As part of the development of a new real-time operating system, an asynchronous communication mechanism, for use between applications, has been implemented in a programming language with an advanced static type system. This mechanism is designed to provide desired properties of asynchronicity, coherency and freshness. We used the features of the type system, including linear and dependent types...

A large class of safety-critical control systems contains monitoring subsystems that display certain system parameters to (human) operators. Ensuring that the displayed data are sufficiently fresh and noncorrupted constitutes an important part of safety requirements. However, the monitoring subsystems are typically not a part of a safety kernel and hence often built of SIL1–SIL2 components. In ...

Simpson’s role model method was designed for the analysis of synchronisation-free data communication mechanisms employing shared memory and has been shown to be especially useful for the representation and analyses of data freshness properties. Previously published analyses using the role model method have employed proprietary state space search techniques developed by Simpson. In this paper, a...

Simpson’s role model method [7, 8] was designed for the analysis of synchronisationfree data communication mechanisms employing shared memory and has been shown to be especially useful for the representation and analyses of data freshness properties. Previously published analyses using the role model method have employed proprietary state space search techniques developed by Simpson. In this re...

In [WK94], we define a real-time producers/consumers problem where all tasks are periodic and all resources are non-sharable/non-reusable. In this paper, we study the same problem but with sharable resources. We define a quantitative measure, resource freshness ratio (RFR), to represent the effect of sharable versus non-sharable resources on improving the resource freshness when tasks start sim...

This chapter presents a new approach to online decision support systems that is scalable, fast, and capable of analysing up-to-date data. It is based on a database cluster: a cluster of commercial off-the-shelf computers as hardware infrastructure and off-the-shelf database management systems as transactional storage managers. We focus on central architectural issues and on the performance impl...