Citation Context

...e it on goal-based RE. and,sparticularly, to provide language support for representing,straversing and manipulating instances of a metamodel forsgoal modeling, for example based on the KAOS metamodel =-=[6]-=-. The meta-model could be provided as a set ofsbuilt-in constructs to a programming language, orsalternatively be provided in the form of (e.g.) a library.sCrucial, the meta-model must provide a way t...

Citation Context

... the four challengessdescribed in the following sections. To support suchsdynamic assessment of requirements, language featuressfound in goal-oriented requirements modeling languagessKAOS [23] and i* =-=[27]-=- hold particular promise. KAOS issparticularly useful here as it integrates the intentional,sstructural, functional, and behavioral aspects of a system,sand offers formal semantics that would allow au...

Citation Context

...g points for such astheory – for example, risk analysis for possible securitysissues in software-intensive systems [29], risk assessmentssin engineering disciplines [30], the economics ofsuncertainty =-=[31]-=-, and uncertainty in management theorys[28], as well as well-known mathematical models ofsuncertainty such as Bayesian networks. All of these fieldsshave developed theories for dealing with uncertaint...

Citation Context

...sFuzzy logic is not the only formalism that could besused to reason about uncertainty in the environment, ofscourse. Numerous mathematical and logical frameworkssexist for reasoning about uncertainty =-=[13]-=-. For example,sprobabilistic model checkers have been used to specifysand analyse properties of probabilistic transition systemss[16] and Bayesian networks enable reasoning oversprobabilistic causal m...

Citation Context

...ntext.sThe provision of understandable explanations ofssystem behaviour has been studied in a number of researchsfields: principally, in knowledge-based systems [35][38],sintelligent tutoring systems =-=[32]-=-, context-aware systemss[37][34], and debugging [39]. Depending on thesapplication, a range of information and a range ofsinteraction styles can be supported in explanations. Lim etsal [37] provide a ...

Citation Context

...es (e.g., Support VectorsMachines or Neural Networks) are black boxes that are notsinherently interpretable. Although there has been someswork on extracting rules from such technical solutionss(e.g., =-=[33]-=-), which can then be used to derive explanations,sexplaining such systems will remain a major challenge forsthe foreseeable future.sIn the context of requirements reflection, as describedsin this pape...

Citation Context

...ility means that programmers nowshave access to programming frameworks and run-timesinfrastructures that support self-adaptation. These includesadaptive architectures [15] such as OpenCom [5] Rainbows=-=[42]-=- and the work of Peyman et al. [43]. OpenCom, forsexample, provides a component model and a set of openscomponent libraries. A programmer can define thesarchitecture and compose it using a set of subs...

Citation Context

...ve access to programming frameworks and run-timesinfrastructures that support self-adaptation. These includesadaptive architectures [15] such as OpenCom [5] Rainbows[42] and the work of Peyman et al. =-=[43]-=-. OpenCom, forsexample, provides a component model and a set of openscomponent libraries. A programmer can define thesarchitecture and compose it using a set of substitutablescomponents from the compo...

Citation Context

...y of the decision model shouldsbe such that it can be evaluated efficiently at run-time.sSuch a framework can build on existing outranking andsinteractive approaches to multi-criteria decision-makings=-=[21]-=- [51] as well as on research on evaluating alternativess[18] and dealing with conflicts in goal models [24].sVII. SELF-EXPLANATIONsA well-known problem with self-adaptive systems issthat users may not...

Citation Context

...tsviable solution.sImproved capability means that programmers nowshave access to programming frameworks and run-timesinfrastructures that support self-adaptation. These includesadaptive architectures =-=[15]-=- such as OpenCom [5] Rainbows[42] and the work of Peyman et al. [43]. OpenCom, forsexample, provides a component model and a set of openscomponent libraries. A programmer can define thesarchitecture a...

Citation Context

...tical and logical frameworkssexist for reasoning about uncertainty [13]. For example,sprobabilistic model checkers have been used to specifysand analyse properties of probabilistic transition systemss=-=[16]-=- and Bayesian networks enable reasoning oversprobabilistic causal models [10]. However, only limitedsattention has been shown so far to the treatment ofsuncertainty in requirements engineering models....

Citation Context

...icipate all the exceptional circumstances.sIn contrast to assumptions made during the specification ofsthe system, the conditions of execution may changesunexpectedly manifesting unforeseen obstacles =-=[56]-=-. As asresult, the selection of the right set of choices, in the casesof self-adaptive systems, may need to be delayed until runtime when the system can reason to make choicessinformed by concrete dat...

Citation Context

...an build on existing outranking andsinteractive approaches to multi-criteria decision-makings[21] [51] as well as on research on evaluating alternativess[18] and dealing with conflicts in goal models =-=[24]-=-.sVII. SELF-EXPLANATIONsA well-known problem with self-adaptive systems issthat users may not understand or trust them. Such a lack ofsintelligibility can mean that users may cease to use a selfadapti...

Citation Context

...on-makings5. Self-explanationsResearch challenges for each of these are developed insmore detail over the next five sections.sIII. RUN-TIME REPRESENTATIONS OF REQUIREMENTSsArchitectural reflection [5]=-=[19]-=- offers a pointer to howsrequirements may become run-time artifacts. Architecturalsreflection allows introspection of the underlyingscomponent-based structures. An architecture meta-modelscan be used ...

Citation Context

...bout which significantsuncertainty exists at design-time. One key contribution tosthe achievement of this has been work on requirementssmonitoring, pioneered by the seminal work of Fickas andsFeather =-=[11]-=-.sRequirements monitoring is necessary becausesdeviations between the system’s run-time behaviour andsthe requirements model may trigger the need for a systemsmodification [9]. Such deviation needs to...

Citation Context

...service subject tosnetwork latency and uneven user demand may be muchsharder to determine on-the-fly.sDespite these difficulties, significant progress has beensmade on requirements monitoring [11][20]=-=[52]-=-. However,son the closely-related issue of how to take correctivesaction to reconcile system behaviour with the requirementssmodel when monitoring detects deviancy, research is stillsin its infancy. S...

Citation Context

...with the KAOS language [23] may provide thesbasis for defining this library. It would also bescomplemented with operators for resolving inconsistenciessbetween multiple views in the spirit of Xlinkit =-=[46]-=- orstechniques for automatically fixing inconsistencies insUML models [47]. Figure 1 summarizes the proposedsstructure.sFigure 1.sSynchronization between run-time requirements and thesarchitecturesThe...

Citation Context

...on of the goals tosbe achieved by the system, the operationalization of suchsgoals as specifications of services and their constrains, andsthe assignment of responsibilities for services amongsagents =-=[23]-=- (i.e. human, physical, and softwarescomponents) forming the system. Goals can besoperationalized in many different ways and the RE processsallows us to explore the choices, detect conflicts betweensr...

Citation Context

...ted efficiently at run-time.sSuch a framework can build on existing outranking andsinteractive approaches to multi-criteria decision-makings[21] [51] as well as on research on evaluating alternativess=-=[18]-=- and dealing with conflicts in goal models [24].sVII. SELF-EXPLANATIONsA well-known problem with self-adaptive systems issthat users may not understand or trust them. Such a lack ofsintelligibility ca...

Citation Context

...k of Fickas andsFeather [11].sRequirements monitoring is necessary becausesdeviations between the system’s run-time behaviour andsthe requirements model may trigger the need for a systemsmodification =-=[9]-=-. Such deviation needs to be correlatedswith the state of the environment so that the reasons can besdiagnosed and appropriate adaptation performed. Wheressystems have the need to adapt dynamically in...

Citation Context

...it is necessary to specify howsthe system’s requirements can evolve dynamically and tosspecify the abstract adaptation thresholds that allow forsuncertainty and unanticipated environmental conditionss=-=[53]-=-[4]. Unfortunately, to our knowledge none of thesexisting techniques deal with this degree of evolution,sincomplete information, or uncertainty.sThe second research issue is the need to maintain thess...

Citation Context

...F-EXPLANATIONsA well-known problem with self-adaptive systems issthat users may not understand or trust them. Such a lack ofsintelligibility can mean that users may cease to use a selfadaptive system =-=[36]-=-. One well-studied approach tosaddressing this problem is to provide human-readablesexplanations of adaptive behaviour. The intuition is that ifsa user can query the system’s decisions, s/he is less l...

Citation Context

...proved capability means that programmers nowshave access to programming frameworks and run-timesinfrastructures that support self-adaptation. These includesadaptive architectures [15] such as OpenCom =-=[5]-=- Rainbows[42] and the work of Peyman et al. [43]. OpenCom, forsexample, provides a component model and a set of openscomponent libraries. A programmer can define thesarchitecture and compose it using ...

Citation Context

...sunderstanding of the system and the context.sThe provision of understandable explanations ofssystem behaviour has been studied in a number of researchsfields: principally, in knowledge-based systems =-=[35]-=-[38],sintelligent tutoring systems [32], context-aware systemss[37][34], and debugging [39]. Depending on thesapplication, a range of information and a range ofsinteraction styles can be supported in ...

Citation Context

...r adapted according to that uncertainty. Othersfields of study offer possible starting points for such astheory – for example, risk analysis for possible securitysissues in software-intensive systems =-=[29]-=-, risk assessmentssin engineering disciplines [30], the economics ofsuncertainty [31], and uncertainty in management theorys[28], as well as well-known mathematical models ofsuncertainty such as Bayes...

Citation Context

...y. It would also bescomplemented with operators for resolving inconsistenciessbetween multiple views in the spirit of Xlinkit [46] orstechniques for automatically fixing inconsistencies insUML models =-=[47]-=-. Figure 1 summarizes the proposedsstructure.sFigure 1.sSynchronization between run-time requirements and thesarchitecturesThe structures in Figure 1 would require coordinationsbetween the upper requi...

Citation Context

...s necessary to specify howsthe system’s requirements can evolve dynamically and tosspecify the abstract adaptation thresholds that allow forsuncertainty and unanticipated environmental conditionss[53]=-=[4]-=-. Unfortunately, to our knowledge none of thesexisting techniques deal with this degree of evolution,sincomplete information, or uncertainty.sThe second research issue is the need to maintain thessync...

Citation Context

...rstandable explanations ofssystem behaviour has been studied in a number of researchsfields: principally, in knowledge-based systems [35][38],sintelligent tutoring systems [32], context-aware systemss=-=[37]-=-[34], and debugging [39]. Depending on thesapplication, a range of information and a range ofsinteraction styles can be supported in explanations. Lim etsal [37] provide a useful classification of exp...

Citation Context

...ed by concrete data sensed from the environments[11].sDynamic assessments and reasoning aboutsrequirements imply a run-time representation of systemsrequirements (i.e. its run-time requirements model =-=[1]-=-) thatsis rich enough to support the wide range of run-timesanalyses concerning stakeholders’ goals, softwaresfunctional and non-functional requirements, alternativeschoices, domain assumptions, scena...

Citation Context

...rtant steps in the directionsof requirements-aware systems.sSutcliffe et al. [55] withstheir PC-RE method allows requirements to change overstime in the face of contextual uncertainty. Epifani et al.s=-=[50]-=- proposed a run-time methodology to use a feedbackscontrol loop between models of non-functional propertiessand implementations. At run-time, the executing systemsprovides information as feedback that...

Citation Context

...ndable explanations ofssystem behaviour has been studied in a number of researchsfields: principally, in knowledge-based systems [35][38],sintelligent tutoring systems [32], context-aware systemss[37]=-=[34]-=-, and debugging [39]. Depending on thesapplication, a range of information and a range ofsinteraction styles can be supported in explanations. Lim etsal [37] provide a useful classification of explana...

Citation Context

...our of others – that is, we envisage run-time trade-offssof requirements being made as the environment changes.sAs a first step, we have developed the RELAXsrequirements language for adaptive systems =-=[26]-=-[4][49].sRELAX defines a vocabulary for specifying varyingslevels of uncertainty in natural language requirements andshas a formal semantics defined in terms of fuzzysbranching temporal logic. This al...

Citation Context

...rent functionality or quality of service to bessubstituted at run-time. Such compositional adaptivity [41]shas made it technically and economically feasible tosengineer systems, such as smart routers =-=[40]-=- that are ablesto optimize their behaviour to prevailing conditions suchsas network loads.sComplementing the bottom-up driversfor self-adaptive systems provided by improved softwarestechnology, is a p...

Citation Context

.... A requirements-awaressystem should be able to introspect about its requirementssin the same way that reflective middleware-based systemsspermit introspection about their architectural configurations=-=[2]-=-. Indeed, since reflective middleware provides anselegant mechanism for the achievement of compositionalsadaptation, requirements reflection would represent aslogical extension of the same principle. ...

Citation Context

...web service subject tosnetwork latency and uneven user demand may be muchsharder to determine on-the-fly.sDespite these difficulties, significant progress has beensmade on requirements monitoring [11]=-=[20]-=-[52]. However,son the closely-related issue of how to take correctivesaction to reconcile system behaviour with the requirementssmodel when monitoring detects deviancy, research is stillsin its infanc...

Citation Context

...lds of study offer possible starting points for such astheory – for example, risk analysis for possible securitysissues in software-intensive systems [29], risk assessmentssin engineering disciplines =-=[30]-=-, the economics ofsuncertainty [31], and uncertainty in management theorys[28], as well as well-known mathematical models ofsuncertainty such as Bayesian networks. All of these fieldsshave developed t...

Citation Context

...ny similarities between requirementssengineering models and architecture descriptionslanguages, subtle semantic differences between existingslanguages make the relation between the two modelsscomplex =-=[48]-=-. Integration between requirements andsarchitecture is already an urgent area for research. It issparticularly important for requirements-aware systems thatsprogress is made.sV. DEALING WITH UNCERTAIN...

Citation Context

...se on howsuncertain a phenomenon is. Although uncertainty can besmeasured on a variety of different scales, at differentslevels of granularity, a useful 4-level classification issprovided by Courtney =-=[28]-=-:s• Level one: general confidence about the shape of thesfuture, but some key variables do not have precisesvalues. It is possible to make some estimates and tosestablish a range of possible outcomes....

Citation Context

...ng able to revise these decisions at run-timeswhen more information can be acquired by observing thessystem in use. Our argument in this paper, which is ansexpansion of the initial ideas presented in =-=[54]-=-, is that tossupport run-time RE, requirements for self-adaptivessystems need to be run-time entities that can be reasonedsover at run-time.sThe essence of our idea is that a self-adaptive systemsshou...

Citation Context

...example,sprobabilistic model checkers have been used to specifysand analyse properties of probabilistic transition systemss[16] and Bayesian networks enable reasoning oversprobabilistic causal models =-=[10]-=-. However, only limitedsattention has been shown so far to the treatment ofsuncertainty in requirements engineering models. Oursongoing work has the objective to develop extensions tosgoal-oriented re...

Citation Context

...others – that is, we envisage run-time trade-offssof requirements being made as the environment changes.sAs a first step, we have developed the RELAXsrequirements language for adaptive systems [26][4]=-=[49]-=-.sRELAX defines a vocabulary for specifying varyingslevels of uncertainty in natural language requirements andshas a formal semantics defined in terms of fuzzysbranching temporal logic. This allows a ...

Citation Context

...sdelete_requirement, replace_requirement, add_goal,sdelete_goal, replace_goal, obtain_agent_from_goal,sassign_agent_to_goal.sA library of requirements modelstransformation operators, in the spirit of =-=[45]-=-, would thensbe defined on top of these primitive operations. The richscatalogue of model transformation patterns for goalsrefinement, conflict resolution and obstacle resolutionsassociated with the K...

Citation Context

...erstanding of the system and the context.sThe provision of understandable explanations ofssystem behaviour has been studied in a number of researchsfields: principally, in knowledge-based systems [35]=-=[38]-=-,sintelligent tutoring systems [32], context-aware systemss[37][34], and debugging [39]. Depending on thesapplication, a range of information and a range ofsinteraction styles can be supported in expl...

Citation Context

...rospect on its requirements modelsis the representation of that model at run-time. Recently,sseveral authors have made important steps in the directionsof requirements-aware systems.sSutcliffe et al. =-=[55]-=- withstheir PC-RE method allows requirements to change overstime in the face of contextual uncertainty. Epifani et al.s[50] proposed a run-time methodology to use a feedbackscontrol loop between model...

Citation Context

...ofssystem behaviour has been studied in a number of researchsfields: principally, in knowledge-based systems [35][38],sintelligent tutoring systems [32], context-aware systemss[37][34], and debugging =-=[39]-=-. Depending on thesapplication, a range of information and a range ofsinteraction styles can be supported in explanations. Lim etsal [37] provide a useful classification of explanation typessas follow...

Citation Context

...anging context. For example,sadaptive middleware systems allow software componentssproviding different functionality or quality of service to bessubstituted at run-time. Such compositional adaptivity =-=[41]-=-shas made it technically and economically feasible tosengineer systems, such as smart routers [40] that are ablesto optimize their behaviour to prevailing conditions suchsas network loads.sComplementi...