Jiale Zhou

Towards Feature-Oriented Requirements Validation for Automotive Systems

In the modern automotive industry, feature models have been widely used as a domain-specific requirements model, which can capture commonality and variability of a software product line through a set of features. Product variants can thus be configured by selecting different sets of features from the feature model. For feature-oriented requirements validation, the variability of feature sets often makes the hidden flaws such as behavioral inconsistencies of features, hardly to avoid. In this paper, we present an approach to feature-oriented requirements validation for automotive systems w.r.t. both functional behaviors and non-functional properties. Our approach first starts with the behavioral specification of features and the associated requirements by following a restricted use case modeling approach, and then formalizes such specifications by using a formal yet literate language for analysis. We demonstrate the applicability of our approach through an industrial application of a Vehicle Locking-Unlocking system.

A TASM-Based Requirements Validation Approach for Safety-Critical Embedded Systems

Requirements validation is an essential activity to carry out in the system development life cycle, and it confirms the completeness and consistency of requirements through various levels. Model-based formal methods can provide a cost-effective solution to requirements validation in a wide range of domains such as safety-critical applications. In this paper, we extend a formal language Timed Abstract State Machine (TASM) with two newly defined constructs Event and Observer, and propose a novel requirements validation approach based on the extended TASM. Specifically, our approach can: 1) model both functional and non-functional (e.g. timing and resource consumption) requirements of the system at different levels and, 2) perform requirements validation by utilizing our developed toolset and a model checker. Finally, we demonstrate the applicability of our approach in real world usage through an industrial case study of a Brake-by-Wire system.

An Ontological Interpretation of the Hazard Concept for Safety-Critical Systems

The hazard concept has been extensively used in the literature and defined in an informal way, which serves as a guidance on identifying the potential hazards during the development of safety-criti ...

The Observer-based Technique for Requirements Validation in Embedded Real-time Systems

Model-based requirements validation is an increasingly attractive approach to discovering hidden flaws in requirements in the early phases of systems development life cycle. The application of using traditional methods such as model checking for the validation purpose is limited by the growing complexity of embedded real-time systems (ERTS). The observer-based technique is a lightweight validation technique, which has shown its potential as a means of validating the correctness of model behaviors. In this paper, the novelty of our contributions is three-fold: 1) we formally define the observer constructs for our formal specification language namely the Timed Abstract State Machine (TASM) language and, 2) we propose the Events Monitoring Logic (EvML) to facilitate the observer specification and, 3) we show how to execute observers to validate the requirements describing the functional behaviors and non-functional properties (such as timing) of ERTS. We also illustrate the applicability of the extended TASM language through an industrial application of a Vehicle Locking-Unlocking system.

A Context-based Information Retrieval Technique for Recovering Use-Case-to-Source-Code Trace Links in Embedded Software Systems

Post-requirements trace ability is the ability to relate requirements (e.g., use cases) forward to corresponding design documents, source code and test cases by establishing trace links. This ability is becoming ever more crucial within embedded systems development, as a critical activity of testing, verification, validation and certification. However, semi-automatically or fully-automatically generating accurate trace links remains an open research challenge, especially for legacy systems. Vector Space Model (VSM), a notably known Information Retrieval (IR) technique aims to remedy this situation. However, VSMs low-accuracy level in practice is a limitation. The contribution of this paper is an improved VSM-based post-requirements trace ability recovery approach using a novel context analysis. Specifically, the analysis method can better utilize context information extracted from use cases to discover relevant source code files. Our approach is evaluated by using three different embedded applications in the domains of industrial automation, automotive and mobile. The evaluation shows that our new approach can achieve better accuracy than VSM, in terms of higher values of three main IR metrics, i.e., recall, precision, and mean average precision, when it handles embedded software applications.

A Hazard Modeling Language for Safety-Critical Systems Based on the Hazard Ontology

Preliminary hazard analysis (PHA) is a key safetyconcerned activity to identify potential hazards. However, since various stakeholders will be involved in the identification process, a common understanding of the nature of hazards among stakeholders, such as what a hazard consists of and how to describe it without ambiguities, is of crucial importance to achieve the goal of PHA. In this work, we propose a hazard modeling language (HML) based on a domain ontology to facilitate the specification of identified hazards. In addition, we present an approach to guide the transformation from natural language hazard descriptions into the HML specification. Finally, an industrial PHA example is used to illustrate the usefulness of our work.

An ontological approach to hazard identification for safety-critical systems

Hazard identification is an essential and demanding task for the development of safety-critical systems (SCSs). Current practices suffer from one or several drawbacks: 1) a common hazard conceptualization is missing and thereby ambiguities may arise and, 2) there is still a need to formalize the experience of analysts and lessons learned from previous system development. It should be done in a structured way to facilitate future reuse and, 3) some hazard identification techniques require well-known system behaviors represented by models, such as automata and sequence diagrams, to identify hazards. However, such models are typically susceptible to changes or even not available in early stages of the development process. In this paper, we propose an ontological approach to support hazard identification in the early stages of the development of SCSs. The approach aims to improve the completeness of hazard identification results and to avoid ambiguities. A robotic strolling assistant system is used to evaluate the proposed approach.

An environment-driven ontological approach to requirements elicitation for safety-critical systems

The environment, where a safety critical system (SCS) operates, is an important source from which safety requirements of the SCS can originate. By treating the system under construction as a black box, the environment is typically documented as a number of assumptions, based on which a set of environmental safety requirements will be elicited. However, it is not a trivial task in practice to capture the environmental assumptions to elicit safety requirements. The lack of certain assumptions or too strict assumptions will either result in incomplete environmental safety requirements or waste many efforts on eliciting incorrect requirements. Moreover, the variety of operating environment for an SCS will further complicate the task, since the captured assumptions are at risk of invalidity, and consequently the elicited requirements need to be revisited to ensure safety has not been compromised by the change. This short paper presents an on-going work aiming to 1) systematically organize the knowledge of system operating environment and, 2) facilitate the elicitation of environmental safety requirements. We propose an ontological approach to achieve the objectives. In particular, we utilize conceptual ontologies to organize the environment knowledge in terms of relevant environment concepts, relations among them and axioms. Environmental assumptions are captured by instantiating the environment ontology. An ontological reasoning mechanism is also provided to support elicitation of safety requirements from the captured assumptions.

Requirements development and management of embedded real-time systems

It is well recognized that most of the anomalies, discovered in the development of embedded real-time systems, belong to requirement and specification phases. To ease the situation, many efforts have been investigated into the area. For requirements development, especially requirements validation and verification, model-driven architecture techniques can be considered as a cost-efficient solution. In order to utilize such advantages, the design of the proposed system is often specified in terms of analyzable models at the certain level of abstraction. Further, different levels of requirements are translated into verifiable queries and fed into the models to be either validated or verified. For requirements management, requirements traceability provides critical support for performing change impact analysis, risk analysis, regression testing, etc. In this thesis, we cover several topics about requirements validation, requirements verification, and requirements traceability. In particular, the technical contributions are three-fold: 1) we propose an approach to requirements validation by using the extended Timed Abstract State Machine (TASM) language with newly defined TASM constructs and, 2) we present a simulation-based method which is powered up by statistical techniques to conduct requirements verification, working with industrial applications and, 3) we introduce an improved VSM-based requirements traceability recovery approach using a novel context analysis. Further, we have demonstrated the applicability of our contributions in real world usage through various case studies.