Automated classification of non-functional requirements

This paper describes a technique for automating the detection and classification of non-functional requirements related to properties such as security, performance, and usability. Early detection of non-functional requirements enables them to be incorporated into the initial architectural design instead of being refactored in at a later date. The approach is used to detect and classify stakeholders’ quality concerns across requirements specifications containing scattered and non-categorized requirements, and also across freeform documents such as meeting minutes, interview notes, and memos. This paper first describes the classification algorithm and then evaluates its effectiveness through reporting a series of experiments based on 30 requirements specifications developed as term projects by MS students at DePaul University. A new and iterative approach is then introduced for training or retraining a classifier to detect and classify non-functional requirements (NFR) in datasets dissimilar to the initial training sets. This approach is evaluated against a large free-form requirements document obtained from Siemens Logistics and Automotive Organization. Although to the NFR classifier is unable to detect all of the NFRs, it is useful for supporting an analyst in the error-prone task of manually discovering NFRs, and furthermore can be used to quickly analyse large and complex documents in order to search for NFRs.     

A Framework for Integrating Non-Functional Requirements into Conceptual Models

The development of complex information systems calls for conceptual models that describe aspects beyond entities and activities. In particular, recent research has pointed out that conceptual models need to model goals, in order to capture the intentions which underlie complex situations within an organisational context. This paper focuses on one class of goals, namely non-functional requirements (NFR), which need to be captured and analysed from the very early phases of the software development process. The paper presents a framework for integrating NFRs into the ER and OO models. This framework has been validated by two case studies, one of which is very large. The results of the case studies suggest that goal modelling during early phases can lead to a more productive and complete modelling activity.       

Feature-Oriented Nonfunctional Requirement Analysis for Software Product Line

Domain analysis in software product line (SPL) development provides a basis for core assets design and implementation by a systematic and comprehensive commonality/variability analysis. In feature-oriented SPL methods, products of the domain analysis are domain feature models and corresponding feature decision models to facilitate application-oriented customization. As in requirement analysis for a single system, the domain analysis in the SPL development should consider both functional and nonfunctional domain requirements. However, the nonfunctional requirements (NFRs) are often neglected in the existing domain analysis methods. In this paper, we propose a context-based method of the NFR analysis for the SPL development. In the method, NFRs are materialized by connecting nonfunctional goals with real-world context, thus NFR elicitation and variability analysis can be performed by context analysis for the whole domain with the assistance of NFR templates and NFR graphs. After the variability analysis, our method integrates both functional and nonfunctional perspectives by incorporating the nonfunctional goals and operationalizations into an initial functional feature model. NFR-related constraints are also elicited and integrated. Finally, a decision model with both functional and nonfunctional perspectives is constructed to facilitate application-oriented feature model customization. A computer-aided grading system (CAGS) product line is employed to demonstrate the method throughout the paper. This work is supported by the National Natural Science Foundation of China under Grant Nos. 60703092 and 90818009, the National High Technology Research and Development 863 Program of China under Grant No. 2007AA01Z125.     

Quality-driven architecture development using architectural tactics

This paper presents a quality-driven approach to embodying non-functional requirements (NFRs) into software architecture using architectural tactics. Architectural tactics are reusable architectural building blocks, providing general architectural solutions for common issues pertaining to quality attributes. In this approach, architectural tactics are represented as feature models, and their semantics is defined using the Role-Based Metamodeling Language (RBML) which is a UML-based pattern specification notation. Given a set of NFRs, architectural tactics are selected and composed, and the composed tactic is used to instantiate an initial architecture for the application. The proposed approach addresses both the structural and behavioral aspects of architecture. We describe the approach using tactics for performance, availability and security to develop an architecture for a stock trading system. We demonstrate tool support for instantiating a composed tactic to generate an initial architecture of the stock trading system.     

Detecting,classifying, and tracing non-functional software requirements

In this paper, we describe a novel unsupervised approach for detecting, classifying, and tracing non-functional software requirements (NFRs). The proposed approach exploits the textual semantics of software functional requirements (FRs) to infer potential quality constraints enforced in the system. In particular, we conduct a systematic analysis of a series of word similarity methods and clustering techniques to generate semantically cohesive clusters of FR words. These clusters are classified into various categories of NFRs based on their semantic similarity to basic NFR labels. Discovered NFRs are then traced to their implementation in the solution space based on their textual semantic similarity to source code artifacts. Three software systems are used to conduct the experimental analysis in this paper. The results show that methods that exploit massive sources of textual human knowledge are more accurate in capturing and modeling the notion of similarity between FR words in a software system. Results also show that hierarchical clustering algorithms are more capable of generating thematic word clusters than partitioning clustering techniques. In terms of performance, our analysis indicates that the proposed approach can discover, classify, and trace NFRs with accuracy levels that can be adequate for practical applications.     

Model-driven development for early aspects

Currently, non-functional requirements (NFRs) consume a considerable part of the software development effort. The good news is that most of them appear time and again during system development and, luckily, their solutions can be often described as a pattern independently from any specific application or domain. A proof of this are the current application servers and middleware platforms that can provide configurable prebuilt services for managing some of these crosscutting concerns, or aspects. Nevertheless, these reusable pattern solutions presents two shortcomings, among others: (1) they need to be applied manually; and (2) most of these pattern solutions do not use aspect-orientation, and, since NFRs are often crosscutting concerns, this leads to scattered and tangled representations of these concerns. Our approach aims to overcome these limitations by: (1) using model-driven techniques to reduce the development effort associated to systematically apply reusable solutions for satisfying NFRs; and (2) using aspect-orientation to improve the modularization of these crosscutting concerns. Regarding the first contribution, since the portion of a system related to NFRs is usually significant, the reduction on the development effort associated to these NFRs is also significant. Regarding the second contribution, the use aspect-orientation improves maintenance and evolution of the non-functional requirements that are managed as aspects. An additional contribution of our work is to define a mapping and transition from aspectual requirements to aspect-oriented software architectures, which, in turn, contributes to improve the general issue of systematically relating requirements to architecture. Our approach is illustrated by applying it to a Toll Gate case study.     

一种面向特征的软件产品线非功能需求建模方法

分析传统非功能需求定义的不足,基于需求分析阶段的系统抽象—"需求模型"重新定义非功能需求,规范并简化功能需求与非功能需求之间的关系。扩展面向特征的软件产品线建模方法,在特征模型中显式地建模功能需求、非功能需求、非功能需求类型以及它们之间的相互关系,沿用传统特征模型中固有的变化性建模机制建模并管理非功能需求的变化性,显式地复用与非功能需求相关的建模知识和资产,为进一步研究定量评估产品线变体质量的新技术奠定基础。设计了一个基于多视图的特征建模方法,指导开发者在迭代的过程中建模非功能需求和功能需求,支持关注点分离和模型的复杂性管控。实现了工具原型并进行了实例验证。     

Dealing with change: An approach using non-functional requirements

Non-functional requirements (or quality requirements, NFRs) such as confidentiality, performance and timeliness are often crucial to a software system. Concerns for such NFRs are often the impetus for change. To systematically support system evolution, this paper adapts the NFR Framework, which treats NFRs as goals to be achieved during development. Throughout the process, consideration of design alternatives, analysis of trade-offs and rationalisation of design decisions are all carried out in relation to the stated goals, and captured in historical records. We show how such historical records of treating NFRs as goals also system-atically support system evolution. This approach is illustrated by a study of changes in loan policies at Barclays Bank. The study considered changes in NFRs, and associated changes in priorities, workload and functionality. The study's historical records helped quickly determine the impact of changes. We also present guidelines for consistently managing historical records, and address tool support for the change process.This is an extended and revised edition of a paper [34] appearing in theProceedings of the Second International Symposium on Requirements Engineering. York, England, March 1995. A draft of that paper was prepared when all three authors were at the Department of Computer Science, University of Toronto.     

面向软件产品线中特征选择的多目标优化算法

软件产品线中产品定制的核心是选择合适的特征集.由于多个非功能需求间往往相互制约甚至冲突,特征选择的本质是多目标优化过程.优化过程的搜索空间被特征间错综复杂的依赖和约束关系以及明确的功能需求大大限制.另外,有些非功能需求有明确的数值约束,而有些则仅要求尽可能得到优化.多样的非功能需求约束类型也给优化选择过程带来极大挑战.本文提出一种含修正算子的多目标优化算法MOOFs.文中首先设计特征间依赖和约束关系描述语言DCF-DL来统一规范特征选择过程中必须遵守的规则.所有的非功能需求都转化为优化目标,相关的数值约束则作为优化过程中特征选择方案的过滤器.另外,设计了修正算子用于保证选择出的特征配置方案必满足产品线的特征规则约束.通过与四个常用的多目标优化算法在四个不同规模的特征模型上的运行结果做对比,证明本文的方法能够更快地产生满足约束的优化解,且优化解具备更好的收敛性与多样性.     

Management of performance requirements for information systems

The management of performance requirements is a major challenge for information systems as well as other software systems. This is because performance requirements can have a global impact on the target system. In addition, there are interactions and trade-offs among performance requirements, other nonfunctional requirements (NFRs), and the numerous alternatives for the target system. To provide a systematic approach to managing performance requirements, this paper presents a performance requirements framework (PeRF). It integrates and catalogues a variety of kinds of knowledge of information systems and performance. These include: performance concepts, software performance engineering principles for building performance into systems, and information systems development knowledge. In addition, layered structures organize performance knowledge and the development process. All this knowledge is represented using an existing goal-oriented approach, the “NFR framework”, which offers a developer-directed graphical treatment for stating NFRs, analyzing and interrelating them, and determining the impact of decisions upon NFRs. This approach allows customized solutions to be built, taking into account the characteristics of the particular domain. The use of PeRF in managing performance requirements is illustrated in a study of performance requirements and other NFRs for a university student record system. This paper concludes with a summary of other studies of information systems, tool support and directions for future work     

A framework for prioritization of quality requirements for inclusion in a software project

Non-functional requirements (NFRs) determine the characteristics of a software product or service as a whole. The research described in this paper presents a quantitative framework involving respondents of both the project and the business organization, in order to determine the priority of a list of NFRs to be considered for implementation during a software development. The framework also provides a quantitative basis for evaluating the extent of value addition that can be achieved while deciding upon whether or not to consider a particular non-functional requirement for inclusion to the project’s requirement set. The assessment process also indicates the extent to which different business values are perceived important by representatives of business organizations, and their perception of the importance of the different NFRs. The work distinguishes from others by explicitly considering dependencies among NFRs in the evaluation process. The final results are expected to be beneficial to both the business and the project organization by identifying and implementing the desired NFRs that contribute to business value in a cost-effective manner.     

基于目标部分满意度的需求设计方案评估

不同的需求设计方案对软件系统中非功能目标的实现具有不同的影响。这些非功能目标一般不能以一种绝对清晰定义的程度来满足，常常是以一种部分满意的方式实现，现实中寻求“满意”解比寻求“最优”解更符合实际情况。为了反映此特性，该文在分析目前已存在方法局限性的基础上，利用Letier和Lamsweedre提出的基于概率理论的面向目标的推理方法，对目标部分满意度建模。模型建立在客观标准基础上，在领域内具有实际物理解释，获得了不同方案对目标满意度的影响，可更好地用于指导需求分析和设计决策。     

基于非功能需求的软件体系结构演化

对非功能需求NFRs进行了描述,根据功能需求、NFRs与SA的关系,定义了基于NFRs的SA演化,使用构件组合运算和结构工作链对软件体系结构的非功能特性进行了评估,根据评估结果,给出了基于NFRs的SA演化模型。     

Identification of non-functional requirements in textual specifications: A semi-supervised learning approach

ContextEarly detection of non-functional requirements (NFRs) is crucial in the evaluation of architectural alternatives starting from initial design decisions. The application of supervised text categorization strategies for requirements expressed in natural language has been proposed in several works as a method to help analysts in the detection and classification of NFRs concerning different aspects of software. However, a significant number of pre-categorized requirements are needed to train supervised text classifiers, which implies that analysts have to manually assign categories to numerous requirements before being able of accurately classifying the remaining ones.ObjectiveWe propose a semi-supervised text categorization approach for the automatic identification and classification of non-functional requirements. Therefore, a small number of requirements, possibly identified by the requirement team during the elicitation process, enable learning an initial classifier for NFRs, which could successively identify the type of further requirements in an iterative process. The goal of the approach is the integration into a recommender system to assist requirement analysts and software designers in the architectural design process.MethodDetection and classification of NFRs is performed using semi-supervised learning techniques. Classification is based on a reduced number of categorized requirements by taking advantage of the knowledge provided by uncategorized ones, as well as certain properties of text. The learning method also exploits feedback from users to enhance classification performance.ResultsThe semi-supervised approach resulted in accuracy rates above 70%, considerably higher than the results obtained with supervised methods using standard collections of documents.ConclusionEmpirical evidence showed that semi-supervision requires less human effort in labeling requirements than fully supervised methods, and can be further improved based on feedback provided by analysts. Our approach outperforms previous supervised classification proposals and can be further enhanced by exploiting feedback provided by analysts.     

Validating a model-driven software architecture evaluation and improvement method: A family of experiments

ContextSoftware architectures should be evaluated during the early stages of software development in order to verify whether the non-functional requirements (NFRs) of the product can be fulfilled. This activity is even more crucial in software product line (SPL) development, since it is also necessary to identify whether the NFRs of a particular product can be achieved by exercising the variation mechanisms provided by the product line architecture or whether additional transformations are required. These issues have motivated us to propose QuaDAI, a method for the derivation, evaluation and improvement of software architectures in model-driven SPL development.ObjectiveWe present in this paper the results of a family of four experiments carried out to empirically validate the evaluation and improvement strategy of QuaDAI.MethodThe family of experiments was carried out by 92 participants: Computer Science Master’s and undergraduate students from Spain and Italy. The goal was to compare the effectiveness, efficiency, perceived ease of use, perceived usefulness and intention to use with regard to participants using the evaluation and improvement strategy of QuaDAI as opposed to the Architecture Tradeoff Analysis Method (ATAM).ResultsThe main result was that the participants produced their best results when applying QuaDAI, signifying that the participants obtained architectures with better values for the NFRs faster, and that they found the method easier to use, more useful and more likely to be used. The results of the meta-analysis carried out to aggregate the results obtained in the individual experiments also confirmed these results.ConclusionsThe results support the hypothesis that QuaDAI would achieve better results than ATAM in the experiments and that QuaDAI can be considered as a promising approach with which to perform architectural evaluations that occur after the product architecture derivation in model-driven SPL development processes when carried out by novice software evaluators.     

Control case approach to record and model non-functional requirements

While the functional requirements of a system can be effectively modeled through the use case driven approach, there is no standard or de facto method for modeling non-functional requirements (NFR) of the system architecture. Often such requirements are dealt with in a reactive manner, rather than proactively. Yet increasingly a contributing factor in project difficulty and failure are the NFR imposed on the solution architecture. This paper outlines a control case approach to record and model NFR. This technique enables the control case to represent the NFR from different perspectives, most typically the various operating conditions. We also propose an extension to the “4 + 1” view model for depicting software architecture by adding the control case view. In addition, a detailed control case modeling example is illustrated to demonstrate how these techniques may be applied during development. Taken together, we suggest that the combination of both the use case and control case views thus reflects the complete requirements across the collective system life cycle views: design, process, implementation and deployment.     

Tool Support for Refinement of Non-functional Specifications

Model driven architecture (MDA) views application development as a continuous transformation of models of the target system. We propose a methodology which extends this view to non-functional properties. In previous publications we have shown how we can use so-called context models to make the specification of non-functional measurements independent of their application in concrete system specifications. We have also shown how this allows us to distinguish two roles in the development process: the measurement designer and the application designer. In this paper we use the notion of context models to allow the measurement designer to provide measurement definitions at different levels of abstraction. A measurement in our terminology is a non-functional dimension that can be constrained to describe a non-functional property. Requiring the measurement designer to define transformations between context models, and applying them to measurement definitions, enables us to provide tool support for refinement of non-functional constraints to the application designer. The paper presents the concepts for such tool support as well as a prototype implementation.     

Modelling non-functional requirements of business processes

This paper presents an approach to the identification and inclusion of ‘non-functional’ aspects of a business process in modelling for business improvement. The notion of non-functional requirements (NFRs) is borrowed from software engineering, and a method developed in that field for linking NFRs to conceptual models is adapted and applied to business process modelling. Translated into this domain, NFRs are equated with the general or overall quality attributes of a business process, which, though essential aspects of any effective process, are not well captured in a functionally oriented process model. Using an example of a healthcare process (cancer registration in Jordan). We show how an analysis and evaluation of NFRs can be applied to a process model developed with role activity diagramming (RAD) to operationalise desirable quality features more explicitly in the model. This gives a useful extension to RAD and similar modelling methods, as well as providing a basis for business improvement.     

Advancing candidate link generation for requirements tracing: the study of methods

This paper addresses the issues related to improving the overall quality of the dynamic candidate link generation for the requirements tracing process for verification and validation and independent verification and validation analysts. The contribution of the paper is four-fold: we define goals for a tracing tool based on analyst responsibilities in the tracing process, we introduce several new measures for validating that the goals have been satisfied, we implement analyst feedback in the tracing process, and we present a prototype tool that we built, RETRO (REquirements TRacing On-target), to address these goals. We also present the results of a study used to assess RETRO's support of goals and goal elements that can be measured objectively.     

基于设计结构矩阵的可信软件非功能需求评估模型

可信软件非功能需求的量化评估是可信软件研究的一个重要领域。依据构件中非功能需求之间的相互关系,结合设计结构矩阵及矩阵变换、运算的方法,提出了非功能需求贡献值的概念,建立了构件和非功能需求关系的相关阵列及具有统一标准和评判尺度的可信软件非功能需求度量模型,并结合该模型构建了一种用来判断软件非功能需求是否符合软件开发者和用户预期的评估决策方法。最后通过一个实例来说明本模型的合理性和有效性。