An Automated Framework for Structural Test-data Generation

Structural testing criteria are mandated in many software development standards and guidelines. The process of generating test data to achieve 100% coverage of a given structural coverage metric is labour-intensive and expensive. This paper presents an approach to automate the generation of such test data. The test-data generation is based on the application of a dynamic optimisation-based search for the required test data. The same approach can be generalised to solve other test-data generation problems. Three such applications are discussed-boundary value analysis, assertion/run-time exception testing, and component re-use testing. A prototype tool-set has been developed to facilitate the automatic generation of test data for these structural testing problems. The results of preliminary experiments using this technique and the prototype tool-set are presented and show the efficiency and effectiveness of this approac

Mapping Needs, Costs and Outcomes: The English Adoption Journey

This presentation will outline the adoption pathways in England and will highlight how a systematic approach to analyzing and costing pathways can, and has, informed strategic planning. Furthermore the presentation will highlight the importance of costing child welfare services using the child as the unit of analysis, rather than focusing purely on fiscal data. Examples will be provided of how this approach facilitates an exploration of children’s needs and circumstances, how they impact on children’s pathways through the child welfare system and the outcomes that are achieved

Shared Use of Diagrams in Requirements Elicitation: roles, expectations and behaviours

This paper describes the results of an action research study whose focus was requirements elicitation for an e-business system. The study showed that analysts and end-users use the same diagrams for quite different purposes, the former for validation and establishing correctness and the latter as a structuring mechanism for uncovering requirements and gaps and reasoning about a system under consideration. A model of cognition that explains this behaviour is proposed

Enhancing Covid-19 Decision-Making by Creating an Assurance Case for Simulation Models

Simulation models have been informing the COVID-19 policy-making process. These models, therefore, have significant influence on risk of societal harms. But how clearly are the underlying modelling assumptions and limitations communicated so that decision-makers can readily understand them? When making claims about risk in safety-critical systems, it is common practice to produce an assurance case, which is a structured argument supported by evidence with the aim to assess how confident we should be in our risk-based decisions. We argue that any COVID-19 simulation model that is used to guide critical policy decisions would benefit from being supported with such a case to explain how, and to what extent, the evidence from the simulation can be relied on to substantiate policy conclusions. This would enable a critical review of the implicit assumptions and inherent uncertainty in modelling, and would give the overall decision-making process greater transparency and accountability.Comment: 6 pages and 2 figure

On the Validation of a UAV Collision Avoidance System Developed by Model-Based Optimization: : Challenges and a Tentative Partial Solution

The development of the new generation of airborne collision avoidance system ACAS X adopts a model-based optimization approach, where the collision avoidance logic is automatically generated based on a probabilistic model and a set of preferences. It has the potential for safety benefits and shortening the development cycle, but it poses new challenges for safety assurance. In this paper, we introduce the new development process and explain its key ideas using a simple collision avoidance example. Based on this explanation, we analyze the challenges it poses to safety assurance, with a particular focus on system validation. We then propose a Genetic-Algorithm-based approach that can efficiently search for undesired situations to help the development and validation of the system. We introduce an open-source tool we have developed to support this approach and demonstrate it on searching for challenging situations for ACAS XU

Testing Method for Multi-UAV Conflict Resolution Using Agent-Based Simulation and Multi-Objective Search

A new approach to testing multi-UAV conflict resolution algorithms is presented. The problem is formulated as a multi-objective search problem with two objectives: finding air traffic encounters that 1) are able to reveal faults in conflict resolution algorithms and 2) are likely to happen in the real world. The method uses agent-based simulation and multi-objective search to automatically find encounters satisfying these objectives. It describes pairwise encounters in three-dimensional space using a parameterized geometry representation, which allows encounters involving multiple UAVs to be generated by combining several pairwise encounters. The consequences of the encounters, given the conflict resolution algorithm, are explored using a fast-time agent-based simulator. To find encounters meeting the two objectives, a genetic algorithm approach is used. The method is applied to test ORCA-3D, a widely cited open-source multi-UAV conflict resolution algorithm, and the method’s performance is compared with a plausible random testing approach. The results show that the method can find the required encounters more efficiently than the random search. The identified safety incidents are then the starting points for understanding limitations of the conflict resolution algorithm

Large-scale Complex IT Systems

This paper explores the issues around the construction of large-scale complex systems which are built as 'systems of systems' and suggests that there are fundamental reasons, derived from the inherent complexity in these systems, why our current software engineering methods and techniques cannot be scaled up to cope with the engineering challenges of constructing such systems. It then goes on to propose a research and education agenda for software engineering that identifies the major challenges and issues in the development of large-scale complex, software-intensive systems. Central to this is the notion that we cannot separate software from the socio-technical environment in which it is used.Comment: 12 pages, 2 figure

Safety Case Workshop

In January 2013, a two-day Safety Case Workshop was conducted in Huntsville, Alabama under the sponsorship of the SAE International G-48 System Safety Committee and A-P-T Research, Inc. (APT). Attendees from industry, government and academia participated, with several making formal presentations on various safety methods. Industry focus is turning to international pursuits, which involve a broader understanding of different approaches to ensuring safety. The United States has typically used a process-based approach in managing system safety programs, but there is a current movement to use the evidence-based Safety Case approach to validate the safety of systems. At the conclusion of the workshop, participants reached the consensus view that the Safety Case approach merits being accepted among the best world-wide system safety practices