A Reasoning Framework for Dependability in Software Architectures

The degree to which a software system possesses specified levels of software quality attributes, such as performance and modifiability, often have more influence on the success and failure of those systems than the functional requirements. One method of improving the level of a software quality that a product possesses is to reason about the structure of the software architecture in terms of how well the structure supports the quality. This is accomplished by reasoning through software quality attribute scenarios while designing the software architecture of the system. As society relies more heavily on software systems, the dependability of those systems becomes critical. In this study, a framework for reasoning about the dependability of a software system is presented. Dependability is a multi-faceted software quality attribute that encompasses reliability, availability, confidentiality, integrity, maintainability and safety. This makes dependability more complex to reason about than other quality attributes. The goal of this reasoning framework is to help software architects build dependable software systems by using quantitative and qualitative techniques to reason about dependability in software architectures

Parameter dependencies for reusable performance specifications of software components

To avoid design-related per­for­mance problems, model-driven performance prediction methods analyse the response times, throughputs, and re­source utilizations of software architectures before and during implementation. This thesis proposes new modeling languages and according model transformations, which allow a reusable description of usage profile dependencies to the performance of software components. Predictions based on this new methods can support performance-related design decisions

State-based Safety of Component-based Medical and Surgical Robot Systems

Safety has not received sufficient attention in the medical robotics community despite a consensus of its paramount importance and the pioneering work in the early 90s. Partly because of its emergent and non-functional characteristics, it is challenging to capture and represent the design of safety features in a consistent, structured manner. In addition, significant engineering efforts are required in practice when designing and developing medical robot systems with safety. Still, academic researchers in medical robotics have to deal with safety to perform clinical studies. This dissertation presents the concept, model and architecture to reformulate safety as a visible, reusable, and verifiable property, rather than an embedded, hard-to-reuse, and hard-to-test property that is tightly coupled with the system. The concept enables reuse and structured understanding of the design of safety features, and the model allows the system designers to explicitly define and capture the run-time status of component-based systems with support for error propagation. The architecture leverages the benefits of the concept and the model by decomposing safety features into reusable mechanisms and configurable specifications. We show the concept and feasibility of the proposed methods by building an open source framework that aims to facilitate research and development of safety systems of medical robots. Using the cisst component-based framework, we empirically evaluate the proposed methods by applying the developed framework to two research systems -- one based on a commercial robot system for orthopedic surgery and another robot soon to be clinically applied for manipulation of flexible endoscopes

Entwurfsoptimierung von selbst-adaptiven Wartungsmechanismen für software-intensive technische Systeme

Diese Arbeit stellt neuartige Konzepte zur effizienten Entscheidungsunterstützung in der Rekonfiguration software-intensiver technischer Systeme mit limitiertem Wartungszugriff vor. Entgegen rein redundanzorientierter Ansätze, basiert die verfolgte Methodik auf der prädiktiven Vorausberechnung adäquater Konfigurationsalternativen im relevanten Lösungsraum. Das Wissen über Konfigurationsbeziehung wird frühzeitig manifestiert und zur autarken kosteneffizienten Abwägung der Alternativen eingesetzt

Early quality prediction of component-based systems - A generic framework

Component-based software engineering is currently an emerging technology used to develop complex embedded systems. These embedded systems need to fulfil requirements regarding quality attributes such as safety, reliability, availability, maintainability, performance, security and temporal correctness. Since quality problems should be identified and tackled early in the development process, there is a rising need to predict and evaluate these properties in the architecture design phase. This paper describes a generic framework for predicting quality properties based on component-based architectures, which is derived from a comprehensive study of recent architecture evaluation methods. This generic framework defines common aspects between the different evaluation methods and enables the improvement of evaluation methods for specific quality properties, by transferring knowledge from one quality domain to the other. Thus, this paper can help to create better evaluation methods in the future. (c) 2006 Elsevier Inc. All rights reserved