Injecting Quality Attributes into Software Architectures with the Common Variability Language

Injec ing Quali y A ibu es in o So wa e A chi ec u es wi h he Common Va iabili y Language Jose-Miguel Ho cas Uni e sidad de Málaga, Andalucía Tech, Spain ho [email protected] Mónica Pin o Uni e sidad de Málaga, Andalucía Tech, Spain pin [email protected] Lidia Fuen es Uni e sidad de Málaga, Andalucía Tech, Spain l @lcc.uma.es ABSTRACT Quali y a ibu es ha add new beha io o he unc ional so wa e a chi ec u e a e known as unc ional quali y a - ibu es (FQAs). These FQAs a e applied o pieces o so - wa e om small componen s o en i e sys ems, usually c oss- cu ing some o hem. Due o his c osscu ing na u e, modeling hem sepa a ely om he base applica ion has many ad an ages (e.g. eusabili y, less coupled a chi ec- u es). Howe e , diffe en applica ions may equi e diffe -en configu a ions o an FQA (e.g. diffe en le els o secu- i y), so we need a language ha : (i) easily exp esses he a iabili y o he FQAs a he a chi ec u al le el; and ha (ii) also acili a es he au oma ic gene a ion o a chi ec u al configu a ions wi h cus om-made FQAs. In his sense, he Common Va iabili y Language (CVL) is ex emely sui ed o use a he a chi ec u al le el, no equi ing he use o a pa icula a chi ec u al language o model base unc ional equi emen s. In his pape we p opose a me hod based on CVL o: (i) model sepa a ely and gene a e FQAs cus- omized o he applica ion equi emen s; (ii) au oma ically injec cus omized FQA componen s in o he a chi ec u e o he applica ions. We quan i a i ely e alua e ou app oach and discuss i s benefi s wi h a case s udy. Keywo ds CVL, quali y a ibu es, SPL, a iabili y, wea ing 1. INTRODUCTION The quali y o a so wa e sys em is measu ed by he ex- en o which i possesses a desi ed combina ion o quali y a ibu es (QAs) [2] such as usabili y, eliabili y, secu i y and scalabili y. Whe he o no a sys em will be able o exhibi i s desi ed (o equi ed) QAs is subs an ially de e mined by i s so wa e a chi ec u e, h ough he use o diffe en a chi- ec u al ac ics [3]. Fo some QAs, he a chi ec u al ac ic o be ollowed consis s in he injec ion (i.e. in oduc ion) o specialized elemen s in o he a chi ec u e (e.g. an au ho- iza ion mechanism o sa is y he secu i y QA) [3]. These QAs a e no mally known as unc ional quali y a ibu es (FQAs) [12], and a e diffe en om o he QAs such as cos o efficiency ha can be mapped o a chi ec u al o imple- men a ion decisions, bu no di ec ly o unc ional compo- nen s. Examples o FQAs a e e o handling, secu i y, con- ex awa eness, usabili y, pe sis ence, eco e y, e c. Ou main idea is o gi e p io i y o he FQAs ha a e equi ed by an applica ion om he ea ly s ages o he so - wa e de elopmen , based on h ee main con ibu ions: (1) he specialized elemen s equi ed o sa is ying he FQAs a e modeled sepa a ely om he base so wa e a chi ec u e; (2) hese elemen s a e hen semi-au oma ically injec ed in o he applica ion a chi ec u e; and (3) he app oach is imple- men ed using he Common Va iabili y Language (CVL) [10]. The mo i a ion o modeling FQAs sepa a ely om he base a chi ec u e is ha FQAs a e no mally equi ed by se - e al applica ions — i.e. hey a e ecu en , and mos o hem c osscu he sys em a chi ec u e. So, modeling hem sepa- a ely om he base applica ion has many ad an ages (e.g. eusabili y, less coupled a chi ec u es, e c.). Fo ins ance, an enc yp ion algo i hm used o enc yp he in o ma ion does no depend on he applica ion ha needs i . Also, diffe en applica ions may equi e diffe en le els o an FQA (e.g. se- cu i y). Fo example, a specific applica ion may equi e ac- cess con ol and anonymi y while ano he may equi e only enc yp ion, o may equi e a diffe en kind o enc yp ion al- go i hm. In o he wo ds, he e is much a iabili y in FQAs, and he So wa e A chi ec (SA) should be able o selec he se o specialized a chi ec u al elemen s ha need o be injec ed o ulfill he applica ion equi emen s ega ding a pa icula FQA, which is no a i ial ask. Rega ding he second pa o ou app oach, once we ha e gene a ed cus om models o he FQAs o a gi en applica- ion, hese models need o be injec ed in o he base model o he applica ion. Being inspi ed by Aspec -O ien ed Mod- eling (AOM)1, in ou app oach, fi s we iden i y and selec he poin s in he base model whe e he cus om FQA mod- els ha e o be injec ed, and hen au oma ically gene a e he applica ion a chi ec u e wo en wi h he cus omized FQAs. Finally, ou hi d con ibu ion is he echnical de ails o ou app oach. In o de o define a amily o FQAs, a lan- guage o model he a iabili y o FQAs is needed. Al hough mos o he a iabili y app oaches use Fea u e Models (FMs), hei main sho coming is ha an addi ional p ocess is e- 1h p://www.aspec -modeling.o g/ qui ed o gene a e an a chi ec u al configu a ion ha mee s an FM configu a ion. CVL is mo e sui able o use a he a chi ec u al le el, since i defines links be ween he a iabil- i y specifica ion and he p oduc line a chi ec u e (PLA). The ad an ages o using CVL a e: (i) i is an MOF-based a iabili y language and his means ha any MOF-based a chi ec u al language can be used wi h he a iabili y in- o ma ion o CVL; (ii) he links be ween he a iabili y and base a chi ec u al models make i possible o au oma ically gene a e so wa e a chi ec u e configu a ions, ensu ing ha hey ulfill he a iabili y specifica ion, (iii) he seman ic o he CVL a ia ion poin s can be ex ended, and (i ) CVL in- cludes he mos impo an cha ac e is ics o simila a iabil- i y models (e.g. FM) such as ca dinali y o a ia ion poin s, c oss- ee cons ain s, e c. Due o all hese ad an ages he e is a g ea in e es in he SPL communi y in adop ing CVL in hei p oposals [5, 6]. Bu , since bo h he CVL language and i s ool suppo a e no el, he effo o using CVL is cu en ly conside able. Summa izing, in his pape we p esen an SPL app oach based on he use o CVL o au oma ically gene a e, om a amily o eusable FQAs, so wa e a chi ec u e configu a- ions ha include cus om made FQAs. As discussed u he on, in Sec ion 3, his app oach is an ex ension o ou p e- ious wo k [11] and defines a mo e gene ic, in eg a ed and ex ensible app oach. One impo an con ibu ion is ha he cus om made FQAs a e au oma ically wo en wi h he base applica ion by ex ending he seman ic o he CVL a ia ion poin s. We quan i a i ely e alua e ou app oach by using app op ia e me ics o assess he benefi s o ou app oach, and illus a e i wi h an In elligen T anspo a ion Sys em case s udy. Also, we discuss he benefi s o using CVL in achie ing he goals posed in his pape . Besides his in oduc ion, Sec ion 2 p esen s he CVL, and desc ibes he case s udy used h oughou he pape . Sec ion 3 o e iews ou app oach and highligh s i s main no el ies in compa ison wi h ou p e ious wo k [11]. In Sec- ion 4 we explain in de ail how we model FQAs by using CVL. The cus omiza ion and injec ion o he FQAs in o he base applica ion o ou case s udy is explained in Sec ions 5 and 6, espec i ely. In Sec ion 7 we e alua e ou p oposal. Sec ion 8 discusses he ela ed wo k. Finally, Sec ion 9 con- cludes he pape and p esen s u he wo k. 2. BACKGROUND INFORMATION In his sec ion we b iefly summa ize CVL.2Then, he case s udy ollowed h oughou he pape is desc ibed. 2.1 CVL The CVL is a domain-independen language o speci ying and esol ing a iabili y o e MOF-complian models. CVL p o ides an execu able engine o au oma ically p o- duce a esol ed model om h ee main models: (1) he base model o e which he a iabili y is specified and esol ed. (2) The a iabili y model ha specificies he a iabili y in an abs ac le el wi h a iabili y specifica ions (VSpecs)and in a conc e e le el h ough a ia ion poin s. VSpecs a e ee s uc u es ep esen ing choices (“ ea u es” in mos SPL e - minologies) and can include logical cons ain s defined in a subse o he Objec Cons ain Language (OCL). Va ia ion poin s define specific modifica ions o be applied o he base 2Comple e desc ip ion in h p://www.omgwiki.o g/ a iabili y/ model du ing ma e ializa ion — i.e. he p ocess o ans- o ming a base model in o a configu ed p oduc model. (3) A esolu ion model ha p o ides esolu ions o he VSpecs in o de o ma e ialize a base model wi h a a iabili y model. The main cha ac e is ics o CVL ha we will use a e: Configu able uni (CU). Se o a ia ion poin s ha hides he in e nal o a base model, exposing a VIn e ace. Va iabili y in e ace (VIn e ace). G oup o VSpecs ha ha e o be esol ed o ma e ialize a CU. Composi e VSpec (CVSpec). VSpec ha is esol ed by esol ing o he VSpecs ha a e a iabili y in e aces. Opaque Va ia ion Poin (OVP). I allows cus omizing he seman ic o he exis ing CVL a ia ion poin s h ough a model ans o ma ion language. 2.2 Case S udy We mo i a e ou p oposal p esen ing a case s udy based on In elligen T anspo a ion Sys ems (ITSs) [1]. In his con ex , he e is a se o se ices (e.g. oad sa e y, wea he condi ions,. . . ) ha all equi e communica ion be ween e- hicles (V2V) and ia oadside access poin s (V2I). An ITS applica ion equi es specific secu i y se ices: p i acy, o p o ec he pe sonal in o ma ion o d i e s such as he ou e ollowed; in eg i y, o ensu e he da a au hen- ici y exchanged o e he ne wo k; and confiden iali y and au hen ica ion, o allow he d i e s o use ce ain se ices o V2I (e.g. paymen a elec onic oll). Con ex awa eness and usabili y FQAsa ealso equi edino de oob aincon- ex in o ma ion o he use (e.g. license de ec o , wea iness) o o he ca (e.g. GPS, p oximi y senso s) and o p o ide con ex ual help acco ding o he use s needs, espec i ely. 3. OUR PROPOSAL This sec ion p esen s a gene al o e iew o ou app oach (Figu e 1). We dis inguish h ee main s ages wi h wo diffe - en ac o s: (1) FQAs modeling, pe o med by a domain ex- pe in quali y a ibu es; (2) FQAs cus omiza ion o he e- qui emen s o a pa icula applica ion, and (3) FQAs wea - ing. S eps (2) and (3) a e pe o med by he SA. S age 1: FQAs modeling. In his s age, an expe in he domain o he QAs mod- els he a iabili y o FQAs ollowing he CVL app oach. To do his, he/she fi s builds he so wa e a chi ec u e o he FQAs by using any MOF-complian language (FQAs Base Model in Figu e 1), and hen defines a a iabili y model o he FQAs in CVL (FQAs Va iabili y Model). This sup- poses a no el y in compa ison wi h ou p e ious wo k [11] in which he FQAs had o be obliga o ily modeled wi h aspec - o ien ed so wa e a chi ec u es, making use o a p opie a y ADL and o p opie a y ools. Mos o he FQAs a e composed by many conce ns. The secu i y FQA, o example, is composed by access con ol, au hen ica ion, p i acy, in eg i y, and enc yp ion, among o he conce ns. Howe e , no all o he conce ns o an FQA a e equi ed by all he sys ems. Fo example, an applica ion may equi e only au hen ica ion and access con ol. Also, he domain expe needs o conside ha some o he con- ce ns o an FQA ha e dependencies be ween hem, such as he confiden iali y conce n ha depends on he enc yp ion conce n o ensu e ha all he in o ma ion is enc yp ed and canno be ob ained by hi d pe sons. We call hese depen- dency ela ionships be ween he conce ns o he same FQA, in aFQA-dependencies. Fu he mo e, FQAs affec each o he , so dependency ela ionships be ween diffe en FQAs mus also be conside ed. Fo ins ance, he con ex ual help conce n o he usabili y FQA depends on he au hen ica ion conce n o he secu i y FQA in o de o p o ide cus omized help based on he p e ious expe ience o he use . We call hese dependency ela ionships be ween conce ns o diffe en FQAs, in e FQA-dependencies. This supposes a diffe ence be ween ou app oach and o he p oposals ha add ess FQAs’ a iabili y (e.g. QADA [13], RiPLE-DE [4]), basically because hey model hese FQAs as pa o he domain analysis o an SPL, and no sepa a ely as we p opose. An impo an hing ha is wo h highligh ing is ha his s age is pe o med only once. This means ha he FQAs base model and he FQAs a iabili y model will be com- ple ely eused by any applica ion ha wan s o inco po a e hese FQAs in o i s so wa e a chi ec u e, jus by ollowing s ages 2 and 3 o ou app oach. S age 2: FQAs cus omiza ion. In he second s age o ou app oach, he SA c ea es a configu a ion o he FQAs (FQAs Resolu ion Model) acco d- ing o he equi emen s o a pa icula applica ion. This means ha hose a iable conce ns ha a e no equi ed by he base applica ion will no be inco po a ed in o he final applica ion. This s age is au oma ed by using he execu ion engine o CVL (CVL Execu ion) ha esol es he a iabili y o he FQAs a ia ion poin s. This is ano he no el y o his app oach. P e iously, in [11], an addi ional language had o be used o link he FQAs a iabili y model wi h he FQAs base model. Mo eo e , he cus omiza ion o he FQAs de- pended on he defini ion and ins an ia ion o aspec -o ien ed a chi ec u al empla es, which we e defined using ou p op i- e a y ADL. The CVL engine akes as inpu s he FQAs Reso- lu ion Model, heFQAs Va iabili y Model and he FQAs Base Model, and au oma ically de i es (ma e ializes) he esol ed model o he FQAs (FQAs Resol ed Model). This model only con ains he so wa e elemen s o he FQAs ha a e needed acco ding o he equi emen s o he applica ion. S age 3: FQAs wea ing. Once he FQA esol ed model has been gene a ed in he p e ious s age, he nex s ep consis s o “wea ing”, o com- posing, i wi h he so wa e a chi ec u e o he base appli- ca ion (Applica ion Base Model in Figu e 1). The ou pu o his wea ing p ocess is an applica ion a chi ec u e ha also inco po a es he FQAs (Applica ion Resol ed Model (appli- ca ion a chi ec u e + FQAs)). This wea ing is no a s aigh - o wa d ask since each FQA will ha e o be wo en a di - e en poin s o he base applica ions (join poin s) and, u - he mo e, each FQA’s conce ns will be wo en acco ding o a diffe en wea ing pa e n, depending on he seman ic o he conce n. Mo eo e , his should be done au oma ically, wi hou manually modi ying he applica ion a chi ec u e. Thus, he challenge he e is o define a p ocess ha sys- ema ically in eg a es high-le el quali y solu ions in o he base a chi ec u e o a gi en applica ion, bu wi hou ha - ing o unde s and he inne wo kings o he quali y solu- ions. In o de o do ha , we need o adap he CVL ap- p oach (see Sec ion 6). Fi s ly, ou based model is o med by wo models, he FQAs Resol ed Model and he Applica- ion A chi ec u al Model. Secondly, du ing he CVL Execu- Figu e 1: Ou app oach o modeling FQAs. ion he con ol mus be delega ed o a Model-2-Model en- gine (M2M Engine) such as QVT, in cha ge o pe o ming he wea ingo hese womodels.Thewea ingispe o medac- co ding o he wea ing in o ma ion p o ided by he Appli- ca ion Wea ing Model. This model uses he OVPs o CVL, which a e he mechanism p o ided by CVL o ex end he seman ic o he CVL a ia ion poin s. Using he OVPs he wea ing ules ha indica e whe e he FQAs mus be in- co po a ed in o he co e so wa e a chi ec u e a e specified as use -defined M2M ans o ma ions (Wea ing Rules (M2M ans o ma ions)). The wea ing p ocess in oduced he e, and de ailed in Sec ion 6, is a new con ibu ion o his pa- pe and was no pa o he p oposal p esen ed in [11]. The es o he pape desc ibes each s age in mo e de ail, using he case s udy desc ibed in he p e ious sec ion. 4. MODELING FQAS WITH CVL This sec ion desc ibes he fi s s age o ou app oach, in which he FQAs (secu i y, con ex awa eness, and usabili y), hei commonali ies and a iabili ies, and he dependencies be ween hem a e modeled. 4.1 FQAs base model In ou app oach he FQAs Base Model specifies he so wa e a chi ec u e o he FQAs. Fo ins ance, he UML so wa e a chi ec u e modeling he unc ionali y o he diffe en con- ce ns o he secu i y FQA is shown a he bo om o Fig- u e 2. This a chi ec u al model should include he comple e unc ionali y o he secu i y FQA. In o de o simpli y he model, we only include he e he In eg i y,Con iden iali y, Enc yp ion,Au hen ica ion,andHash componen s. These a e composi e componen s ha include o he necessa y compo- nen s o implemen he unc ionali y o each conce n. Fo ins ance, Enc yp ion includes componen s o enc yp and de- c yp in o ma ion using diffe en enc yp ion algo i hms. In o de o achie e a be e modula iza ion we model each FQA independen ly o each o he and hen we model he de- pendencies and in e ac ions be ween hem. Thus, he bo - om o Figu e 3 shows he high-le el a chi ec u al model o all he FQAs oge he . Al hough no included due o Secu i y_In Secu i y_CU Con iden iali y Au hen ica ion Use PassAu h Ca dAu h Au hLogging BioAu h Symme ic Asymme ic 1..1 1..1 1..* Enc yp ion P i acy Au hen ica ion In eg i y SHA-2 MD5 Hash Enc yp ion Secu i y 1..1 Hash :Objec Exis ence DSA RSA ECDSA AES DES 1..* 1..* SHA-1 ... Limi edSession Secu i y_C KeyS o age PseudonymousCe i ica e Op ional Manda o y Choice OCL Cons ain min..max Mul iplici y Binding Base model e e ence Composi e VSpec Va iabili y In e ace Con igu able Uni :LinkExis ence :Objec Exis ence :Objec Exis ence :LinkExis ence :Objec Exis ence :Objec Exis ence VSpec ee Va ia ion poin s Base model Figu e 2: Modeling secu i y FQA in CVL. he lack o space, he so wa e a chi ec u es o he con ex awa eness and he usabili y FQAs a e modeled in a simila way as o he secu i y FQA. 4.2 FQAs a iabili y model Once he FQAs base model has been specified, he nex s ep is o model he FQAs Va iabili y Model.ThisCVL a i- abili y model includes he VSpecs, he a ia ion poin s, he bindings be ween he a ia ion poin s and he VSpecs, and he e e ences om he a ia ion poin s o he base model. As an example, he a iabili y model o he secu i y FQA is shown in Figu e 2. We dis inguish h ee pa s: (1) he VSpec ee o he secu i y FQA ( op o Figu e 2), (2) he base model o he secu i y FQA (bo om o Figu e 2), and (3) he a ia ion poin s (middle o Figu e 2). The a ia- ion poin s a e g ouped in o he secu i y configu able uni (Secu i y_CU). Then, he Secu i y_CU is bound o a com- posi e VSpec (Secu i y_C ) which e e s o he a iabili y in e ace Secu i y_In — i.e. he VSpec ee. In he Secu i y_In VSpec we iden i y all he conce ns ha a e pa o he secu i y a ibu e, model hem by choices whose la e esolu ion equi es a yes/no decision, indica e which a e op ional and which a e manda o y, and wha he in aFQA-dependencies be ween hem a e. As s a ed, in his VSpec ee we only show a subse o he secu i y conce ns. These conce ns a e also composed by o he conce ns. Fo ins ance, he e a e diffe en kinds o au hen ica ion: use + passwo d (Use PassAu h), in elligen ca d (Ca dAu h), and biome ic (BioAu h). The kind o a iabili y ha we need o exp ess is ha “no all o he conce ns o an FQA a e equi ed by an ap- plica ion and hus, no all o he componen s o ha FQA base model need o be inco po a ed in o he applica ion a - chi ec u e”. In CVL his kind o a iabili y is exp essed by using he “exis ence” a ia ion poin ha indica es he exis- ence o a pa icula objec , link, o alue in he base model. Finally, in CVL, he a ia ion poin s need o be bound o elemen s o he VSpec ee and need o e e o elemen s o he FQA base model. This is how he ela ionship be ween he a iabili y model and he base model is specified in CVL. Mo eo e , hese links a e used by he CVL execu ion engine o au oma e he gene a ion o a p oduc configu a ion. Fo ins ance, he a ia ion poin bound o he Con iden iali y conce nin heSecu i y_In VSpec (:Objec Exis ence)in- dica es ha i confiden iali y is decided posi i ely (ma ked as “T ue” in he esolu ion model) in a configu a ion, he ela ed elemen s ( he Con iden iali y componen and he associa ed in e aces and po s wi h hei a achmen s) in he base model will exis in he final applica ion and i con- fiden iali y is decided nega i ely (ma ked as “False” in he esolu ion model) hose ela ed elemen s will be emo ed om he FQA esol ed model. In o de o main ain he consis ency and o achie e a good modula iza ion o he design, we speci y he a iabil- i y model a he same abs ac ion le el as we did o he FQA base model. This means ha he a iabili y o each FQA is specified independen ly om he a iabili y o he o he FQAs. This can be done in CVL by using composi e VSpecs and configu able uni s. Then, we ela e he diffe en a iabili y models defining a “comple e” a iabili y model including all he FQAs wi h hei ela ionships (Figu e 3). We apply he concep ual in eg i y p inciple3 o compose he diffe en FQAs configu able uni s. As Figu e 3 shows, he FQAs VSpec includes he h ee FQAs by including he h ee 3The o e all design pa e n o a sys em is eflec ed in any pa o he sys em. composi e VSpecs p e iously c ea ed (Secu i y_C ,Usabil- i y_C ,andCon ex Awa eness_C ). These VSpecs e e o he in e aces o he configu able uni o each FQA (Secu i y_CU, Usabili y_CU,andCon ex Awa eness_CU). Each configu able uni e e s o i s own composi e componen in he FQAs base model (bo om o Figu e 3). Each o hese componen s ha e inne a iabili y ha we ha e p e iously modeled o each FQA. 4.2.1 Dependency modeling Ou app oach models he dependencies by using he CVL cons ain s. CVL cons ain s exp ess ela ionships be ween elemen s o he VSpec ha canno be di ec ly defined by hie a chical ela ions. We define he in aFQA- and he in e FQA-dependencies a a diffe en le el o abs ac ion: in aFQA-dependencies a e defined in he con ex o each FQA configu able uni while in e FQA-dependencies a e de- fined in he con ex o he comple e FQAs a iabili y model. In aFQA-dependencies. In Figu e 2, each in aFQA- dependency is ep esen ed by a p eposi ional cons ain (ex- p essed in OCL) in a pa allelog am ha cap u es a condi ion in a choice. Fo ins ance, he dependency 'confiden iali y equi es enc yp ion'is modeled by a aching he cons ain Enc yp ion o he choice Con iden iali y.Thus, hechoice Enc yp ion has o be posi i ely decided whene e Con iden- iali y is posi i ely decided. Dependencies a e also p esen ed in he secu i y base model. Fo ins ance, al hough confiden iali y affec s da a in gen- e al and only equi es enc yp ion, p i acy also affec s peo- ple’s in o ma ion and equi es he au hen ica ion o he use . So, he e is a dependency be ween he p i acy conce n and he au hen ica ion conce n. In Figu e 2, he a ia ion poin (:LinkExis ence) bound o he P i acy choice e e s o a e- qui ed in e ace o he Con iden iali y componen in he UML secu i y base model. This link ep esen s he depen- dency ela ionship be ween he p i acy and he au hen ica- ion conce ns. The a ia ion poin indica es he exis ence o ha pa icula link. I P i acy is decided posi i ely in a es- olu ion model he link will exis in he esol ed model, and i P i acy is decided nega i ely, he link will be emo ed. In e FQA-dependencies. The FQAs_In VSpec o Fig- u e 3 includes he CVL cons ain s ha speci y he in e FQA- dependencies. Fo ins ance, he cons ain Au hLogging im- plies His o yLog ep esen s he dependency be ween he au- hen ica ion logging conce n o he secu i y FQA and he his o y log conce n o he usabili y FQA, and means ha i he Au hLogging choice is decided posi i ely, he His o- yLog choice has o be posi i ely decided oo. In e FQA- dependencies a e also p esen ed in he FQAs base model. I shows how he Secu i y componen ela es wi h he Con ex - Awa eness and Usabili y componen s due o he exis ing de- pendencies be ween hem. Fo ins ance, Au hen ica ion is equi ed by Usabili y in o de o p o ide con ex ual help. Also, Secu i y equi es Feedback om Usabili y and TimeAwa e om Con ex -Awa eness in o de o allow he au hen ica ion logs and he con ol o he session ime espec i ely. Finally, Con ex -Awa eness equi es Feedback o p o ide ale s when he in o ma ion con ex demands i . 5. CUSTOMIZATION OF THE FQAS In he second s age o ou app oach a alid configu a ion (cus omiza ion) o he FQAs a iabili y model is gene a ed, FQAs_In FQAs_CU Secu i y_CU Con ex Awa eness_CU Usabili y_CU FQAs 1..* Secu i y_C Con ex Awa eness_C Usabili y_C FQAs_C Au hLogging implies His o yLog Limi edSession implies TimeAwa e Wea iness implies Ale s Con ex ualHelp implies Au hen ica ion Figu e 3: FQAs a iabili y model. aken as inpu he equi emen s o he applica ion unde de elopmen , which in ou case is he ITS case s udy. As shown in Figu e 1, he cus omiza ion o he FQAs im- plies he defini ion o a FQAs Resolu ion Model.A esolu ion model is c ea ed by deciding which choices o he VSpec ee a e posi i ely decided and which ones a e nega i ely decided. The VSpec a he op o Figu e 44shows a alid configu a ion o he FQAs (a esolu ion model) ha sa isfies he equi emen s o ou ITS applica ion. Some o he choices shown in Figu e 4 ha e been selec ed because he applica- ion equi emen s explici ly iden ified hem as needed, such as p i acy, in eg i y, confiden iali y, au hen ica ion, loca ion awa e, use awa e and con ex ual help. O he conce ns, such as enc yp ion, hash, eedback, and ime awa e, had o be se- lec ed in o de o ob ain a alid configu a ion due o he ex- is ing dependencies be ween hose conce ns and hose ha we e o iginally equi ed. Fo ins ance, he e a e conce ns ha had o be selec ed due o he pa en -child ela ionship in he VSpec (e.g. he Con iden iali y and he P i acy choices). O he conce ns had o be selec ed because o he in aFQA-dependencies be ween conce ns o he same FQA (e.g. Con iden iali y and Enc yp ion). Finally, o he conce ns had o be selec ed due o he in e FQA-dependencies be ween conce ns o di - e en FQAs (e.g. Au hLogging o he Au hen ica ion conce n in he secu i y FQA and Log o he usabili y FQA). Thus, in ou case s udy, he e a e conce ns, as is he case o he enc yp ion o he hash conce ns, ha a e equi ed by o he conce ns bu had no explici ly specified as pa o he applica ion equi emen s. This occu s basically because hese dependencies a e no always ob ious o he applica ion equi emen s enginee o he SA. By ha ing a domain expe speci ying he in aFQA- and in e FQA-dependences as pa o he defini ion o he FQAs a iabili y in he fi s s age o ou app oach, in his second s age ou app oach helps he SAs o speci y so wa e a chi ec u es ha a e mo e accu a e ega ding he specifica ion and cus omiza ion o he FQAs o he necessi ies o he applica ions. Once he esolu ion model has been c ea ed, he CVL Exe- cu ion engine is execu ed o au oma ically gene a e he FQAs Resol ed Model, which is shown in Figu e 5. Only he nec- essa y unc ional componen s a e included in he esul ing FQAs so wa e a chi ec u e. 4Middle and bo om o Figu e 4 a e desc ibed in he nex sec ion. We show only one figu e o easons o space. Wea ing ules FQAs esol ed model (FQAsModel) Con iden iali y Ca dAu h Au hLogging 1..* Enc yp ion P i acy Au hen ica ion In eg i y HashEnc yp ion Secu i y Hash ECDSA SHA-2 Limi edSession KeyS o age Au hen ica ion Asymme ic TimeAwa e 1..* Loca ionAwa e Con ex Awa eness Use Awa e Wea iness TimeAwa e GPS P oximi ySenso LicenseDe ec o 1..* FQAs 1..* Au hLogging implies His o yLogs Limi edSession implies TimeAwa e Wea iness implies Ale s Con ex ualHelp implies Au hen ica ion PseudonymousCe i ica e OpaqueVa ia ionPoin 1 Applica ion a chi ec u al model (appModel) OpaqueVa ia ionPoin 2 OpaqueVa ia ionPoin 3 SpecialSubs i u ionAu h spec ype SpecialSubs i u ionEnc yp spec ype ... ... FQAs esolu ion model used as VSpec ee o he Applica ion Wea ing model sou ceObjec a ge Objec Feedback His o yLog Ale s 1..* Con ex ualHelp Usabili y Logs 1..* Seman icSpec1 Seman icSpec2 VSpec ee ( esolu ion model) Va ia ion poin s Base models Figu e 4: CVL model o he injec ion o he FQAs inside he applica ion a chi ec u e. 6. WEAVING THE CUSTOMIZED FQAS A his poin , an a chi ec u al model cus omized wi h he equi ed FQAs and conce ns has been gene a ed (high le el iew in he FQAsModel in Figu e 4 and low le el iew in Fig- u e 5). Now, in he hi d s age o ou app oach his FQAs esol ed model has o be inco po a ed in o he so wa e a - chi ec u e o he co e applica ion (appModel in Figu e 4). As p e iously s a ed, each conce n o he FQAs needs a pa icula ans o ma ion because i is wo en wi h he ap- plica ion in a diffe en way. The Applica ion Wea ing Model (Figu e 4) uses he OVPs o CVL o define a new seman ic o a a ia ion poin using model ans o ma ion ules. The s eps a e: (1) binding an OVP o each o he conce ns o he FQAs in he esolu ion model (e.g. enc yp ion, con ex- ual help); (2) speci ying a e e ence o he specific a chi ec- u al elemen s ha model ha conce n in he FQAs esol ed model, and (3) indica ing how he conce n will be wo en wi h he applica ion base model. OVPs a e also bound o an OVPType, whe e his ype explici ly defines he seman- ic o a special subs i u ion. A special subs i u ion implies he combina ion o a s anda d subs i u ion and use defined ans o ma ions. In ou case he special subs i u ion is done om he “sou ce objec ” o he “ a ge objec ” e e enced by he OVP as we show in Figu e 4. Based on his special subs i u ion he SA needs o e e o one o mo e join poin s ( a ge objec s) in he applica ion model whe e he beha io o he selec ed conce n (sou ce objec ) will be inco po a ed. We ha e iden ified a se o wea ing pa e ns (Table 1) ha ulfil ou needs o inco po a e he FQAs conce ns based on how he unc ionali y o he conce ns (ad ices) needs o be applied in o he diffe en poin s o he applica ion (join poin s). The special subs i u ion needed by each conce n is mapped o one wea ing pa e n p esen ed in Table 1.5Fo ins ance, he p i acy and he au hen ica ion conce ns ha e he same special subs i u ion ha indica es ha only one ad ice (e.g. au hen ica e()) o he selec ed conce n (e.g. au hen ica ion) is wo en in o he selec ed join poin (e.g. an in e ace o he base applica ion). Con inuing wi h ou example, o simpli y Figu e 4, we only show h ee OVPs bound o h ee conce ns: confiden- iali y, which is achie ed using enc yp ion, p i acy, and au- hen ica ion. Fo ins ance, he OpaqueVa ia ionPoin 1 is bound o he P i acy conce n in he VSpec ee and i is also bound o he OVPType SpecialSubs i u ionAu h6 (OVPType 1 in Table 1). This in u n specifies he seman- ics o he special subs i u ion wi h he necessa y ans o - ma ions (wea ing ules) o inco po a e he ela ed elemen (Con iden iali y ha con ains he P i acy unc ionali y) o he FQAs esol ed model (FQAsModel in Figu e 4) in o he applica ion base model (AppModel in Figu e 4). Algo i hm 1 shows he wea ing p ocess du ing he a i- abili y esolu ion pe o med by he CVL engine. I akes he se o OVPs defined (SOV P ) and o each OVP he seman- ic o he special subs i u ion associa ed (OVPType) is exe- cu ed by he M2M ans o ma ion engine (line 4). Sjoinpoin s is he se o join poin s e e enced by he OVP. When CVL is execu ed aking as inpu s he applica ion wea ing model, he applica ion base model (appModel) and he FQAs esol ed model, he ou pu is an au oma ically gene a ed model ep- esen ing he comple e applica ion so wa e a chi ec u e (Fig- u e 6), which includes he cus om FQAs. No e ha he configu a ion o he a chi ec u e ( he com- ponen s and hei ela ionships) is clea ly isible in he s a ic pa o he design. Addi ionally, s e eo yped dependencies 5Implemen a ion in ATL o he M2M ans o ma ions a e a ailable in h p://caosd.lcc.uma.es/spl/c l/CVL-models- ans o ma ions.zip 6In ou app oach p i acy is achie ed using au hen ica ion. «componen » Con ex -Awa eness «componen » Use Awa e «componen » Wea inessDe ec o «componen » LicenseDe ec o «componen » Use Awa e Manage TimeAwa e «componen » Loca ionAwa e «componen » Loca ion Manage «componen » P oximi y Senso «componen » GPS «componen » TimeAwa e «componen » Secu i y «componen » Au hen ica ion «componen » Pseudonymous Ce i ica e «componen » Session Manage «componen » Digi al Iden i y TimeAwa e Logs «componen » Enc yp ion «componen » Key Reposi o y «componen » Enc yp ion Manage «componen » ECDSA «componen » Hash «componen » HashManage «componen » SHA-2 «componen » Con iden iali y «componen » In eg i y Hash «componen » Usabili y «componen » Feedback «componen » Ale s «componen » Logs «componen » Con ex ual Help Au hen ica ion Con ex ual Help Loca ionAwa e Au hen ica ion Con iden iali y TimeAwa e Use Awa e Enc yp ion Feedback In eg i y Hash Figu e 5: FQAs esol ed model. Table 1: Special subs i u ions. OVPType Desc ip ion Example 1 Only one ad ice o a conce n is wo en in o a join poin . Au hen ica ion: he au hen ica e() ad ice is pe o med a ound he join poin . 2 The same ad ice is wo en mul iple imes in o a join poin . Time awa e:cu en Time() is applied wice (be o e and a e ) o measu e he ime session o he use . 3 The same ad ice is wo en in o diffe en join poin s. Loca ion awa e: he acqui ePosi ion() ad ice needs o be applied on he clien and on he se e side o es ablish loca ions. 4 Mul iple ad ices o he same conce n a e wo en in o a join poin . Feedback:log() ad ices a e in oked be o e and a e he join poin . 5 Mul iple ad ices o he same conce n a e wo en in o diffe en join poin s. Enc yp ion: enc yp he in o ma ion (enc yp (Objec ))be o e sending i and de- c yp i (dec yp (Objec ))a e ecei ing i . 6 Ad ices o diffe en conce ns a e wo en in o a join poin . Con ex ual help: fi s check whe he he use is au hen ica ed (isAu hen ica ed()) and hen show in o ma ion (showHelp()) based on he p e e ences o he use . 7 Ad ices o diffe en conce ns a e wo en in o diffe en join poin s. In eg i y:hash(Objec ) is applied be o e sending in o ma ion o he se e and checkIn eg i y(Objec ) is applied be o e use he in o ma ion in he se e . Algo i hm 1 Wea ing p ocess using CVL. Requi e: SOV P Ensu e: Resol edModel 1: o all p in SOV P do 2: c← p.sou ceObjec 3: Sjoinpoin s ← p. a ge Objec s 4: Resol edModel ←specialSubs i u ion(c,Sjoinpoin s, p. ype) 5: end o 6: e u n Resol edModel be ween componen s o he FQAs and componen s o he base applica ion make explici ha he sou ces o he ela- ionships c osscu s he a chi ec u al le el, and he a ge s a e he poin o he applica ion whe e hey ake place (i.e. he join poin s in he AOM e minology). Howe e , his is insufficien because he in e ac ions be ween he compo- nen s a e no ep esen ed. In o de o sol e his limi a- ion, in ou app oach he in e ac ions be ween he compo- nen s a e ep esen ed in a se o sequence diag ams ha a e also au oma ically gene a ed [14] by he ans o ma ion ules o he special subs i u ions. Fo ins ance, he beha io o he c osscu ing ela ionship o he au hen ica ion con- ce n is ep esen ed in he sequence diag am in Figu e 6 (b). This diag am shows how he V2V componen in okes he paymen Toll() me hod o he In aSe ice in e ace, and ha be o e he call is effec i e he au hen ica e() me hod o he Au hen ica ion componen is in oked. Simila ly, he sequence diag am o Figu e 6 (c) shows he beha io o he enc yp ion conce n when he V2V componen ansmi s in- o ma ion; ha is, be o e sending he message o he Commu- nica ion componen he enc yp () me hod o he Enc yp ion componen is in oked. 7. EVALUATION We e alua e ou wo k bo h quan i a i ely, by using me - ics o quan i y he benefi s p o ided by ou app oach, and quali a i ely, when he use o a me ic does no make sense. Table 2 desc ibes he me ics sui e ha ha e been used o e alua e ou app oach. Using hese me ics we ha e iden i- fied ha he e is: (1) a deg ee o dependency be ween FQAs (me ics 1–3). This means ha he e is a significan numbe o conce ns whose inclusion in a pa icula solu ion depends on he co ec iden ifica ion o hese dependencies, which a e no always s aigh o wa dly de i ed om he equi e- men s o he sys em. Consequen ly, hese dependencies may go unno iced by he SA e en i hey should be aken in o accoun o sa is y he equi emen s o a sys em; (2) a high deg ee o a iabili y (me ics 4–6), since modeling he FQAs as a “ amily” o p oduc s, and he au oma ic ma e ializa ion o he FQAs base model conside ably inc eases he num- be o “ alid” esolu ions o a FQA ha can be gene a ed; (3) a high deg ee o au oma ion, due o he high numbe o a chi ec u al elemen s ha a e au oma ically gene a ed in compa ison wi h he manual effo ha needs o be made in o de o include he FQAs inside he so wa e a chi ec u es o he applica ions. This deg ee o au oma ion implies a lowe de elopmen effo and gains in p oduc i i y; and (4) ahighdeg ee o sepa a ion o conce ns (me ics 7–8), which is imp o ed due o spli ing ou app oach in o h ee s ages. We p esen he esul s o modeling he h ee FQAs de- sc ibed in his pape : secu i y, con ex awa eness and us- abili y. Figu e 6: Comple e applica ion a chi ec u e (a); au hen ica ion (b) and enc yp ion (c) sequence diag ams. Table 2: Me ic Sui e Dependency Me ics 1. #in aFQA-dependencies: I measu es he numbe o dependencies ( ee-cons ain s and OCL cons ain s) be ween he conce ns o a FQA. 2. #in e FQA-dependencies: I measu es he numbe o dependencies (c oss ee-cons ain s and OCL cons ain s) be ween diffe en FQAs. 3. #dependen -elemen s: I measu es he minimum numbe o a chi ec u al elemen s (componen s, in e aces, ela- ionships,.. . ) ha need o be defined due o he exis ence o a dependency. Va iabili y Me ics 4. #choices: I measu es he o al numbe o choices in a VSpec. 5. # esolu ions: I measu es he o al numbe o alid esolu ions ha can be gene a ed om a VSpec. 6. Va iabili y le el: Exp essed as he a io #choices:# alid esolu ions. Sepa a ion o Conce ns Me ics 7. Lack o conce n-based cohesion (LCC): I measu es he numbe o conce ns angled in a pa icula componen . 8. Conce n diffusion o e a chi ec u al componen s (CDAC): I measu es he numbe o componen s in which a conce n is sca e ed. Deg ee o Dependency. The deg ee o dependency o he FQAs is shown in Ta- ble 3. By applying he dependency me ics (see Table 2), we coun he numbe o in aFQA- and in e FQA- dependen- cies, as well as he numbe o a chi ec u al elemen s ha a e needed in o de o sa is y hose dependencies. No e ha hese numbe s co espond only wi h he conce ns o he h ee FQAs p esen ed in his pape . A his poin , we would like o highligh ha each FQA dependency can imply he inco po a ion o a conside able numbe o a chi ec u al elemen s in o he so wa e a chi ec- u e. Fo ins ance, he secu i y FQA has only ou in aFQA- dependencies bu , in o de o sa is y hese ou dependen- cies, he SA needs o define a leas 33 a chi ec u al ele- men s. In e FQA-dependencies a e e en mo e difficul o sa is y because hey in ol e conce ns o he o he FQAs. Fo ins ance, o sa is y he in e FQA-dependency o he us- abili y FQA wi h he secu i y FQA, he SA needs o define a leas 13 a chi ec u al elemen s. The ele an issue he e is ha , using ou app oach, his complexi y is no managed di ec ly by he SA. Basically, because we make hose dependencies explici o make su e he/she is made awa e o hem and mus only selec he desi ed conce ns ha sa is y he dependencies. Then, he equi ed a chi ec u al elemen s a e au oma ically inco po- a ed in o he a chi ec u e. No e ha his is ce ain only by assuming ha he domain expe s co ec ly do hei job o modeling he FQAs and he dependencies be ween hem. Table 3: Deg ee o dependency Dependencies Secu i y Con ex awa eness Usabili y #in aFQA 4 3 1 #elemen s 33 12 3 #in e FQA 2 1 1 #elemen s 21 11 13 Table 4: Deg ee o a iabili y Secu i y Con ex awa eness Usabili y To al #choices 23 15 10 48 #componen s 21 19 7 47 # esolu ions 5354 575 79 313784 Deg ee o Va iabili y. Table 4 shows he numbe o choices ha we e specified in he VSpec o he secu i y, he con ex awa eness, and he usabili y FQAs, he numbe o componen s ha we e defined in he so wa e a chi ec u e o each FQA and he numbe o diffe en “ alid” esolu ions (configu a ions) ha can be gene a ed using ou app oach. The numbe o possible esolu ions will depend on he numbe o ini ial choices and on he numbe o dependen- cies be ween choices in he VSpec. In Table 4, we see ha , o secu i y, he domain expe will only once ha e o make, he effo o defining a VSpec wi h 23 choices and o speci- ying an a chi ec u al model wi h 21 componen s. Then he CVL engine au oma ically gene a es one o he 5354 alid secu i y configu a ions based on he selec ions in he VSpecs done by he SA. The co ec ness o he gene a ed so wa e a chi ec u es will depend on he co ec specifica ion o he a iabili y model. The a iabili y le el is lowe o con ex Table 5: Deg ee o au oma ion Case s udy Specified elemen s Deg ee o au oma ion manually au oma ically ITS 27 25 48.08% HW 42 38 47.50% TS 115 16 12.20% CS 43 34 44.20% awa eness (15 choices: 575 esolu ions) and usabili y (10 choices: 79 esolu ions) han o secu i y. These numbe s indica e ha some FQAs ha e a high de- g ee o a iabili y — i.e. he e a e many diffe en configu a- ions o secu i y ha can be c ea ed o sa is y he secu i y equi emen s o diffe en applica ions, and he manual spec- ifica ion o hese configu a ions by he SA (5354 in he case o secu i y) is a ha d and e o -p one ask. So, his me ic indica es ha he use o an SPL app oach makes sense. Deg ee o Au oma ion. Defining he a chi ec u al model o he FQAs and he a i- abili y model wi h he VSpecs and he a ia ion poin s is a difficul and specialized ask. Howe e , in ou app oach, his effo only needs o be made once and hen he FQA models can be eused in he de elopmen o many sys ems. The e o e, he main effo consis s o modeling he co e a - chi ec u e o he applica ion. Thus, in o de o speci y he deg ee o au oma ion o ou app oach, we compa e he num- be o a chi ec u al elemen s (i.e. componen s, p o ided and equi ed in e aces, and ela ionships) ha a e manually c e- a ed in he specifica ion o he co e so wa e a chi ec u e wi h he numbe o a chi ec u al elemen s ha a e au o- ma ically gene a ed, as defined in Equa ion 1. This is an adap a ion o he deg ee o au oma ion defined in [8], o be able o use his me ic a he a chi ec u al le el. Basically, a he a chi ec u al le el, he complexi y o defining a so - wa e a chi ec u e is measu ed by he complexi y o designing hei componen s, in e aces, and he ela ionships be ween hose componen s; and i does no depend on he complexi y o he pa icula implemen a ion o he componen s. Deg ee o Au oma ion = #elemen s FQAs #elemen s co e +#elemen s FQAs (1) We ha e applied he deg ee o au oma ion in ou ap- p oach when: (1) secu i y, con ex awa eness and usabili y a e added o he ITS case s udy, and (2) secu i y and us- abili y a e added o a heal h wa che (HW) indus ial case s udy, a oll (TS) case s udy and a c isis managemen (CS) case s udy (see Table 5). We no e ha , in he case s udy o his pape , he co e applica ion is composed by 27 a chi- ec u al elemen s, and when he FQAs a e inco po a ed, 25 new elemen s a e added o he a chi ec u e, ob aining a de- g ee o au oma ion o 48.08%. This alue is highe han in o he case s udies because he ITS equi es mo e QAs con- ce ns, and hose conce ns ha e many dependencies be ween hem. Thus, he esul s ob ained by applying his me ic indica es ha ou app oach can be use ul. Howe e , an em- pi ical s udy ha imply SAs de eloping p ojec s o diffe en complexi ies using ou app oach needs o be pe o med o confi m he benefi s sugges ed by his me ic. Deg ee o Sepa a ion o Conce ns. In ou app oach, he sepa a ed modeling o he FQAs om he co e applica ion a chi ec u e and he subsequen combi- na ion wi h he use o CVL and he c osscu s ela ionships all con ibu e o imp o e he sepa a ion o conce ns. On he one hand, we ha e modeled each FQA sepa a ely om each o he in o de o (1) iden i y he conce ns and hei depen- dencies, and (2) a oid he duplica ion o conce ns in diffe en FQAs. The esul is ha he conce ns o he FQAs a e well- encapsula ed only in hose componen s ha we e pa o he secu i y, he con ex awa eness, and he usabili y composi e componen s ( he CDAC me ic o all o hem is 1). The LCC me ic has also been applied o he same componen s, and he esul s show ha hey only con ain secu i y, con ex awa eness, o usabili y conce ns, espec i ely, and he in o - ma ion o he equi ed conce ns o he o he FQAs o sa is y hei dependencies. On he o he hand, his good deg ee o sepa a ion is kep a e he inco po a ion o he FQAs in o he applica ion a chi ec u e due o he use o he c osscu s ela ionships a he a chi ec u al le el. 7.1 Discussion The e alua ion esul s ob ained indica e ha he effo o sepa a ely defining FQAs o ming an SPL amily p esen s he ollowing ad an ages: (i) helps he SA o iden i y he dependencies, ake hem in o accoun and esol e hem; (ii) helps he SA o c ea e diffe en configu a ions o he FQAs; (iii) helps he SA o inco po a e he cus omized FQAs in o he a chi ec u e; (i ) he e is a be e deg ee o sepa a ion o conce ns due o he encapsula ion o he c osscu ing beha - io o he FQAs in sepa a e so wa e componen s. This acil- i a es he subsequen modifica ion o he applica ion and/o he FQAs. The ini ial esul s ob ained by some o he me - ics (deg ee o dependency and deg ee o a iabili y) suppo ou decision o use echniques and ools o SPLs o model- ing he FQAs. O he s (sepa a ion o conce ns) suppo ou decision o model hem sepa a ely om he base applica- ion. Finally, he deg ee o au oma ion sugges s ha i is wo h using ou app oach wi h ega d o he effo equi ed o gene a e and in oduce he cus omized FQAs models in o a so wa e a chi ec u e. Howe e , we need o comple e he e alua ion wi h empi ical s udies in o de o e idence he benefi s and use ulness o ou app oach. Despi e he benefi s o using he echniques and ools o SPLs and CVL in pa icula , we ha e also iden ified some sho comings o ou app oach. A possible disad an age is ha he SA has o deal wi h many models. Howe e , we need o ake in o accoun ha some o hese models a e jus configu a ions o he o he s (e.g. he esolu ion mod- els), o he s a e au oma ically gene a ed by CVL (e.g. he esol ed models), and o he s a e defined only once and a e eusable in o he applica ions (e.g. he FQAs base model and he FQAs a iabili y model). Ano he disad an age o ou app oach is ha he wea ing ules implemen ed as model- o-model ans o ma ions in he las s age o ou app oach depend on he me a-model used o speci y he co e so wa e a chi ec u e. This means ha hese ules will need o be adap ed o edefined i he SA decides o use a so wa e a chi ec u al model ha , in spi e o being MOF-dependen , does no inco po a e he same me a-model cons uc o s ha we used o define he wea ing ules. This is howe e a mino limi a ion in he sense ha ou app oach enables he in eg a ion o diffe en model- o- model ans o ma ions as pa o he wea ing s ep, by using he ex ension mechanism p o ided by CVL (i.e. he OVPs). Also no e ha e en i he wea ing ules need o be adap ed,