System Requirements Specification Research Articles

Towards a Graphical Tool for Refining User to System Requirements

Informal and abstract user requirement specifications are usually complemented by formal and detailed system requirement specifications. While user requirements provide a high level description of what services the system is expected to provide, system requirements provide a more technical specification of how that services should be provided by the system. One of the relevant problems that arise during the Requirement Engineering process is the result of failing to make a clear transition between different levels of requirements description.Goal of this paper is to introduce a graphical tool for requirements refinement which guides software architects while moving from user requirements to (architec-tural-level) system requirements. The tool makes use of a previous work that gives a simple but expressive graphical formalism, based on UML2.0 Sequence Diagrams, for specifying temporal properties.

Specification and analysis of timing requirements for real-time systems in the CBD approach

In real-time software, not only computation errors but also timing errors can cause system failures, which eventually result in significant physical damages or threats to human life. To efficiently guarantee the timely execution of expected functions, it is necessary to clearly specify and formally verify timing requirements before performing detailed system design. With the expected benefit of reusability and extensibility, component technology has been gradually applied to developing industrial applications including real-time systems. However, most of component-based approaches applied to real-time systems lack in a systematic and rigorous approach to specifying and verifying timing requirements at an earlier development stage. This paper proposes a component-based approach to specifying and verifying timing requirements for real-time systems in a systematic and compositional manner. We first describe behaviors of the constituent components including timing requirements in UML diagrams, and then translate the UML diagrams into MTER nets, an extension of TER nets, to perform timing analysis in a compositional way. The merit of the proposed approach is that the specification and analysis results can be reused and independently maintained.

Safety analysis of autonomous systems by extended fault tree analysis

AbstractSafety is of major concern in many autonomous functions in automotive systems and aerospace. In these application areas, it is standard to use fault trees, and a natural question in many modern systems that include sub‐systems like diagnosis, fault‐tolerant control, and autonomous functions is how to include the performance of these algorithms in a fault tree analysis for safety. Many possibilities exist but here a systematic way is proposed. It is shown both how safety can be analysed and how the interplay between algorithm design in terms of missed detection rate and false alarm rate is included in the fault tree analysis. Examples illustrate analysis of diagnosis system requirement specification and algorithm tuning. Copyright © 2006 John Wiley & Sons, Ltd.

THE USE OF BUSINESS RULES FOR THE SPECIFICATION OF DYNAMIC ASPECTS OF IS

In the paper Output driven Information systems (IS) requirements specification method (ODRES) is overviewed emphasizing the problems of recording certain requirements. It is suggested that the method can be extended with business rules recording capabilities. Business rules-based requirements specification method is used to extend ODRES by incorporating method’s rules submodel into an ODRES metamodel in order to support non-structural business rules as additional knowledge about static and dynamic aspects of IS. Presented extension of ODRES concerns only the specification of dynamic aspects of IS. BRS RuleSpeak, which is the basis for a suggested rules submodel, is also overviewed in the paper and the benefits of the extension are outlined.

Verification and Validation of a Fingerprint Image Registration Software

The need for reliable identification and authentication is driving the increased use of biometric devices and systems. Verification and validation techniques applicable to these systems are rather immature and ad hoc, yet the consequences of the wide deployment of biometric systems could be significant. In this paper we discuss an approach towards validation and reliability estimation of a fingerprint registration software. Our validation approach includes the following three steps: (a) the validation of the source code with respect to the system requirements specification; (b) the validation of the optimization algorithm, which is in the core of the registration system; and (c) the automation of testing. Since the optimization algorithm is heuristic in nature, mathematical analysis and test results are used to estimate the reliability and perform failure analysis of the image registration module.

User-Centred Design of Flexible Hypermedia for a Mobile Guide: Reflections on the HyperAudio Experience

A user-centred design approach involves end-users from the very beginning. Considering users at the early stages compels designers to think in terms of utility and usability and helps develop a system based on what is actually needed. This paper discusses the case of HyperAudio, a context-sensitive adaptive and mobile museum guide developed in the late 1990s. User requirements were collected via a survey to understand visitors' profiles and visit styles in natural science museums. The knowledge acquired supported the specification of system requirements, helping define the user model, data structure and adaptive behaviour of the system. User requirements guided the design decisions on what could be implemented by using simple adaptable triggers, and what instead needed more sophisticated adaptive techniques. This is a fundamental choice when all the computation must be done on a PDA. Graphical and interactive environments for developing and testing complex adaptive systems are discussed as a further step in an iterative design process that considers the user interaction to be the central point. This paper discusses how such an environment allows designers and developers to experiment with different system behaviours and to widely test it under realistic conditions by simulating the actual context evolving over time. The understanding gained in HyperAudio is then considered from the perspective of later developments: our findings still appers to be valid despite the time that had passed.

4.4.1 A Hybrid Requirements Capture Process

AbstractSystems engineers traditionally produce a system requirements specification containing shall‐statement requirements. However, the rapid adoption of use case modeling for capturing functional requirements in the software community has caused systems engineers to examine the utility of use case models for capturing system‐level functional requirements. A transition from traditional shall‐statement requirements to use case modeling has raised some issues and questions. This paper advocates a unified requirements engineering method in which use case modeling and traditional shall‐statement requirements are applied together to effectively express both functional and non‐functional requirements for complex, hierarchical systems. This paper also presents a practical method for extracting requirements from the use case text to produce a robust requirements specification.

From requirements to multi-agent architecture using organisational concepts

There is a clear relationship between requirements and architectures. However, evolving and elaborating system requirements into a software architecture satisfying those requirements is still a difficult task, mainly based on intuition. To narrow these problems, we are investigating techniques for deriving architectural model in concert with Multi-Agent System (MAS) requirement specifications. Our framework advocates that a multi-agent system corresponds to the organisational structure, in which actors are members of a group in order to perform specific roles. An organisation comprises groups, goals, members, roles and interactions.

A SYSTEMATIC INCLUSION OF DIAGNOSIS PERFORMANCE IN FAULT TREE ANALYSIS

Safety is of major concern in many applications such as in automotive systems and aerospace. In these applications it is standard to use fault trees, and a natural question in many modern systems that include sub-systems like diagnosis, fault tolerant control and autonomous functions, is how to include the performance of these algorithms in a fault tree analysis for safety. Many possibilities exist but here a systematic way is proposed. It is shown both how safety can be analyzed and how the interplay between algorithm design in terms of missed detection rate and false alarm rate is included in the fault tree analysis. Examples illustrate analysis of diagnosis system requirement specification and algorithm tuning.

The hybrid process that combines traditional requirements and use cases

AbstractFor many years systems engineers have produced traditional system requirements specifications containing shall‐statement requirements. The rapid adoption of use case modeling for capturing functional requirements in the software community has caused systems engineers to examine the utility of use case models for capturing system‐level functional requirements. A transition from traditional shall‐statement requirements to use case modeling has raised some issues and questions. This paper advocates a hybrid requirements process in which use case modeling and traditional shall‐statement requirements are applied together to effectively express both functional and nonfunctional requirements for complex, hierarchical systems. This paper also presents a practical method for extracting requirements from the use case text to produce a robust requirements specification. © 2004 Wiley Periodicals, Inc. Syst Eng 7: 303–319, 2004

Visualizing graphical and textual formalisms

ViSta is a tool suite designed to support the requirements specification of reactive systems. It guides the user through the steps necessary for the visualization of statechart diagrams from an informal document. The user first extracts information from a textual document and stores into a set of interactive templates. The information is used by the tool to automatically generate statechart layouts. In this paper we describe how ViSta is augmented with a tool that automatically translates statecharts into Z specifications. The template, statechart and Z representations are inter-related. This ensures consistency between the different representations, and therefore facilitates the verification and validation effort.

Extending standard UML with model composition semantics

There is a well documented problem in the software engineering field relating to a structural mismatch between the specification of requirements for software systems and the specification of object-oriented software systems. The structural mismatch happens because the units of interest during the requirements phase (for example, feature, service, capability, function, etc.) are different to the units of interest during object-oriented design and implementation (for example, object, class, method, etc.). The structural mismatch results in support for a single requirement being scattered across the design units and a single design unit supporting multiple requirements—this in turn results in reduced comprehensibility, traceability and reuse of design models. This paper presents an approach to designing systems based on the object-oriented model, but extending this model by adding new decomposition capabilities. The new decomposition capabilities support a way of directly aligning design models with individual requirements. Each model contains a design of an individual requirement, with concepts from the domain (which may appear in multiple requirements) designed from the perspective of that requirement. Standard UML is used to design the models decomposed in this way. Composition of design models is supported, and it is specified with a composition relationship. A composition relationship specifies how models are to be composed by identifying overlapping concepts in different models and specifying how models should be integrated. This paper describes changes required to the UML metamodel to support composition relationships. Two kinds of integration strategies are discussed— merge and override.

Requirements specification and analysis of fault-tolerant digital systems

We present an integrated computer-aided design environment, the PrT (predicate/transition) net system, in order to systematically introduce fault-tolerant properties into the design of complicated digital systems. This is accomplished by exploiting a formal specification of the system requirements in which the amount of necessary redundancy can be determined. The system is based on an integration of PrT nets with regular expressions. PrT nets are used to describe and analyze a high level system and regular expressions are used to describe and analyze the more detailed system structures. Both models provide us with well-defined levels of fault diagnosis needed in the digital system design. An S-invariant technique can be used to check the constancy of PrT nets; and a finite state automaton can be used to check the acceptability of regular expressions. Furthermore, the regular expression can also enable a system designer to determine redundancy in order to perform error correction. In consequence, our approach is superior to the current techniques for requirements analysis. Finally, main results are presented in the form of four propositions and supported by some experiments.

Requirements Reuse for Improving Information Systems Security: A Practitioner’s Approach

Information systems security issues have usually been considered only after the system has been developed completely, and rarely during its design, coding, testing or deployment. However, the advisability of considering security from the very beginning of the system development has recently begun to be appreciated, and in particular in the system requirements specification phase. We present a practical method to elicit and specify the system and software requirements, including a repository containing reusable requirements, a spiral process model, and a set of requirements documents templates. In this paper, this method is focused on the security of information systems and, thus, the reusable requirements repository contains all the requirements taken from MAGERIT, the Spanish public administration risk analysis and management method, which conforms to ISO 15408, Common Criteria Framework. Any information system including these security requirements must therefore pass a risk analysis and management study performed with MAGERIT. The requirements specification templates are hierarchically structured and are based on IEEE standards. Finally, we show a case study in a system of our regional administration aimed at managing state subsidies.

Java-MaC: A Run-time Assurance Tool for Java Programs

We describe Java-MaC, a prototype implementation of the Monitoring and Checking (MaC) architecture for Java programs. The MaC architecture provides assurance about the correct execution of target programs at run-time. Monitoring and checking is performed based on a formal specification of system requirements. MaC bridges the gap between formal verification, which ensures the correctness of a design rather than an implementation, and testing, which only partially validates an implementation. Java-MaC provides a lightweight formal method solution as a viable complement to the current heavyweight formal methods. An important aspect of the architecture is the clear separation between monitoring implementation-dependent low-level behaviors and checking high-level behaviors against a formal requirements specification. Another salient feature is automatic instrumentation of executable codes. The paper presents an overview of the MaC architecture and a prototype implementation Java-MaC.

High-level Petri net for incremental analysis of object-oriented system requirements

To complement the weakness of Petri nets in terms of naturalness, modularity, and reusability, high-level Petri nets with object concepts have been suggested. It is difficult to apply these nets to the requirements specification of object-oriented software systems because of insufficient support for the object-oriented concepts. A hierarchical object-oriented Petri net (HOONet) is developed to complement the weakness of the existing formalisms and formally define its syntax and semantics. A reachability analysis method is provided to check such behavioural properties as boundedness, liveness and persistence of the HOONet models. The HOONet provides incremental modelling and analysis of the requirements with the support of object-oriented concepts.

A Method for Extracting and Stating Software Requirements that a User Interface Prototype Contains

User interface and requirements prototyping is a requirements elicitation technique. A user interface and requirements prototype is built during the requirements engineering phase of a software system development. Along with the user interface prototype are produced various documents such as the system requirement specification. When a prototype and other documents exist, they may not describe the same functionality, particularly because there may be behaviour of the prototype, artefacts of prototyping, that may not be intended. The problem is that in later development stages, when there is a prototype and other documents, it is often difficult to reconcile the difference between the prototype and the other documents. This paper presents an approach for avoiding this difficulty. It demonstrates the approach by showing its application to parts of a real software development.

On the quality and usefulness of the specification in determining a customer’s requirements: a survey of UK library system suppliers

An effective library management system is essential to the operation of services but the procurement of a system is an infrequent activity with little opportunity for librarians to build on or consolidate their experience. The common activity of specifying the operational requirements of a system can consequently be problematic. The procurement process is also difficult for potential system suppliers who must respond to specifications (or RfPs) which are very variable in terms of content, format and quality. A survey of UK library system suppliers was undertaken in January 2000 as part of the UK LIC‐funded HARMONISE Project to determine their views on the quality and usefulness of the specification in the procurement process. The suppliers indicated a number of problems inherent in specifications produced by libraries, such as a lack of clarity, poor structure, variable in technical understanding and with too great a focus on basic functionality which has been tried and tested. A model specification of system requirements for libraries is recommended.

Logics for hybrid systems

Hybrid systems are heterogenous dynamical systems characterized by interacting continuous and discrete dynamics. Such mathematical models have proved fruitful in a great diversity of engineering applications, including air-traffic control, automated manufacturing, and chemical process control. The high-profile and safety-critical nature of the application areas has fostered a large and growing body of work on formal methods for hybrid systems: mathematical logics, computational models and methods, and computer-aided reasoning tools supporting the formal specification and verification of performance requirements for hybrid systems, and the design and synthesis of control programs for hybrid systems that are provably correct with respect to formal specifications. This paper offers synthetic overview of, and original contributions to, the use of logics and formal methods in the analysis of hybrid systems.

Qualitative formal method for requirements specification and validation of hybrid real-time safety systems

The difficulties that engineers have in understanding and applying the quantitative methods in an abstract requirements phase are major obstructions in using formal methods for hybrid real-time safety systems. While formal methods technology in safety-critical systems can help increase confidence of software, the difficulty and complexity in using them can cause another hazard. The authors have proposed a framework for requirements engineering, called the qualitative formal method (QFM) for the specification and validation of hybrid real-time safety systems. The QFM emphasises the idea of a causal and qualitative reasoning in formal methods to reduce the difficulty of specifying and validating the software requirements of hybrid safety systems. They use the qualitative formal languages, Compositional Modelling Language, and Causal Functional Representation Language in particular, to specify hybrid system dynamics and the required behaviour, respectively. The system behaviour has been simulated by the Device Modelling Environment, and validated against the required behaviour. Using the Shutdown System 2 of Wolsong nuclear power plants as a realistic example, they demonstrate the effectiveness of their approach.