基于消息驱动Bean的异步通信模型设计

异步通信是一种松耦合的分布式通信模式,允许应用程序以发送方和接受方相互独立的形式,通过交换消息进行通信.消息驱动Bean作为处理异步消息的EJB组件,因其支持异步非阻塞的消息传递机制,在基于EJB的应用系统中日渐得到应用.提出了一种基于消息驱动Bean的异步通信模型.该模型使用MDB实现消息的异步消费,解决了EJB远程方法调用开销大等问题,降低了应用程序和EJB组件之间的依赖性,从而有效地提高了异步通信的性能和可靠性.     

Spring boot集成 RabbitMQ

RabbitMQ是一个在AMQP基础上完整的,可复用的企业消息系统.MQ全称为Message Queue,消息队列(MQ)是一种应用程序对应用程序的通信方法.应用程序通过读写出入队列的消息(针对应用程序的数据)来通信,而无需专用连接来链接它们.消息传递指的是程序之间通过在消息中发送数据进行通信,而不是通过直接调用彼此来通信,直接调用通常是用于诸如远程过程调用的技术.排队指的是应用程序通过队列来通信.队列的使用除去了接收和发送应用程序同时执行的要求.AMQP就是一个协议,是一个高级抽象层消息通信协议.虽然在同步消息通讯的世界里有很多公开标准(如COBAR的IIOP,或者是SOAP等),但是在异步消息处理中却不是这样,只有大企业有一些商业实现(如微软的MSMQ,IBM的Websphere MQ等),因此,在2006年的6月,Cisco、Redhat、iMatix等联合制定了AMQP的公开标准.也就是说AMQP是异步通讯的一个协议.     

消息传递型MPSoC通信过程分析及其优化设计

通过分析消息传递型MPSoC通信过程,总结出提高通信性能的有效途径——降低一对多消息发送延迟和提高多条消息并发接收效率.从减少数据拷贝延迟的角度提出了基于硬件抽象层广播优化策略,有效地降低了一对多消息发送延迟;针对并发接收瓶颈,充分考虑减少交互次数和提高长消息通信效率,提出一种基于查找表和DMA模式相结合的接收策略.实验结果表明,广播优化策略及接收策略均能明显提高性能;在64×64的矩阵乘法中,采用优化策略整体性能提高接近1.5倍.     

一种新的移动Agent间通信算法

在分析已有广播通信机制的基础上,提出了一种新的移动Agent间通信算法。通过可靠扩散来实现广播,保证接收者至少接收一次消息;通过接收者主动请求消息,保证接收者只能接收一次消息。新算法保证可靠地完成消息发送以及消息传递的exactly—once语义,并在效率上有了进一步的提高。除了基本的算法,还讨论了一些改进的算法以及实现中遇到的一些问题。     

基于消息传递的构件组装模型

利用构件组装分布式系统是软件开发的流行趋势,但由于构件之间规范不一致,相互联系和相互依赖,降低了构件的复用程度,限制了生成目标系统的灵活性.消息传递是应用程序和软件构件之间进行通信的一种方式,基于消息传递的构件组装模型采用了XML技术,通过连接子和消息总线进行消息传递,实现构件之间的交互,使构件在组装时对外呈现出一致的视图.     

基于J2EE技术的企业异步通信解决方案

解释了为什么异步通信对于企业的体系结构来说是至关重要的。借助J2EE平台跨平台、中间件技术、多层结构等技术性能优点，采用了基于J2EE技术的Java消息服务（JMS）和消息驱动bean（MDB）的解决方案，用来实现应用程序各个部件之间的异步消息传递，从而达到在分布式企业级应用系统中，异步通信机制有效地协调各个部分子系统的工作的目的。     

DELPHI环境下WIN32钩子程序编制详解

WIND0WS操作系统是基于消息处理的系统,系统内部及系统与应用程序之间都是通过消息传递信息的,钩子就是监视系统中消息来往的程序,它能够在消息到达目的地之前截获消息并根据用户要求做出相应处理。WIN—DOWS提供了10种钩子,见表一。     

Android应用中消息传递方法分析

一个Android应用中存在各种消息,这些消息在不同组件中生成,在Activity界面之间,Fragment之间以及多个线程间传递。程序员需要深入了解Android应用中消息产生的原理,并熟练掌握消息传递的不同方法,才能合理控制程序运行的方向,创作正确的Android手机端软件。     

并发程序设计概念和记法(续)

4 基于消息传递的同步原语临界区、管程和路径表达式都是信号量的发展,都是提供控制共享变量访问的结构化方法。另一种不同的发展是消息传递(message passing),它可以看成是把信号量扩充为不仅能进行数据传送而且能实现同步。当使用消息传递进行通信和同步时,进程用发送和接收消息代替对共享变量的读和写。因为进程一收到消息就从发送进程获得了值,因此也达到了通信的目的。因为一个消息只有在被发送后才能被接收,从而控制了这两个事件发生的顺序,也达到了同步的目的。     

Android应用中消息传递方法分析

一个Android应用中存在各种消息,这些消息在不同组件中生成,在Activity界面之间,Fragment之间以及多个线程间传递。程序员需要深入了解Android应用中消息产生的原理,并熟练掌握消息传递的不同方法,才能合理控制程序运行的方向,创作正确的Android手机端软件。     

OilCL:一个面向油藏数值模拟并行计算的通信库

ＯｉｌＣＬ是一个用于油藏数值模拟计算的可移植的通信库,虽然目前存在很多的通信库,如ＭＰＩ,ＰＶＭ等,但由于它们的通用性,而且其界面较低级而不适合油藏模拟数值计算,ＯｉｌＣＬ为油藏数值模拟计算程序员提供一个方便、自然的界面,它支持动态地建立和释放通信上下文／逻辑进程网格;支持基于源的消息选择;逻辑拓扑作为群通信子程序的参数并提供开发和运行模式,这些机制便于油藏数值模拟计算程序的设计,使程序可读性更强     

An Adaptive Causal Ordering Algorithm Suited to Mobile Computing Environments

Causal message ordering is required for several distributed applications. In order to preserve causal ordering, only direct dependency information between messages, with respect to the destination process(es), need be sent with each message. By eliminating other kinds of control information from the messages, the communication overheads can be significantly reduced. In this paper we present an algorithm that uses this knowledge to efficiently enforce causal ordering of messages. The proposed algorithm does not require any prior knowledge of the network topology or communication pattern. As computation proceeds, it acquires knowledge of the communication pattern and is capable of handling dynamically changing multicast communication groups, and minimizing the communication overheads. With regard to communication overheads, the algorithm is optimal for the broadcast communication case. Extensive simulation experiments demonstrate that the algorithm imposes lower communication overheads than previous causal ordering algorithms. The algorithm can be employed in a variety of distributed computing environments. Its energy efficiency and low bandwidth requirement make it especially suitable for mobile computing systems. We show how to employ the algorithm for causally ordered multicasting of messages in mobile computing environments.     

Optimal NODUP all-to-all broadcast schemes in distributed computingsystems

Broadcast, referring to a process of information dissemination in a distributed system whereby a message originating from a certain node is sent to all other nodes in the system, is a very important issue in distributed computing. All-to-all broadcast means the process by which every node broadcasts its certain piece of information to all other nodes. In this paper, we first develop the optimal all-to-all broadcast scheme for the case of one-port communication, which means that each node can only send out one message in one communication step, and then, extend our results to the case of multi-port communication, i.e., k-port communication, meaning that each node can send out k messages in one communication step. We prove that the proposed schemes are optimal for the model considered in the sense that they not only require the minimal number of communication steps, but also incur the minimal number of messages     

基于MPI的Jacobi迭代算法的并行化

Jacobi迭代算法是解线性方程组的最常用的方法,具有广泛的应用。Jacobi迭代属于计算密集型[1],将并行计算技术应用到Jacobi迭代中,具有重要的意义。通过使用消息传递编程模型mpi提供的向量数据类型和虚拟进程拓扑来实现Jacobi迭代的并行化。     

Portable and Scalable Algorithm for Irregular All-to-All Communication

In irregular all-to-all communication, messages are exchanged between every pair of processors. The message sizes vary from processor to processor and are known only at run time. This is a fundamental communication primitive in parallelizing irregularly structured scientific computations. Our algorithm reduces the total number of message start-ups. It also reduces node contention by smoothing out the lengths of the messages communicated. As compared to the earlier approaches, our algorithm provides deterministic performance and also reduces the buffer space at the nodes during message passing. The performance of the algorithm is characterised using a simple communication model of high-performance computing (HPC) platforms. We show the implementation on T3D and SP2 using C and the message passing interface standard. These can be easily ported to other HPC platforms. The results show the effectiveness of the proposed technique as well as the interplay among the machine size, the variance in message length, and the network interface.     

Object, message, and performance: how they coexist in Self

The Self programming language, which distills object-oriented computation down to a simple story based on copying prototypes to create objects, inheriting from objects to share their contents, and passing messages to invoke methods, is discussed. It is shown that Self's uniform application of the object-message paradigm gives programmers unusual flexibility. Unconventional optimizations can bring its peak performance to within a factor of two of optimized C's performance. Overviews of Self and its message passing performance are presented     

一种带有路由反射的BGP路由预测算法

由于路由反射器的影响,路由器可能只知道非常有限的到达外部目的地的路由的子集,BGP路径选择过程并不会形成一个确定的路径等级顺序,使得路径预测变得非常困难.给出了一种算法,该算法不需要对路由协议动态进行复杂的模拟,只需要静态的路由数据就可以计算出带有路由反射的路由选择结果,并在一个模拟的大型ISP上验证了预测算法的正确性.结果显示配置的改变可以引起路由表的变化.     

位置透明的MA可靠消息传递机制

移动Agent系统中的通信机制多由RMI加上消息发送机制实现，在现有的三种主流消息发送机制上进行改进，提出了新的消息转发策略——资源分散模型(Resource Distributed Model)。RDM提供了一种类似于结合了Homeagent和按路径转发方式的寻址策略，达到消息可达的目的，基于RDM的移动服务(Mobile Service)是一种在快速寻址后将消息快速转发的方式，MS减少了消息缓存部件的消息缓存量，并可用多个MS同时寻址从而提高消息发送速度。     

Tuning collective communication for Partitioned Global Address Space programming models

Partitioned Global Address Space (PGAS) languages offer programmers the convenience of a shared memory programming style combined with locality control necessary to run on large-scale distributed memory systems. Even within a PGAS language programmers often need to perform global communication operations such as broadcasts or reductions, which are best performed as collective operations in which a group of threads work together to perform the operation. In this paper we consider the problem of implementing collective communication within PGAS languages and explore some of the design trade-offs in both the interface and implementation. In particular, PGAS collectives have semantic issues that are different than in send-receive style message passing programs, and different implementation approaches that take advantage of the one-sided communication style in these languages. We present an implementation framework for PGAS collectives as part of the GASNet communication layer, which supports shared memory, distributed memory and hybrids. The framework supports a broad set of algorithms for each collective, over which the implementation may be automatically tuned. Finally, we demonstrate the benefit of optimized GASNet collectives using application benchmarks written in UPC, and demonstrate that the GASNet collectives can deliver scalable performance on a variety of state-of-the-art parallel machines including a Cray XT4, an IBM BlueGene/P, and a Sun Constellation system with InfiniBand interconnect.     

带回馈机制网格资源发现算法在多域环境中的改进

网格资源发现算法是网格资源发现机制的核心,带回馈机制的网格资源发现算法充分利用响应报文与请求报文可能经不同路径返回的特点,在正向搜索失败时,启动反向搜索机制,在一个往返时间里进行二次搜索.但是算法在讨论时将整个网格的拓扑结构看成是一个全分布的系统,所有节点位置平等,而现实中的网格大部分是由多个不同的自治系统联结而成,具有一定的区域性.本文对带回馈机制的网格资源发现算法在多域环境中进行了改进,将资源发现过程分为域内发现和域间发现两部分,分别采用不同的资源发现机制,性能分析和模拟实验表明该算法具有良好的可扩展性和较高的性能,更适合真实的网格环境.