Web Service核心协议与实施研究

本文首先介绍了Web Services、中间件和SCA。着重分析了Web Services的主要协议WSDL和SOAP，及其典型实施Axis，最后指出了Web Services的新规范VVS-Addressing及其带来的挑战。     

一种支持多协议的超高速转发引擎的设计与实现

从节约FPGA资源的角度出发,分析了超高速条件下多协议支持策略的实现难点,设计了一种可支持10Gbps速率下多协议报文线速转发的引擎结构,解决了FPGA“资源与速度互换”的矛盾。     

On the secure implementation of security protocols

We consider the problem of implementing a security protocol in such a manner that secrecy of sensitive data is not jeopardized. Implementation is assumed to take place in the context of an API that provides standard cryptography and communication services. Given a dependency specification, stating how API methods can produce and consume secret information, we propose an information flow property based on the idea of invariance under perturbation, relating observable changes in output to corresponding changes in input. Besides the information flow condition itself, the main contributions of the paper are results relating the admissibility property to a direct flow property in the special case of programs which branch on secrets only in cases permitted by the dependency rules. These results are used to derive an unwinding theorem, reducing a behavioural correctness check (strong bisimulation) to an invariant.     

面向对象通信协议的设计与实现

文章介绍了如何利用面向对象技术构建模块化通信系统，并给出了作者设计的TCP模块化实例。     

短消息网关协议的异步实现

研究分析了中国移动的CMPP协议和中国电信的SMGP协议,提出了一套兼容两大运营商的短消息网关协议的完善的异步双工实现方法,能很好地支持大流量的高速并发通信,具有独特的基于滑动窗口的流量控制机制和重发机制,适用于短消息网关系统的设计或服务提供商的网关接口设计。对短消息网关协议提出了一些改进建议。     

ARINC735A接口协议的设计与实现

为了实现机载防撞系统(TCAS)主机与外围功能单元的高效连接,需要定义和设计相关的接口协议.根据美国航空无线电设备标准ARINC735A定义的TCAS系统必须满足的DO-185A的接口和协议,分析和讨论了ARINC735A协议模块在TCAS系统中的功能和上下文关系,在此基础上详细描述了ARINC735A协议模块各组件的功能.采用软件工程的设计方法,系统地定义和设计了实现该协议模块功能组件的状态和流程,并给出了相应的状态转换图.讨论了在嵌入式环境下对AR-INC735A的多任务实现方法,并且在VxWorks嵌入式操作系统环境下,实现了ARINC735A协议的多任务软件模块.     

实现Ad-hoc按需路由协议的关键技术

首先分析了Linux操作系统路由体系结构的特点,分析了在这种路由体系结构中实现按需路由协议的主要困难,给出了解决方法。在此基础上,提出实现按需路由协议的方案。最后根据此方案实现了无线自组网按需平面距离向量路由协议(Ad hoc on demand distance vector, AODV),并在实际网络中验证了方案的可行性。     

无线局域网安全协议的研究和实现

描述了无线局域网及其安全协议的发展,并对发展过程中的主要安全协议进行了分析。针对这些安全协议的特点给出了安全协议的实现方案。     

Grid-distributed visualizations using connectionless protocols

The NERSC and Lawrence Berkeley National Laboratory visualization group has developed the Visapult tool to attack grand challenge problems. Visapult is a distributed, parallel, volume rendering application that leverages parallel computation and high-performance networking resources that are on the same scale as the supercomputers generating the data. We've improved Visapult's effectiveness using aggressive network tuning and network protocol modifications. In particular, we used a new connectionless user datagram protocol (UDP) to improve network efficiency from a 25 to 88 percent line rate increase for multigigabit networks. This connectionless protocol also dramatically reduces the latency of network event delivery, improving the responsiveness of wide area distributed interactive graphics applications as compared to transmission control protocol (TCP) streams. We believe that this UDP protocol, as well as transport encodings and algorithms that can tolerate loss gracefully, will become a fundamental component of future grid visualization architectures.     

Evolution of networks using standard protocols

The UK South West Universities Computer Network (SWUCN) was implemented on a homogenous set of computers, before the emergence of accepted standard protocols for networking. The paper outlines problems of evolving from this network to a heterogeneous one, in which standard protocols are used. A particular application of the strategy involved is described that includes the implementation of a network connection using the X.25 Recommendation on the Honeywell Multics system.     

密码协议安全性证明系统解析器的设计与实现*

可证明安全性是密码协议安全性评估的重要依据,但手写安全性证明容易出错且正确性难以判定,利用计算机辅助构造游戏序列进而实现自动化证明是当前一种可行的方法。为此提出一种基于进程演算的密码协议形式化描述模型,定义了描述密码协议安全性证明中攻击游戏的语法规则,并借助工具LEX和YACC,设计出解析器程序,将密码协议及其安全性的形式化描述解析为自动化安全性证明系统的初始数据结构,并用实例来说明这种方法的可行性。     

Semiautomatic method for histomorphometry

A semiautomatic measurement system for histomorphometry is presented. The system is based on a steppermotor-driven scanning stage which the operator controls via a digitizer. Movement in the scanning stage is carried out with respect to stationary cross-wires in the ocular of the microscopy. The system is connected to a PC-AT computer which utilizes the x- and y-coordinates of these movements for the calculation of the morphometric measurements. In addition, the system is supplemented by software for storage and analysis of measurement data.     

Design and implementation of a room thermostat using an agent-based approach

A large number of control systems operate in the real-world and are expected to deal with the range of changing conditions of the physical process that is being controlled. It may be a laborious and difficult task to design one controller that fits all operating conditions. In reality, several controllers, each suitable for a particular operating regime, are often combined in order to solve the problem. This paper describes a method that facilitates the design and implementation of these so-called multi-controller systems. It is based on the concept of an autonomous agent, which has recently been introduced in the field of artificial intelligence. The method enables the use of heterogeneous control algorithms and integrating techniques. Furthermore, it allows for an incremental design of the control system, which is attractive from a designer's point of view. The proposed framework is applied to the design and implementation of an ‘intelligent’ room thermostat in order to illustrate the applicability and usefulness of this method.     

FPGA-based implementation of a chirp signal generator using an OpenCL design

A novel approach to developing an FPGA-based chirp signal generator using high-level synthesis implementation is proposed. OpenCL, which is a framework used for high-level synthesis (HLS) methodologies, is employed instead of the Verilog/VHDL language to program FPGA. OpenCL has been used for FPGA programming, particularly in high-performance computing applications. Utilizing OpenCL for FPGA development reduces development time because of the high-level abstraction of the code. However, compared to Verilog/VHDL, standard OpenCL does not enable direct access to the FPGA's I/O. In this study, the FPGA needs to access the I/O pins to communicate with the DAC and generate the chirp signal. Thus, direct access to the FPGA I/O pin from the OpenCL environment is required. Therefore, a new OpenCL component is developed to enable the FPGA to communicate with the DAC, thus allowing data streaming to generate the chirp signal. This OpenCL component enables us to stream the data from the FPGA to generate the chirp signal. Here, we demonstrate that by using OpenCL implementation, the FPGA can generate an I/Q chirp signal efficiently. Moreover, the same OpenCL kernel can be employed to generate different bandwidths of the chirp signal without having to reprogram the FPGA. To demonstrate the capability of the system, we generated the I/Q chirp signal from 1 MHz to 5 MHz, 5 MHz to 10 MHz, 10 MHz to 15 MHz and 15 MHz to 20 MHz for a period of 10 µs.     

Design and implementation of an augmented reality system using gaze interaction

In this paper, we discuss an interactive optical see-through head-mounted device (HMD) which makes use of a user’s gaze for an augmented reality (AR) interface. In particular, we propose a method to employ a user’s half-blink information for more efficient interaction. Since the interaction is achieved using a user’s gaze and half-blinks, the proposed system can create a more efficient computing environment. In addition, the proposed system can be quite helpful to those who have difficulties in using their hands for conventional interaction methods. The experimental results present the robustness and efficiency of the proposed system.     

A scalable implementation of barrier synchronization using an adaptive combining tree

Barrier synchronization is commonly used for synchronizing processors prior to a join operation and to enforce data dependencies during the execution of parallelized loops. Simple software implementations of barrier synchronization can result in memory hot-spots, especially in large scale shared-memory multiprocessors containing hundreds of processors and memory modules communicating through an interconnection network. A software combining tree can be used to substantially reduce memory contention due to hot-spots. However, such an implementation results inO(logn) latency in recognition of barrier synchronization, wheren is the number of processors. In this paper anadaptive software combining tree is used to implement a scalable barrier withO(1) recognition latency. The processors that arrive early at the barrier adapt the combining tree so that it has a structure appropriate for reducing the latency for the processors that arrive later. We also show how adaptive combining trees can be used to implement the fuzzy barrier. The fuzzy barrier mechanism reduces the idling of processors at the barriers by allowing the processors to execute useful instructions while they are waiting at the barrier.     

Collision detection between point clouds using an efficient k-d tree implementation

Context: An important task in civil engineering is the detection of collisions of a 3D model with an environment representation. Existing methods using the structure gauge provide an insufficient measure because the model either rotates or because the trajectory makes tight turns through narrow passages. This is the case in either automotive assembly lines or in narrow train tunnels.Objective: Given two point clouds, one of the environment and one of a model and a trajectory with six degrees of freedom along which the model moves through the environment, find all colliding points of the environment with the model within a certain clearance radius.Method: This paper presents two collision detection (CD) methods called kd-CD and kd-CD-simple and two penetration depth (PD) calculation methods called kd-PD and kd-PD-fast. All four methods are based on searches in a k-d tree representation of the environment. The creation of the k-d tree, its search methods and other features will be explained in the scope of their use to detect collisions and calculate depths of penetration.Results: The algorithms are benchmarked by moving the point cloud of a train wagon with 2.5 million points along the point cloud of a 1144 m long train track through a narrow tunnel with overall 18.92 million points. Points where the wagon collides with the tunnel wall are visually highlighted with their penetration depth. With a safety margin of 5 cm kd-PD-simple finds all colliding points on its trajectory which is sampled into 19,392 positions in 77 s on a standard desktop machine of 1.6 GHz.Conclusion: The presented methods for collision detection and penetration depth calculation are shown to solve problems for which the structure gauge is an insufficient measure. The underlying k-d tree is shown to be an effective data structure for the required look-up operations.     

Optimizing an APSP implementation for NVIDIA GPUs using kernel characterization criteria

During the last years, GPU manycore devices have demonstrated their usefulness to accelerate computationally intensive problems. Although arriving at a parallelization of a highly parallel algorithm is an affordable task, the optimization of GPU codes is a challenging activity. The main reason for this is the number of parameters, programming choices, and tuning techniques available, many of them related with complex and sometimes hidden architecture details. A useful strategy to systematically attack these optimization problems is to characterize the different kernels of the application, and use this knowledge to select appropriate configuration parameters. The All-Pair Shortest-Path (APSP) problem is a well-known problem in graph theory whose objective is to find the shortest paths between any pairs of nodes in a graph. This problem can be solved by highly parallel and computational intensive tasks, being a good candidate to be exploited by manycore devices. In this paper, we use kernel characterization criteria to optimize an APSP algorithm implementation for NVIDIA GPUs. Our experimental results show that the combined use of proper configuration policies, and the concurrent kernels capability of new CUDA architectures, leads to a performance improvement of up to 62 % with respect to one of the possible configurations recommended by CUDA, considered as baseline.