End-to-end predictability of remote operations is essential for many fixed-priority distributed real-time and embedded (DRE) applications, such as command and control systems, manufacturing process control systems, large-scale distributed interactive simulations, and testbeam data acquisition systems. To enhance predictability, the Real-time CORBA specification defines standard middleware features that allow applications to allocate, schedule, and control key CPU, memory, and networking resources necessary to ensure end-to-end quality of service support.

Abstract — End-to-end middleware predictability is essential to support quality of service (QoS) capabilities needed by distributed real-time and embedded (DRE) applications. Real-time CORBA is a middleware standard that allows DRE applications to allocate, schedule, and control the QoS of CPU, memory, and networking resources. Existing Real-time CORBA solutions are implemented in C++, which is generally more complicated and error-prone to program than Java. The Real-Time Specification for Java (RTSJ) provides extensions that enable Java to be used for developing DRE systems. Real-time CORBA does not currently leverage key RTSJ features, such as scoped memory and real-time threads. Thus, integration of Real-Time CORBA and RTSJ is essential to ensure the predictability required for Java-based DRE applications. This paper provides the following contributions to the study of middleware for DRE applications. First we analyze the architecture of ZEN, our implementation of Real-time CORBA, identifying sources for the application of RTSJ features. Second, we describe how RTSJ features, such as scoped memory and real-time threads, can be associated with key ORB components to enhance the predictability of DRE applications using Realtime CORBA and the RTSJ. Third, we perform preliminary qualitative and quantitative analysis of predictability enhancements arising from our application of RTSJ features. Our results show that use of RTSJ features can considerably improve the predictability of DRE applications written using Real-time

The Real-Time CORBA and minimumCORBA specifications are important steps towards defining standard-based middleware which can satisfy real-time requirements in an embedded system. These real-time middlewares must be based on a real-time operating system (RTOS) and a real-time network. This article presents a new timetriggered ethernet protocol that has been implemented under RTLinux. Furthermore it describes a Real-Time CORBA implementation called ROFES, which is based on this new real-time network.

The Real-Time CORBA and minimumCORBA specifications are important steps towards defining standard-based middleware which can satisfy real-time requirements in an embedded system. These requirements can only be fulfilled if the middleware utilizes the features of a real-time network. The Controller Area Network (CAN) is one of the most important networks in the field of real-time embedded systems. Consequently, this paper presents a CAN-based connection-oriented point-to-point communication model and its integration into Real-Time CORBA. In order to make efficient use of the advantages of CAN, we present an inter-ORB protocol, which uses smaller message headers for CAN and maps the CAN priorities to a band of CORBA priorities. We also present design and implementation details with some preliminary performance results.

The Real-Time CORBA and minimumCORBA specifications are important steps towards defining standard-based middleware which can satisfy real-time requirements in an embedded system. These real-time middlewares must be based on a real-time operating system (RTOS) and a real-time network. This article presents a new timetriggered ethernet protocol that has been implemented under RTLinux. Furthermore it describes a Real-Time CORBA implementation called ROFES, which is based on this new real-time network.

This paper describes RTC, a set of software layers based on the ISO/OSI standard that implements a complete real-time communication platform on a cluster running under realtime Linux. A modified TDMA protocol is implemented as Media Access Control (MAC) discipline, and at the application level the communication approachischannel-oriented.