USING A CONCEPT-BASED APPROACH TO ASPECT-ORIENTED SOFTWARE DESIGN

格式：pdf
大小：115.29 KB
文档页数：10

U SING A C ONCEPT-B ASED A PPROACH TOA SPECT-O RIENTED S OFTWARE D ESIGNDennis Wagelaar&Lodewijk BergmansTRESE GROUP–U NIVERSITY OF T WENTE,P.O.B OX217,7500AE,E NSCHEDE,T HE N ETHERLANDS{wagelaar|bergmans}@cs.utwente.nlhttp://trese.cs.utwente.nlA BSTRACT–Aspect-oriented programming(AOP)has received considerable interest,in particular as an extension of object-oriented programming.However,current object-oriented software design techniques, such as UML,are not well suited to cope with aspect orientation.In this paper we discuss a design ap-proach,called CoCompose,which supports aspect orientation and software evolution.The CoCompose de-sign language adopts a generic concept construct for describing software systems.Design-level relationships between concepts can be expressed by applying the parameterised feature -plete CoCompose models can be translated into executable programs using an automatic translation proc-ess.KeywordsAspect Orientation,Advanced Separation of Concerns,Composition Filters,Design Patterns,software design, software evolution.1.I NTRODUCTION&P ROBLEM S TATEMENT One of the goals of software design models is to achieve/retain an overview of the software system under con-struction.It determines the high-level structure and behaviour of a software system that an implementation should follow. Because of this,software design techniques should leverage the programming techniques that can be used for describing behaviour and structure.Aspect-oriented programming[1]has received considerable interest,in particular as an extension of object-oriented pro-gramming.However,current object-oriented software design techniques,such as the Unified Modeling Language(UML) [2],are not well suited to cope with aspect orientation and evolving software requirements.Some of the problems that may arise are discussed below:There are numerous design concepts(e.g.described by Design Patterns[3]),which cannot all be offered as(de-sign)language nguage extension mecha-nisms can be used to facilitate newly introduced design concepts.Currently used extension mechanisms do not offer a way to describe well-defined semantics for these design concepts,however.For example,we can treat Design Patterns as design con-cepts.It is not feasible to present each design pattern as a separate design language construct.When using UML,we can use the stereotype extension mechanism to introduce the syntactic part of a design pattern.However,it is not possible to define the semantic part(i.e.how the application of the design pattern affects the design)for the new stereotype.In current design approaches,the implementation seman-tics(e.g.aspect,class,interface,method,etc.)of each de-sign element need to be fixed when introducing thedesign element,even though it may be difficult to choose the exact semantics.When adding new design elements and/or requirements,existing design elements may re-quire adopting different implementation semantics.If such a transformation is not possible,removal and re-introduction of the design elements is required.For example,UML represents design elements using a fixed set of constructs(e.g.class,interface,method,etc.).It is not possible to introduce design elements in UML without de-termining their construct form.Consider a situation in which we want to be able to exchange an existing method within an object class with methods that follow a different strategy.We can apply the Strategy design pattern[3](315)to achieve this, but that requires changing the structure of the design.If the design does not map injectively to the implementa-tion,automated translation from design to implementa-tion is difficult and may be incomplete.Updates to the design require separate updates to the implementation.If, in addition,the structures of implementation and design differ,a design update may cause a disproportional amount of updates in the implementation.This is par-ticularly well exemplified if the design represents cross-cutting concerns that cannot be expressed in the implementation language.For example,the Java[4]programming language does not natively support aspects.When modelling aspects in the de-sign language,the aspects do not map proportionately to Java.The Java implementation does not preserve the struc-ture of the design.If the mapping from the design to the im-plementation is not automated,a change to the aspect in the design may require many changes in the implementation. This paper is structured as follows:in the next section we will present some further requirements.The approach to our design technique will be discussed next,followed by an ex-planation of the design language and the translation of thisdesign language.The design language and its translation will both be illustrated by an example.2.R EQUIREMENTSIn addition to addressing the problems stated in the previous section,we have defined a number of additional requirements for our design language:Well-defined semantics of(design)language constructs: in order to reason about the semantics of a design and to automate implementation,the semantics of the design language constructs must be well defined.Scalability of design concept representation:by express-ing the semantics of a design concept in the design lan-guage itself,we can recursively define design concepts. Comprehensibility and intuitiveness of the design:the de-signs expressed in the design language are meant to be comprehensible and intuitively clear.Design evolution:one should be able to introduce the de-sign elements in an abstract way.The design elements can gradually be refined to achieve an executable design.3.A PPROACHThis section describes the approach used to solve the prob-lems and meet the requirements stated in the previous sec-tions.Our design approach,called CoCompose,will be explained by discussing the language constructs(features and concepts),automated implementation and the visualisation of the language.3.1F EATURES AND C ONCEPTSCoCompose offers a mechanism,called feature,to represent (abstractions of)design concepts,which allows the designers to introduce new design concepts(e.g.relations or design patterns),to be used within one or more concrete designs. The definition of a feature can contain a description of the structure of the design concept,again expressed in terms of concepts and features.This means that features can be de-fined recursively.To avoid forcing designers to prematurely select a particular implementation construct,our design language adopts the generic notion of concepts to represent elements in a design. Only when implementing the design,the concrete imple-mentation constructs(e.g.aspects,object classes,methods, interfaces,etc.)of those concepts are determined.Changing concrete implementation constructs for concepts does not change the design.3.2E XECUTABLE DESIGNCoCompose designs are executable,in the sense that a(com-plete)design can be translated into an executable language. This translation can be fully automated,thereby allowing each update of the design model to immediately result in an updated implementation,regardless of the impact upon the implementation.This is only possible because the elements of the design language(most notably concept and feature), have well-defined semantics.This differs from UML stereo-types,for example,where the meaning of a stereotype is de-fined outside the model.The approach used for translation of CoCompose designs is based upon Design Algebra[6](150),which introduces tech-niques for determining and selecting concrete(programming) language constructs for implementing concepts(i.e.finding a Design Space alternative).Design Algebra introduces several techniques to reduce the possible alternatives in the design space.Eventually that should result in a balanced alternative that best meets the qualities needed.CoCompose uses a method that is based upon these techniques.It will be referred to as the Transla-tion Process and is described in section6.3.3V ISUALISING D ESIGNTo address the comprehensibility and intuitiveness of de-signs,a visual representation of the language has been adopted.The ability to apply abstractions of design concepts (features)allows us to express a design at a high level of ab-straction,hiding many details.This allows for the number of design elements to stay at an acceptable level for human un-derstanding.4.T HE C O C OMPOSE D ESIGN L ANGUAGEThe CoCompose design language allows the designer to model a software system using concepts.This design can then be translated into a target(programming)language.The design language elements will be discussed in the following paragraphs.4.1C ONCEPTSConcepts are the basic language constructs for CoCompose. They represent parts of a software system and can have rela-tions to other concepts.CoCompose visualises concepts as shown in Figure1.Figure1:A concept.I MPLEMENTATIONSConcepts can have implementations for several target lan-guages and several concept forms.For example,a concept can have an implementation as a Method in Java.This im-poses a constraint on the concept,which states that this con-cept can only be implemented in Java and only as a Method. By specifying several(alternative)implementations,the con-straints on the concept will be less strict.If no implementations are specified for a concept,it is as-sumed that features(described in the next paragraph)will define all of its implementation.4.2F EATURESFeatures are reusable abstractions of design concepts,such as an Association relation or an Observer design pattern.They can be applied to concepts to describe them and the relations between them.Features have well-defined semantics,formand constraints.The name,type,comments and specificationof the feature describe its semantics.The form is describedby the feature’s roles(explained below).The constraints re-strict the possible applications of features(e.g.only to con-cepts with certain properties).A feature type represents a specific feature form and seman-tics.Several feature instances of a type can exist.Feature in-stances can be applied to concepts through roles(describedbelow).CoCompose visualises features as shown in Figure2.Figure3:An example CoCompose model.The model in Figure3shows a feature named MetalWin-ControlFactory of the high-level feature type ObserverWin-ControlFactory.This means that MetalWinControlFactory isan application of the ObserverWinControlFactory featuretype to the concepts update,MetalWindowManager,Metal-Label,MetalColorPanel and MetalSlider.The application ofthe feature is done through roles;each concept fills a role inthe application of the feature,as designated by connecting theconcepts to the roles using solid lines.For example,the MetalWindowManager concept fills theWindowManager role in the application of the MetalWin-ControlFactory feature,which means that the MetalWin-ControlFactory feature will impose WindowManagerfunctionality on MetalWindowManager concept.Now that the top-level model is given,we can show how to “solve”this feature by means of a solution pattern 1.This so-lution pattern is depicted in Figure 4.Label [0..1]Figure 4:The solution pattern for the ObserverWinControl-Factory feature type.Note that the larger circles in this model represent the roles of the ObserverWinControlFactory feature type.These circles are called role concepts and will be filled by concepts when the feature is applied.The Observer design pattern has been used in this model to add Observer functionality to the Win-dowedControlFactory feature type.The SliderObserver fea-ture hasthe same colouras theSlider role conceptto show thatthis feature belongs tothe Sliderrole part ofthe solution pattern 2.Thesolution pattern for a WindowedControlFactory featuretype isgiven inFigure5.the implementation pattern for the selected concept forms.The result is an implementation in the target lan-guage.Each of these steps will be explained in the next paragraphs.6.1F LATTENING THE M ODELBefore one can translate a CoCompose model into a target language,all dependencies and links should be reachable in order to check them.To make this easier,one could flatten the model to a lowest abstraction level model,which no longer contains features without implementation patterns ex-pressed in the target language.For each feature it should be checked whether it has an im-plementation pattern expressed in the target language.If no such implementation pattern exists,the solution patterns will have to be checked for eventual translation into the target language1.A solution pattern traversal mechanism is used for this.This mechanism builds a tree of nodes represented by solution patterns.The algorithm for building this tree is described be-low in pseudo-code:boolean CheckFeature(feature,tree)//Checks if the feature will eventually translate to nguage if feature.hasImplemPatternIn(nguage)thenreturn true;else if feature.hasSolutionPattern()thenforall solution in feature.getSolutionPatterns()tree.insert(solution);if not CheckSolution(solution,tree)thentree.remove(solution);//dead branchelsereturn true;end if;end forall;end if;end CheckFeature;boolean CheckConcept(concept)//Checks if the concept will translate into nguageif not concept.hasImplementations()thenreturn true;else if concept.hasImplementationIn(nguage)thenreturn true;end if;return false;end CheckConcept;boolean CheckSolution(solution,tree)//Checks if applying the solution pattern will result in a model//that eventually translates to nguageforall concept in solution.conceptsif not CheckConcept(concept)thenreturn false;end if;end forall;forall feature in solution.featuresif not CheckFeature(feature,tree)thenreturn false;end if;end forall;1This means checking whether the resulting model,after applying the solution patterns,contains features with implementation patterns expressed in the target language and concepts that have either no implementation or an implementation expressed in the target languagereturn true;end CheckSolution;The first step is to call CheckSolution using the model and an empty tree as arguments.When CheckSolution returns true, there is a valid tree for flattening the model in a way that it can be translated to the target language.The target in this al-gorithm refers to the target environment,e.g.a Java source path.If the tree has been determined,the solution patterns in this tree can be applied2.This will result in a model containing only features having implementation patterns expressed in the target language and concepts having either no implemen-tation or an implementation expressed in the target language. When a solution pattern is applied,first the default part is applied once for every feature type.Note that this is done globally and not per feature.Then,for each time a concept fills a feature role,the role part is applied for that concept. Below is the pseudo-code for applying a solution pattern: ApplySolution(solution,target)//Applies the solution pattern to the target environmentApplyDefaultPart(solution,target);forall role in solution.feature.rolesforall concept in role.getLinks()ApplyRolePart(solution,target,role,concept);end forall;end forall;end ApplySolution;ApplyDefaultPart(solution,target)//Applies the default part of the solution patternif not target.featureTypeApplied(solution.feature.type)thentarget.insert(solution.getDefaultpart());end if;end ApplyDefaultPart;ApplyRolePart(solution,target,role,concept)//Applies the role part of the solution pattern for the given concept target.insert(solution.getRolepart(role,concept));end ApplyDefaultPart;6.2D ETERMINE C ONCEPT F ORMSWhen translating a CoCompose model into a target(pro-gramming)language,the concepts will need to be translated into constructs of that target language.The construct into which a concept will be translated is called the concept form for that target language(this is called property in[6]).It is based upon the available implementation patterns of features, for which the concept fills a role,and concept implementa-tions,if any.Each feature that has an implementation pattern in the target language can have several role-part implementations for the same role.Each role-part implementation for that role pro-vides an implementation for a different concept form.For example,the Parent role of an Inheritance feature may have an implementation in Java for a concept form of Class or Interface.This is described as follows:F Parent={Class,Interface}2Note that applying a path of solution patterns from the tree elimi-nates flattening alternatives that might have been useful or even better,depending on the result of the second step(Determine Concept Forms).This problem will be addressed in the future.A concept filling this role can now be implemented as one of these concept forms.In a CoCompose model a concept will often fill more than one role.Consider a SingleRelation fea-ture,which models a one-way,one-to-one relation between two concepts.It has an Owner and Property role.The Prop-erty role has a solution in Java for a concept form of Class, Interface or Method1.This is described as follows:F Property={Class,Interface,Method}If a concept fills this role as well,the intersection of the con-cept form sets for each role must be taken:F Concept=F Role_1∩…∩F Role_nWhich in this case results in:F Concept=F Parent∩F Property={Class,Interface}If a concept has pre-defined implementations,the concept forms of these implementations will have to be taken into account as well.Otherwise,the concept form will be com-pletely determined by the available solution patterns of the feature types(Inheritance and SingleRelation in this case).If there are multiple valid concept forms,one of them must be selected.This selection process could be automated through the use of heuristics.One straightforward heuristic is a user-defined translation priority for all concept forms available for a target language.This translation priority de-termines what concept form will be chosen from a set of pos-sible concept forms.The CoCompose translation priority heuristic chooses the concept form with the highest defined priority.For example,in the Java language the priority of language constructs can be described as follows:C Class<C Interface<C Method<C BasicTypeThis results in the described example concept being trans-lated to an Interface,because it is considered the highest pri-ority concept form possible.Of course,any other definition of translation priority is possible.6.3G ENERATE I MPLEMENTATIONTo generate an implementation of the model in the target lan-guage,the concepts should first be translated into the concept forms that were determined in the previous step.Then,the concept implementations for the selected concept form should be applied to all concepts that have an implementa-tion.Finally,the implementation patterns of the features for the selected concept forms should be applied.Below is the pseudo-code that describes this:forall concept in model.conceptstarget.insert(concept,concept.form);if concept.hasImplemAs(concept.form)thentarget.insert(concept,concept.getImplemAs(concept.form));end if;end forall;forall feature in model.featuresfeature.applyImplemPattern(target);end forall;1Note that the possible concept forms of a feature role may depend on the concept form chosen to fill the other role.For example,a Method can fill the Owner role of the SingleRelation as long as a Method does not fill the Property role.The algorithm for feature.applyImplemPattern is variable and it is defined externally.7.A PPLYING THE T RANSLATION P ROCESSTO THE E XAMPLELet us now see how the translation process works for the ex-ample model shown in Figure3.The example model will be translated into a ConcernJ[5]implementation in order to show the mapping to an Aspect Oriented programming lan-guage.The translation process application will be explained for each step.Note that the result of each step can be found in the appendices.7.1F LATTENING THE M ODELThe example model has one feature,of which the solution pattern is described in CoCompose.This feature will be solved in the first flattening iteration.The flattening step will have to be repeated another two times to eliminate all Co-Compose solutions.The flattening of the example model is described in Appendix A.7.2D ETERMINE C ONCEPT F ORMSNow that all concepts are visible in the flattened example model,the target language construct forms,to which the con-cepts will translate,can be determined.The target language in this case is ConcernJ,a programming language that facili-tates Composition Filters and Aspect Orientation in Java.The concept form translation priority heuristic can be described as follows:C Concern<C Method<C BasicTypeNote that only the concept forms used for the example are described here.We can describe the deduction of a concept form using the following template:Feature1.Role {Concern,Method,…}…Feature n.Role {Concern,…} Concept.Implementation {Concern,…} Concept.Forms={Concern,Method,…}∩{Concern,…}={Concern,…} Concept.Form=Priority({Concern,…})In the template,the possible concept forms of the feature roles are determined first.Then the possible concept forms for the concept implementations are determined.The inter-section of these sets of possible concept forms is taken and the concept form with the highest priority heuristic value is chosen.For each concept the form and its deduction is given in Appendix B.Note that the concept form of the concept filling the Property role determines the possible concept forms for the Owner role of a SingleRelation feature.For example,if a Method fills the Property role,a Class can only fill the Owner role.If a Class fills the Property role,then Owner can be a Class ora Method.7.3G ENERATE I MPLEMENTATIONThe ConcernJ concept implementations and feature imple-mentation patterns will not be given here.Instead,the result-ing ConcernJ implementation is given in Appendix C.We will illustrate this step by focusing on the implementation of the MetalSliderObserver feature introduced in Appendix A,Figure8.This feature translates into a ConcernJ concern construct,preserving part of the structure used in the Co-Compose model.This shows ConcernJ can describe the ap-plication of a feature.A filtermodule is used to describe the Subject role and the Observer role.The update role is encap-sulated in the AbstractObserver concern.8.R ELATED W ORKIn this section we briefly point to a selection of related work. K.Czarnecki and U.Eisenecker have also used the notion of concept and feature in[7]in the area of Domain Engineering. Concepts in Conceptual Modeling differ from CoCompose concepts in that they are not necessarily disjoint.Features in Feature Modeling are meant to describe the possible proper-ties of a single concept,unlike CoCompose features that de-scribes the actual properties of several concepts.The idea of abstracting from programming language con-struct forms is also used in the area of template/generic pro-gramming.In[8],the word“concept”is also used to describe an abstraction from a programming language construct.The difference with CoCompose concepts is that these concepts fully specify their own interface or common form.CoCom-pose concepts can have their form imposed by features,thus separating each aspect of the concept form in a dedicated feature.The Composition Patterns design approach introduced by S. Clarke and R.Walker in[9]also uses parameterisation in composing several UML models.The most important differ-ence with CoCompose is that the application of a composi-tion pattern is not described explicitly in the UML model that uses it,but it is described separately by composition opera-tors.N.Noda and T.Kishi have researched the application of de-sign patterns in[10].They make a separation between the Design Pattern and Application Core.A similar approach is used by CoCompose,with the difference that the Design Pattern Application is,in turn,separated from the rest of the design,or Application Core.9.D ISCUSSION&C ONCLUSIONThe concept-based approach that has been explained in this paper improves stability of designs by postponing the choice for specific language constructs.The recursive modelling of concepts supports a focus on design semantics.The feature mechanism can be used to model many design concepts,ranging from aspects to design patterns.Because feature solution patterns can be CoCompose models them-selves(parameterised by the concepts that fill the roles of the feature),features can be defined recursively.This allows for composition of separate concerns.By imposing semantics upon concepts through the use of features,the concept semantics can be separated per concern. The feature solution patterns allow for several solutions to be defined for one feature.Choosing between several solution patterns for application within the same context(same con-cept forms,same target language)is not yet researched.As this paper has shown,CoCompose maps well to an as-pect-oriented programming language,such as ConcernJ.By using feature implementation patterns expressed in other tar-get languages,a mapping to other programming languages, such as AspectJ[11],Hyper/J[12],Java or C++,can be made as well.Of course,implementation pattern definition is more straightforward for a programming language that already supports several advanced composition mechanisms(such as aspects,hyperslices,composition filters,etc.),since the structure of the design can then be(partially)preserved. 10.A CKNOWLEDGEMENTSWe would like to thank Bedir Tekinerdogan and Joost Nop-pen for reviewing this paper and their comments on this sub-ject.R EFERENCES[1]Aspect Oriented Software Development,[2]UML specification,OMG website,/uml.[3] E.Gamma,R.Helm,R.Johnson,J.Vlissides,Design Patterns:Elements of Reusable Object-Oriented Software,AddisonWesley Longman,Inc.,Reading,Massachusetts,1995,ISBN0-201-63361-2.[4]Java,.[5]L.Bergmans,M.Akşit,On the Role of Encapsulation in Aspect-Orientation,University of Twente,Enschede,The Netherlands, 2001,to appear on http://trese.cs.utwente.nl.[6] B.Tekinerdogan,Synthesis-Based Software ArchitectureDesign,PhD Thesis University of Twente,Enschede,TheNetherlands,2000,ISBN90-365-1430-4.[7]K.Czarnecki,U.Eisenecker,Generative Programming:Meth-ods,Tools,and Applications,Addison Wesley,2000,ISBN0-201-30977-7.[8]J.Willcock,J.Siek,A.Lumsdaine,Caramel:A Concept Repre-sentation System for Generic Programming,Indiana University, Bloomington,USA,in OOPSLA2001C++Template Workshop.[9]S.Clarke,position Patterns:An Approach toDesigning Reusable Aspects,in proceedings of the23rd Interna-tional Conference on Software Engineering(ICSE),Toronto,Canada,May2001.[10]N.Noda,T.Kishi,Implementing Design Patterns Using Ad-vanced Separation of Concerns,NEC Corporation,Japan,inOOPSLA2001workshop on Advanced Separation of Concerns in Object-Oriented Systems.[11]G.Kiczales,E.Hilsdale,J.Hugunin,M.Kersten,J.Palm,W.Griswold,An Overview of AspectJ,University of British Co-lumbia,Vancouver,Canada,Xerox Palo Alto Research Center, Palo Alto,USA,University of California,San Diego,USA,inProceedings of ECOOP2001,pp.327-353,2001.[12]H.Ossher,P.Tarr,Multi-Dimensional Separation of Concernsand The Hyperspace Approach,IBM T.J.Watson ResearchCenter,Yorktown Heights,USA,in Software Architectures and Component Technology,Kluwer,2000,ISBN0-7923-7576-9.。

社会科学研究方法与论文写作智慧树知到期末考试章节课后题库2024年北京第二外国语学院

社会科学研究方法与论文写作智慧树知到期末考试答案章节题库2024年北京第二外国语学院1.What are key components of research design? （）答案:Timeframe.###Sampling Strategy.###Data Collection Methods.2.The following aspects of informed consent that are essential in researchethics include （）.答案:Researchers explaining potential risks andbenefits.###Participants being allowed to withdraw from the study.3.When should all authors be included in the in-text citation, according to theAPA style? （）答案:When there are two authors.###When there are three to fiveauthors.4.What are some essential tips for writing an effective abstract? （）答案:Use keywords###Emphasize points differently from thepaper.###Use passive verbs5.Which statements are suggested solutions for improving the Methodologysection? （）答案:Eliminate the use of first-person pronouns.###Provide a clearrationale for the chosen methods.6.What's the difference between methodology and method? （）答案:Methodology encompasses the broader theoretical framework and guiding philosophy of the research process.###Methods encompass the specific techniques and procedures employed for data collection andanalysis.###Methodology is presented as a distinct section in aresearch thesis, explaining the overall approach and rationale.7.What are the downsides of mere listing in a literature review? （）答案:It does not present themes or identify trends.###It often indicatesa lack of critical synthesis.8.The common problems to be aware of in thesis writing include（）.答案:Excessive reliance on qualitative data###Lack of theoreticalsupport###Failure to integrate theory and practice.###Misuse of tense ponents that are typically embedded in the structure of an academicpaper, especially the journal article, include （）答案:Introduction###Results and Discussion10.Which of the following examples are misconducts? （）答案:Facilitating academic dishonesty.###Unauthorizedcollaboration###Misuse of Patients11.What are the three main elements of a definition, as mentioned in the lecture?（）答案:Term, Category, and Features.12.In the Methods section, why is it important to detail the tools or materials fordata collection? （）答案:To explain how instruments to be used to answer researchquestions.13.Which is the method suggested to avoid plagiarism when summarizinginformation from sources? （）答案:Summarize immediately after reading without referring back tothe source.14.The purpose of control variables in research is （）.答案:To keep certain factors constant and prevent them frominfluencing the dependent variable.15.What is the purpose of using sampling techniques in research? （）答案:To draw conclusions about the population based on data collected from the sample.16.According to Wallwork’s tips for the final check, what is one way to ensureyour paper is as good as possible before submission? （）答案:Anticipate referees’ comments.17.What does external validity assess? （）答案:The extent to which research findings can be applied orgeneralized to other situations and populations.18.Which of the following expressions are correctly used in the Methods Section?（）答案:"We conducted the experiment in a controlled environment."19.Which of the following is NOT a recommended guideline for using tables in aresearch paper? （）答案:Using as many tables as possible to provide comprehensiveinformation.20.What does a structured abstract typically include to make it more readable?（）答案:Eye-catching font for the title21.What is the main function of the preparation stage in writing a literaturereview? （）答案:To locate relevant literature and prepare for writing.22.The primary focus of academic integrity is （）.答案:Fostering honesty and responsible behavior.23.The act of using someone else’s ideas and writings as your own can beconsidered as （）.答案:Plagiarism24.Which step is NOT part of the suggested three-step approach for revisingyour paper? （）答案:Rewrite the entire paper.25.Which is not the reason for an overly broad title being problematic? （）答案:It encourages depth in the study.26. A good thesis or dissertation should tell the reader not just “what I havedone,” but “why what I have done matters.” （）答案:对27.Coherence in academic writing refers to the clarity of the thesis statementand the organization of the paper. （）答案:对28.The research methods section helps readers and reviewers gauge thetransparency, validity, and reliability of the research. （）答案:对29.Research papers are published to share new, original results and ideas withthe academic community. （）答案:对30.Relying solely on secondary sources ensures the originality of researchfindings. （）答案:错31.In introduction writing, it is recommended to delve into an exhaustive reviewof the entire field to provide comprehensive context. （）答案:错32.The Background Method in introduction writing kicks off by presenting aproblem and then addressing the solution. （）答案:错33.Multiculturalism seeks to enhance the self-esteem and identities ofmarginalized groups. （）答案:对34. A Doctoral-level literature review is typically less comprehensive than aMaster's-level literature review. （）答案:错35."Hoaxing" involves deliberately publishing false information with theintention of deceiving others. （）答案:对36.Reflecting on the research process at the end is essential for evaluating itsstrengths and limitations. （）答案:对37. A well-crafted title should engage a wide audience effectively. （）答案:对38.In order to avoid plagiarism, it is suggested to avoid citing references. （）答案:错39.Predicting difficulties and providing countermeasures in a research proposalis essential to show the depth of thinking and enlist expected guidance. （）答案:对40.Conducting a literature review is not necessary when selecting a researchtitle. （）答案:错41.What can authors do to ensure a timely publication in a journal that reviewspapers for job hunting purposes?（）答案:Submit the manuscript without checking for errors###Seekinformation from editors about review times###Be efficient in making revisions42.When preparing a manuscript for publication, it is crucial to focus on ethicalstandards.（）答案:对43.Why do researchers want to publish their papers?（）答案:To share new results and ideas44.How can you identify an appropriate journal for publication? （）答案:Look for journals that publish work similar to your research.45.The editor-in-chief makes the final decision on whether a submitted paper isaccepted or rejected in the review process.（）答案:对ing cut and paste extensively is recommended during the final check tosave time.（）答案:错47.Exchanging texts with another student for proofreading is encouraged to findcareless errors in your own work.（）答案:对48.What is the key idea that should be remembered by the audience from yourtalk？（）答案:The key idea of your research49.Why is it important to avoid errors that may distort meaning in your writtenwork? （）答案:To enhance the quality of your writing###To ensure clarity ofcommunication50.What is the main purpose of doing a presentation?（）答案:To engage, excite, and provoke the audience51.Making academic writing more tentative involves avoiding over-generalizations and using linguistic hedges and tentative phrases.（）答案:对52.What is the purpose of the checklist questions provided for paper revision?（）答案:To help improve the writing53.Which of the following are strategies for achieving cohesion in academicwriting? （）答案:Organizing the paper logically###Using transitional words andphrases###Employing reference words54.Redundancy and colloquialisms are considered desirable features ofconciseness in academic writing. （）答案:错55.What should you do when revising your paper writing to improve clarity andspecificity? （）答案:Be self-contained56.What are the characteristics of informative abstracts? （）答案:They may replace the need for reading the full paper###Theycommunicate specific information about the paper###They provide aconcise summary of the paper’s content57.Structured abstracts may have clear subheadings to mark different sections.（）答案:对58.What is the recommended maximum word limit for a conference abstract?（）答案:250 words59.Which tense is often used when writing an abstract? （）答案:Present tense60.The primary purpose of an informative abstract is to indicate the subjectsdealt with in a paper. （）答案:错61.What are some reasons for using citations in academic writing? （）答案:To show you are a member of a particular disciplinarycommunity###To acknowledge the intellectual property rights ofauthors###To avoid plagiarism62.Self-plagiarism is not considered an ethical concern in academic writing.（）答案:错63.What is the primary purpose of citation in academic writing? （）答案:To acknowledge the intellectual property rights of authors64.What is self-plagiarism? （）答案:Presenting one's own previously published work as new65.All sources cited in the text must be documented in the References section.（）答案:对66.Which type of conclusion is more common in research papers and theses andfocuses on summarizing research outcomes and aligning them with the initial thesis? （）答案:Thesis-oriented Conclusion67.What are the four sections typically found in the Conclusion section of aresearch paper, according to the material? （）答案:Summary of findings, implications, limitations, further studies68.What is one of the purposes of the conclusions chapter? （）答案:To forestall criticisms by identifying limitations of the research69.Which of the following are types of conclusions discussed in the material? （）答案:Summary type###Field-oriented conclusion###Evaluation type of conclusion###Recommendation type of conclusion70.The conclusion section in academic papers typically follows a uniformstructure across all disciplines.（）答案:错71.What is one of the purposes of making comparisons with previous studies inacademic writing? （）答案:To justify the methods or procedures followed72.Which of the following is NOT mentioned as a common type of graphicalfigure in the material? （）答案:Map illustrations73.What can we do in demonstrating our research results in paper? （）答案:Use figures and tables to summarize data###Show the results ofstatistical analysis74.In which field are Qualitative Research methods often used?（）答案:Liberal Arts and Social Sciences75.What factors should be considered when choosing research methods for athesis? （）答案:Traditional approaches.###Research questions andobjectives.###Nature of the subject matter.76.What does "Research Design" refer to in the research process?（）答案:The overall plan guiding the research study.77.All the following moves are included in the method section except （）.答案:Describing the commonly used methods in certain field.78.The research methods section in a thesis is often presented as a distinctsection, separate from the literature review.（）答案:对79.What are the two core abilities essential for writing an effective literaturereview? （）答案:Information seeking and critical appraisal.80.Where can a literature review be placed in a research paper or thesis? （）答案:In different places depending on research goals and fieldconventions.81.Which type of literature review focuses on organizing literature aroundspecific research questions?（）答案:Question-oriented review.82.The purpose of creating a visual representation, such as a literature map, isto replace the need for drafting concise summaries.（）答案:错83.What are the recommended tenses to use when discussing the content of thesources in a literature review? （）答案:Simple Past.###Present Perfect.###Simple Present.84.What is the role of the Problem Statement in the Introduction? （）答案:Justify the importance of the research.85.Which is NOT one of the three methods could be used to write anintroduction? （）答案:Reference Method86.The location and structure of the introduction are standardized across alltypes of research theses. （）答案:错87.In Metadiscourse research, what is the recommended way for a researcher torefer to themselves in the introduction?（）答案:Refer to themselves as "this thesis" or a specific section.88.What are the key elements included in Move 2 of the "Create a ResearchSpace" (CARS) framework?（）答案:Identifying gaps in prior research.###Indicating a gap.89.What role do Research Grant Proposals play?（）答案:Both securing financial support and convincing funding agencies.90.What questions does a research proposal eloquently answer? （）答案:How are you going to do it?###What do you plan toaccomplish?###Why do you want to do it?91.The "Aims/Purposes" section in a research proposal outlines the centralissues to be tackled in the study. （）答案:对92.To whom is a research proposal usually submitted for approval and support?（）答案:Funding agencies, academic institutions, or research supervisors.93.What is the purpose of predicting difficulties and providing countermeasuresin the research proposal?（）答案:To show the depth of thinking and enlist expected guidance.94.The recency of sources is crucial in research, and older sources are alwayspreferred for their depth.（）答案:错95.Which database is specifically mentioned for searching Master's and DoctoralDissertations? （）答案:CNKI96.When conducting a critique of a study, what should be considered about themethods used?（）答案:The validity for studying the problem.97.What is the primary characteristic of primary sources in research materialcollection? （）答案:They offer synthesized information from various perspectives. 98.What are common approaches to collecting primary source materialsmentioned in the lecture? （）答案:Surveys and questionnaires###Controlled experiments###One-on-one interviews99.What are potential mistakes in the title selection process? （）答案:Having unclear titles that do not convey the subjectmatter.###Using contemporary language to make the title appearoutdated.100.How does the researcher balance the focus of a research title?（）答案:By clearly defining the scope of the study.101.What is the purpose of conducting a comprehensive literature review in the title selection process? （）答案:To identify gaps, controversies, or areas requiring furtherexploration.102.An overly narrow title might limit the potential impact and relevance of the research. （）答案:对103.What is the significance of a well-chosen title? （）答案:It significantly enhances the academic value of the work.104.What are key characteristics of deconstruction in literary theory? （）答案:Highlighting textual undecidability and paradoxes.###Challenging traditional assumptions about language and meaning.###Questioning binary oppositions.105.What distinguishes quantitative data from qualitative data in research? （）答案:Quantitative data are numerical, while qualitative data can bedescribed in words.106.What is the primary goal of case studies in applied linguistics? （）答案:To enhance understanding of a phenomenon, process, person, or group.107.Case studies use a single data source, such as interviews, to explore particular phenomena. （）答案:错108.What are the three types of cultural studies? （）答案:New historicism, postcolonialism, American multiculturalism. 109.The dependent variable in a study investigating the effects of different study methods on exam performance is （）.答案:Exam performance110.What role does a moderating variable play in a research study? （）.答案:It influences the strength or direction of the relationship between independent and dependent variables.111.External validity assesses the extent to which research findings can be applied to populations, settings, or conditions beyond the specific study. （）答案:对112.How does deduction differ from induction in research? （）答案:Deduction is the process of reasoning from general principles tospecific predictions.113.The purposes of research include （）答案:Solving real-world problems###Testing existingtheories###Meeting graduation requirements###Advancingknowledge114.The potential academic consequences for students who engage in academic dishonesty include （）.答案:Monetary fines、Academic suspension and Expulsion from theInstitute115.The three key principles that experimental researchers need to carefully consider and implement before, during and after recruiting researchparticipants are （）.答案:Anonymity###Informed consent###Confidentiality116.It is unethical to conduct research which is badly planned or poorly executed.（）答案:对117.The primary focus of academic integrity in the context of research ethics is （）.答案:Fostering responsibility and trustworthiness in academic work 118.The pillars of academic integrity include all the aspects except （）答案:Excellence119.The primary purpose of literature reviews in research articles is （）.答案:To evaluate previously published material120.Methodological articles typically present highly technical materials, derivations, proofs, and details of simulations within the main body of thearticle. （）答案:对121.In a research article, many different sections can be found in empirical studies, including （）.答案:Method###Literature review###Introduction###Discussion 122.According to the lecture, which step in the procedures of thesis writing involves drafting a title and abstract? （）答案:Step 1: Choice of Topic123.The primary use of case studies is （）.答案:To illustrate a problem or shed light on research needs。

高三英语学术文章单选题50题

高三英语学术文章单选题50题1. In the scientific research paper, the term "hypothesis" is closest in meaning to _.A. theoryB. experimentC. conclusionD. assumption答案：D。

解析：“hypothesis”的意思是假设，假定。

“assumption”也表示假定，假设，在学术语境中，当提出一个假设来进行研究时，这两个词意思相近。

“theory”指理论，是经过大量研究和论证后的成果；“experiment”是实验，是验证假设或理论的手段；“conclusion”是结论，是研究之后得出的结果，所以选D。

2. The historical article mentioned "feudal system", which refers to _.A. democratic systemB. hierarchical social systemC. capitalist systemD. modern political system答案：B。

解析：“feudal system”是封建制度，它是一种等级森严的社会制度。

“democratic system”是民主制度；“capitalist system”是资本主义制度；“modern political system”是现代政治制度，与封建制度完全不同概念，所以选B。

3. In a literary review, "metaphor" is a figure of speech that _.A. gives human qualities to non - human thingsB. compares two different things without using "like" or "as"C. uses exaggeration to emphasize a pointD. repeats the same sound at the beginning of words答案：B。

2020届南京竹山中学高三英语期末试题及答案解析

2020届南京竹山中学高三英语期末试题及答案解析第一部分阅读（共两节，满分40分）第一节（共15小题；每小题2分，满分30分）阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项AShopping centers，stadiums and universities may soon have a new tool to help fight crime.ACaliforniacompany called Knightscope says its robots can predict and prevent crime. Knightscope says the goal is to reduce crime by half in areas the robots guard.William Santana Li is the chief executive officer of Knightscope. He says，"These robot security guards will change the world. Our planet has more than seven billion people on it. It's going to quickly get to nine billion people. The security equipmentthat we have globally is just not going to develop that fast. The company's Autonomous Data Machines can become the eyes and ears of law enforcement（执法）.""You want them to be machines plus humans. Let. the machines do the heavy and sometimes dangerous work and let the humans do the strategic decision-making work，so it's always working all together."The machines do not carry weapons but they have day and night video cameras which are able to turn 360 degrees and can also sense chemical and biological weapons.Some people may become concerned about their privacy, especially in connection with the video recordings. Some people may worry that such recordings will appear on the Internet. Eugene Volokh, a law professor at the UCLA School of Law, says the machines have to be used in the right way and it will be interesting to see how state laws deal with this kind of video.William Santana Li says there is a long waiting list for the robots in theUS. Workers in the company are working overtime to meet the demands of the market. At least 25 other countries are also interested in these robot security guards.1. What can this new tool do for humans?A. Make strategic decisions.B. Keep watching day and night.C. Carry heavy weapons.D. Stop crime autonomously.2. Why are some people worried about the new robots?A. Their privacy may be let out.B. The robots are very expensive.C. Robots will replace humans.D. They will be out of work soon.3. Which of the following can be the best title of the text?A. Robots Are Becoming More PopularB. Robots Contribute aLotto the WorldC. Robots Are in Great Demand NowD. Security Robots Could Help Cut CrimeBThis year researchers expect the world to snap 1.35 trillion photographs, or about 3.7 billion per day. All those pixels (像素) take up a lot of room if they are stored on personal computers or s phones, which is one reason why many people store their images in the cloud. But unlike a hard on drive which can be encrypted to protect its data, cloud storage users have to trust that a tech platform will keep their private pictures safe. Now a team of Columbia University computer scientists has developed a tool to encrypt (加密) images stored on many popular cloud services while allowing authorized users to browse and display their photographs as usual.Malicious (恶意的) attempts to access or leak cloud-based photographs can expose personal information. In November 2019, for example, a bug in the popular photograph storage app Google Photos mistakenly shared some users' private videos with strangers. Security experts also worry about employees at cloud storage companies on purpose accessing users' images.So the Columbia researchers came up with a system called Easy Secure Photos (ESP), which they presented at a recent conference. “We wanted to see if we could make it possible to encrypt data while using existing services,” says computer scientist Jason Nieh, one of the developers of ESP. “Everyone wants to stay with Google Photos and not have to register on a new encrypted-image cloud storage service.”To overcome this problem, they created a tool that preserves blocks of pixels but moves them around to effectively hide the photograph. First, ESP's algorithm (算法) divides a photograph into three separate files, each one containing the image's red, green or blue color1 data. Then the system hides the pixel blocks around among these three files (allowing a block from the red file, for instance, to hide out in the green or blue ones). But the program does nothing within the pixel blocks, where all the image processing happens. As a result, the files remain unchanged images but end up looking like grainy black-and-white ones to anyone who accesses them without the decryption (解密) key.4. What's probably the main purpose for people to store images in the cloud?A. To save storage room.B. To make photos beautiful.C. To try a new storage way.D. To keep their privacy safe.5. Why might employees in cloud storage companies be distrusted by experts?A. They sell users' passwords.B. They have invented new tools.C. They often let out personal information.D. They may steal a glance at users' images.6. What's the advantage of ESP?A. It can provide clear images.B. It can decrease the upload time.C. It can classify images automatically.D. It can encrypt data on the original platform.7. What does paragraph 4 mainly talk about?A. Method of decryption.B. Image-processing technique.C. Separate files of images.D. Data analysisof color1 s.CAfter years of releasing e-readers that compete directly with Amazon’s Kindle, Rakuten Kobo’s latest device offers something totally different: theability to draw and write directly on the screen.With a large 10.3-inch E-ink display, the Kobo Elipsa looks more like an electronic clipboard than the standard paperpack-sized e-reader. Although the ability to write on the screen is no big deal — especially given its high price tag of $ 600 — the overall package is impressively functional.In terms of reading, the Elipsa packs just about everything you’d expect in a Kobo. You can purchase and download books from the store, read web articles you’ve saved online via Pocket, and connect to your local library to borrow e-books and magazines. It’s known that Kindle basically requires you to buy books from Amazon. Unlike Kindles, Kobos are pretty open with the formats they support; you can connect the Elipsa to a computer and transfer over any PDF books you have bought or downloaded from stores like Booktopia or Google Books.You can fill your virtual notepads with notes using brush and pen types, and export them as PDFs or images to a PC. There’s also an “advanced” notebook that can turn your writing into typed and editable text for exporting to Microsoft Word format. You can also write directly onto documents themselves, with all your word circling andunderlining saved as you go to review later. This is especially handy when it comes to PDFs, as changes you make are synced（同步）automatically when you have Wi-Fi, so you can move between your Elipsa, PC and phone and keep your notes.With all that said, we can see it really appealing to e-reader fans who also tend to do a lot of work on paper. If you ever print things out to mark them up, fill notepads with writing or drawing that you later have to transcribe or scan, or just wish you could write all over your library books, this could be the device for you.8. Which of the following best describes the Elipsa?A. Automatic.B. Traditional.C. Useful.D. Standard.9. How is a Kobo different from a Kindle in reading?A. A Kindle has a larger screen.B. A Kindle can support more formats.C. A Kobo supports books from various sources.D. A Kobo should be connected to local libraries.10. What does paragraph 4 mainly tell us about Kobos?A Their function in syncing. B. Their function in typing.C. Their function in writing.D. Their function in reading.11. In which section of a newspaper can the text probably be found?A. Education.B. Technology.C. Lifestyle.D. Business.DTaking an afternoon nap could keep your brain sharp, a new study has said. Adults ages 60 and older who took afternoon naps showed signs of better mental ability compared to those who didn’t nap, according to a study published in General Psychiatry earlier this week.Researchers analyzed napping habits in 2, 214 older Chinese people and measured their cognitive abilities using several cognitive tests. Participants took the Mini-Mental State Examination and theBeijingversion of the Montreal Cognitive Assessment, both of which test for memory, language and other cognitive abilities. In every category listed in the study, nappers tested statistically higher on average compared to their non-napping counterparts.Researchers did not gather data from people under 60, so a correlation cannot be drawn between napping and younger generations. The study also noted that there are conflicting studies about the benefits and risks ofnapping.Sleeping behaviors can be affected by a multitude of factors, said Dr. David Neubauer, associate professor atJohnsHopkinsUniversity. “Daily routines, medication use and sleep disorders can all play a role in how frequently someone takes a nap.” he said.Neubauer recommended taking a shorter “power nap” of up to 20 minutes to decrease the chances of transitioning into slow-wave sleep, which makes people feel groggy when they wake up. “Napping can be a healthy part of an older adult’s day”, Neubauer acknowledged, but make sure “sleepiness isn’t due to a treatable nighttime sleep disorder.” Older individuals who want to do all they can to preserve their cognitive functioning should put nighttime sleep first.12. What is the best way to keep a better cognitive ability for the old?A. Take a nap every day.B. Take sleep disorder seriously.C. Have a good sleep at night.D. Do exercise regularly.13. How did the researchers reach the conclusion?A. By taking the examinations and assessment.B. By analyzing napping habits and giving tests.C. By measuring nappers’ ability and analyzing them.D. By doing an experiment.14. Which has NO effect on one’s sleeping behaviors?A. Taking a nap.B. Medicine treatmentC. Sleep problemsD. Everyday activities.15. What can we know about “slow-wave sleep”?A. It appears in short nap up to 20 minutes.B. People should avoid it in their naps.C. It is a healthy part of an elder’s day.D. It was recommended by Neubauer.第二节（共5小题；每小题2分，满分10分）阅读下面短文，从短文后的选项中选出可以填入空白处的最佳选项。

Abstract A Relation-based Approach to Use Case Analysis

A Relation-based Approach to Use Case AnalysisA.Fantechi*, S.Gnesi^, mi^*Dip. di Sistemi e Informatica - Università di Firenze - Italy^ISTI - C.N.R. - Area della Ricerca C.N.R. di Pisa - ItalyAbstractUse Cases are an effective tool for modeling functionalrequirements of software systems. A well written Use Caseallows to depict a large amount of information regarding the behaviour of the system, as perceived by the actors. UseCases have the advantage to be expressed using Natural Language expressions that have a fixed structure and this can mitigate some of the usual, NL-inherent, problems of interpretation. In this paper, we present an approach that, starting with the application of NL processing techniques to the Use Case scenarios, derives semantic information on the relations between the actors. This information, largely achievable in an automatic way, can be used to support the analysis of Use Case requirements document and it represents a starting point towards the formal verification of some relevant aspects.1. IntroductionThe problem of the analysis of software requirements with respect to some consistency and correctness parameters has been extensively exploited in several ways in recent years [14]. For example, formal methods and tools have been used for this purpose when a formal representation of software requirements has been adopted.Currently, in the common practice formal notations are not always used in the first description of the system. More frequently Natural Language (NL) expressions are used to represent software requirements [12, 15]. It is hence quite important to provide methods and tools for the consistency and correctness analysis of them starting from their NL representation.Use Cases are a powerful tool to capture functional requirements for software systems. They allow structuring requirements documents with user goals and provide a means to specify the interactions between a certain software system and its environment. In his book [3], Alistair Cockburn presents an effective technique for specifying the interactions between a software system and its environment. The technique is based on natural language specification for scenarios and extensions. Scenarios and extensions are specified by phrases in plain English language. This makes requirements documents easy to understand and communicate even to non-technical people.The typical structure of Use Cases makes their analysis easier and more effective than classic Natural Language sentences. Quality is determined by the fulfilment of some predefined characteristics (target qualities) that in the case of Use Cases can be classified into three main groups: Expressiveness, Completeness and Consistency. • Expressiveness category: it includes those characteristics dealing with the understanding of the meaning of Use Cases by humans, such as Ambiguity orUnderstandability• Consistency category: it includes those characteristics dealing with the presence of semantics contradictions and structural incongruities in the NL requirement document.• Completeness category: it includes those characteristics dealing with the lack of necessary parts within the requirement specifications.The quality of NL components of Use Cases (typically sentences), may be analysed from a lexical, syntactical or semantical point of view [8]. For this reason it is proper to talk about, for example, lexical non-ambiguity or semantical non-ambiguity rather than non-ambiguity in general [10,11,13]. For instance, a NL sentence may be syntactically non-ambiguous (in the sense that only one derivation tree exists according to the syntactic rules applicable) but it may be lexically ambiguous because it contains wordings that have not a unique meaning.In the practice expressiveness-related issues can be addressed by means of existing NL-based techniques and tools [2,6,9,17]. For example, ambiguity mitigation may be addressed in the following ways:• By lexical evaluation: using lexical parsers to detect and possibly correct terms or wordings that are ambiguous. • By syntactical evaluation: using syntactical analysers to detect sentences having different interpretations. Understandability improvement may be addressed by lexical and syntactical evaluation as well: using linguistic parsers both to detect poorly understandable or complex parts of the document and to achieve readability indicators (metrics) based on the count of elements of the sentences (e.g. the number of characters or words of the sentences, the average length of the sentences, …).It is more difficult to exploit NL-based techniques and tools able to provide some help in addressing Consistency and Completeness issues, because it is necessary to capture, at least at some level, the semantics of the Use Case under evaluation.In this paper we present a methodology for the analysis of the Use Case based requirements documents. This methodology is aimed to extract semantic information from the Use Cases, based on NL processing techniques. This information regards the functional relations between the actors of the Use Case based requirements specification. From the elementary relation between two actors determined by the verb in a sentence we discuss how to derive more complex relations between the concepts present in the Use Cases description, which may help in assessing consistency and completeness issues. This derivation can be largely supported by automatic tools.This paper is structured as follows: in section 2 we describe the kind of Use Cases we will consider and in section 3 we present our approach to support the analysis of consistency and completeness based on linguistic techniques. In section 4 we discuss how to derive the relations, presenting an integrated environment for the lexical, syntactical and semantic analysis of NL requirements that can be used to this aim. In section 6 we discuss the possible use of the relational approach and the related opportunities to improve the analysis of Use Case-based requirements documents. 2. Use CasesA Use Case describes the interaction (triggered by an external actor in order to achieve a goal) between a system and its environment. A Use Case defines a goal-oriented set of interactions between external actors and the system under consideration. The term actor is used to describe the person or system that has a goal against the system under discussion. A primary actor triggers the system behaviour in order to achieve a certain goal. A secondary actor interacts with the system but does not trigger the Use Case.A Use Case is completed successfully when that goal is satisfied. Use Case descriptions also include possible extensions to this sequence, e.g., alternative sequences that may also satisfy the goal, as well as sequences that may lead to failure in completing the service in case of exceptional behaviour, error handling, etc.. The system is treated as a "black box”, thus, Use Cases capture who (actor) does what (interaction) with the system, for what purpose (goal), without dealing with system internals. A complete set of Use Cases specifies all the different ways to use the system, and therefore defines the whole required behaviour of the system. Generally, Use Case steps are written in an easy-to-understand, structured narrative using the vocabulary of the domain. The language used for the description is English. Any other natural language can be used as well, and although our analysis focuses on English, the same reasoning can be applied to other languages (considering the obvious differences in syntax and grammar rules). A scenario is an instance of a Use Case, and represents a single path through the Use Case. Thus, there exists a scenario for the main flow through the Use Case, and other scenarios for each possible variation of flow through the Use Case (e.g., triggered by options, error conditions, security breaches, etc.). Scenarios may also be depicted in a graphical form using UML sequence diagrams. Figure 1 shows the template of the Cockburn’s Use Case taken from [4].In this textual notation, the main flow is expressed, in the “Description” section, by an indexed sequence of NL sentences, describing a sequence of actions of the system. Variations are expressed (in the "Extensions" section) as alternatives to the main flow, linked by their index to the point of the main flow in which they branch as a variation. Developers have always used scenarios in order to understand what the requirements of a system are and how a system should behave with respect to its environment. The work we present in this paper is an attempt to provide means to identify possible flaws in the textual scenario descriptions.Figure 1. Use Case template3. Towards Linguistic Evaluation of Consistency and CompletenessTo effectively address the Consistency and Completeness aspects of requirements specification, we should resort to their formalization, [9,18]. Indeed formal methods are a powerful mean to evaluate requirements because they provide a theoretical framework to verify their correctness. Formal methods require, however, a specific skill and this has increased their cost and prevented their wide application.In this paper we investigate methods and tools that may provide an effective support to deal with Consistency and Completeness issues, but that are still based on NL analysis and then are more user-friendly.Other works aiming at the improvement of the correctness of requirements relying on the Use Cases structure exist [1,5]. The methods and tools we are presenting in this paper also rely on the structure of the Use Cases and are based on the study of the relations between actors of Use Case-based description of a system.The relations we are interested in are the “functional” relations, i.e. the relations or dependencies between two actors. These relations can be determined looking at the syntactical structure of each sentence of the Use Case scenarios defining a set of items (quadruples) where each primary actor (the subject of the sentence) has been put in relation with the secondary actor (the complement) according to the verb. The canonical form of these relations is:(1.) (Actor_1, verb_i, Actor_2, Use_Case_id).Each item compliant with (1.) describes an occurrence of a functional relation between two actors established by the verb and indicates the Use Case in which this relation occurs.The functional relations between two actors, in the form (1.), can be extended, by transitivity, to other actors when two items with the following form exist: (A i , v 1, A j,, UC x ) and (A j , v 2, A k , UC y ). In this way, hence, an indirect functional relation between the actor A i and the actor A k is also established by transitivity. Starting from this consideration, chains joining different actors can be built, where each item (A i , v x , A j ,UC x ) of the chain is such that the previous item has the form (A k , v y , A i , UC y ) and the following has the form (A j , v z , A h , UC z ). The collection of all the items derivable from a Use Case-based requirements document is said Relations core . The Relations core embeds all the elementary functional relations between actors that can be extracted directly by the NL description.We can derive specific, non-elementary, relations from the relations core. In the following we provide some definitions and define some properties based on the elementary relations (1.).The drives relation, that we denote by A ² B, holds if at least one relation (A, verb_i, B, Use_Case_id) exists.The ignores relation, denoted by A ~ B, holds if no relation (A, verb_i, B, Use_Case_id) exists.The drives relation between actors can be used to build the Relation Graph . The nodes of this graph represent the actors and an oriented arc connecting two nodes (A and B) indicates that A drives B.Two nodes are adjacent if an arc from A to B exists.A path from the node A to the nodeB on this graph is a sequence of adjacent nodes in a graph starting from the node A and arriving to the node B. On the basis of the Relations graph some further relations between actors can be defined: The is connected to relation, denoted by A B , holds if at least one path from A to B exists on the graph.The is chief relation, denoted by A B, holds if B is not connected to A and A is connected to B.The chief graph (derived from the chief relation) is an acyclic graph composed of nodes (the actors) and oriented arcs connecting two actors, an arc originating from the node A and arriving in the node B means that A is chief of B. Nodes of the chief graph having no incoming arcs are said leader nodes and nodes having no out arc are said e xecutors nodes.An example of Relation and Chief graphs are provided in Figure 2.The availability of the functional relations and of the graphs derived from them enable the capturing of some semantic information on the system we are describing. In particular, this information can be used to support the detection of critical points (in terms of consistency and completeness) in the interactions between different actors. These critical points can be revealed by analysing the set of derived direct and indirect relations.4. Derivation of the relations between actorsThe derivation of the relations core and the consequent construction of the relation chains, relations graph and chief graph, can be supported by automatic tools based on NL processing techniques.In fact, the basic relations (1.) are detectable by using a syntactical parser able to identify the different components of a NL sentence. To our purpose, the key components to be identified are the subject(s), the verb and the complement(s) associated to the verb. Once this information is achieved, it is possible to define the relations and to build a data base containing the relations core derivable from the collection of Use Cases under analysis.4.1 An example of Derivation of RelationsIn this section we present an application of the relational approach to a sample Use Case document, with the aim to clarify the concepts discussed above.The example we present in this section is derived, with few changes, from a sample System Requirements Document available on the web at the Cockburn’s home page, which is reported in Appendix 1[/acockburn/papers/prts_req.htm]. This document, describing a Purchase Request Tracking System, has the purpose to provide the functional requirements of a basic system for the official Buyers of the company, to track what they have ordered from Vendors against what they have been delivered. The documents is organised as a set of Use Cases.The primary actors of this document are:• Approver: typically the requestor’s manager, who must approve the request.• Authorizer: person who validates the signature from the Vendor.• Buyer: person who manages the order, talking with the Vendor.• Vendor: person or company who sells and delivers goods. • Requestor: person putting in a request to buy something. • Receiver: takes care of the arriving deliveriesThe document contains fifteen Use Cases describing the behaviour of the system. We slightly modified it by adding two new Use Cases to make it more precise and suitable for the analysis. The Use Cases included into the document are compliant with the Cockburn’s style, and they include several data as, for example, Preconditions, Post-conditions, Trigger, Extensions, etc. We simplified each Use Case by reducing the information associated to them. In particular, we took into account only the Primary Actor, the statement of the Goal and the description of the Scenario. These data represent the minimum set of information necessary to save the essential meaning of the Use Case. In Appendix 1, the set of the simplified Use Case we used for the experiment is shown.The outcomes of the application of the relational approach to the simplified Use Cases of the case study are summarized in a collection of relations items between actors and a set of relations chains derived from the relations items.For simplicity let us identify the actors of the case study by a letter:A. AuthorizerB. ApproverC. RequestorD. BuyerE. VendorF. Receiver Figure 6. contains the relations derived from the case study where each actor is identified by the corresponding letter along with the corresponding relation graph and chief graph. In the following a possible set of relations chains starting from the relation (A, notify, B, UC3), is provided:− (A, notify, B, UC3), (B, send, C, UC6), (C, send, B, UC7).− (A, notify, B, UC3), (B, send, C, UC6), (C, send, B, UC8).− (A, notify, B, UC3), (B, send, C, UC9), (C, send, B, UC7).− (A, notify, B, UC3), (B, send, C, UC9), (C, send, B, UC8).− (A, notify, B, UC3), (B, send, A, UC12).− (A, notify, B, UC3), (B, send, A, UC12), (A, change, B, UC3).− (A, notify, B, UC3), (B, send, A, UC12), (A,send, C, UC9).− (A, notify, B, UC3), (B, send, A, UC12), (A,send, D, UC16).− (A, notify, B, UC3), (B, send, A, UC12), (A,send, C, UC9), (C, send, B, UC7).− (A, notify, B, UC3), (B, send, A, UC12), (A,send, C, UC9), (C, send, B, UC8).− (A, notify, B, UC3), (B, send, A, UC12), (A,send, D, UC16), (D, change, E, UC4).− (A, notify, B, UC3), (B, send, A, UC12), (A,send, D, UC16), (D, send, C, UC9).− (A, notify, B, UC3), (B, send, A, UC12), (A, send, D, UC16), (D, send, C, UC9), (C, send, B, UC7)− (A, notify, B, UC3), (B, send, A, UC12), (A, send, D, UC16), (D, send, C, UC9), (C, send, B, UC8).4.2 An integrated environment for Use Case AnalysisIn this section we provide a description of MAIGRET, an integrated environment for natural language analysis. MAIGRET was built with the goal to provide an automatic support for the analysis framework of expressiveness, consistency and completeness aspects of natural language requirements documents. To reach this goal we have realized and integrated a set of tools, each one dedicated to a specific linguistic analysis purpose of NL sentences. In particular (figure 3), the involved tools are a lexical analyzer (QuARS) [6,7], a syntactical analyzer (SyTwo/Cmap) [16,19] able to extract items representing relations between the entities (actors) described in the requirements document and a third tool (Relation Manager) having the aim of storing and managing these relations. Figure 4 shows the high level architecture of MAIGRET.Figure 2: Relations between actors and graphsMAIGRET is composed of a processing part (theintegrated tools) and of a static part (composed of the following modules: the WordNet English dictionary; a semantic network modelling the domain; and a requirements-specific dictionary) that represents the knowledge base for MAIGRET.In the following we provide a more detailed functional description of the integrated tools.• QuARS (Quality Analyzer for Requirements Specifications) is a sentence analyser aiming at reducing linguistic defects by pointing out those wordings that make the document ambiguous or not clear from a lexical point of view. The tool points out these defects without forcing any corrective actions, leaving the user free to decide whether modifying the document or not. Moreover the sentences are analyzedFigure 3: high level architecture of MAIGRETtaking into account the particular application domain, and this is possible through the use of targeted dictionaries. In this sense the tool has been designed to be easily adaptable. The following are examples of expressiveness defects pointed out by QuARS; the underlined wordings are the indicators used by QuARS to point out the sentence as defective:- the C code shall be clearly commented (vaguesentence)- the system shall be as far as possible (subjective sentence)- the system shall be such that the mission can be pursued, possibly without performance The first sentence contains the word “clearly” that makesthe whole sentence vague. The second contains the wording “as far as possible” that makes it subjective. The third sentence is pointed out as defective because contains the word “possibly” that determines an option in it.SyTwo/Cmap is a syntactical analyser. Starting with a Use Case description (possibly already analyzed by QuARS), we can use SyTwo/Cmap to perform a syntactical analysis making the detection of syntactically ambiguous sentences possible. A syntactically ambiguous sentence can be pointed out if it has more than one derivation tree (i.e. the sequences of syntactical rules to be applied to build the sentence): this implies that the sentence may be understood in different ways. For example the sentence “The system shall not remove faults and restore service ” may be syntactically understood at least in these two ways:1. The negation not of the auxiliary verb shall is related to the first verb remove only, and not to the other verb restore . In this case, the meaning of theRelation GraphChief Graphsentence is that the system shall not remove thefaults and it shall restore the service.2. The negation not of the auxiliary verb shall isrelated to both the verbs remove and restore. In thiscase, the meaning of the sentence is that the systemshall not remove the fault and shall not restore theservice.The functionalities described above for both tools allow therefore expressiveness characteristics to be analyzed. More interesting for the methodology presented in this paper is the additional functionality offfered by SyTwo/Cmap, which is able, on the basis of the knowledge of the syntactical structure, also to extract the relations between subjects, verbs and objects in a sentence, in a format compliant with (1.).This allows to capture all the relations between two actors in the problem domain.• Relations Manager: it receives as input the set of relations derived by SyTwo/Cmap and it puts them in a database for analysis. Once such a database has been populated it is possible to:• extract, by means of queries, sub-sets of relations.• extract, by means of queries, sets of relation chains.The outcomes derived from the data-base, can be used in support of the analysis of the requirements document in order to extract the interactions between actors and build the relation and the chief graphs.5. Applying the Relational ApproachIn this section we discuss possible applications and developments of the relational approach to the Use Case-based requirements engineering.Since relations indicate the presence of a verb in the use case relating two actors, they often indicate possible interactions between actors. Hence, relations chains can be interpreted as interaction schemata. Walkthroughs of these interaction schemata may be performed in search of undesired, inconsistent and incomplete dynamic behaviour of the system.These schemata may also form the basis for a formal analysis of interactions, which however we do not address in this context.Walkthroughs of interaction schemata may be aimed at detecting relation chains containing loops, because loops indicate a more complex kind of interaction, and may point to a possible synchronization problem (such as a deadlock). It is possible, in this way, to point out some potential synchronization problems in a sequence of actions.Let us consider, for instance, the example of section 5.1. In this case we detect the relation chain: (A, notify, B, UC3), (B, send, C, UC6), (C, send, B, UC7), presenting a loop. If carefully walk through this chain, and we represent this interactions sequence on a time scale (see figure 6), it is possible to understand that some potential synchronisation problems may occur.Figure 6: Interactions sequenceIn fact, if the Approver AP1 sends the changed request to the Requestor R1 and, before that R1 tells A1 that this change is refused, Authorizer AU1 change the authorization to AP1 and makes A2 the Approver of R1, then who should manage R1’s refusal?In this case, it is possible to detect an inconsistency in the requirements due to an incomplete specification of the requirements because the notification of the changed Approver is not sent also to the associated Requestors. This kind of problems, that are hidden if we consider only the Use Cases-based requirements document, may be easily detected by using the relations chains.Another possibility of exploiting this information is to point out those pairs of actors that have an higher number of interactions than the others. The pairs that, in the case study, have the highest number of different interactions are Approver-Requestor (5 interactions), Authorizer-Approver (4 interactions) and Buyer-Requestor (3 interactions). The indication that can be derived from these data is that the interactions between these actors are at the core of the functionality of the system, and therefore should be analysed in more detail in order to point at possible problems. Also, this information can give an indication to which parts of the system should be stressed at testing time.The semantic information derivable from the derived relations and graphs can help the analysis of correctness and completeness of the requirements because some gaps in the specification of use cases can be easily found.In fact, the graphs defined above (and in particular the chief graph) allow some interesting considerations to be made. The chief relation it is not to be intended as determining a hierarchy in terms of the importance of the role played by the actors. This relation and the information derivable from the graph is a semantic information that allows to enlighten the influence of an actor on the others. In particular, if a node A of the chief graph is connected with the node B by an arc (A, B), then it can be argued that the behaviour of B doesn’t influence that of A. This kind of semantic information about the actors, that cannot be directly derived from the set of use cases, can play a relevant role for the analysis. In particular, it is possible to easily detect lacks in the relational structure of the requirements.In the example shown in section 5.1, the relation F D occurs. This occurrence enlighten a gap in the specifications because the buyer should have the capability of having a relation with the receiver (for instance, to ask the status of an on-going acquisition).The relational approach can be oriented to achieve a guidance for systematic construction of the Use Case requirements documents. In fact, building the relations graphs in parallel with the definition of the use cases impels a continuing series of walkthroughs to check the part of the relations graph completed so far and examine how remaining relations should be added to the graphs themselves.We wish in the end point at another application of the relational approach, which spans outside the context of Use Cases. A concept that has gained importance in the last years, especially in the telecommunication field, is the concept of feature. A feature is a capability of a system which provides value to the users, but is conceived as separate from the other features provided by a system to its users. However, at the system level, features can interact in a complex manner (a problem often referred as “Feature interaction”), so they cannot be treated as separate in the development of the system, and especially in the requirements document. A feature may even prevents other system activities: for instance, in a mobile handset user interface the “keyguard” feature prevents almost all other user-originated activities (but not incoming call handling).The description of a feature by Use Cases can be trivial (in the keyguard example the scenario might be composed simply of the “set the keyguard on” activity) and the Use Cases may be not able to represent how the system behaviour is affected by a feature.The knowledge of the influence of the features on the UCs can be important mainly for the testing of the system because the Use Cases are not enough for representing the consequences of the features on the functionalities they describe. For this reason the relational approach to the Use Case analysis can be of interest to identify those Use Casesaffected by a feature.For example in order to identify the Use Cases affected bythe keyguard feature, those UC can be detected having in their scenario a sentence like “User digit a key”. These UCare influenced in case of the keyguard is set on.6. Conclusions and Future worksIn this paper we presented an approach to the analysis ofUse Case requirements documents based on the relationsbetween the actors. Starting from the simple relation between two actors derivable from a scenario sentence, bymeans of NL parsing tools, some more complex, derived relations have been defined. These relations are able to provide semantic information on the content of a requirements document, supporting the completeness andconsistency analysis. The semantic information on the Use Case requirements documents that can be captured with this approach is only partial, w.r.t. the semantic of the whole requirements. Anyway, this information is able to provide a concrete support for the analysis.The use of the semantic information derivable with the relation-based approach has been discussed in this paper. In particular, the knowledge of the functional relations between actors expressed by the Use Cases allows to perform walkthroughs in the relation core to detect possible gaps in terms of consistency and completeness. Moreover, a guidance for a systematic construction of the Use Cases requirements document can be obtained by the parallel development of graphs and schemata representing the relations.A related work to ours is that reported in [20], in whichmore sophisticated NL techniques are used to extract concept lattices out of Use Cases, which offer a richer information to the analysis. Our approach use simpler, low cost NL techniques to extract useful information: it would be interesting to see whether the benefits obtained by heavier NL techniques balance their higher costs.The relation-based approach to the analysis of Use Casesis a promising research direction because it can be used asa mean to bridge the gap between the use of the informal NL descriptions typical of requirements documents, and the more formal artefacts typical of later stages of the development process. In particular, the study of the relations between actors, though starting from a light formalism as the Use Cases are, can provide enough information to move towards the application of formal methods with the support of automatic tools and in a user friendly way. We plan to investigate at this regard the annotation of the relation graph with pre-conditions and post-condition in order to perform simulations of the system and perform a more refined analysis.。

下载提示

1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。

USING A CONCEPT-BASED APPROACH TO ASPECT-ORIENTED SOFTWARE DESIGN

合集下载

社会科学研究方法与论文写作智慧树知到期末考试章节课后题库2024年北京第二外国语学院

高三英语学术文章单选题50题

2020届南京竹山中学高三英语期末试题及答案解析

Abstract A Relation-based Approach to Use Case Analysis

文档推荐

最新文档