Safety-critical systems require high quality and dependability levels, where system correctness and safety are major features to avoid any severe outcome. Time and cost are also important challenges that are imposed during the development process. Describing the behavior of a system in a high level provides a realistic vision and anticipation of the system. This presents a valuable opportunity for verifying the system before wasting the intended resources to develop the system. Architecture Description Languages (ADLs) provide the ability to comprise and represent the system level details of components, interactions and configuration. Architecture Analysis and Design Language (AADL) as a family member of ADLs proved its effectiveness in designing software intensive systems. In this report, we present a case study to validate “An Architecture-Based Verification Technique for AADL Specifications”. The technique involves a combination of model checking and model-based testing approaches adapted to an architectural perspective. The objectives of the verification process are 1) to ensure completeness and consistency of an AADL specification, and 2) to ensure conformance of an implementation with respect to its AADL specification. The technique has only been applied to small examples, and the goal of this thesis work is to validate it against a safety-critical system developed by a major vehicle manufacturer. Validation of the technique begins by investigating the system and specifying it in AADL. The defined verification criteria are subsequently applied to the AADL specification which drives the verification process. The case study presents interesting results while performing the model checking (the completeness and consistency checking). Conformance testing, on the other hand, could not be performed on the implemented system but is an interesting topic for future work.

<p>Development of software-intensive systems such as embedded systems for telecommunications, avionics and automotives occurs under severe quality, schedule and budget constraints. As the size and complexity of software-intensive systems increase dramatically, the problems originating from the design and specification of the system architecture becomes increasingly significant. Architecture-based development approaches promise to improve the efficiency of software-intensive system development processes by reducing costs and time, while increasing quality. This paradox is partially explained by the fact that the system architecture abstracts away unnecessary details, so that developers can concentrate both on the system as a whole, and on its individual pieces, whether it's the components, the components' interfaces, or connections among components. The use of architecture description languages (ADLs) provides an important basis for verification since it describes how the system should behave, in a high level view and in a form where automated tests can be generated. Analysis and testing based on architecture specifications allow detection of problems and faults early in the development process, even before the implementation phase, thereby reducing a significant amount of costs and time. Furthermore, tests derived from the architecture specification can later be applied to the implementation to see the conformance of the implementation with respect to the specification. This thesis extends the knowledge base in the area of architecture-based verification. In this thesis report, an airplane control system is specified using the Architecture Analysis and Description Language (AADL). This specification will serve as a starting point of a system development process where developed architecture-based verification algorithms are applied.</p>

Development of software-intensive systems such as embedded systems for telecommunications, avionics and automotives occurs under severe quality, schedule and budget constraints. As the size and complexity of software-intensive systems increase dramatically, the problems originating from the design and specification of the system architecture becomes increasingly significant. Architecture-based development approaches promise to improve the efficiency of software-intensive system development processes by reducing costs and time, while increasing quality. This paradox is partially explained by the fact that the system architecture abstracts away unnecessary details, so that developers can concentrate both on the system as a whole, and on its individual pieces, whether it's the components, the components' interfaces, or connections among components. The use of architecture description languages (ADLs) provides an important basis for verification since it describes how the system should behave, in a high level view and in a form where automated tests can be generated. Analysis and testing based on architecture specifications allow detection of problems and faults early in the development process, even before the implementation phase, thereby reducing a significant amount of costs and time. Furthermore, tests derived from the architecture specification can later be applied to the implementation to see the conformance of the implementation with respect to the specification. This thesis extends the knowledge base in the area of architecture-based verification. In this thesis report, an airplane control system is specified using the Architecture Analysis and Description Language (AADL). This specification will serve as a starting point of a system development process where developed architecture-based verification algorithms are applied.

Quality assurance of dependable embedded systems is becoming increasingly difficult, as developers are required to build more complex systems on tighter budgets. As systems become more complex, system architects must make increasingly complex architecture design decisions. The process of making the architecture design decisions of an intended system is the very first, and the most significant, step of ensuring that the developed system will meet its requirements, including requirements on its ability to tolerate faults. Since the decisions play a key role in the design of a dependable embedded system, they have a comprehensive effect on the development process and the largest impact on the developed system. Any faulty architecture design decision will, consequently, propagate throughout the development process, and is likely to lead to a system not meeting the requirements, an unacceptable level of dependability and costly corrections. Architecture design decisions are in turn critical with respect to quality and dependability of a system, and the cost of the development process. It is therefore crucial to prevent faulty architecture design decisions and, as early as practicable, detect and remove faulty decisions that have not successfully been prevented. The use of Architecture Description Languages (ADLs) helps developers to cope with the increasing complexity by formal and standardized means of communication and understanding. Furthermore, the availability of a formal description enables automated and formal analysis of the architecture design. The contribution of this licentiate thesis is an architecture quality assurance framework for safety-critical, performance-critical and mission-critical embedded systems specified by the Architecture Analysis and Design Language (AADL). The framework is developed through the adaption of formal methods, in particular traditional model checking and model-based testing techniques, to AADL, by defining formal verification criteria for AADL, and a formal AADL-semantics. Model checking of AADL models provides evidence of the completeness, consistency and correctness of the model, and allows for automated avoidance of faulty architecture design decisions, costly corrections and threats to quality and dependability. In addition, the framework can automatically generate test suites from AADL models to test a developed system with respect to the architecture design decisions. A successful test suite execution provides evidence that the architecture design has been implemented correctly. Methods for selective regression verification are included in the framework to cost-efficiently re-verify a modified architecture design, such as after a correction of a faulty design decision. / Kvalitetssäkring av tillförlitliga inbyggda system är en ständigt växande utmaning då utvecklare av sådana system är tvungna att bygga allt mer komplexa system inom allt mer begränsade budgetar. Då komplexiteten av systemen ökar måste systemarkitekter göra allt mera komplicerade beslut om systemens arkitekturdesign. Processen att besluta arkitekturdesignen av ett tilltänkt system är det allra första, och det mest signifikanta, steget att försäkra att det utvecklade systemet kommer uppnå dess krav, inklusive krav på dess möjlighet att tolerera defekter. Då dessa designbeslut dessutom har en nyckelroll i designen av ett tillförlitligt inbyggt system har de en omfattande effekt på utvecklingsprocessen samt den största påverkan på det utvecklade systemet. På grund av detta kommer ett felaktigt beslut om arkitekturdesignen propagera igenom hela utvecklingsprocessen och sannolikt resultera i ett system som inte uppnår kraven, får en oacceptabel tillförlitlighetsnivå, och kostsamma korrigeringar. De är därmed kritiska med hänsyn till kvaliteten och tillförlitligheten av ett inbyggt system, och kostnaden av utvecklingsprocessen. Således är det kritiskt att förhindra felaktiga beslut om arkitekturdesign och, så tidigt som möjligt, detektera och avlägsna felaktiga beslut som inte har lyckats att förhindras. Användningen av språk för arkitekturbeskrivning hjälper utvecklare att hantera den ökande komplexiteten genom standardiserade kommunikationsmedel och förståelsemedel. Dessutom möjliggör en formell beskrivning automatiserad och formell analys av arkitekturdesignen. Bidraget av denna licentiatavhandling är ett formellt kvalitetssäkringsramverk för säkerhetskritiska, prestandakritiska och uppdragskritiska inbyggda system specificerade i arkitekturbeskrivningsspråket ”Architecture Analysis and Design Language” (AADL). Ramverket är utvecklat genom adaptionen av formella metoder, i synnerhet traditionella modellkontrolltekniker och modellbaserad testningstekniker, till AADL, med hjälp av att definiera formella verifikationskriterier för AADL och en formell AADL-semantik. Modellkontroll av AADL-modeller analyserar modellens fullständighet, konsistens och korrekthet och möjliggör automatisk undvikande av felaktiga arkitekturdesignbeslut, kostsamma korrigeringar och hot mot kvalitet och tillförlitlighet. Därutöver kan ramverket automatiskt generera testsviter från AADL-modeller för att testa ett utvecklat system mot den bestämda arkitekturdesignen. En lyckad testsvitexekvering garanterar att arkitekturdesignen är korrekt implementerad. Metoder för selektiv regressionsverifiering är inkluderade i ramverket för att på ett kostnadseffektivt tillvägagångssätt verifiera en, tidigare verifierad, arkitekturdesign som har blivit modifierad, såsom efter en korrigering av ett felaktigt designbeslut.