Composite systems are generally comprised of heterogeneous components whose specifications are developed by many development participants. The requirements of such systems are invariably elicited from multiple perspectives which overlap, complement and contradict each other. Furthermore, these requirements are generally developed and specified using multiple methods and notations respectively. It is therefore necessary to express and check the relationships between the resultant specification fragments. In this paper we deploy multiple "ViewPoints" that hold partial requirements specifications, described and developed using different representation schemes and development strategies. We discuss the notion of interViewPoint communication in the context of this ViewPoints framework, and propose a general model for ViewPoint interaction and integration. We elaborate on some of the requirements for expressing and enacting inter-ViewPoint relationships - the vehicles for consistency che...

Large-scale software development is an evolutionary process. In an evolving specification, multiple development participants often hold multiple, inconsistent views on the system being developed, and considerable effort is spent handling recurrent inconsistencies. Detecting and resolving inconsistencies is only part of the problem: a resolved inconsistency might not stay resolved as a specification evolves. Frameworks in which inconsistency is tolerated help by allowing resolution to be delayed. However, the evolution of a specification may affect both resolved and unresolved inconsistencies. We present and elaborate a framework in which software development knowledge is partitioned into multiple views called "ViewPoints". Inconsistencies between ViewPoints are managed by explicitly representing relationships between them, and recording both resolved and unresolved inconsistencies. We assume that ViewPoints will often be inconsistent with one another, and we ensure that a complete wor...

The process of understanding the system under analysis, the services required of it, its environment and associated constraints involves the capture, analysis and resolution of many ideas, perspectives and relationships at varying levels of detail. We believe requirements methods based on global reasoning lack the expressive framework to adequately articulate this distributed requirements knowledge structure. This paper describes the problems faced in trying to establish an adequate and stable set of requirements and proposes a novel ViewpointOriented Requirements Definition method (VORD) as a means of tackling some of these problems. This method structures the requirements engineering process using viewpoints which are associated with sources of requirements. The paper describes VORD in the light of current viewpoint-oriented requirements approaches and shows how its improves on them. A simple example of a bank auto-teller system is used to demonstrate the method. 3 1.0 Introduction...

In an evolving specification, considerable development time and effort is spent handling recurrent inconsistencies. Tools and techniques for detecting and resolving inconsistencies only address part of the problem: they do not ensure that a resolution generated at a particular stage will apply at all subsequent stages of the specification process. Previously, we have advocated tolerance and management of inconsistency, rather than strict enforcement of consistency. The advantages of this approach include the ability to delay resolution, facilitation of concurrent development, and greater flexibility in development strategies. However, this approach does not prevent inconsistencies themselves from evolving, and it does not ensure that resolved inconsistencies remain resolved throughout subsequent developments. We address these problems by explicitly recording relationships between partial specifications (ViewPoints), representing both resolved and unresolved inconsistencies. ...

This paper outlines a method, called reconciliation, for managing interference between partial specifications or viewpoints. The method supports the detection, verification and tracking of ontological overlaps. The paper describes the heuristics on which the method is based and illustrates the application of the method to a scenario. 1. Introduction The construction of a complex software system involves many agents (aka participants or actors). These agents have different perspectives or views of the artifact or system they are trying to describe or model. This gives rise to many partial specifications (or viewpoints) reflecting those perspectives (Nuseibeh et al. 1993, Maiden et al. 1994). These specifications "interfere" with each other to the extent they refer to, or assert properties of common aspects of the system under development and its domain. This is a particular feature of the requirements engineering setting. Interference between specifications can occur at two different l...

An approach to software development problems is presented, and illustrated by an example. The approach is based on the ideas of problem frames and structuring specifications by views. It is claimed that decompositions obtained by this approach result in a more effective separation of concerns, and that the resulting components are more likely to be reusable than those obtained by more conventional approaches. The characteristics of desirable integration mechanisms are discussed, together with some other considerations arising out of the approach presented. 1 Introduction Problem decomposition serves two purposes. By decomposing a large problem into smaller subproblems we hope to master its complexity: the smaller subproblems should be simpler than the large problem. By the same decomposition we hope to factor out subproblems that are already solved, and to re-use their existing solutions. Hierarchical decomposition can rarely achieve these goals. It is not difficult to sketch a plau...

In this paper we argue that industrial development of interactive systems has to recognise the social dimension of work if they are to fully meet the real needs of their users Under current approaches this depends on whether an individual requirements engineer implicitly applies a user-centred approach and recognises the importance of cooperation and is sufficiently sympathetic and intuitive to understand the work and reflect this in the system requirements. We wish to move beyond this by allowing for the provision of a more systematic incorporation of the social dimensions of work. To this end we focus on developing a number of alternative models for involving ethnography in the requirements process and a more systematic approach to the presentation of ethnographic material. Our approach to presented ethnographic information is based on the use of number of defined viewpoints and is embodied within a general hypertext tool.

Multiple viewpoints are often used in Requirements Engineering to facilitate traceability to stakeholders, to structure the requirements process, and to provide richer modelling by incorporating multiple conflicting descriptions. In the latter case, the need to reason with inconsistent models introduces considerable extra complexity. This paper describes an empirical study of the utility of multiple world reasoning (using abduction) for domain modelling. In the study we used a range of different models (ranging from correct to very incorrect), different fanouts, different amounts of data available from the domain, and different modelling primitives for representing time. In the experiments there was no significant change in the expressive power of models that incorporate multiple conflicting viewpoints. Whilst this does not negate the advantages of viewpoints during requirements elicitation, it does suggest some limits to the utility of viewpoints during requirements modelling. 1. Int...

Software-intensive systems are systems of systems that rely on complex interdependencies among themselves as well as with their operational environment to satisfy the required behavior. As we integrate such systems to create information infrastructures that are critical to the quality of our lives and the businesses they support, the need to effectively predict, control and evolve their behavior is ever increasing. To deal with their complexity, an important first step is to understand and model software-intensive systems, their environments and the interdependencies among them at different levels of abstractions from multiple dimensions. In this paper, we present an Ontology-based Active Requirements Engineering (Onto-ActRE [onto-�kt�r]) framework that adopts a mixed-initiative approach to elicit, represent and analyze the diversity of factors associated with software-intensive systems. The Onto-ActRE framework integrates various RE modeling techniques with complementary semantics in a unifying ontological engineering process. We also present examples from the practice of our framework with appropriate tool support that combines theoretical and practical aspects. 1.

The success of large-scale software systems depends on how accurate the huge amount of requirements is elicited and analysed by software engineers. Requirements engineering provides suitable approaches to define requirements of such systems in a systematic way. For example, viewpoint and object-oriented approaches have adequate mechanisms to reach these purposes. Nevertheless, the crosscutting nature of requirements is not addressed by these approaches, but this can be managed using aspect-oriented concepts. This work describes how aspects could be integrated to Vision, a viewpoint-oriented requirements method that integrates UML models. 1