Dual ceiling protocol for real-time synchronization under preemption threshold scheduling

The application of object-oriented design methods to real-time embedded systems is seriously hindered by the lack of existing real-time scheduling techniques that can be seamlessly integrated into these methods. Preemption threshold scheduling (PTS) enables a scalable real-time system design and thus has been suggested as a solution to this problem. However, direct adoption of PTS may lead to long priority inversion since object-oriented real-time systems require synchronization considerations in order to maintain consistent object states. In this paper, we propose the dual ceiling protocol (DCP) in order to solve this problem. While DCP exploits both priority ceilings and preemption threshold ceilings, this is not a straightforward integration of existing real-time synchronization protocols for PTS. We present the rationale for the locking conditions of DCP and show that it leads to the least blocking and response times by comparison with other real-time synchronization protocols. We also present its blocking properties and schedulability analyses. We implemented PTS and DCP in a real-time object-oriented CASE tool and present the associated experimental results, which show that the proposed protocol is a viable solution that is superior to other real-time synchronization protocols for PTS.     

一种改进的2pc协议及其性能

提出了一种改进的事务提交协议pg2pc(谨慎成组两阶段提交协议),支持成组全局事务处理,与传统的2pc相比降低了事务提交过程的消息量,提高了事务处理的吞吐量和可靠性,同时对节点故障问题提出解决方案。     

基于控制及信息协议的计算机监控通信软件

为使车间监控计算机通过以太网实现与PLC的可靠通信,选用以太网工业协议作为监控通信协议.分析了以太网工业协议的层次结构,指出CIP(控制及信息协议)中的显式消息传递方式适合作为监控计算机和PLC通信的协议.通信软件被设计为两层——基于以太网的CIP通信类和基于CIP通信类的监控通信类.CIP通信类提供了读写PLC各种内存变量的接口函数,采用互锁机制避免多线程操作中潜在的资源竞争冲突问题.监控通信类为应用程序提供向PLC发送命令和从PLC读取报告的接口函数和PLC状态的订阅服务.开发的通信软件已在某货物柔性处理线监控系统中应用.     

一种基于CSMA/CA的无线局域网协议的实现方法

论述了一种基于CSMA／CA的无线局域网协议的实现方法,按照IEEE8802．11协议标准以及通过无线传输特性的分析,提出了一种利用时间片的方法来实现CSMA／CA协议的方案,详述了基于时间片CSMA／CA协议的无线局域网适配器YH－TLAN工作过程,并给出了具体的实现方法。     

基于Modbus RTU协议的ProConOS I/O驱动设计

介绍了Modbus RTU通信协议的特点,提出了一种基于Modbus RTU协议的可编程逻辑控制内核软件ProConOS的I/O驱动设计方案,并进行了测试与分析。测试和应用结果表明,该方案能有效实现支持Modbus RTU协议的不同控制设备的互连互通、工业组网和集中控制,为Modbus RTU协议在嵌入式系统中的运用提供了依据。     

新型PM传感器通信协议设定与软件设计

为了使集成CAN总线技术的颗粒物(PM)传感器能够与发动机的其它控制单元之间实现数据共享,以汽车行业比较通用的SAE J1939协议为传感器制定通信协议.同时采用模块化思路设计PM传感器控制系统软件,最后对控制系统的各个功能模块进行了实验验证.结果表明:PM传感器控制系统的设计和制作能够满足应用需求,为进一步推进PM传感器在实车上的应用打下了基础.     

HLC-PCP: A resource synchronization protocol for certifiable mixed criticality scheduling

Today’s safety-critical Cyber-Physical Systems (CPS) often need to integrate multiple diverse applications with varying levels of importance, or criticality. Mixed-Criticality Scheduling (MCS) has been proposed with the objectives of achieving certification at multiple criticality levels and efficient utilization of hardware resources. Current work on MCS typically assumes tasks at different criticality levels are independent and do not share any resources (data). We propose HLC-PCP (Highest-Locker Criticality, Priority-Ceiling Protocol), which extends the well-known Priority Ceiling Protocol (PCP) to be applicable to AMC (Adaptive Mixed-Criticality), a variant of MCS. We present methods for worst-case blocking time computation with HLC-PCP, used for schedulability analysis of AMC with resource sharing, for both the dual-criticality model and the general multi-criticality model.     

A flaw in the electronic commerce protocol SET

The Secure Electronic Transaction (SET) protocol has been developed by the major credit card companies in association with some of the top software corporations to secure e-commerce transactions. This paper recalls the basics of the SET protocol and presents a new flaw: a dishonest client may purchase goods from an honest merchant (with the help of another merchant) for which he does not pay. Fortunately, by checking his balance sheet, the merchant may trace with the help of his bank the client and his accomplice. We also propose a modification to fix the flaw.     

一种跨平台的实时TCP/IP协议栈设计

为提高异构系统下网络通信的实时性,提出一种跨平台的实时TCP/IP协议栈(RTTCP/IP)实现方法。运用操作系统适配技术屏蔽底层数据处理的差异性,增强协议栈的可移植性和可扩展性;通过简化TCP/IP协议栈的结构,减少协议栈对系统资源的占用;采用内存映射技术,将内核空间地址映射到用户空间,避免用户与内核间的数据拷贝操作;引入基于时分多址的介质访问机制和数据包优先级策略,防止网络传输冲突,解决数据包优先级倒置问题。测试结果表明,RTTCP/IP实现方法能够减少系统开销和通信延迟,提高系统实时性和稳定性。     

基于ＴＣＰ／ＩＰ的多媒体通信实现

论述了基于ＩＣＰ／ＩＰ的端－端通信的实现和多媒体组播的实现,提出了一种数据流方式下实现多媒体组播的方法,有效地解决了数据流方式下不能进行组播的问题。     

一种基于TCP/IP协议报文头部的隐蔽通道技术

借鉴隐蔽通道技术思想提出了一种基于TCP/IP协议报文头部的隐蔽通信方法.该方法利用IP报文的特定字段隐藏额外数据,并通过模拟同步通信的方式实现密文数据的完整传输.与加密技术相结合可进一步提高通信隐蔽性.     

基于TCP／IP网络的多媒体通信研究

多媒体信息在网络上的传播涉及到网络带宽和同步的问题,TCP／IP网络协议提供了各种协议来保证多媒体信息传递的快速和可靠,要更好地实现多媒体信息的传送还要引入其它协议来保证传输质量。本文介绍多媒体信息是如何实现在网络上的传输。     

A discrete-time analysis of the cyclic reservation multiple access protocol

In this paper a performance analysis of the CRMA (Cyclic Reservation Multiple Access) medium access protocol, which is proposed as an access mechanism for high-speed LANs and MANs is presented. An approximate computational method is derived to obtain the distribution functions of performance measures of interest like the medium access delay and the packet transfer time. The analysis is done in discrete-time domain using a decomposition approach for the access delay in conjunction with a G/G/1 queue with control-feedback and a M/G/1 queue with server vacation. In the model the reservation-cancelation backpressure mechanism is also taken into account. Numerical results are obtained to investigate the efficiency of the backpressure scheme and the scaling issues of the interreserve interval under various load conditions and system configurations. Furthermore, results addressing performance aspects like the fairness issues, the jitter of maximum access delay and the system behavior under station-wise saturated conditions are also discussed.     

A presentation protocol for videotex network systems

The environment, motivations and design concepts which lead to the development of this presentation level protocol have produced an application-independent protocol. As an introduction to the basic components of a network presentation protocol, explanations of a presentation image, commands, and presentation image-definition and how to use them to their best advantage are given. A specific example of a presentation image for videotex systems demonstrates the protocol's feasibility, usefulness, and simplicity.     

LyraNET: A zero-copy TCP/IP protocol stack for embedded systems

Embedded systems are usually resource limited in terms of processing power, memory, and power consumption, thus embedded TCP/IP should be designed to make the best use of limited resources. Applying zero-copy mechanism can reduce memory usage and CPU processing time for data transmission. Power consumption can be reduced as well. In this paper, we present the design and implementation of zero-copy mechanism in the target embedded TCP/IP component, LyraNET, which is derived from Linux TCP/IP codes and remodeled as a reusable software component that is independent from operating systems and hardware. Performance evaluation shows that TCP/IP protocol processing overhead can be significantly decreased by 23–63%. Besides, object code size of this network component is only 77.64% of the size of the original Linux TCP/IP stack. The experience of this study can serve as the reference for embedding Linux TCP/IP stack into a target system that requires network connectivity and improving the transmission efficiency of Linux TCP/IP by zero-copy implementation. This paper is an extended version of the paper “LyraNET: A Zero-Copy TCP/IP Protocol Stack for Embedded Operating Systems” that appeared in the 11th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications. Mei-Ling Chiang received the B.S. degree in Management Information Science from National Chengchi University, Taipei, Taiwan, in 1989. She received the M.S. degree in 1993 and her Ph.D degree in 1999 in Computer and Information Science from National Chiao Tung University, Hsinchu, Taiwan. Now she is an Assistant Professor in the Department of Information Management at National Chi-Nan University, Puli, Taiwan. Her current research interests include operating systems, embedded systems, and clustered systems. Yun-Chen Lee received the B.S degree in 2002 and the M.S. degree in 2005 in Information Management from National Chi-Nan University, Puli, Taiwan. He is currently a software engineer in InterVideo Digital Tech., responsible for software development of multimedia-related products.     

在以太网上TCP／IP协议下实现多媒体信息的实时通信

本文介绍作者在以太网上流行的ＴＣＰ／ＩＰ协议下对多媒体信息－－视频和音频所进行的实时性传输和同步方案的研究，介绍并比较了几种不同的网络传输方案。     

可寻址加解扰系统底层通信协议设计与分析

从加解扰系统中重要的技术指标“寻址速度”入手,分析了影响该指标的软硬件和协议因素,提出了综合的自适应高速寻址算法和相关协议设计,并简要分析了算法设计的理论基础。通过统计分析可知本算法寻址速度平均提高了近48倍,并且设计的协议在多项技术指标上取得了重要进展。     

基于LabWindows/CVI的网络通信设计与实现

为实现对基站监控系统的遥调、遥控和遥信,本文制定了监控系统数据传输协议,设计了基于LabWindows/CVI平台的网络通信软件.在恶劣的网络环境下的测试结果表明,采用该数据传输协议可有效的实现远程多数据的可靠性与稳定性传输.     

BCL—3：Aigh Performance Basic Communication Protocol for Commodity Superserver DAWNING—3000

This paper introduces the design and implemetation of BCL-3,a high performance low-level communication software running on a cluster of SMPs(CLUMPS) called DAWNING-3000,BCL-3 provides flexible and sufficient functionality to fulfill the communication requirements of fundamental system software developed for DAWNING-3000 while guaranteeing security,scalability,and reliability,Important features of BCL-3 are presented in the paper,including special support for SMP and heterogeneous network environment,semiuser-level communication,reliable and ordered data transfer and scalable flow control,The performance evaluation of BCL-3 over Myrinet is also given.     

基于TCP/IP协议栈的网络家电家庭网关的设计

提出了一种基于TCP/IP协议栈来实现网络家电网关的方法.利用TCP/IP协议栈中的IP,TCP,DHCP,DDNS等协议来实现一个完整的具备各种功能的家庭网关.这种设计将可以使现有的家庭计算机网络中的网关,如宽带路由器等只需要做少量的改动,就可成为一个网络家电的网关,满足实现未来网络家电远程控制和集中控制的需求.