Research On Some Issues In Requirements Engineering

In recent years, IT technology and its application has made rapid development, the totalinvestment of government and enterprise on IT application project has made rapid growth, atthe same time the software requirements are also increasing, the size and complexity ofsoftware is also growing, faced with this situation, software development and softwaremanagement tools are still faced with a variety of problems, making the development of manyprojects finally ending with a lot of problems or totally failure.Among the factors that lead tothe project problems and failures, requirements-related factors account for over50%of theproportion, so the processing of the requirements is a prerequisite for decide weather thesoftware development is success or not.The goal of software requirements engineering is to use systematic methods andengineering management tools to efficiently develop the software requirements specificationwhich accurate expresses the needs of the user. In other words, the purpose of the softwarerequirements engineering is to provide a reasonable and correct development documentationfor software systems.Software requirements engineering is divided into5stages, they arerequirements elicitation, requirements modeling, formal description of requirements,requirements validation and requirements management, different requirements analysisanalyze the requirements through different aspects, and give a series of methods andtechniques range from requirements elicitation to requirements management, the currentpopular requirements analysis methods mainly are goal-oriented, object-oriented,feature-oriented and aspect-oriented.This paper is based on aspect-oriented document-driven requirement method and has aseries of deep research on formal description method of software requirements, formalrequirement modeling process, the consistency detection of aspect-oriented requirementmodel, the requirement change impact analysis.The main work is as follows:1) The definition of denotational semantics in Tabular expressionsTabular expressions is a formal description tool using form structure to organize function orrelationship, and it has a wide range of application in the field of requirement engineering,and it is very necessary to establish a form of semantic model for Tabular expressions. Atpresent most of the semantic description of traditional Tabular expressions is from the angle of evaluation, but there are some limitations on the semantic description of general tabularexpressions from the angle of evaluation. According to the general model for Tabularexpressions, this paper put forward the formal grammatical and denotational semantics ofTabular expressions. This method describes Tabular expressions denotational semanticsthrough defining every semantics assigned equation of the syntax unit in the formal grammar,and describes some typical form type denotational semantics in traditional and new typeTabular expressions respectively, the analysis shows that the semantic description in thispaper does not only accurately describes the semantic of Tabular expressions and is no longersubject to the Tabular expressions model and Tabular expressions type and break thelimitations of existing method, an it is a very effective method.2) The definition method of requirement document based on Tabular expressions4-variable model is a requirement description model using environment variables and theirrelation to characterize the software behavior, it has a wide range of application inrequirements engineering.Tabular expressions general model is a formal description tool, inorder to make the4-variable model formally described and verifiable, we use Tabularexpressions general model gives a formal description of the4-variable model and give theappropriate authentication method. First, the method use Tabular expressions general model todescribe the monitor variable, control variable, and variables such as NAT, REQ, and therelation between different variables, and defines the mapping rules from4-variable model toTabular expressions; then Tabular expressions is converted to the logic system, and defines aseries of constraints and proposes the requirements integrity verification method andfeasibility authentication method based on these constraints; and put forward the acceptableverification of software system on the constructed Tabular expressions instance; for theanalysis of the feasibility and effectiveness of the proposed method, this paper uses thefamous light control system in the field of requirements engineering verified this method, theexperimental results show that the proposed method can effectively describe the4-variablemodel and verify it.3) Integrity and consistency verification based on aspect-oriented requirements modelsEstablish the requirement model which satisfied with the integrity and consistency is thefundamental to the success of software project, verify whether requirements model related tothe nature of software development is of great significance. Aspect-oriented requirementsanalysis method is a method which takes the separation of concerns, crosscutting concernsdecision, construct the concern model as the core. This paper proposed a series strategy andmeans to improve the modeling accuracy and the integrity and consistency of verify model. First，in the acquisition process for concern model, from the requirements dependencyaccuracy, the candidate concern grouping reliability and crosscutting concerns determine thethree angles given validation strategy, to improve the accuracy of the modeling; then it gives aconcern model definition and validation method which is based on ontology, it also gives thedefinition of the concepts and their relationship in the concerns models based on ontology,and summarized the existing ontology-based requirement model integrity and consistencyconstraint rules, combined with the actual characteristics of aspect-oriented requirementsmodel defines the integrity and consistency constraints in the concerns model based onontology，and introduces the mapping rules from concern model to ontology-based concenrmodel and the verification method after mapping. Finally use an example to verify thereliability of the method, and provide useful information for the design and implementation ofa reliable sotfware system.4) Quantified requirements change impact analysis methodSince the requirements changes in the sotfware development is inevitable, thereforeeffective software change impact analysis on the assessment and management of softwaredevelopment is necessary, requirements change impact dialysis via its assessment of thescope and extent, provide effective information for sotfware developers and managers.Aspect-oriented document-driven requirements engineering departures from the documentrequirement to provide the processes and methods based on the concerns and theirrelationship such as requirements modular, crosscutting concerns decision, and generateformalized requirements documents, under this framework, this paper proposed arequirements change impact analysis method base on the reachable matrix, in this method theassociated matrix and reachable matrix were constructed from concerns and variables the twolevel, and according to the definitions such as the importance of the concerns, the concernsdistance, the degree of inlfuence, and under the impact of the extent of the same and differentvariables concerns, it gives the quantified algorithm to calculate the scope and extend of therequirements changes impact. The change impact analysis of the concerns layer and variableslayer in this paper has good continuity, and the results can provide effective reference for thesubsequent design and code writing.Aspect-oriented document-driven requirements method is a new requirements engineeringmethod proposed in recent years, in this paper, a lot of research work carried out under theframework of the method, and in the aspects of requirements formal deifnition, formalrequirement document method, requirement model validation and change impact analysishave got a series of achievements, and an example is given to verify.