Peter Sawyer

Ethnographically-informed systems design for air traffic control

This paper relates experiences of a project where an ethnographic study of air traffic controllers is being used to inform the design of the controllers’ interface to the flight data base. We outline the current UK air traffic control system, discuss the ethnographic work we have undertaken studying air traffic control as a cooperative activity, describe some of the difficulties in collaboration between software developers and sociologists and show how the ethnographic studies have influenced the systems design process. Our conclusions are that ethnographic studies are helpful in informing the systems design process and may produce insights which contradict conventional thinking in systems design.

Viewpoints: principles, problems and a practical approach to requirements engineering

The paper includes a survey and discussion of viewpoint‐oriented approaches to requirements engineering and a presentation of new work in this area which has been designed with practical application in mind. We describe the benefits of viewpoint‐oriented requirements engineering and describe the strengths and weaknesses of a number of viewpoint‐oriented methods. We discuss the practical problems of introducing viewpoint‐oriented requirements engineering into industrial software engineering practice and why these have prevented the widespread use of existing approaches.We then introduce a new model of viewpoints called Preview. Preview viewpoints are flexible, generic entities which can be used in different ways and in different application domains. We describe the novel characteristics of the Preview viewpoints model and the associated processes of requirements discovery, analysis and negotiation. Finally, we discuss how well this approach addresses some outstanding problems in requirements engineering (RE) and the practical industrial problems of introducing new requirements engineering methods.

RELAX: Incorporating Uncertainty into the Specification of Self-Adaptive Systems

Self-adaptive systems have the capability to autonomously modify their behaviour at run-time in response to changes in their environment. Self-adaptation is particularly necessary for applications that must run continuously, even under adverse conditions and changing requirements; sample domains include automotive systems, telecommunications, and environmental monitoring systems. While a few techniques have been developed to support the monitoring and analysis of requirements for adaptive systems, limited attention has been paid to the actual creation and specification of requirements of self-adaptive systems. As a result, self-adaptivity is often constructed in an ad-hoc manner. In this paper, we argue that a more rigorous treatment of requirements explicitly relating to self-adaptivity is needed and that, in particular, requirements languages for self-adaptive systems should include explicit constructs for specifying and dealing with the uncertainty inherent in self-adaptive systems. We present RELAX, a new requirements language for self-adaptive systems and illustrate it using examples from the smart home domain.

A Goal-Based Modeling Approach to Develop Requirements of an Adaptive System with Environmental Uncertainty

Dynamically adaptive systems (DASs) are intended to monitor the execution environment and then dynamically adapt their behavior in response to changing environmental conditions. The uncertainty of the execution environment is a major motivation for dynamic adaptation; it is impossible to know at development time all of the possible combinations of environmental conditions that will be encountered. To date, the work performed in requirements engineering for a DAS includes requirements monitoring and reasoning about the correctness of adaptations, where the DAS requirements are assumed to exist. This paper introduces a goal-based modeling approach to develop the requirements for a DAS, while explicitly factoring uncertainty into the process and resulting requirements. We introduce a variation of threat modeling to identify sources of uncertainty and demonstrate how the RELAX specification language can be used to specify more flexible requirements within a goal model to handle the uncertainty.

Requirements-Aware Systems: A Research Agenda for RE for Self-adaptive Systems

Requirements are sensitive to the context in which the system-to-be must operate. Where such context is well understood and is static or evolves slowly, existing RE techniques can be made to work well. Increasingly, however, development projects are being challenged to build systems to operate in contexts that are volatile over short periods in ways that are imperfectly understood. Such systems need to be able to adapt to new environmental contexts dynamically, but the contextual uncertainty that demands this self-adaptive ability makes it hard to formulate, validate and manage their requirements. Different contexts may demand different requirements trade-offs. Unanticipated contexts may even lead to entirely new requirements. To help counter this uncertainty, we argue that requirements for self-adaptive systems should be run-time entities that can be reasoned over in order to understand the extent to which they are being satisfied and to support adaptation decisions that can take advantage of the systems’ self-adaptive machinery. We take our inspiration from the fact that explicit, abstract representations of software architectures used to be considered design-time-only entities but computational reflection showed that architectural concerns could be represented at run-time too, helping systems to dynamically reconfigure themselves according to changing context. We propose to use analogous mechanisms to achieve requirements reflection. In this paper we discuss the ideas that support requirements reflection as a means to articulate some of the outstanding research challenges.

RELAX: a language to address uncertainty in self-adaptive systems requirement

Self-adaptive systems have the capability to autonomously modify their behavior at run-time in response to changes in their environment. Self-adaptation is particularly necessary for applications that must run continuously, even under adverse conditions and changing requirements; sample domains include automotive systems, telecommunications, and environmental monitoring systems. While a few techniques have been developed to support the monitoring and analysis of requirements for adaptive systems, limited attention has been paid to the actual creation and specification of requirements of self-adaptive systems. As a result, self-adaptivity is often constructed in an ad-hoc manner. In order to support the rigorous specification of adaptive systems requirements, this paper introduces RELAX, a new requirements language for self-adaptive systems that explicitly addresses uncertainty inherent in adaptive systems. We present the formal semantics for RELAX in terms of fuzzy logic, thus enabling a rigorous treatment of requirements that include uncertainty. RELAX enables developers to identify uncertainty in the requirements, thereby facilitating the design of systems that are, by definition, more flexible and amenable to adaptation in a systematic fashion. We illustrate the use of RELAX on smart home applications, including an adaptive assisted living system.

Integrating ethnography into the requirements engineering process

Experiences from an interdisciplinary project involving software engineers and sociologists are reported. The project is concerned with discovering the requirements of a user interface to a flight database which is used to provide real-time information to air-traffic controllers. The sociologists are conducting an ethnographic analysis of the activity of air-traffic control, and this is being used for the development of a prototype system. An overview of the project is given, the contribution of sociologists to requirements engineering is discussed, and tool support which will allow ethnographic observations to be integrated into the requirements engineering process is suggested.<<ETX>>

Goal-Based Modeling of Dynamically Adaptive System Requirements

Self-adaptation is emerging as an increasingly important capability for many applications, particularly those deployed in dynamically changing environments, such as ecosystem monitoring and disaster management. One key challenge posed by dynamically adaptive systems (DASs) is the need to handle changes to the requirements and corresponding behavior of a DAS in response to varying environmental conditions. Berry et al. previously identified four levels of RE that should be performed for a DAS. In this paper, we propose the levels of RE for modeling that reify the original levels to describe RE modeling work done by DAS developers. Specifically, we identify four types of developers: the system developer, the adaptation scenario developer, the adaptation infrastructure developer, and the DAS research community. Each level corresponds to the work of a different type of developer to construct goal model(s) specifying their requirements. We then leverage the levels of RE for modeling to propose two complementary processes for performing RE for a DAS. We describe our experiences with applying this approach to GridStix, an adaptive flood warning system, deployed to monitor the River Ribble in Yorkshire, England.

Requirements reflection: requirements as runtime entities

Computational reflection is a well-established technique that gives a program the ability to dynamically observe and possibly modify its behaviour. To date, however, reflection is mainly applied either to the software architecture or its implementation. We know of no approach that fully supports requirements reflection- that is, making requirements available as runtime objects. Although there is a body of literature on requirements monitoring, such work typically generates runtime artefacts from requirements and so the requirements themselves are not directly accessible at runtime. In this paper, we define requirements reflection and a set of research challenges. Requirements reflection is important because software systems of the future will be self-managing and will need to adapt continuously to changing environmental conditions. We argue requirements reflection can support such self-adaptive systems by making requirements first-class runtime entities, thus endowing software systems with the ability to reason about, understand, explain and modify requirements at runtime.

Requirements process improvement through the phased introduction of good practice

Current process improvement and maturity models pay little attention to requirements engineering. Typically, requirements engineering is considered to be a single activity in the overall development process. Even where this is not strictly the case, the requirements activities are not elaborated in sufficient detail to permit the derivation of an improvement plan. This is unfortunate because requirements engineering is increasingly recognized as a problem. Despite the regular improvement of techniques for eliciting, analysing, validating and managing requirements, even otherwise mature organizations repeatedly experience requirements problems. This paper describes a good practice-based approach to requirements engineering process improvement which aims to fill the gap left by existing process improvement methods. This distils practical information from over 60 requirements practices and provides a framework to help organizations identify their problem areas and deploy the practices most appropriate to their needs.