The impact of requirements changes on specifications and state machines

Requirements change both during and after a phase of development for a variety of reasons, including error correction and feature changes. Requirements change management is one of the most complex and difficult problems to deal with in requirements elicitation and tracking. It is generally not understood how a specific change propagates through the specification and into the code. In this paper we capture requirements changes as series of atomic changes in specifications. Using a rigorous specification method called sequence‐based specification, we propose a set of algorithms for managing all possible atomic requirements changes. The algorithms have been formulated within an axiom system for sequence‐based specification and proven for correctness. They have also been implemented in a prototype tool with which users are able to push requirements changes through to changes in specifications, maintain old specifications over time and evolve them into new specifications with the least amount of human interaction and rework. The approach of utilizing state machines to model and manage requirements changes guarantees strong evidence about the correctness and completeness of the proposed theory that will lead to more reliable software in the presence of change, especially with embedded systems and safety‐critical systems. The solution described is general enough for adoption by software and system developers, and well suited for incremental development. Copyright © 2008 John Wiley & Sons, Ltd.     

User interface specification with sequence diagrams: an application to the AIRBUS A380 Datalink system

The development of user interfaces for safety critical systems is driven by requirements specifications. Because user interface specifications are typically embedded within complex systems requirements specifications, they can be intractable to manage. Proprietary requirements specification tools do not support the user interface designer in modelling and specifying the user interface. In this paper, a new way of working with embedded user interface specifications is proposed, exploiting sequence diagrams with a hypertext structure for representing and retrieving use cases. This new tool concept is assessed through an application to the requirements specification for the Airbus A380 air traffic control Datalink system; engineers involved in the development of the Airbus cockpit used a prototype of the tool concept to resolve a set of user interface design anomalies in the requirements specification. The results of the study are positive and indicate the user interface to requirements specification tools which user interface designers themselves need.     

An approach to user knowledge acquisition in product design

As the world increasingly moves towards a knowledge-based economy, user requirements become an important factor for enterprises to drive product collaborative design evolution. To map user requirements to the product model, user requirements are generally extracted into knowledge that can be used for design decisions. However, because users are interest-driven participants and not professional design engineers, the effect of user knowledge acquisition is not ideal. There are significant challenges for rapid knowledge acquisition with dynamic user requirements. This paper presents an approach to user knowledge acquisition in the product design process, which obtains the tangible requirements of users under the premise that users are adequate for participation. In this approach, the typical information flow is divided into four stages: submission, interaction, knowledge discovery, and model evolution. In the submission stage, natural language processing technology is used to transform text form solutions into data, so that computer technology can be applied to manage large-scale user requirements. In the interaction stage, users are helped to improve their solutions by the iterative recommendation process. In the knowledge discovery stage, after less concerned partial solutions are removed and vacant items are predicted to be supplemented, the final collection of user design information is obtained. Finally, based on rough set theory, design knowledge can be extracted to support the decision of the product model. The washing machine design project is used as a case study to explain the implementation of the proposed approach.     

Formal models for user interface design artefacts

There are many different ways of building software applications and of tackling the problems of understanding the system to be built, designing that system and finally implementing the design. One approach is to use formal methods, which we can generalise as meaning we follow a process which uses some formal language to specify the behaviour of the intended system, techniques such as theorem proving or model-checking to ensure the specification is valid (i.e., meets the requirements and has been shown, perhaps by proof or other means of inspection, to have the properties the client requires of it) and a refinement process to transform the specification into an implementation. Conversely, the approach we take may be less structured and rely on informal techniques. The design stage may involve jotting down ideas on paper, brainstorming with users etc. We may use prototyping to transform these ideas into working software and get users to test the implementation to find problems. Formal methods have been shown to be beneficial in describing the functionality of systems, what we may call application logic, and underlying system behaviour. Informal techniques, however, have also been shown to be useful in the design of the user interface to systems. Given that both styles of development are beneficial to different parts of the system we would like to be able to use both approaches in one integrated software development process. Their differences, however, make this a challenging objective. In this paper we describe models and techniques which allow us to incorporate informal design artefacts into a formal software development process.     

Applying ontology-based blog to detect information system post-development change requests conflicts

Post-development change requests are user requirements for information systems changes after development. Conflicts might occur as contradictive or inconsistent relationships between requests and existing system design. Detecting conflicts in post-developmenet change requests is an important task during requests management processes. To address this topic, this article proposes an ontology-based blog for automatically discovering conflicts in the extended use-case models of requests from users. This study proposed an information system maintenance process. The proposed approach applies ontologies to represent domain knowledge. A set of rules are used to detect conflicts. This study developed a prototype and invited two companies to evaluate it. Usage feedback opinions about ontology-based blog from two companies indicated the usefulness. The ontology-based blog is a relatively new approach which bridge requirements blogs with a formal and machine interpretable representational model. The automatic conflicts detection capability of the ontology-based blog can reduce the labor cost in requirements analysis phase.     

A methodological approach for user interface development of collaborative applications: A case study

In the last few years, the production of systems which support learning and group work has been high. However, the design and development of these types of systems are difficult, mainly due to the multidisciplinarity involved. Furthermore, the Graphic User Interface (GUI) of an application is receiving greater attention, since it can be decisive in determining if the application is accepted or rejected by users. Model-based design is a widespread technique in the user interface development process. While reviewing approaches that deal with the modeling and design of user interfaces supporting collaborative tasks, we have detected that there is no proposal that links interactive and collaborative issues. We have introduced a methodological approach to solve this shortcoming. This approach is called CIAM (Collaborative Interactive Application Methodology) and it is composed of several stages in which conceptual models are created using CIAN (Collaborative Interactive Application Notation). These models start by modeling the organization in which the application will be used, as well as the tasks that must be supported. In the initial stages, the organization and the collaborative tasks are modeled using high-level specifications. In the following stages, the level of detail increases and, finally, the interaction between the individual users and the application is modeled using ConcurTaskTrees (CTT) notation. The interaction model acts as a bridge between the design and the implementation of the Graphic User Interface. In this paper we present our methodological approach and an example of applying this method for user interface design of collaborative and interactive applications.     

A computational framework for authoring and searching product design specifications

The development of product design specifications (PDS) is an important part of the product development process. Incompleteness, ambiguity, or inconsistency in the PDS can lead to problems during the design process and may require unnecessary design iterations. This generally results in increased design time and cost. Currently, in many organizations, PDS are written using word processors. Since documents written by different authors can be inconsistent in style and word choice, it is difficult to automatically search for specific requirements. Moreover, this approach does not allow the possibility of automated design verification and validation against the design requirements and specifications.In this paper, we present a computational framework and a software tool based on this framework for writing, annotating, and searching computer-interpretable PDS. Our approach allows authors to write requirement statements in natural language to be consistent with the existing authoring practice. However, using mathematical expressions, keywords from predefined taxonomies, and other metadata the author of PDS can then annotate different parts of the requirement statements. This approach provides unambiguous meaning to the information contained in PDS, and helps to eliminate mistakes later in the process when designers must interpret requirements. Our approach also enables users to construct a new PDS document from the results of the search for requirements of similar devices and in similar contexts. This capability speeds up the process of creating PDS and helps authors write more detailed documents by utilizing previous, well written PDS documents. Our approach also enables checking for internal inconsistencies in the requirement statements.     

Deriving static and dynamic concepts from software requirements using sophisticated tagging

Natural language requirements specifications form the basis for the subsequent phase of the information system development process, namely the development of conceptual schemata. Both, the textual as well as the conceptual representations are not really appropriate for being thoroughly captured and validated by the ‘requirement holders’, i.e. the end users. Therefore, in our approach the textual specifications are firstly linguistically analyzed and translated into a so-called conceptual predesign schema. That schema is formulated using an interlingua which is based on a lean semantic model, thus allowing users to participate more efficiently in the design and validation process. After validation, the predesign schema is mapped to a conceptual representation (e.g. UML). The sequence of these translation and transformation steps is described by the “NIBA workflow”. This paper focuses on the information supporting a step by step mapping of natural language requirements specifications to a conceptual model, and on how that information is gained. On particular, we present a four-level interpretation of tagging-output.     

An analysis of specialist and non-specialist user requirements for geographic climate change information

The EU EuroClim project developed a system to monitor and record climate change indicator data based on satellite observations of snow cover, sea ice and glaciers in Northern Europe and the Arctic. It also contained projection data for temperature, rainfall and average wind speed for Europe. These were all stored as data sets in a GIS database for users to download. The process of gathering requirements for a user population including scientists, researchers, policy makers, educationalists and the general public is described. Using an iterative design methodology, a user survey was administered to obtain initial feedback on the system concept followed by panel sessions where users were presented with the system concept and a demonstrator to interact with it. The requirements of both specialist and non-specialist users is summarised together with strategies for the effective communication of geographic climate change information.     

多Agent系统可视化开发环境的设计与实现

多Agent系统是构造复杂的分布式软件的一种新方法,有广阔的应用前景。但设计多Agent系统难度很大,除了要考虑传统的分布式系统的所有问题外,还要考虑Agent的灵活性需求。为了支持多Agent系统的开发,提出并实现了一个可视化开发环境,用户可以从描述任务出发,经过一系列步骤,半自动化地生成多Agent系统,极大地减轻了编程负担。     

Using abstraction and model checking to detect safety violations inrequirements specifications

Exposing inconsistencies can uncover many defects in software specifications. One approach to exposing inconsistencies analyzes two redundant specifications, one operational and the other property-based, and reports discrepancies. This paper describes a “practical” formal method, based on this approach and the SCR (software cost reduction) tabular notation, that can expose inconsistencies in software requirements specifications. Because users of the method do not need advanced mathematical training or theorem-proving skills, most software developers should be able to apply the method without extraordinary effort. This paper also describes an application of the method which exposed a safety violation in the contractor-produced software requirements specification of a sizable, safety-critical control system. Because the enormous state space of specifications of practical software usually renders direct analysis impractical, a common approach is to apply abstraction to the specification. To reduce the state space of the control system specification, two “pushbutton” abstraction methods were applied, one which automatically removes irrelevant variables and a second which replaces the large, possibly infinite, type sets of certain variables with smaller type sets. Analyzing the reduced specification with the model checker Spin uncovered a possible safety violation. Simulation demonstrated that the safety violation was not spurious but an actual defect in the original specification     

用UML与Petri网为智能代理建模

统一建模型语言（UML）已经成为软件系统的分析与设计的标准工具，但由它扩充而成的代理统一建模型语言（AUML）还没变成一个标准，目前的AUML规格说明还有很多的局限性，还不能胜任多代理系统的开发．Petri网是仿真、验证软件系统执行的正确性与有效性的形式化工具．本文主要分析当前AUML规格说明和Petri网概念．找出它们之间的结合点，提出用Petri网扩充AUML的方法．将其应用于多代理系统的开发，就能实施之前运用Petri网进行系统的正确性与有效性验证．     

A design of a controller as a component of a robotic manufacturing system

This paper specifies the functional design of a robot or machine tool controller suitable for inclusion in robotic manufacturing systems. The principle interest is the unmanned manufacturing cells which are being developed as major components of new manufacturing facilities. The functional specifications are motivated by recent experiences with the creation of a prototype cell for an open die forging process. There are two key technical design requirements. The first relates to the robot or machine tool being controlled. The controller must direct the machine actions, and, for unmanned operation, the controller must receive and process sensor information for process modification and for fault tolerance. The second relates to communication with the central cell computer (the host). The operation of an unmanned system requires a robot communication channel between the host and the controller; the controller must also respond to a variety of instructions transmitted from the host. Additional controller design requirements are imposed by economics. The proposed controller can be used today, and can develop in an evolutionary manner to meet the needs of future manufacturing systems. The evolutionary development is made possible by modular design, organized in a hierarchical manner.     

Improving accessibility with user-tailored interfaces

The first stage in the design of a user interface is the quest for its ‘typical user’, an abstract generalization of each user of the application. However, in web systems and other scenarios where the application can be used by dozens of different kinds of users, the identification of this ‘typical user’ is quite difficult, if not impossible. Our proposal is to avoid the construction of interactive dialogs during the design stage, building them dynamically once the specific cognitive, perceptual and motor requirements of the current user are known: that is, during the execution stage. This is the approach used by GADEA, an intelligent user interface management system (UIMS) able to separate the functionality of an application from its interface in real time. The system adapts the components of the interface depending on the information stored in a user model which is continuously updated by a small army of data-gathering agents.     

TAPAS: A tangible End-User Development tool supporting the repurposing of Pervasive Displays

These days we are witnessing a spread of many new digital systems in public spaces featuring easy to use and engaging interaction modalities, such as multi-touch, gestures, tangible, and voice. This new user-centered paradigm — known as the NUI — aims to provide a more natural and rich experience to end users; this supports its adoption in many ubiquitous domains, as it naturally holds for Pervasive Displays: these systems are composed of variously-sized displays and support many-to-many interactions with the same public screens at the same time. Due to their public and moderated nature, users need an easy way of adapting them to heterogeneous usage contexts in order to support their long-term adoption. In this paper, we propose an End-User Development approach to this problem introducing TAPAS, a system that combines a tangible interaction with a puzzle metaphor, allowing users to create workflows on a Pervasive Display to satisfy their needs; its design and visual syntax stem from a study we carried out with designers, whose findings are also part of this work. We then carried out a preliminary evaluation of our system with second year university students and interaction designers, gathering useful feedback to improve TAPAS and employ it in many other domains.     

Creativity and evolution: a metadesign perspective

Abstract

In a world that is not predictable, improvisation and evolution are more than a luxury: they are a necessity. The challenge of design is not a matter of getting rid of the emergent, but rather of making it an opportunity for more creative and more sustainable solutions. User-centered and participatory design approaches have focused primarily on activities taking place at design time. These approaches have not given enough emphasis and they have provided few mechanisms to support systems as living entities that can evolve over time. Metadesign is a unique design approach concerned with opening up solution spaces rather than complete solutions (hence the prefix meta-), and aimed at creating social and technical infrastructures in which new forms of collaborative design can take place. This approach extends the traditional notion of design beyond the original development of a system to include co-adaptive processes between users and systems that enable the users to act as designers in personally meaningful activities and be creative.     

Abstract Requirements Specification: A New Approach and Its Application

An abstract requirements specification states system requirements precisely without describing a real or a paradigm implementation. Although such specifications have important advantages, they are difficult to produce for complex systems and hence are seldom seen in the "real" programming world. This paper introduces an approach to producing abstract requirements specifications that applies to a significant class of real-world systems, including any system that must reconstruct data that have undergone a sequence of transformations. tions. It also describes how the approach was used to produce a requirements document for SCP, a small, but nontrivial Navy communications system. The specification techniques used in the SCP requirements document are introduced and illustrated with examples.     

一种XMPP即时消息系统的动态模型的实现

针对用户在利用现有即时消息系统的在线感知模块所提供的感知信息寻找正确交互对象时碰到的问题,通过分析现有的基于XMPP即时消息系统结构和在线感知实现的基本方法,结合在现有XMPP客户端中加入收集用户事件信息组件进行数据的收集,并利用决策树的分类算法对收集数据进行处理,从而实现一种可以预测的用户回应可能性的动态在线感知模型,最后利用仿真实验的方式,对模型进行了仿真分析和验证,从而得出在XMPP协议的即时消息系统中实现这种可预测用户回应的动态的在线感知模型的是可行的(其准确率约为90%),与现有其他在线感知功能模块相比,运用该方法实现的模型由于引入了预测用户行为的动态感知,因此用户在利用该模型寻找正确交互对象时的效率更高,并被用于国家网络科技环境建设的多个项目中,收到了良好效果.