Abstract
Recently, a framework was proposed intended to support the development of replicated and distributed Ravenscar applications. This framework provides a transparent abstraction for application replication, allowing applications to be developed without considering replication and distribution issues. However, it is also necessary to assess if the Ravenscar profile is expressive enough for the implementation of this complex middleware. Therefore, this paper presents some conclusions that were drawn on the implementation of a prototype of the framework.

Abstract
In this paper, we present some of the fault tolerance management mechanisntv being implemented in the Multi-/z architecture, namely ira support for replica non-determinism. In thia architecture, fault tolerance is achieved by node active replication, with software based replica management and fault tolerance transparent algorithms. A software layer implemented between the application and the real-time kernel, the Fault Tolerance Manager (FTManager), is the responsible for the transparent incorporation of the fault tolerance mechanisms The active replication model can be implemented either imposing replica determinism or keeping replica consistency at critical points, by means of interactive agreement mechanisms. One of the Multi-I~ architecture goals is to identify such critical points, relieving the underlying system from performing the interactive agreement in every Ada dispatching point. © ACM 1999.

Abstract
In Distributed Computer-Controlled Systems (DCCS), a special emphasis must be given to the communication infrastructure, which must provide timely and reliable communication services. CAN networks are usually suitable to support small-scale DCCS. However, they are known to present some reliability problems, which can lead to an unreliable behaviour of the supported applications. In this paper, an atomic multicast protocol for CAN networks is proposed. This protocol explores the CAN synchronous properties, providing a timely and reliable service to the supported applications. The implementation of such protocol in Ada, on top of the Ada version of Real-Time Linux is presented, which is used to demonstrate the advantages and disadvantages of the platform to support reliable communications in DCCS.

Abstract
We present a group membership protocol specially designed for next generation communication systems for real-time safety-critical applications such as FlexRay and FTT-CAN. The proposed protocol imposes an overhead of two bits per processor per communication cycle, when the system is in a quiescent state, and is able to tolerate benign failures of up to half of the group members between consecutive executions. Additionally, it removes a faulty processor within two communication cycles in the worst case and reintegrates a processor at the latest two communication cycles after it recovers. Compared with protocols developed for similar systems, it is as tolerant as the most robust protocol with a traffic overhead slightly higher than the most efficient protocol, which is much less robust. © 2006 IEEE.

Abstract

Abstract
Fieldbus networks aim at the interconnection of field devices such as sensors, actuators and small controllers. Therefore, they are an effective technology upon which distributed computer-controlled systems (DCCS) can be built. DCCS impose strict timeliness requirements to the communication network. In essence, by timeliness requirements we mean that traffic must be sent and received within a bounded interval, otherwise a timing fault is said to occur. P-NET is a multi-master fieldbus standard based on a virtual token passing scheme. In P-NET each master is allowed to transmit only one message per token visit, which means that in the worst-case the communication response time could be derived considering that the token is fully utilized by all stations. However, such analysis can be proved to be quite pessimistic. In this paper, we propose a more sophisticated P-NET timing analysis model, which considers the actual token utilization by different masters. The major contribution of this model is to provide a less pessimistic, and thus more accurate, analysis for the evaluation of the worst-case communication response time in P-NET fieldbus networks.