UML-based specification, validation, and log-file based verification of the Orion Pad Abort Software

This paper described the first end to end application of a novel light weight formal specification, validation, and verification technique. The technique is novel is two aspects. First, it uses an intuitive, familiar, and diagrammatic notation for formal specification, a notation that being Turing equivalent and supports the capture of real-life requirements. Second, the technique includes a computer aided approach for validating the correctness of requirements early in the development process, allowing sufficient time for the correction of ambiguous and underspecified requirements. In the verification phase the technique is based on off-line verification using log-files. This approach scales well and is applicable to almost every mission critical system, including real-time systems. The paper describes the application of this technique towards the specification, validation, and verification of the Pad Abort subsystem of NASA's Orion mission.Approved for public release; distribution is unlimited

An Adaptive Design Methodology for Reduction of Product Development Risk

Embedded systems interaction with environment inherently complicates understanding of requirements and their correct implementation. However, product uncertainty is highest during early stages of development. Design verification is an essential step in the development of any system, especially for Embedded System. This paper introduces a novel adaptive design methodology, which incorporates step-wise prototyping and verification. With each adaptive step product-realization level is enhanced while decreasing the level of product uncertainty, thereby reducing the overall costs. The back-bone of this frame-work is the development of Domain Specific Operational (DOP) Model and the associated Verification Instrumentation for Test and Evaluation, developed based on the DOP model. Together they generate functionally valid test-sequence for carrying out prototype evaluation. With the help of a case study 'Multimode Detection Subsystem' the application of this method is sketched. The design methodologies can be compared by defining and computing a generic performance criterion like Average design-cycle Risk. For the case study, by computing Average design-cycle Risk, it is shown that the adaptive method reduces the product development risk for a small increase in the total design cycle time.Comment: 21 pages, 9 figure

VERIFICATION AND VALIDATION OF A SOFTWARE: A REVIEW OF THE LITERATURE

With the development of the Internet, making software is often essential, also it is complicated to succeed in the project’s development. There is a necessity in delivering software of top quality. It might be accomplished through using the procedures of Verification and Validation (V&V) via development processes. The main aim of the V&V has been checking if the created software is meeting the needs and specifications of clients. V&V has been considered as collections related to testing as well as analysis activities across the software’s full life cycle. Quick developments in software V&V were of high importance in developing approaches and tools for identifying possible concurrent bugs and therefore verifying the correctness of software. It has been reflecting the modern software V&V concerning efficiency. The main aim of this study has been retrospective review related to various researches in software V&V and conduct a comparison between them.               In the modern competitive world related to the software, the developers of software must be delivering on-time quality products, also the developers should be verifying that the software has been properly functioning and validating the product for each one of the client’s requirements. The significance of V&V in the development of software has been maintaining the quality of software. The approaches of V&V have been utilized in all stages of the System Development Life Cycle. Furthermore, the presented study also provides objectives of V&V and describes V&V tools that can be used in the process of software development, the way of improving the software’s quality

A Visual Tradeoff Space for Formal Verification and Validation Techniques

Numerous techniques exist for conducting computer-assisted formal verification and validation. The cost associated with these techniques varies, depending on factors such as ease of use, the effort required to construct correct requirement specifications for complex real-life properties, and the effort associated with instrumentation of the software under test. Likewise, existing techniques differ in their ability to effectively cover the system under test and its associated requirements. To aid software engineers in selecting the appropriate technique for the formal verification and validation task at hand, we introduce a three-dimension tradeoff space encompassing both cost and coverage

Proceso de requisitos validado empíricamente

La construcción del Proceso de Requisitos basado en Escenarios, tema central de la presente tesis, ha comenzado hace más de dos décadas. Durante este tiempo, se lo ha revisado en diferentes proyectos de investigación, mientras que simultáneamente se lo ha aplicado en numerosos casos. La detección de algunos problemas ha generado una alerta en la calidad y consistencia de los modelos construidos y, por consiguiente, de los requisitos del software obtenidos. Su estrategia de construcción consta de tres etapas: Comprender el Universo de Discurso actual, Planificar el Universo de Discurso futuro y Explicitar los Requisitos del Software. En la secuencia de ejecución del proceso se utilizan básicamente dos modelos: el Léxico Extendido del Lenguaje (LEL) y los Escenarios, cada uno con sus particularidades. Tanto el proceso como los modelos han sido analizados empíricamente en esta tesis. Parte de los resultados obtenidos consisten en reemplazar la Actividad Derivar Escenarios Actuales con un nuevo mecanismo cognitivo que ayuda a construir una primera versión de los Escenarios de mejor calidad, ya que la actividad existente genera Escenarios con problemas de consistencia y completitud. El principal origen de estos problemas ha sido ignorar que el LEL es declarativo y los Escenarios son procedurales. La nueva heurística utiliza un mecanismo procedural e incremental por proximidad de situaciones, y, además, se nutre de todo el conocimiento existente en el macrosistema. En forma análoga, se ha detectado que la Heurística de Construcción del LEL, la cual es conducida por una lista inicial de símbolos, dificulta la detección de nuevos símbolos, afectando la completitud del glosario. En este caso también se propone reemplazarla por una nueva heurística que utiliza la lista inicial a modo recordatorio y propone identificar los símbolos por proximidad, arrojando mejoras significativas en los LEL construidos. Otros cambios son transversales, como es la incorporación de las jerarquías conceptuales y de los puntos de vista del contexto ya que afectan tanto al LEL como a los Escenarios. De esta manera se incluye información sensible para los requisitos, incrementando el nivel de detalle y la precisión de todas las representaciones. Con el objetivo de reducir los errores involuntarios, durante la descripción del LEL y de los Escenarios, se propone una Vista Clasificación, que puede activarse por demanda, con información adicional de cada símbolo del LEL. Las restantes modificaciones son nuevos modelos agregados al proceso, el primero de ellos es la Construcción del LEL de Requisitos, lo que ha puesto de manifiesto una importante omisión en el proceso existente al no contemplar la evolución que sufre el léxico durante el proceso de Ingeniería de Requisitos. La utilización del LEL en los Escenarios Futuros y en el documento de especificación de requisitos de software, paradójicamente, es una nueva fuente de ambigüedades ya que el léxico de los clientes y usuarios no es apto para describir el proceso del negocio futuro con el sistema de software en ejecución. Finalmente, el segundo agregado está relacionado con aquella información que aparece espontáneamente, pero que no tiene cabida en el modelo que se está construyendo. Esta información extemporánea requiere ser resguardada en el momento que aparece para recuperarla oportunamente, asegurando su comprensión cuando llegue el momento de incorporarla a un modelo. A tal efecto, se describe un mecanismo que ayuda el tratamiento efectivo de este tipo de información en cualquier proceso de requisitos. Todos los cambios y agregados al Proceso de Requisitos basado en Escenarios contribuyen a obtener una Especificación de Requisitos de Software de la mayor calidad posible, proporcionando modelos más completos y consistentes.The development of the Scenario-based Requirements Process, the main subject of this thesis, started two decades ago. Meanwhile, during that time, it has been reviewed in several research projects, while simultaneously it has been applied in many cases. The detection of some problems raised an alert on the quality and the evenness of the constructed models and, therefore, on the quality of the software requirements produced. Their construction process consists of three stages: comprehend the current context in which the future system will be introduced, plan how such context will behave in the future, and make explicit the software requirements. During the process, two models have used the Language Extended Lexicon and the Scenarios, each one with its distinctiveness. Both the process and the models has been empirically tested as a part of this thesis. Some of the obtained results comprise the substitution of the Derive Actual Scenarios Activity with a mechanism involving a new cognitive standpoint that helps to construct the first version of the Scenarios with better quality, improving the existing activity, which produces Scenarios with consistency and completeness problems. The main source of these problems has been disregarding that the LEL is declarative and the Scenarios are procedural. The new heuristic uses a procedural and incremental mechanism by proximity of situations, in addition besides it is fed by all the existent knowledge in the macro system. Likewise, it has been detected that the LEL Construction Heuristic, which is conducted by an initial list of symbols, difficult the detection of new symbols, harming the completeness of the glossary. In this case, it is also proposed to replace it with a new heuristic that uses the initial list as a reminder and recommends identifying the symbols by their proximity, leading to significant improvements in the LEL built. Some other changes introduced such as the incorporation of the conceptual hierarchies and the context points of view are of a wider scope since they affect the LEL and the Scenarios. Therefore, sensitive information for the requirements is added, incrementing the level of detail and the precision of all representations. In order to reduce unintentional errors during the description of the LEL and the Scenarios, a Classification View is proposed, it may be activated by demand giving additional information on each LEL symbol. The rest of the modifications are new models added to the process, the first one is the Requirements LEL Construction, which has revealed an important omission in the existent process, by not considering the evolution that suffers the lexicon along the Requirements Engineering process. The use of the LEL in the future Scenarios and the software requirements specification document, paradoxically, is a new source of ambiguities since the client’s and user´s lexicon is not apt to describe the future business process with the software system running. Finally, the second addition is related to the information that appears spontaneously but does not have room in the model that is currently being built. This extemporaneous information requires to be recorded when appears to be able to be recovered opportunely, allowing its comprehension when the moment of incorporating it to a new model comes. To that end, a mechanism, to help the treatment of this type of information in every requirement process, is described.Facultad de Informátic