oduc ion o a new dona ion s ep in he wo k low, whe e use s can choose be ween di e en p e-se amoun s o money o dona e. This change will e- qui e a leas a se o modi ica ions: •Implemen a page ha holds a dona ion o m wi h i s co esponding ields; •The co esponding s ep mus be placed in he wo k low and he wo k low mus be modi ied o be cohe en ; •New da a needs o be s o ed and he e o e we need o add pe sis ence machine y o hese da a; •Na iga ion models demands modi ica ion o le use s na iga e o hei dona ions o example. In his case he se o changes mus be p esen only when he ca as ophe campaign is ac i e o he wise hey make no sense. In he mid- e m we ha e an adap a ion equi e- men ( he exis ing o a ca as ophe and he dona ion campaign) which lead o a “con- ex -awa e” wo k low beha iou . Addi ionally, he impac in he applica ion o he adap a ion may no be simple; ha is, he in oduc ion o his adap a ion may c oss o he wo k lows such as icke booking o a eci al, p oduc p e-o de , e c. The e o e, he way in which he adap a- ion equi emen s a e modelled is c i ical o assu e ha hey co ec ly implemen ed. To make ma e wo s , he incoming o new con ex -awa e equi emen s ha c oss- cu se e al wo k lows make he si ua ion mo e complex since di e en business do- mains a e comp omised by he same se o e en s. 3 Rela ed Wo k Adams [1] e al. p esen s he so ie “Ac i i y Theo y" as a d i e o a mo e lexible and be e di ec ed wo k low suppo . A subse o he main heo y´s p inciples high- ligh s he need o con ex awa eness in each possible wo k low ac ion execu ion. The au ho s p opose a se o c i e ia as equi emen s o Wo k low Managemen Sys ems (W MSs). One c i e ia “adap a ion by e lec ion” p omo es lexible, dynamic and e ol ing wo k lows. In his case, sys ems mus eco d de i a ions (excep ional lows in he wo k low de ini ion) cap u ing i s easons and i s esolu ion ha la e can be- come pa o he nex wo k low ins an ia ion. Al hough his a emp will help o im- plemen awa eness wo k lows, i wo ks eac i ely om excep ion ins ead o being a p oac i e solu ion. As excep ions a e cap u ed in eal- ime, he solu ion eco ded is ad-hoc and isn´ nei he modelled no op imized by domain expe s. This wo k was assessed wi h he implemen a ion o a W MS so called YAWL [2] ha allows imple- men ing dynamic wo k lows. The pla o m de ines Wo kle as a eusable uni o wo k. Each ime a wo k low de i a ion e en is de ec ed i is ei he possible o choose an al eady de ined wo kle o de ine a new one. AO4BPEL [3] is an aspec -o ien ed ex ension o BPEL ha allows desc ibing wo k low´s c osscu ing beha iou . The ex ension comp ises a language ha is used o decla e aspec s and an execu ion engine ha is esponsible o wea ing co e wo k- lows wi h wo k low aspec s. The language in oduces cons uc o s o poin cu , join poin and ad ice concep s. I is no ewo hy ha he ex ension suppo s p ocess- le el aspec s being ac i a ed in all wo k low ins ances and ins ance-le el being ac i- a ed on ce ain ins ance o he wo k low. AO4BPEL is a powe ul ool o desc ib- ing aspec s in Business P ocess models bu aspec s a e aken in o accoun la e (in he design phase) whe e c osscu ing can no be iden i ied and checked wi h s akeholde s. We a e no awa e abou any app oach ha allows iden i ying wo k lows and speci- ying i s aspec s in he equi emen ga he ing phase in such a way ha he whole ap- plica ion beha iou is desc ibed allowing assessing i s beha iou i s wi h he use and la e by au oma ic es ing. 4 Backg ound In his sec ion we in odu c namely WebSpec o mode speci ying he binding o e 4.1 WebSpec WebSpec [9] is a isual la n WebSpec diag am which c a A WebSpec diag am de is y. An in e ac ion (deno use can in e ac wi h he a p ions ha e a name (uniqu e boxes, e c. In WebSpec, a cally ep esen ed wi h a o igge ing ac ions a e disp l wi h a p e ix o he cha ac ollowing lines. The scena ios speci ied b g am using he dep h- i s s nodes called “s a ing” no d he edges ( ansi ions) o h As an example o Web S he use s o y: “As a cus o m de ails” in an e-comme ce a ica ion and i con ains 2 w i u he de ails). Fig. 1. We b WebSpec has a suppo i n equi emen ga he ing, ea in e aces and gene a ing i esul . c e some base wo k which we ha e used in ou app o a lling wo k low equi emen s and Pa e n Speci ica ions e qui emen s belonging o di e en conce ns. n guage; i s main a e ac o speci ying equi emen s is a n con ain in e ac ions, na iga ions and ich beha io s. ines a se o scena ios ha he web applica ion mus ed wi h a ounded ec angle) ep esen s a poin whe e p plica ion by using i s in e ace objec s (widge s). In e e pe diag am) and may ha e widge s such as labels, ansi ion (ei he na iga ion o ich beha io ) is g a p ws be ween in e ac ions while i s name, p econdi ion l ayed as labels o e hem. In pa icula , i s name app e e ‘#’, he p econdi ion be ween {} and he ac ions in b y a WebSpec diag am a e ob ained by a e sing he d s ea ch algo i hm. The algo i hm s a s om a se o spe d es (in e ac ions bo de ed wi h dashed lines) and ollo w h e g aph (diag am). S pec’s concep s we p esen in Fig. 1 he speci ica ion m e , I would like o sea ch p oduc s by name and see h a pplica ion. Home ep esen s he s a ing poin o he sp e i dge s: sea chField ex ield and sea ch bu on (see [9] b Spec diag am o he Sea ch by name scena io n g ool [16] wi h ea u es ha allows, in he ea ly phase lizing simula ion o applica ion in e ac ion agains m i ndependen Web es s o es ing he inal de elop m a ch, o he sa - he ac- lis p hi- and e a s he d ia- e cial w ing o h ei e ci- o s o m ock m en 4.2 Pa e n Speci ica ion Pa e n Speci ica ions (PSs) [6] is a ool o o malizing he euse o models. O igi- nally he no a ion o PSs was p esen ed using he Uni ied Modelling Language (UML) as a base bu in his wo k we will ins ead use he concep in he WebSpec ealm. A Pa e n Speci ica ion desc ibes a pa e n o s uc u e de ined o e he oles which pa icipan s o he pa e n play. Role names a e p eceded by a e ical ba (“|”). A PS can be ins an ia ed by assigning conc e e elemen s o play hese oles. 5 C osscu ing Beha iou Modelling Using Pa e n Speci ica ion WebSpec p o ides a powe ul language o desc ibing use ’s in e ac ion o Web ap- plica ion as i was in oduced in p e ious sec ion. None heless i lacks a means o po aying gene aliza ion o in e ac ion pa e ns; o example, common pa e ns e- qui ed in de e mined wo k lows’ poin s ( asks o ansi ions) ha s op he wo k low execu ion up o he manage au ho izes o con inue, o landma ks-like beha iou whe e a gi en subwo k low can be accessed om s eps belonging o a main wo k- low. This es ic ion inc ease size and complexi y o diag ams, and e o o docu- men he equi emen . So, we p opose he use o Pa e n Speci ica ions (PS) whe e, in ou case, a ole is a specializa ion o a WebSpec In e ac ion es ic ed by addi ional p ope ies ha any In e ac ion ul illing he ole mus possess. A model con o ms o a PS i i s model elemen s ha play he oles o he PS, sa is y he p ope ies de ined by he oles. In Figu e 2, a equi emen ha gene alizes an in e ac ion pa e n de ines wo oles: |sou ceIn e ac ion and | a ge In e ac ion. The |sou ceIn e ac ion ole (no ice ha ole’s name s a s wi h “|”) demands a widge o ype Label called manda o yWidge ha mus be p esen in he In e ac ion ha con o ms he ole, and de ines a new wid- ge o ype Tex Field called in oducedWidge ha will be pa o con o ming In e ac- ion. The | a ge In e ac ion ole is analogous o he p e ious ole; i demands a widge o ype Combobox called manda o yWidge o be pa o he in e ac ion ha ma ches he ole. Finally, when bo h oles a e bound in a gi en diag am, a new in e ac ion is in oduced wi h he co esponding ansi ions called In oducedIn e ac ion as i is de ined in Figu e 2. Fig. 2. In oducing in e ac ions and elemen s in a Wo k low equi emen In Figu e 2, PS was used o in oducing a new In e ac ion. Al e na i ely, i can be used o de ining cons ain s o e a diag am ha may lead o an o e iding o exis ing de ini ions. E.g. Na iga ions p econdi ions and ac ions may be in oduced by PS in o de o en ich he scena io o making consis en a se o changes. This kind o si ua- ions is usually p esen in adap i e equi emen s whe e some beha iou is in ended o be eplaced by o he . In Figu e 3, we show a gene aliza ion o a Web applica ion equi emen s ha p o- ides he op ion o dona e. This in oduces a banne be ween wo oles desc ibing he dona ion goal and allows a e sing owa ds a dona ion o m. This equi emen can be ins an ia ed in Figu e 1 example whe e |s epOne ole is bound wi h he Home in e ac- ion and |s epTwo wi h he Sea chResul in e ac ion. Fig. 3. Dona ion equi emen model using PS 5.1 Ye Ano he AOSD Visual Language? Al hough he e a e se e al AOSD (Aspec -O ien ed So wa e De elopmen ) o mal and isual languages al eady de ined o almos any model o a Web applica ion (concep ual, na iga ional, and in e ace models), none o hem co e s equi emen ga he ing phase and indeed hese a e ocused on desc ibing jus unc ional ea u es close o he concep ual model [17]. Tackling c osscu ing wo k low beha iou in he ea ly equi emen analysis phase allows iden i ying c osscu ing beha iou s in he sys em, and con ex a iables ha ules adap a ion beha iou . The use o WebSpec wi h PS, will help o sepa a e ma e o in e es in (WebSpec) equi emen diag ams and hus in he whole Sys em Re- qui emen Speci ica ion (SRS) documen s. In his case, he ex ension p o ided o WebSpec using PS no only allows de ining high le el eusable equi emen s o Web Applica ions; i also helps o de i e he se o es s ha will be used o alida ing he inal esul o he applica ion design and implemen a ion. 6 Ou App oach in a Nu shell Nex , we will p esen ou app oach o iden i y, design and implemen adap i e e- qui emen s in Web Wo k lows. The app oach is based on he idea ha any adap i e equi emen mus be ea ed as i s –class; as a consequence we conside hese e- qui emen s as belonging o sepa a e conce n1 [11] allowing us o isola e, model and la e compose bo h co e applica ion wo k lows wi h adap i e equi emen s. In his aspec we ocus on Web wo k low equi emen s, speci ically in analysis and model- ling aspec s. Thei impac in di e en applica ion ie s has been al eady p esen ed in[14,12]. Co e Web wo k low p ocess Adap a ion equi emen li ecycle Inconsis encies ound Fig. 4. O e all schema o wo k low equi emen modelling The app oach comp ises a se o s eps ha a e depic ed in Figu e 4 and desc ibed below: S ep 1: Wo k low equi emen ga he ing. Using well-known equi emen elici a- ion echniques such as mee ings, su eys, Join Applica ion De elopmen (JAD), e c. a So wa e Requi emen Speci ica ion (usually in na u al lan- guage) is p oduced. In he case o an agile unde lying de elopmen p ocess, a b ie e desc ip ion is usually p oduced wi h use s o ies [4]. S ep 2: Wo k low equi emen modelling. Web applica ion equi emen s a e o - malized using a equi emen Domain Speci ic Language (DSL). This o mal- iza ion is essen ial du ing he equi emen ga he ing p ocess wi h s ake- holde s. By means o using a equi emen DSL, he asks such as es s de i- a ion and scena ios simula ions can be au oma ed easily. In his wo k, we selec ed WebSpec as equi emen DSL. S ep 3: Wo k low equi emen gene aliza ions modelling. Base Wo k low changes a e modelled using he Pa e n Speci ica ion ex ension o he e- qui emen DSL; in his pape we exempli y wi h he WebSpec ex ension. S ep 4: Consis ency alida ion. Syn ac ic and seman ic analysis is pe o med o e equi emen s. By means o an algeb aic compa ison o models, candida e 1 In so wa e enginee ing a conce n ep esen s a ma e o in e es ha g oups a cohe en se o equi emen s. s uc u al and na iga ional con lic s a e de ec ed. On he o he hand, candi- da e con lic s a e analyzed and seman ic equi alences a e de ec ed. Fo each candida e con lic , bo h he new equi emen and he comp omised equi e- men a e ansla ed om a high abs ac ion le el ( he equi emen s DSL) o a minimal o m, using an a omic cons uc o in o de o de ec seman ic di e - ences. Seman ic equi alences be ween equi emen s a e de ec ed o wa ning equi emen analys s. Fo mo e in o ma ion see [13]. In he case o adap a ion equi emen s, a p e ious wea ing is pe o med among bo h kind o equi emen s ob aining ins an ia ed PS. S ep 5: Tes de i a ion. In his s ep, bo h adi ional WebSpec diag am and Web- Spec PS ex ension a e p ocessed o p oducing es s ha allow alida ing he inal Web Applica ion. This also allows assessing he se o equi emen wi h use s by using simula ions in he ea ly s ages o UI mocking. La e he same es s a e used in he es ing phase o he so wa e de elopmen p ocess. In he ollowing sec ion we p esen a simple bu illus a i e example o modeling wo k low equi emen s. Fi s , a simple wo k low o checking ou p oduc s in an e- comme ce Web applica ion is modelled using WebSpec. On he o he hand, a simple equi emen ha in oduces con ex awa eness in he wo k low is designed using PS. 6.1 Requi emen Ga he ing (S ep 1) We use as a unning example he de elopmen o an e-comme ce si e. In Figu e 5, use s o ies [4] de i ed om ga he ed equi emen s a e shown. The e a e h ee use s o ies: “Checkou p ocess” (US1), “Reduced checkou p ocess om sma phone” (US2), and “O de ing a p oduc ” (US3). The i s , on he le -hand side, de ines a basic wo k low o checking ou selec ed p oduc s in a s aigh o wa d way whe e issues such as p oduc w apping, deli e y and paymen me hod mus be co e ed. In he middle, i is equi ed ha he deli e y con igu a ion s ep in he wo k low mus be emo ed and in i s place he cu en loca ion is used o se ing up he shipping ad- d ess. Finally, on he igh -hand side, a use s o y de ines ano he iew poin o he checkou p ocess de ined by a di e en s akeholde . Fig. 5. Applica ion’s use s o ies 6.2 Wo k low Requi emen Modelling (S ep 2) Fo his s ep we will adop a wo k low’s de ini ion p esen ed in [15] whe e a wo k- low has as a main objec i e o deal wi h a case. A wo k low has a se o elemen s ha allows achie ing he objec i e: a s a e and a se o in e connec ed ask whe e each one can ha e condi ions ha enable i s execu ion. F om his de ini ion, we claim ha WebSpec can help modelling Wo k lows equi emen om a use in e ac ion pe spec- i e. Use s o ies de ine he case ha mo i a es wo k low design wi h WebSpec. WebSpec in e ac ion a e used o p esen ing a ailable asks and s a e in o ma ion, meanwhile ansi ion a e used o desc ibing wo k low condi ions and s a e changes. The e o e wo k lows a e desc ibed in a WebSpec scena io ha comp ises a se o (WebSpec) in e ac ions and ansi ion. Each In e ac ion desc ibes he expec ed wo k- low’s inpu and ou pu using widge s (Labels, Radio Bu on, e cs.) meanwhile ansi- ions ep esen s ac ions ha applica ion mus pe o m wi h i s co esponding gua d. In Figu e 6, he checkou p ocess in a Web applica ion is depic ed as a se o in e - ac ions whe e he use is able o selec a p oduc o s a se ing ou i s pu chase (in- e ac ion P oduc s); nex she is able o choose whe he a simple o gi w ap should be used; nex , deli e y in o ma ion mus be in oduced such as add ess and ci y; and inally he lis o cu en o de s is shown. Fig. 6. WebSpec scena io o Checkou p ocess based on US1 6.3 Wo k low Requi emen Gene aliza ions Modelling (S ep 3) So a , we ha e modelled wo k lows in Web applica ion using WebSpec. Some imes he e a e equi emen s, such as US2 – “Reduced checkou p ocess om sma phone”, ha in oduce enhancemen s o e main wo k lows like adap a ions o empo al changes. In o de o model his kind o equi emen s, we will use he p oposed ex en- sion o WebSpec ha in oduces PS concep s o gene alizing beha iou s. In Figu e 7, Use S o y 2 (US2) is modelled o e iding he de aul na iga ion p e- sen ed in Figu e 6 whe e deli e y in o ma ion speci ica ion (Deli e y in e ac ion) is by-passed, and, ins ead, O de S a us in e ac ion is exhibi ed a e selec ing Packag- ing con igu a ion. This “by passing” is achie ed de ining a ansi ion ha goes om “Packing” in e ac ion o “O de s a us” in e ac ion. As he speci ica ion is abs ac , i de ines he “|Packaging” ole ha la e binds o Packaging in e ac ion and “|O de s a us” ha la e binds o O de s a us in e ac ion o e iding he ansi ion iden i ied wi h #nex o iginally de ined in Figu e 6. Fig. 7. WebSpec diag am o “Reduced checkou p ocess o sma phones” use s o y {con ex [de ice.kind]=sma phone} click(Packaging.nex )