AspectC++: An integrated approach for static and dynamic adaptation of system software

Modern computer systems require an enormous amount of flexibility. This is especially the case in low-level system software, from embedded devices to networking services. From literature and practice, various approaches to modularize and integrate adaptations have been investigated. However, most of this work is implemented with dynamic languages that offer extensive run-time support and enable easy integration of such approaches. System software is written in languages like C or C++ in order to minimize utilization of system resources and maximize efficiency. While for these languages highly optimized and reliable compilers are available, the support for static and dynamic adaptation is rather limited. In order to overcome these limitations, we present an adaptation approach that is based on a sophisticated combination of static and dynamic aspect weaving for aspects written in AspectC++. This facilitates the incremental evolution and deployment of system software that has to be “always on”. We demonstrate the feasibility of our approach and its applicability to two pieces of system software, namely the Squid web proxy and the eCos operating system, which is used in the domain of resource-constrained deeply embedded systems.     

元组容器在C++中的设计与实现

C 是一种静态类型语言,这就使实现可以容纳不同种类型元素的容器——元组变得十分困难。C 的标准容器库STL虽然提供了丰富的容器,但其都只能容纳相同类型的元素,没有提供对元组容器的支持。其实C 的模板机制为它的静态类型系统增加了很大的灵活性,再使用一些其它的技巧,使得实现元组容器成为可能。wyf::tuple就是如此实现的一个元组容器的程序库。wyf::tuple不但可以保证类型安全,并且是高效的。测试数据表明,它要比一些动态语言如Python中的类似容器高效得多。     

The design and implementation of Object Grammars

An Object Grammar is a variation on traditional BNF grammars, where the notation is extended to support declarative bidirectional mappings between text and object graphs. The two directions for interpreting Object Grammars are parsing and formatting. Parsing transforms text into an object graph by recognizing syntactic features and creating the corresponding object structure. In the reverse direction, formatting recognizes object graph features and generates an appropriate textual presentation. The key to Object Grammars is the expressive power of the mapping, which decouples the syntactic structure from the graph structure. To handle graphs, Object Grammars support declarative annotations for resolving textual names that refer to arbitrary objects in the graph structure. Predicates on the semantic structure provide additional control over the mapping. Furthermore, Object Grammars are compositional so that languages may be defined in a modular fashion. We have implemented our approach to Object Grammars as one of the foundations of the Ensō system and illustrate the utility of our approach by showing how it enables definition and composition of domain-specific languages (DSLs).     

Anon-line C++ class: implementation and experience

The on-line classroom project includes support for Web-based exams as well as a C++ program compile-execute-and-grade server. The paper discusses the design and implementation of the system as well as the experience to date.     

YHFT-D4汇编器的设计与实现

YHFT-D4是一款具有分簇的VLIW体系结构的DSP，它有多个功能单元，可在单个时钟周期并行地执行多条指令。指令执行的功能单元是哪个，哪些指令并行执行，这些由编译器或程序员静态决定，文章给出了YHFT-D4汇编器的设计和实现方法。     

智慧家庭管家设计与实现

为解决机器人设计功能单一而结构复杂,智能家居产品依赖终端而用户体验度差等问题,结合Kinect v2体感交互设备设计一种仿人形智慧家庭机器人,借助嵌入式硬件技术、语音合成技术、动态区域滤波算法、图像分割避障算法、二阶差分边缘检测方法和姿势序列有限状态机的动作识别方法,实现可自定义内容的自然语音交流与语音控制功能、可自动调速的自主避障与路径规划功能、可锁定目标的人物跟踪与动作识别功能。设计实现的机器人具有成本低廉、结构简单、适应性强、功能多样等优点。经实际测试,该智慧家庭管家机器人运行稳定,用户体验良好,可作为智能家居行业探索方向。     

一种数据仓库工具集的设计与实现

文章就目前提供的数据仓库开发工具的不足,设计了一个适合当前数据仓库建设需要,规模适中、实用性强、可扩充的数据仓库工具集。     

COSIX连网子系统的设计与实现

COSIX连网子系统是基于国产中文操作系统COSIX V1．4开发的。该系统实现PPP协议,提供网络接入和出功能,不仅可用于客户端系统,也可用于服务器端系统。文章对子系统的设计与实现进行说明。     

无线IPPBX系统的设计与实现

描述了无线VOIP交换机的硬件设计原理与软件实现方法。在描述系统整体架构的基础上,介绍了其硬件设计部分的GSM工作单元、PCM编解码单元、语音压缩解压处理单元和总线端口适配单元的设计方法以及工作原理;描述了系统软件分层思想,介绍各层的功能和设计方法。     

The design and implementation of non-verbal auditory warnings

There are many common problems in the use of non-verbal auditory warnings in the working environment. They are often too loud, too numerous, and they are frequently confusing. These problems have a range of consequences, many of them serious. However, there now exist a number of guidelines and sets of experimental data that address these problems and provide fairly comprehensive solutions. In this article the underlying problems are highlighted, and the guidelines and research that have addressed the central issues of correct loudness levels and psychological appropriateness, particularly warning confusion and 'urgency mapping', are reviewed and evaluated. It is argued that a proper ergonomics approach to auditory warning design and implementation is not a luxury, but a necessity. A number of projects in which advanced, ergonomic auditory warning systems have been developed are described in detail, and some new research questions are proposed.     

广义模型服务器的设计与实现

模型的管理与运行一直是决策支持系统的核心,为了有效地实现广义模型的管理,组合和运行,文章设计和实现了一个广义模型服务器。它基于TCP／IP协议,采用三层客户／服务器机制,对模型的表示和运行进行了规范化,通过命令语言在客户端进行模型的管理和运行。该服务器可以对模型、算法、实例、工具等决策支持资源进行有效地管理,它既可广泛地应用于各领域的决策支持系统的开发,也可单独作为决策支持工具进行各种领域问题的辅助决策,文中系统地介绍了该服务器的设计和实现的理论和技术问题。     

高效匹配引擎的设计与实现

针对软件模式匹配引擎速度慢、占用系统资源大的问题,提出了一种基于Bloom Filter的FIBF结构,结合FPGA NIOSII微处理器(MUP),设计了软硬核相结合的匹配引擎方案。引擎通过FIBF过滤过滤掉大部分正常数据,将过滤出的可疑字符串输入到NIOSII软核进行精确匹配,两者之间通过一个指针产生器连接,整个系统以流水线方式工作。FIBF结构资源消耗低,n-FIBF并行处理,系统引擎可以达到较高的吞吐率。实验表明,在使用相同资源的情况下,本方案系统吞吐率要优于其他算法。     

为C++语言开发长度可变的数组类模板

本文详细讨论了可以代替C 数组的C 数组类模板的设计及实现过程，并举例说明了数组类模板的使用。     

Web++ architecture,design and performance

We describe the design of a system for fast and reliable HTTP service which we call Web++. Web++ achieves high reliability by dynamically replicating web data among multiple web servers. Web++ selects the available server that is expected to provide the fastest response time. Furthermore, Web++ guarantees data delivery given that at least one server containing the requested data is available. After detecting a server failure, Web++ client requests are satisfied transparently to the user by another server. Furthermore, the Web++ architecture is flexible enough for implementing additional performance optimizations. We describe implementation of one such optimization, batch resource transmission, whereby all resources embedded in an HTML page that are not cached by the client are sent to the client in a single response. Web++ is built on top of the standard HTTP protocol and does not require any changes either in existing web browsers or the installation of any software on the client side. In particular, Web++ clients are dynamically downloaded to web browsers as signed Java applets. We implemented a Web++ prototype; performance experiments indicate that the Web++ system with 3 servers improves the response time perceived by clients on average by 36.6%, and in many cases by as much as 59%, when compared with the current web performance. In addition, we show that batch resource transmission can improve the response time on average by 39% for clients with fast network connections and 21% for the clients with 56 Kb modem connections. This revised version was published online in August 2006 with corrections to the Cover Date.     

网站系统信息安全设计与实现

网站系统是各种信息发布的中心平台,其数据库中存放着大量的供用户共享的重要信息。本文从网站应用程序开发出发、部署等两个方面,就用户登录,信息传输以及网络安全等方面,并结合当前流行的实用系统,阐述了网站系统信息安全设计。     

大型会议会务管理系统的设计与实现

“办会”是各级党政机关的重要职能。尽管目前有多种会议的组织形式,但传统的面对面的会议方式仍然是主要的会议组织形式,因此“办会”也是电子政务建设的重要内容之一。大型会议的会务管理是一项非常繁重而压力大的工作。文章分析了党政机关会务管理工作的需求,实现了一个会务管理系统,讨论了一种随需应变的软件开发模型。     

基于C＋＋和OpenCV的人脸识别系统的设计与实现

人脸识别是通过对人的脸部特征信息进行身份识别的一种生物识别技术.研究现实基于人脸识别的身份验证系统具有重要意义.提出一种基于C＋＋和OpenCV的人脸识别系统的设计与实现方法.系统实现的功能模块包括人脸图像采集、图像预处理、人脸检测与定位、人脸特征提取与识别、人脸数据库管理等.系统中人脸检测采用基于Haar-like特征的Haar 分类器,人脸识别采用Eigenfacae算法.系统经过运行测试,结果表明该系统能够满足一般的基于人脸识别的身份验证需求.     

The design and implementation of a grammar-based data generator

DGL is a context-free grammar-based language for generating test data. Although many of the features of DGL are implemented in a straighforward way, the implementation of several of the most important features is neither trivial nor obvious. Before one can understand the implementation of these features, however, it is necessary to understand the overall structure of the compiler and its output, which was designed to be flexible enough to incorporate new features easily. Variables and chains are two of the most important features of DGL, and also two of the trickiest features to implement. The run-time dictionaires, which are built into the C code generated by the compiler, are implemented as pure code rather than as table-look-up routines. The compiler itself is reasonably straightforward, except for the expansion of character sets and compile-time macros. These two features can cause the ‘multi-dimensional’ expansion of a string, the implementation of which must be carefully designed.     

The design and implementation of a high-level language converter

There is now a good understanding of problems encountered in the design, implementation and use of a high-level language converter. These general issues are illustrated in terms of an account of the design and implementation of one particular converter, which converts programs from Pascal-SC (a Pascal dialect) to Ada. A specific aim of the presentation is to provide guidance for those contemplating future language conversion projects.