The Key Implementation Technology of Client／Server‘s Asyncgrnous Communication Programs

is paper introduces the implementation method,ke technology and flowchart of Client/Server‘s asynchronous communication programs on Linux or Unix,and further explains a few problems to which should pay attention for improving CPU‘s efficiency in implementing asynchronous communication programs.     

Modeling and analyzing mixed communications in service-oriented trustworthy software

Communication is an essential part of service-oriented trustworthy software.The actual communication mechanism among services adopts asynchronous communications and supports broadcast communications.However,in order to achieve a better performance in analysis and verification,most existing formal languages rely on the strong hypothesis:the communication between services is synchronous.In this paper,we propose a novel model,which can model synchronous communications,asynchronous communications and broadcast communications in a uniform way.Moreover,we investigate the preservation problem of the weak termination and deadlocks of a composite service under the hierarchical communication models.     

DGLa: A Distributed Graphics Language

A distributed graphics programming language called DGLa is presented,which facilitates the development of distributed graphics application.Facilities for distributed programming and graphics support are included in it,It not only supports synchronous and asynchronous communication but also provides programmer with multiple control mechanism for process communication.The graphics support of DGLa is powerful,for both sequential graphics library and parallel graphics library are provided.The design consideration and implementation experience are discussed in detail in this paper.Application examples are also given.     

生物网络通信语言的设计和实现

In our bio-network computation model ,it urgently needs a kind of network communication language to solve the communication and cooperation problems among bio-entities. Then the bio-entities can interact each other to implement emergent service and computation better. In this paper,we design a kind of bio-network communication language (BNCL)by combining the advantages of the Agent Communication Language (ACL)and XML. BNCL is simple, flexible and can implement the complicated coordination strategies in the bio-network. We examine the feasibility of BNCL by an application instance of the merchandise sales service with discount. BNCL also offers a new solution to interaction and cooperation problems of application programs in multi-agent systems and distributed systems.     

Parallel computing for lattice Monte Carlo simulation of large-scale thin film growth

This paper proposes two viable computing strategies for distributed parallel systems: domain division with sub-domain overlapping and asynchronous communication. We have implemented a parallel computing procedure for simulation of Ti thin film growing process of a system with 1000 x 1000 atoms by means of the Monte Carlo (MC) method. This approach greatly reduces the computation time for simulation of large-scale thin film growth under realistic deposition rates. The multi-lattice MC model of deposition comprises two basic events: deposition, and surface diffusion. Since diffusion constitutes more than 90% of the total simulation time of the whole deposition process at high temperature, we concentrated on implementing a new parallel diffusion simulation that reduces communication time during simulation. Asynchronous communication and domain overlapping techniques are used to reduce the waiting time and communication time among parallel processors. The parallel algorithms we propose can simulate the thin     

Synthesis of Communicating Process Skeletons from Temporal-Spatial Logic Specifications

Temporal-spatial logic is a propositional logic with temporal and spatial modalities asserting on a network.In this paper,a tableau-like decision procedure for network satisfiability in the logic is presented and used in the synthesis of communicating skeletons of CSP-like programs.By explicitly introducing communication network in the logic system,our approach has some advantages over the temporal one.     

Timing-sequence testing of parallel programs

Testing of parallel programs involves two parts-testing of control flow within the processes and testing of timing-sequence.This paper focuses on the latter,particularly on the timing-sequence of message-passing paradigms.Firstly the coarse-grained SYN-sequence model is built up to describe the execution of distributed programs.All of the topics discussed in this paper are based on it .The most direct way to test a program is to run it.A fault-free parallel program should be of both correct computing results and propoer SYN-sequence.In order to analyze the validity of observed SYN-sequence,this paper presents the formal specification (Backus Normal Form) of the valid SYN-sequence.Till now there is little work about the testing coverage for distributed programs.Calculating the number of the valid SYN-sequences is the key to coverage problem,while the number of the valid SYN-sequences is terribly large and it is very hard to obtain the combination law among SYN-events.In order to resolve this problem,this paper proposes an efficient testing strategy-atomic SYN-event testing,which is to linearize the SYN-sequence (making it only consist of serial atomic SYN-events)first and then test each atomic SYN-event independently.This paper particularly provides the calculating formula about the number of the valid SYN-sequences for tree-topology atomic SYN-event(broadcast and combine),Furthermore,the number of valid SYN-sequences also,to some degree,mirrors the testability of parallel programs.Taking tree-topology atomic SYN-event as an example,this paper demonstrates the testability and communication speed of the tree-topology atomic SYN-event under different numbers of branches in order to achieve a more satisfactory tradeoff between testability and communication efficiency.     

Shared Variable Oriented Parallel Precompiler for SPMD Model

For the moment,commercial parallel computer systems with distributed memory architecture are usually provided with parallel FORTRAN or parallel C compliers,which are just traditional sequential FORTRAN or C compilers expanded with communication statements.Programmers suffer from writing parallel programs with communication statements. The Shared Variable Oriented Parallel Precompiler (SVOPP) proposed in this paper can automatically generate appropriate communication statements based on shared variables for SPMD(Single Program Multiple Data) computation model and greatly ease the parallel programming with high communication efficiency.The core function of parallel C precompiler has been successfully verified on a transputer-based parallel computer.Its prominent performance shows that SVOPP is probably a break-through in parallel programming technique.     

Hierarchical bulk synchronous parallel model and performance optimization

Based on the framework of BSP,a Hierarchical Bulk Synchronous Parallel(HBSP)performance model is introduced in this paper to capture the performance optimization problem for various stages in parallel program development and to accurately predict the performance of a parallel program by considering factors causing variance at local computation and global communication.The related methodology has been applied to several real applications and the results show that HBSP is a suitable model for optimizing parallel programs.     

An analytical model for source code distributability verification简

ne way to speed up the execution of sequential programs is to divide them into concurrent segments and execute such segments in a parallel manner over a distributed computing environment. We argue that the execution speedup primarily depends on the concurrency degree between the identified segments as well as communication overhead between the segments. To guar-antee the best speedup, we have to obtain the maximum possible concurrency degree between the identified segments, taking communication overhead into consideration. Existing code distributor and multi-threading approaches do not fulfill such re-quirements;hence, they cannot provide expected distributability gains in advance. To overcome such limitations, we propose a novel approach for verifying the distributability of sequential object-oriented programs. The proposed approach enables users to see the maximum speedup gains before the actual distributability implementations, as it computes an objective function which is used to measure different distribution values from the same program, taking into consideration both remote and sequential calls. Experimental results showed that the proposed approach successfully determines the distributability of different real-life software applications compared with their real-life sequential and distributed implementations.     

一种高可靠性的PC机与单片机间的串行通讯方法

介绍了一种高可靠性的ＰＣ机与８０Ｃ１９６ＫＣ单片机之间异步串行通讯的方法,即握手通讯约定法。详细讨论了实现这一通讯方法的软件设计、硬件接口电路。并给出了实例。     

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.     

基于UART8250的PC机与MCU多机串行通信的研究

简要介绍了一种异步通讯收发器INS8250的内部结构及其与MCU实现多机通讯功能的方法,并给出了多机通讯的实用程序。     

基于UART8250的PC机与MCU多机串行通信的研究

简要介绍了一种异步通讯收发器INS8250的内部结构及其与MCU实现多机通讯功能的方法,并给出了多机通讯的实用程序。     

UC: A Set-Based Language for Data-Parallel Programming

UC is a data-parallel extension of C designed for scientific computations on synchronous and asynchronous parallel architectures. The primary constructs of the language include sets, reductions, and parallel and asynchronous composition. Its communication model is that of a globally addressable memory, with no syntactic distinction between local and remote data references, Unlike most existing data-parallel languages, UC programs may be synchronized at multiple levels of granularity, from a strict expression-level synchronization to a coarser statement or function-level synchronization. This paper describes the language and its implementation on the Connection Machine CM-2. Experimental measurements that compare the performance of the UC compiler with that of programs written in commercial parallel languages such as CM Fortran, C*, and *Lisp are also presented.     

基于非交互式Petri网的异步程序验证模型和方法

异步程序使用异步非阻塞调用方式来实现程序的并发, 被广泛应用于并行与分布式系统中. 验证异步程序复杂性很高, 无论是安全性还是活性均达到EXPSPACE难. 提出一个异步程序的程序模型系统, 并在其上定义两个异步程序上的问题: $ \epsilon $等价性问题和$ \epsilon $可达性问题. 通过将3-CNF-SAT规约到这两个问题, 再将其规约至非交互式Petri网的可达性证明两个问题是NP完备的. 案例表明, 这两个问题可以解决异步程序上一系列的程序验证问题.     

A dynamic analysis of the interplay between asynchronous and synchronous communication in online learning: The impact of motivation

With the increased affordances of synchronous communication tools, more opportunities for online learning to resemble face‐to‐face settings have recently become available. However, synchronous communication does not afford as much time for reflection as asynchronous communication. Therefore, a combination of synchronous and asynchronous communication in e‐learning would seem desirable to optimally support learner engagement and the quality of student learning. It is still an open question though, how to best design online learning with a blend of synchronous and asynchronous communication opportunities over time. Few studies have investigated the relationship between learners' actual use of synchronous and asynchronous communication over time. Therefore, this study addressed that relationship in an online course (N = 110), taking into account student motivation, and employing a dynamic inter‐temporal perspective. In line with our assumptions, we found some support for the expected association between autonomous motivation and engagement in asynchronous and synchronous communication, be it restricted primarily to the first course period. Also, positive relations between engagement in synchronous and asynchronous communication were found, with the strongest influence from using asynchronous to synchronous communication. This study adds to the knowledge base needed to develop guidelines on how synchronous communication can be combined with asynchronous learning.     

An Asynchronous Protocol for Release Consistent Distributed Shared Memory Systems

Distributed shared memory (DSM) systems provide a simple programming paradigm for networks of workstations, which are gaining popularity due to their cost-effective high computing power. However, DSM systems usually exhibit poor performance due to the large communication delay between the nodes; and a lot of different memory consistency models have been proposed to mask the network delay. In this paper, we propose an asynchronous protocol for the release consistent memory model, which we call an Asynchronous Release Consistency (ARC) protocol. Unlike other protocols where the communication adheres to the synchronous request/receive paradigm, the ARC protocol is asynchronous, such that the necessary pages are broadcast before they are requested. Hence, the network delay can be reduced by proper prefetching of necessary pages. We have also compared the performance of the ARC protocol with the lazy release protocol by running standard benchmark programs; and the experimental results showed that the ARC protocol achieves a performance improvement of up to 29%.     

A distributed simplex algorithm for degenerate linear programs and multi-agent assignments

In this paper we propose a novel distributed algorithm to solve degenerate linear programs on asynchronous peer-to-peer networks with distributed information structures. We propose a distributed version of the well-known simplex algorithm for general degenerate linear programs. A network of agents, running our algorithm, will agree on a common optimal solution, even if the optimal solution is not unique, or will determine infeasibility or unboundedness of the problem. We establish how the multi-agent assignment problem can be efficiently solved by means of our distributed simplex algorithm. We provide simulations supporting the conjecture that the completion time scales linearly with the diameter of the communication graph.     

Bounded phase analysis of message-passing programs

We describe a novel technique for bounded analysis of asynchronous message-passing programs with ordered message queues. Our bounding parameter does not limit the number of pending messages, nor the number of “context-switches” between processes. Instead, we limit the number of process communication cycles, in which an unbounded number of messages are sent to an unbounded number of processes across an unbounded number of contexts. We show that remarkably, despite the potential for such vast exploration, our bounding scheme gives rise to a simple and efficient program analysis by reduction to sequential programs. As our reduction avoids explicitly representing message queues, our analysis scales irrespectively of queue content and variation.