RTZen: Highly Predictable, Real-Time Java Middleware for Distributed and Embedded Systems

Distributed real-time and embedded (DRE) applications possess stringent quality of service (QoS) requirements, such as predictability, latency, and throughput constraints. Real-Time CORBA, an open middleware standard, allows DRE applications to allocate, schedule, and control resources to ensure predictable end-to-end QoS. The Real-Time Specification for Java (RTSJ) has been developed to provide extensions to Java so that it can be used for real-time systems, in order to bring Java's advantages, such as portability and ease of use, to real-time applications.In this paper, we describe RTZen, an implementation of a Real-Time CORBA Object Request Broker (ORB), designed to comply with the restrictions imposed by RTSJ. RTZen is designed to eliminate the unpredictability caused by garbage collection and improper support for thread scheduling through the use of appropriate data structures, threading models, and memory scopes. RTZen's architecture is also designed to hide the complexities of RTSJ related to distributed programming from the application developer. Empirical results show that RTZen is highly predictable and has acceptable performance. RTZen therefore demonstrates that Real-Time CORBA middleware implemented in real-time Java can meet stringent QoS requirements of DRE applications, while supporting safer, easier, cheaper, and faster development in real-time Java

The RTSORAC Real-Time Object-Oriented Database Model and Prototype

This paper presents a model and prototype implementation of a real-time object-oriented database system. In addition to traditional database system requirements, a real-time database must support data temporal consistency requirements and timeconstrained transactions. The RTSORAC database model supports these requirements by specifying objects that contain: attributes with value, time and imprecision fields; constraints on each of those fields; and semantically defined compatibility of object methods. It also specifies first-class relationships that can express inter-object constraints, and specifies time-constrained transactions with varying tolerances for data consistency. The implementation of the RTSORAC model in the Open Object-Oriented Database System is described

Multilevel Static Real-Time Scheduling Algorithms Using Graph Partitioning

5th International Conference on Computational Science - ICCS 2005; Atlanta, GA; United States; 22 May 2005 through 25 May 2005We propose static task allocation algorithms for the periodic tasks of a distributed real-time system. The cyclic task consists of task threads which may communicate and share resources. A graph partitioning process and a thread sequencing algorithm are applied to these threads to yield local schedules. The exact analysis is then obtained and further refinements are performed if the worst case response time of a task is greater than its deadline