Using the Architecture Analysis & Design Language (AADL) modeling notation early in the development process not only helps the development team detect design errors before implementation, but also supports implementation efforts and produces high-quality code. Our recent blog posts and webinar have shown how AADL can identify potential design errors and help avoid propagating them through the development process, where remediation can require massive re-engineering, delay the schedule, and increase costs.
Mismatched assumptions about hardware, software, and their interactions often result in system problems detected too late in the development lifecycle, which is an expensive and potentially dangerous situation for developers and users of mission- and safety-critical technologies. To address this problem, the Society of Automotive Engineers (SAE) released the aerospace standard AS5506, named the Architecture Analysis & Design Language (AADL). The AADL standard,defines a modeling notation based on a textual and graphic representation used by development organizations to conduct lightweight, rigorous--yet comparatively inexpensive--analyses of critical real-time factors, such as performance, dependability, security, and data integrity.
Introducing new software languages, tools, and methods in industrial and production environments incurs a number of challenges. Among other necessary changes, practices must be updated, and engineers must learn new methods and tools. These updates incur additional costs, so transitioning to a new technology must be carefully evaluated and discussed. Also, the impact and associated costs for introducing a new technology vary significantly by type of project, team size, engineers' backgrounds, and other factors, so that it is hard to estimate the real acquisition costs. A previous post in our ongoing series on the Architecture Analysis and Design Language (AADL) described the use of AADL in research projects (such as System Architectural Virtual Integration (SAVI)) in which experienced researchers explored the language capabilities to capture and analyze safety-critical systems from different perspectives. These successful projects have demonstrated the accuracy of AADL as a modeling notation. This blog post presents research conducted independently of the SEI that aims to evaluate the safety concerns of several unmanned aerial vehicle (UAV) systems using AADL and the SEI safety analysis tools implemented in OSATE.
The Architecture Analysis and Design Language (AADL) is a modeling language that, at its core, allows designers to specify the structure of a system (components and connections) and analyze its architecture. From a security point of view, for example, we can use AADL to verify that a high-security component does not communicate with a low-security component and, thus, ensure that one type of security leak is prevented by the architecture. The ability to capture the behavior of a component allows for even better use of the model. This blog post describes a tool developed to support the AADL Behavior Annex and allow architects to import behavior from Simulink (or potentially any other notation) into an architecture model.
As part of our mission to advance the practice of software engineering and cybersecurity through research and technology transition, our work focuses on ensuring that software-reliant systems are developed and operated with predictable and improved quality, schedule, and cost. To achieve this mission, the SEI conducts research and development activities involving the Department of Defense (DoD), federal agencies, industry, and academia. As we look back on 2013, this blog posting highlights our many R&D accomplishments during the past year.
Safety-critical avionics, aerospace, medical, and automotive systems are becoming increasingly reliant on software. Malfunctions in these systems can have significant consequences including mission failure and loss of life. So, they must be designed, verified, and validated carefully to ensure that they comply with system specifications and requirements and are error free. In the automotive domain, for example, cars contain many electronic control units (ECU)--today's standard vehicle can contain up to 30 ECUs--that communicate to control systems such as airbag deployment, anti-lock brakes, and power steering.
The size and complexity of aerospace software systems has increased significantly in recent years. When looking at source lines of code (SLOC), the size of systems has doubled every four years since the mid 1990s, according to a recent SEI technical report. The 27 million SLOC that will be produced from 2010 to 2020 is expected to exceed $10 billion. These increases in size and cost have also been accompanied by significant increases in errors and rework after a system has been deployed. Mismatched assumptions between hardware, software, and their interactions often result in system problems that are detected only after the system has been deployed when rework is much more expensive to complete.
When life- and safety-critical systems fail (and this happens in many domains), the results can be dire, including loss of property and life. These types of systems are increasingly prevalent, and can be found in the altitude and control systems of a satellite, the software-reliant systems of a car (such as its cruise control and anti-lock braking system), or medical devices that emit radiation. When developing such systems, software and systems architects must balance the need for stability and safety with stakeholder demands and time-to-market constraints. The Architectural Analysis & Design Language (AADL) helps software and system architects address the challenges of designing life- and safety-critical systems by providing a modeling notation with well-defined real-time and architectural semantics that employ textual and graphic representations. This blog posting, part of an ongoing series on AADL, focuses on the initial foundations of AADL.
When life- and safety-critical systems fail, the results can be dire, including loss of property and life. These types of systems are increasingly prevalent, and can be found in the altitude and control systems of a satellite, the software-reliant systems of a car (such as its cruise control and GPS), or a medical device. When developing such systems, software and systems architects must balance the need for stability and safety with stakeholder demands and time-to-market constraints. The Architectural Analysis & Design Language (AADL) helps software and system architects address the challenges of designing life- and safety-critical systems by providing a modeling notation that employs textual and graphic representations. This blog posting, part of an ongoing series on AADL, describes how AADL is being used in medical devices and highlights the experiences of a practitioner whose research aims to address problems with medical infusion pumps.
Aircraft and other safety-critical systems increasingly rely on software to provide their functionality. The exponential growth of software in safety-critical systems has pushed the cost for building aircraft to the limit of affordability. Given this increase, the current practice of build-then-test is no longer feasible. This blog posting describes recent work at the SEI to improve the quality of software-reliant systems through an approach known as the Reliability Validation and Improvement Frameworkthat will lead to early defect discovery and incremental end-to-end validation.
Software and systems architects face many challenges when designing life- and safety-critical systems, such as the altitude and control systems of a satellite, the auto pilot system of a car, or the injection system of a medical infusion pump. Architects in software and systems answer to an expanding group of stakeholders and often must balance the need to design a stable system with time-to-market constraints. Moreover, no matter what programming language architects choose, they cannot design a complete system without an appropriate tool environment that targets user requirements. A promising tool environment is the Architecture Analysis and Design Language (AADL), which is a modeling notation that employs both textual and graphical representations. This post, the second in a series on AADL, provides an overview of existing AADL tools and highlights the experience of researchers and practitioners who are developing and applying AADL tools to production projects.
When a system fails, engineers too often focus on the physical components, but pay scant attention to the software. In software-reliant systems ignoring or deemphasizing the importance of software failures can be a recipe for disaster. This blog post is the first in a series on recent developments with the Architecture Analysis Design Language (AADL) standard. Future posts will explore recent tools and projects associated with AADL, which provides formal modeling concepts for the description and analysis of application systems architecture in terms of distinct components and their interactions. As this series will demonstrate, the use of AADL helps alleviate mismatched assumptions between the hardware, software, and their interactions that can lead to system failures.
Testing plays a critical role in the development of software-reliant systems. Even with the most diligent efforts of requirements engineers, designers, and programmers, faults inevitably occur. These faults are most commonly discovered and removed by testing the system and comparing what it does to what it is supposed to do. This blog posting summarizes a method that improves testing outcomes (including efficacy and cost) in a software-reliant system by using an architectural design approach, which describes a coherent set of architectural decisions taken by architects to help meet the behavioral and quality attribute requirements of systems being developed.
Using the Architecture Analysis & Design Language (AADL) modeling notation early in the development process not only helps the development team detect design errors before implementation, but also supports implementation efforts and produces high-quality code. Our recent blog posts and...