Aspect-Oriented Real-Time Architectures

AORTA项目的目标是通过提取关键路径来增强动态混合临界实时系统的可预测性。这些路径将被转换为它们的静态等价物，并在运行时以时间触发的方式执行。与事件触发的进程相比，时间触发的执行往往会使用不足的资源。因此，混合临界实时系统的乐观执行模型将被保留。只有在紧急情况下，实时系统才会按照静态时间表执行。同时，第一个资助阶段的结果将被推广到动态实时架构。特别地，重点将放在具有复杂依赖模式的混合临界系统上。该研究项目将调查实时Linux的几个变体，以及控制工程领域的应用。项目第二个资助阶段的主要焦点将放在关键和非关键执行路径之间的依赖关系上。这些依赖关系可能是潜在的问题，并且可以在系统的所有级别上找到：例如，应用软件可能将非关键的舒适功能与关键的控制功能结合起来，导致耦合组件。在操作系统中，缓冲区可用于共享通信栈。通常，这样的耦合是可取的，然而，在动态系统中，运行时的许多可能的执行路径可能导致系统设计（如WCET和WCRT）严重过度供应。因此，保证执行时间往往会导致从动态实时系统设计中获得的效率损失。这个项目的三个关键活动将在运行时为关键的应用程序核心提供硬保证：分析、裁剪和机制。这个项目的基础将是现有的在硬实时约束下设计混合临界系统的技术。对于AORTA，通常假设关键路径具有确定性结构，因此它们与非关键路径的耦合可以映射为静态等效路径。在本项目的过程中，将仔细检查实时Linux的不同变体所提供的简单通信模式的适用性，以确定这些模式是否能够保证安全关键控制应用程序的严格截止日期，以及在第一个资助阶段开发的用于静态分析、裁剪和调度的概念和技术是否适合于此目的。此外，将在混合临界实时系统的上下文中研究耦合实时体系结构、调度和依赖关系的必要性，以确定实时Linux设计概念在运行时切换实时范式的一般适用性。

The goal of the AORTA project is to enhance the predictability of dynamic mixed-criticality real time systems by extracting critical paths. These paths are to be transformed into their static equivalents and to be executed in a time-triggered fashion at run-time. In comparison to event triggered processes, time-triggered execution tends to underuse resources. Therefore the optimistic execution model of mixed-criticality real-time systems will be retained. Only in case of an emergency the real-time system will be executed according to the static schedule. At the same time the results of the first funding phase will be generalized to dynamic real-time architectures. In particular, the focus will be on mixed-criticality systems with complex dependency patterns. The research project will investigate several variants of real-time Linux, as well as applications from the domain of control engineering.The main focus during the second funding phase of the project is going to be on dependencies between critical and non-critical paths of execution. These dependencies may potentially be problematic and can be found on all levels of the system: For example, application software may combine non-critical comfort functions with critical control functionality, leading to coupled components. In the operating system buffers may be used for shared communication stacks. Often such coupling may be desirable, however, in dynamic systems a host of possible execution paths at run-time may lead to dramatically overprovisioned system designs w.r.t. WCET and WCRT. Therefore, guaranteed execution times often lead to a loss of the efficiency gained from the dynamic real-time system design. Three key activities of this project will provide hard guarantees at run-time for the critical application core: analysis, tailoring and mechanisms.The basis for this project will be existing techniques for designing mixed-criticality systems under hard real-time constraints. For AORTA, it will be assumed that in general critical paths have deterministic structure and therefore their coupling with non-critical paths may be mapped to static equivalents. In the course of this project the applicability of the simple communication patterns provided by different variants of real-time Linux will be scrutinized to determine if these can guarantee the hard deadlines of safety-critical control applications, and if the concepts and techniques for static analysis, tailoring and scheduling developed in the first funding phase are suitable for this purpose. In addition the necessity of coupling the real-time architecture, scheduling and dependencies will be investigated in the context of mixed-criticality real-time systems to determine the general fitness of real-time Linux's design concepts for switching real time paradigms at run-time.