A real-time fault-tolerant multicast protocol is necessary for obtaining high performance in operating distributedreal-timecomputing systems. This paper shows the efficiency of the RFRM (Release-time based Fault-tol...
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A real-time fault-tolerant multicast protocol is necessary for obtaining high performance in operating distributedreal-timecomputing systems. This paper shows the efficiency of the RFRM (Release-time based Fault-tolerant real-time Multicasting) protocol, which is based on the idea of attaching the official release time to each multicast message. As a part of this, a real-time simulation based on the TMO (time-triggered Message-triggered object) structuring scheme is conducted in order to evaluate the proposed approach. We experiment with a real-time multicast model which does not receive ACK messages, with the purpose of reducing the message traffic on the network by employing a fault detection mechanism. Simulation results promise good efficiency for the proposed real-time multicast protocol.
The following topics were discussed: advanced techniques for real-time systems; real-time and fault tolerant techniques for CORBA; worst case execution time; fault-tolerant systems; real-timeobject models; distribute...
The following topics were discussed: advanced techniques for real-time systems; real-time and fault tolerant techniques for CORBA; worst case execution time; fault-tolerant systems; real-timeobject models; distributed and ubiquitous computing; operating systems and middleware; design and testing; object-oriented design and scheduling.
The distributedreal-time services are developing as a new programming paradigm of the distributedobjectcomputing systems. For supporting these services, we construct a new model of a real-timeobject group (RTOG) p...
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The distributedreal-time services are developing as a new programming paradigm of the distributedobjectcomputing systems. For supporting these services, we construct a new model of a real-timeobject group (RTOG) platform that can manage and group distributedobjects for reducing their complicated managements and interfaces, and add distributedreal-time requirements to real-timeobjects without modifying the ORB itself To construct our RTOG platform, we designed the RTOG structure, defined the timing constraints of real-timeobjects, and explained the functional definitions and interconnections of the components from the following viewpoints: object managements and real-time services. As results, we showed the real-time executing procedures and verified our findings by using an EDF mechanism to see whether real-time services can be applied to our platform.
Query cost models are widely used, both for performance analysis and for comparing execution plans during query *** essence, a cost model predicts where time is being spent during query evaluation. Although many cost ...
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Developers of mission-critical distributedreal-time and embedded (DRE) systems face a fundamental tension between: (1) the performance gains achievable with hand-crafted optimizations to systems built largely from sc...
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Developers of mission-critical distributedreal-time and embedded (DRE) systems face a fundamental tension between: (1) the performance gains achievable with hand-crafted optimizations to systems built largely from scratch and (2) the development cost and cycle-time reductions offered by common off-the-shelf (COTS) middleware. The paper describes how the Kokyu portable middleware scheduling framework, which is built using standards-based COTS middleware and OS primitives, can be used both to: (1) maintain the flexibility and reuse offered by COTS middleware, and (2) provide opportunities for domain-specific optimizations that are needed to meet stringent real-time performance requirements.
This paper presents the design of HIDOORS, an integrated development environment suitable for embedded distributedreal-time systems, based on the Java programming language. HIDOORS will cover all the life-cycle of re...
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This paper presents the design of HIDOORS, an integrated development environment suitable for embedded distributedreal-time systems, based on the Java programming language. HIDOORS will cover all the life-cycle of real-time software development with extensions to existing tools (UML modeling, Java compiler Java Virtual Machine, and a worst case execution time analysis tool) that will all be integrated into a single integrated development environment. The system will also assist the developer in distributing the application, by providing faster RMI and a distributed event manager that provides strict timing guarantees. This paper is written at the beginning of HIDOORS development, and as such, it presents only, the defined objectives and the early, architecture of the system; further developments will be the Subject of future works.
Mobile devices, such as cellular phones, personal digital assistants (PDAs), and organizers, are becoming increasingly popular. Due to the high volatility of those devices, the achievable quality-of-service (QoS) for ...
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Mobile devices, such as cellular phones, personal digital assistants (PDAs), and organizers, are becoming increasingly popular. Due to the high volatility of those devices, the achievable quality-of-service (QoS) for mobile services can hardly be predicted. Even for one particular type of device - say a PDA - the implementation of a mobile service may use different communication interfaces over time (i.e.; wireless LAN, IrDA). Within this paper we present a new approach towards configuration of component-based services for mobile systems. Starting from a XML-based configuration language, which defines a set of rules for component configuration depending on a number of environmental parameters, our approach allows for instantiation and configuration of components. In contrast to many other approaches targeting distributed multimedia-style application on PC-class computers, our framework focuses on the extension of distributed services onto mobile devices. As proof-of-concept scenario we have implemented a configurable distributed video surveillance application on the basis of the Microsoft distributed Component object Model on Windows 2000 and on the Windows CE-based Pocket PC platform.
Many applications from scientific computing can benefit from object-oriented programming techniques because of their flexible and modular program development support. On the other hand, acceptable execution time can o...
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Many applications from scientific computing can benefit from object-oriented programming techniques because of their flexible and modular program development support. On the other hand, acceptable execution time can often only be reached by using a parallel machine. We investigate the support of Java for parallel execution. By using Java's thread mechanism we study how basic numerical methods can be expressed in parallel and which overhead is caused by thread management. We consider implementations that differ in scheduling, synchronization, and the management of threads. We obtain some guidelines to organize a multithreaded Java program to get best performance.
The emerging distributed applications require end-to-end support for various quality-of-service (QoS) aspects, including bandwidth, latency, jitter, and dependability. The Common object Request Broker Architecture (CO...
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The emerging distributed applications require end-to-end support for various quality-of-service (QoS) aspects, including bandwidth, latency, jitter, and dependability. The Common object Request Broker Architecture (CORBA) is an open distributedobjectcomputing infrastructure, standardized by the object Management Group (OMG). Its goal is to minimize the effort required to develop high-quality systems by composing applications using reusable software components. However, CORBA is not sufficient to provide QoS guarantees in a distributed environment as it lacks capabilities to specify and enforce QoS constraints. For enforcing these constraints, OMG came up with real-time CORBA (RTCORBA) specification that can guarantee end-to-end predictability in a complex realtime system. Currently, RTCORBA specification addresses the location transparency, but does not address the resource monitoring and management issues critical for meeting the QoS constraints in a multi-server distributed processing environment. In this paper, we identify the functionalities that are required to ensure predictability in such an environment and propose a resource management framework for RTCORBA. We present its design, a prototype implementation using ORBit ORB, and an example to illustrate its use.
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