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.       

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.     

Large-Scale Requirements Analysis Revisited: The need for Understanding the Political Ecology of Requirements Engineering

This paper addresses the political nature of requirements for large systems, and argues that requirements engineering theory and practice must become more engaged with these issues. It argues that large-scale system requirements is constructed through a political decision process, whereby requirements emerge as a set of mappings between consecutive solution spaces justified by a problem space of concern to a set of principals. These solution spaces are complex socio-technical ensembles that often exhibit non-linear behaviour in expansion due to domain complexity and political ambiguity. Stabilisation of solutions into agreed-on specifications occurs only through the exercise of organisational power. Effective requirements engineering in such cases is most effectively seen as a form of heterogeneous engineering in which technical, social, economic and institutional factors are brought together in a current solution space that provides the baseline for construction of proposed new solution spaces.     

非功能需求的结构化定义以及概念性追踪管理框架

针对需求工程中非功能需求概念非常模糊甚至相互矛盾、非功能需求与其他非功能需求及功能需求之间的关系繁复而难以分析和建模、非功能需求与设计阶段制品之间的追踪关系模糊而不易记录和维护等问题,分析了与非功能需求相关的概念在需求分析阶段和体系结构设计阶段的表现形式,给出了一个结构化的非功能需求定义;规范了不同类型需求之间的各种复杂关系,建立了一个跨越分析和设计阶段的概念性非功能需求追踪管理框架,规范了需求分析和体系结构设计阶段与非功能需求相关的概念和制品之间的关系。提出的结构化定义以及概念性追踪管理框架明确地刻画了非功能需求概念的外延,为简化需求模型以及进一步研制系统化、实用化的非功能需求建模及追踪管理技术奠定了理论基础。     

Coupling Use Cases and Class Models as a Means for Validation and Verification of Requirements Specifications

In many applications, especially from the business domain, the requirements specification mainly deals with use cases and class models. Unfortunately, these models are based on different modelling techniques and aim at different levels of abstraction, such that serious consistency and completeness problems are induced. To overcome these deficiencies, we refine activity graphs to meet the needs for a suitable modelling element for use case behaviour. The refinement in particular supports the proper coupling of use cases via activity graphs and the class model. The granularity and semantics of our approach allow for a seamless, traceable transition of use cases to the class model and for the verification of the class model against the use case model. The validation of the use case model and parts of the class model is supported as well. Experience from several applications has shown that the investment in specification, validation and verification not only pays off during system and acceptance testing but also significantly improves the quality of the final product.       

Analysing Action Sequences: Variations in Action Density in the Administration of Anaesthesia

Anaesthesia may be characterised as a paradigmatic field of activity in complex work environments. The aim of this study is to achieve an in-depth understanding of the anaesthetists’ clinical practice by investigating the operational composition of action sequences. Previous time and motion studies have all faced the methodological problem of recording and interpreting concurrent operations. This study, however, aims to approach this problem by applying a new observation method, sensitive to overlapping operations in action sequences. The analysis of overlapping operations provides us with a means of describing action density. The results of our process-oriented case analysis show that action density exhibits a characteristic and distinct distribution during the administration of anaesthesia. Moreover, overlapping operations seem to have a central position when dealing with the varying requirements related to the occurrence of unexpected events. Some implications of our approach for the design of simulator settings will be discussed.     

Rationale-Based Use Case Specification

The requirements specification – as outcome of the requirements engineering process – falls short of capturing other useful information generated during this process, such as the justification for selected requirements, trade-offs negotiated by stakeholders and alternative requirements that were discarded. In the context of evolving systems and distributed development, this information is essential. Rationale methods focus on capturing and structuring this missing information. In this paper, we propose an integrated process with dedicated guidance for capturing requirements and their rationale, discuss its tool support and describe the experiences we made during several case studies with students. Although the idea of integrating rationale methods with requirements engineering is not new, few research projects so far have focused on smooth integration, dedicated tool support and detailed guidance for such methods.     

Patterns Approach to Product Information Systems Engineering

This paper deals with the application of the pattern approach to product information systems (PIS) engineering. Two kind of patterns are distinguished: business patterns used for specification and providing solutions for application field problems, and software patterns used for implementation and providing solutions for technical problems (software). Particular attention is given to identifying and specifying different business patterns. The main focus is on the activity of design for reuse, i.e. discovery of business patterns and their integration in a pattern catalogue. The first step consisted of a field analysis providing a common terminology and a semantic of the principal concepts managed in PIS and proposing various models to fix these concepts. It forms a basis for exploring the problems frequently occurring during PIS specification. A pattern catalogue is then proposed to solve the identified problems.     

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.     

Negotiating and Understanding Information Systems Requirements: The Use of Set Diagrams

A major contributor to the failure of information technology-based systems is the problem of understanding user or customer requirements in the initial analysis and requirements identification stage of development. This paper identifies and describes an approach to help overcome some of these problems, particularly the mismatch or understanding gap between the customer and the developer. The approach is intended to be used at the early stages of requirement determination and introduces techniques from operational research into the process. In particular set theory and Venn diagrams are used as a way of graphically representing the relationships and gaps in understanding that may exist. The benefit obtained from the use of the technique is partly in the graphical representations themselves but mainly in the dialogue and negotiation that result from the construction of the diagrams. The technique has been developed in a research study of retail organisations’ use of information technology in the UK and an example case study from the sector is used to illustrate and discuss the technique.     

Tracing Requirements Errors to Problems in the Requirements Engineering Process

A case study of requirements engineering practice is reported. The application, a decision support system for the Greek Ministry of Health, was investigated by studying the process of requirements analysis through to design and implementation. A usability analysis was then conducted on the designed system with the users. Several usability problems were discovered, and interviews uncovered further problems with the system that could be attributed to failure in requirements engineering (RE). Even though requirements were explicitly stated and the system was an evolution from an existing legacy system, functionality was defective and usability was poor. The client’s prime concern for redeveloping the system was to improve usability; unfortunately communications problems in the RE process meant that the developers did not appreciate this. The implications for RE methods and understanding the RE process are discussed.     

Patterns of Mobile Interaction

The design of systems for mobile scenarios covers a wide range of issues, ranging from mobile networking to user interface design for mobile devices. Mobile applications often run distributed on several connected devices, used by many users simultaneously. Considering all issues related to mobile scenarios, a designer might be overwhelmed. As a solution, we propose a specific kind of design patterns which we call mobility patterns, derived from successful mobile applications. They allow a designer to re-use design elements as building blocks in their own designs. After describing the idea of mobility patterns, we give a brief overview of patterns we have identified so far. Two patterns are described in more detail with the help of our research platforms QuickStep and Pocket DreamTeam.     

Socio-Technical and Soft Approaches to Information Requirements Elicitation in the Post-Methodology Era

The contributors to this special issue focus on socio-technical and soft approaches to information requirements elicitation and systems development. They represent a growing body of research and practice in this field. This review presents an overview and analysis of the salient themes within the papers encompassing their common underlying framework, the methodologies and tools and techniques presented, the organisational situations in which they are deployed and the issues they seek to address. It will be argued in the review that the contributions to this special edition exemplify the ‘post-methodological era’ and the ‘contingency approaches’ from which it is formed.     

Scenario Development and Practical Decision Making under Uncertainty: Application to Requirements Engineering

In this paper, we address the question of how flesh and blood decision makers manage the combinatorial explosion in scenario development for decision making under uncertainty. The first assumption is that the decision makers try to undertake ‘robust’ actions. For the decision maker a robust action is an action that has sufficiently good results whatever the events are. We examine the psychological as well as the theoretical problems raised by the notion of robustness. Finally, we address the false feeling of decision makers who talk of ‘risk control’. We argue that ‘risk control’ results from the thinking that one can postpone action after nature moves. This ‘action postponement’ amounts to changing look-ahead reasoning into diagnosis. We illustrate these ideas in the framework of software development and examine some possible implications for requirements analysis.     

The Human Communication Space: Towards I-centric Communications

In the last few years, a variety of concepts for service integration and corresponding systems have been developed. On the one hand, they aim for the interworking and integration of classical telecommunications and data communications services. On the other, they are focusing on universal service access from a variety of end-user systems. Many of the technical problems, resulting from the service integration, and service personalisation have been solved during the last years. However, all these systems are driven by the concept of providing several technologies to users by keeping the peculiarity of each service.  Looking at humans’ communication behaviour and their communication space, it is obvious that human beings interact habitually in a set of contexts with their environment. The individual information preferences and needs, persons to interact with, and the set of devices controlled by each individual define their personal communication space. Following this view, a new approach is to build communication systems not on the basis of specific technologies, but on the analysis of the individual communication spaces. The result is a communication system adapted to the demands of each individual (I-centric). The communication system will act on behalf of users’ demands, reflecting recent actions to enable profiling and self-adaptation to contexts and situations.  In this paper, we introduce I-centric Communications, an approach to design communication systems that adapt themselves to the individual communication space and individual environment and situation. In this context “I” means I, or individual, “Centric” means adaptable to I requirements and a certain user environment.     

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.     

The Importance of Context in Information System Design: An Assessment of Participatory Design

This paper is predicated on requirements analysis as the Achilles heel of information systems development, and accepts that information systems often disappoint. Most design paradigms can be located within a rationalistic framework polarised by requirements analysis and system delivery. Such traditional design paradigms are seen as palliatives that prevent us moving toward more satisfying information systems. It is argued that this rationalistic framework forces us to identify, and attempt to solve, problems that are symptomatic of the approach adopted. A pluralistic framework for information system development is presented which rejects the notions of requirements analysis and system optimality. Participatory design, derived from the field of human computer interaction, is located within this framework and identified as a possible paradigm for information system development. A case study is conducted to assess the benefits of participatory design techniques and to evaluate the extent to which participatory design can overcome the failings of traditional methodologies.