一种基于构件演算的主动构件精化方法

现代构件系统通常包含多个并发执行的主动构件,这使得验证构件系统的正确性变得十分困难.通过对构件演算进行扩展,提出了一种主动构件的精化方法.在构件接口层引入契约.契约使用卫式设计描述公共方法和主动活动的功能规约.通过一对发散、失败集合定义契约的动态行为,并利用发散、失败集合之间的包含关系定义契约间的精化关系.证明了应用仿真技术确认契约精化关系的定理.定义构件的语义为其需求接口契约到其服务接口契约的函数,以此为基础,可以通过契约的精化来证明构件的精化.给出了构件的组装规则.在构件系统自底向上的构造过程中,应用构件的精化方法和组装规则可以保证最终系统的正确性.     

软件体系结构中接口连接规则研究

基于体系结构的软件开发方法以构件作为最小组装粒度,构件通过其自身定义的接口与外界进行交互.连接件作为一种特殊的构件,它主要负责管理构件之间信息的交换.构件与连接件之间通过接口进行数据的传递,因此,如何从体系结构层次上定义构件及连接件接口的交互规则是构件组装的关键所在.在现有动态体系结构描述框架的基础上,定义了端口以及通道的连接规则,并结合实际的案例,采用动态体系结构描述语言D-ADL进行描述,具体说明了这些规则的应用.从而为系统行为的形式化分析、验证和仿真奠定了基础.     

实时嵌入式构件模型组装方法及时间性推理

针对实时嵌入式系统特点,提出一种可行的具有较好普适性的软构件模型及构件组装机制,使用形式化方法描述构件接口规约及组装规约,并给出构件时间性的推理方法,旨在实时嵌入式系统中构建更加通用、简易、开放的构件模型和更加合理的构件组装推理机制。     

接口连接式构件组装的一种形式化方法

构件组装是基于构件的软件开发的研究重点之一,能够有效地提高软件开发的效率和质量。以往大部分构件组装技术是在“成功组装路线”的前提条件下实现的,缺乏对构件组装正确性的检验。本文改进了常用的接口连接式构件组装技术,采用形式化方法描述和推导与构件以及构件组装相关的问题,给出了映射算法,实现了从构件组装规约向粘合代码的自动转换,为构件组装形式化分析、组装正确性检验提供了保证。     

面向服务的构件规约

目前已有构件规约大多是面向接口方法的型构和行为描述,其主要不足是缺乏针对业务逻辑的完整性描述, 而这种规约描述的脆弱性直接影响到构件复用的效率。在需求分析和获取基础上给出构件原子服务、服务的定义及 其描述方法;然后在此基础上制定面向服务的构件规约,它是对目前方法级构件规约的扩展;最后从CI31〕过程层面分 析讨论了规约的具体应用。     

软件体系结构中接口连接规则研究

基于体系结构的软件开发方法以构件作为最小组装粒度,构件通过其自身定义的接口与外界进行交互。连接件作为一种特殊的构件,它主要负责管理构件之间信息的交换。构件与连接件之间通过接口进行数据的传递,因此,如何从体系结构层次上定义构件及连接件接口的交互规则是构件组装的关键所在。在现有动态体系结构描述框架的基础上,定义了端口以及通道的连接规则,并结合实际的案例,采用动态体系结构描述语言D-ADL进行描述,具体说明了这些规则的应用。从而为系统行为的形式化分析、验证和仿真奠定了基础。     

构件组装及其形式化推导研究

基于构件的软件工程(component based software engineering,简称CBSE)能够有效地提高软件开发的质量和效率.构件组装和组装推导(compositional reasoning)是CBSE的关键技术.基于软件构件的特点,借鉴进程代数中进程构造的方法,提出6种构件组装机制,能够灵活、简便地集成软件构件,并主张在构件组装的同时进行接口组装,通过生成功能更强、抽象级别更高的复合接口,提高构件组装的抽象级别和粒度.同时,基于Wright的形式化规约软件体系结构的研究,给出了复合构件和复合接口的组装推导算法,为系统行为的形式化分析、验证和仿真奠定了基础.     

基于XML的具有性能约束构件的组装技术

采用在软总线TAO(The ACE ORB)上利用XML文档中所包含的语义化的抽象数据类型对构件对象进行操作,从而实现语义化的性能约束构件组装。建构的XML模式描述了构件组装相关的构件接口、交互及配置规约,并通过接口显式地表达构件对环境的依赖,使得能在一个分布式的网络环境里,将多个处于不同节点、提供紧密相关服务的构件在运行时动态地组装成功能系统。在给出的示例中,实现了将三个分布在不同节点的性能约束构件通过它们接口的交互及配置,实现在运行时开放的松散式组装。最后给出了下一步研究工作的重点及方向。     

面向对象范型体系结构中构件行为相容性研究

软件体系结构(SA)为基于构件的软件开发提供了一种高层次的抽象.如何有效描述体系结构中构件的对外交互行为、验证组装构件间的行为相容及保证整个体系结构行为无死锁是其中较为重要的研究内容.在基于面向对象范型这类重要的软件体系结构中,构件组装通常是通过接口方法调用加以实现.针对这样一类基于软件体系结构的构件组装问题,形式描述与定义了构件及其对外交互协议,分析了服务请求构件与服务提供构件所能展示的不同行为,给出了组装交互的构件在请求/提供接口上协议级行为相容的一组验证规则及相关定理.最后,通过一个电子商务应用实例来说明所提出途径的可用性和针对性.     

场景驱动的构件行为抽取

如果构件含有冗余的功能,特别是含有用户不想要的功能,则无法被用户正确使用.因此,如何从构件中提取场景规约中所描述的用户想要的行为便是一个亟待解决的问题.给出了解决该问题的一种方法.该方法通过为构件构造一个环境,即极大包含环境,使得场景规约中所描述的所有行为可以从构件中抽取出来,并保留到该构件与其极大包含环境的组合中.同时,构件中的其他行为,即不在场景规约中的行为,被尽可能地舍弃.用接口自动机为构件的行为建模,并将用消息序列图描述的场景规约抽象为一组活动序列.构件的组合描述为接口自动机的乘积.给出了基于场景进行构件行为抽取的相关算法,并用一个实例对文中所述方法进行了说明.     

Port-based ontology modeling to support product conceptualization

In today's rapidly changing marketplace, product demand is one of the most powerful driving forces behind design, thus rendering product conceptualization full of challenges. As a port can be defined as the point of action between a component and its environment, it plays a crucial role in capturing component concepts and realizing conceptual design. This paper presents a convenient approach to representation of the intended exchange of signals, energy, and/or materials and the generation and management of port-based knowledge (PBK). A port-based ontology modeling (PBOM) process that supports product conceptualization is described. A port definition and port functional representation are provided first with their semantic synthesis then employed to describe a port ontology. Second, details of the construction of a port-based ontology (PBO) repository that contains the assorted primitive functions, similarity calculations, and primitive concepts needed to map component connections and interactions are provided. The hierarchical attributes and taxonomy of ports are established, and the compatibility rules are then used to determine the connectability of two components. Next, the PBOM process is presented and a port-based, multi-view model is articulated, with the definition of each view and the projected relationships among the views given. Furthermore, a port-based ontology language (PBOL) that represents the process of port ontology refinement is presented, and a port-based function–behavior–structure (FBS) modeling framework is constructed for primitive system configuration. Finally, the results of a correction tape dispenser case study carried out to validate the efficiency of the port ontology for product conceptualization are presented.     

POEMS: end-to-end performance design of large parallel adaptive computational systems

The POEMS project is creating an environment for end-to-end performance modeling of complex parallel and distributed systems, spanning the domains of application software, runtime and operating system software, and hardware architecture. Toward this end, the POEMS framework supports composition of component models from these different domains into an end-to-end system model. This composition can be specified using a generalized graph model of a parallel system, together with interface specifications that carry information about component behaviors and evaluation methods. The POEMS Specification Language compiler will generate an end-to-end system model automatically from such a specification. The components of the target system may be modeled using different modeling paradigms and at various levels of detail. Therefore, evaluation of a POEMS end-to-end system model may require a variety of evaluation tools including specialized equation solvers, queuing network solvers, and discrete event simulators. A single application representation based on static and dynamic task graphs serves as a common workload representation for all these modeling approaches. Sophisticated parallelizing compiler techniques allow this representation to be generated automatically for a given parallel program. POEMS includes a library of predefined analytical and simulation component models of the different domains and a knowledge base that describes performance properties of widely used algorithms. The paper provides an overview of the POEMS methodology and illustrates several of its key components. The modeling capabilities are demonstrated by predicting the performance of alternative configurations of Sweep3D, a benchmark for evaluating wavefront application technologies and high-performance, parallel architectures.     

An efficient composition of Web services with active network support

Composition of Web services enables collaboration among autonomous business organisations such that they can integrate their services to perform collaborative business activities. It facilitates the development of new services using pre-existing Web services thus reducing development and operational costs. However, the highly distributed, dynamic, and autonomous nature of component Web services gives rise to various issues such as service matchmaking, reliability, availability, security and efficiency. This paper presents a new protocol in order to improve the efficiency of Web services composition. The proposed protocol is based on the peer-to-peer paradigm which exploits the capabilities of underlying networks such that part of the processing is carried out at the network nodes. Efficiency of the proposed protocol is tested through various experiments. Experimental results show that the proposed protocol significantly improves performance by reducing the system response time in the composition of Web services.     

An efficient composition of Web services with active network support

Composition of Web services enables collaboration among autonomous business organisations such that they can integrate their services to perform collaborative business activities. It facilitates the development of new services using pre-existing Web services thus reducing development and operational costs. However, the highly distributed, dynamic, and autonomous nature of component Web services gives rise to various issues such as service matchmaking, reliability, availability, security and efficiency. This paper presents a new protocol in order to improve the efficiency of Web services composition. The proposed protocol is based on the peer-to-peer paradigm which exploits the capabilities of underlying networks such that part of the processing is carried out at the network nodes. Efficiency of the proposed protocol is tested through various experiments. Experimental results show that the proposed protocol significantly improves performance by reducing the system response time in the composition of Web services.     

An efficient fault-tolerant multicast routing protocol withcore-based tree techniques

In this paper, we design and analyze an efficient fault-tolerant multicast routing protocol. Reliable multicast communication is critical for the success of many Internet applications. Multicast routing protocols with core-based tree techniques (CBT) have been widely used because of their scalability and simplicity. We enhance the CBT protocol with fault tolerance capability and improve its efficiency and effectiveness. With our strategy, when a faulty component is detected, some pre-defined backup path(s) is (are) used to bypass the faulty component and enable the multicast communication to continue. Our protocol only requires that routers near the faulty component be reconfigured, thus reducing the runtime overhead without compromising much of the performance. Our approach is in contrast to other approaches that often require relatively large tree reformation when faults occur. These global methods are usually costly and complicated in their attempt to achieve theoretically optimal performance. Our performance evaluation shows that our new protocol performs nearly as well as the best possible global method while utilizing much less runtime overhead and implementation cost     

MEDIA: a semantically annotated corpus of task oriented dialogs in French

The aim of the French Media project was to define a protocol for the evaluation of speech understanding modules for dialog systems. Accordingly, a corpus of 1,257 real spoken dialogs related to hotel reservation and tourist information was recorded, transcribed and semantically annotated, and a semantic attribute-value representation was defined in which each conceptual relationship was represented by the names of the attributes. Two semantic annotation levels are distinguished in this approach. At the first level, each utterance is considered separately and the annotation represents the meaning of the statement without taking into account the dialog context. The second level of annotation then corresponds to the interpretation of the meaning of the statement by taking into account the dialog context; in this way a semantic representation of the dialog context is defined. This paper discusses the data collection, the detailed definition of both annotation levels, and the annotation scheme. Then the paper comments on both evaluation campaigns which were carried out during the project and discusses some results.     

安全协议的规范化设计

提出运用组合方法进行安全协议设计。给出了协议中基件与组件的定义,根据组件的安全属性设计实现相应安全目标的单步协议;定义组合规则,确保不同的单步协议能够组合成为一个复合协议,同时各个单步协议还能实现各自的安全目标。根据具体的应用背景选择合适的单步协议,按照组合规则组合后可得到满足需求的安全协议。该组合方法可将一个复合协议分解为若干基于组件的简单单步协议,使得协议的设计与分析易于实现。     

基于LabVIEW的KWP2000协议串行通信的实现

针对汽车发动机ECU与计算机通信方法研究,为了实现KWP2000协议的串行通信,采用通过串口/K线转换器将计算机串口与K线连接,在分析研究KWP2000通信协议的基础上,通过LabVIEW图形化编程界面,按照串口通信实现的基本流程,运用LabVIEW中串口VISA组件,包括串口初始化、写入串口、读取串口和关闭串口等函数,进行了初始化程序子模块、读写程序子模块和整合母模块的设计缩短了程序开发周期,提高了编程效率,并使程序框图界面达到简洁、美观的效果,实现了基于LabVIEW的KWP2000通信系统开发。     

基于适应性构件模型的软件产品线设计和实现

在当前面向特征的软件产品线开发方法中,需求级的可变性分析、可变点表示以及面向应用的定制已经得到了较好的支持。但是,从需求级的定制和裁剪( 特征模型) 到实现级( 体系结构和构件) 的映射仍然存在许多困难。针对这一问题,文章提出了一种基于适应性构件模型的软件产品线开发方法。这种适应性构件模型引入基于特征的领域模型作为构件端口( 包括内部端口和外部端口) 的语义基础。另一方面, 适应性构件模型所具有的微体系结构使得面向特定应用的构件行为定制成为可能。为了实现构件级面向特征的定制, 构件内部负责内部和外部协作的控制中心与构件的计算逻辑被分离开来执行经定制后的构件行为协议和端口语义。构件协作和计算功能的分离使针对构件行为的面向应用的定制更加便利。这样,产品线应用开发中需求级的特征定制就可以映射为体系结构和构件级的结构和行为调整。     

Hash length: a neglected element

Hash representation has attracted increasing attentions in recent years, but hash length is still a neglected element in the evaluation of hashing. Hash length is the dimension of hash representation, which is important for the performance of video hash. In this paper, we try to define the optimal hash length according to the probability of collision (PoC) of hash. Based on this definition, we demonstrate that this optimal hash length can be predicted from a small portion of dataset, which could be a reference for practical applications. The verification experiments are performed on several classical hashing methods in the case of video copy detection on different datasets. The experimental results show that each hash method has its own optimal hash length, and the performance can be improved as the length increases.