通过TCP／IP网络访问MS—DOS应用文件

基于ＭＳ－ＤＯＳ平台运行的特殊应用程序在网络环境里如果能够为网络所共享将是十分有用的。为了让ＵＮＩＸ操作系统的机器能够访问,需要有ＴＣＰ／ＩＰ网络协议和相应的支撑软件。本文即介绍了这样一个软件包,包括ＴｅＩｎｅｔｓｅｒｖｅｒ和ＦＴＴｓｅｒｖｅｒ。Ｔｅｌｎｅｔｓｅｒｖｅｒ用来连接ＭＳ－ＤＯＳ机器,运行上面的程序;ＦＴＰｓｅｒｖｅｒ用来在两机之间传输文件。很多其他功能,象身份识别和设置文件访问权限等,Ｔｅｌｎｅｔｓｅｒｖｅｒ和ＦＴＰｓｅｒｖｅｒ支持。     

AS/400与 RS/6000互连通讯平台的设计

该文介绍了在某银行全区互连中利用ＴＣＰ／ＩＰ网间进程通讯的机制和ＲＳ／６００与ＡＳ／４００上的消息队列机制实现位置分布机型不同的主机进程间通讯及相关进程调度的通讯平台的设计思想和具体实现。该平台对应用程序透明,具有较好的可伸缩性。     

TCP／IP与NETBIOS

简述了ＴＣＰ／ＩＰ用于基于ＰＣＬＡＮ时所存在的问题，阐明了ＮＥＴＢＩＯＳ在ＰＣＬＡＮ中的作用和它作为一种ＨＦＰ（ＨｏｓｔｔｏＦｒｏｎｔｅｎｄＰｒｏｔｏｃｏｌ）与ＴＣＰ／ＩＰ的关系。最后介绍了用于ＰＣＬＡＮ的ＴＣＰ／ＩＰ产品和一个简单实例     

在TCP／IP协议网络中实现任务间的数据通讯

本文通过简单介绍ＴＣＰ／ＩＰ协议的Ｓｏｃｋｅｔ界面以及ＴＣＰ的Ｃｌｉｅｎｔ客户进程建立，ＴＣＰ的Ｓｅｒｖｅｒ服务器进程的建立，使读者初步了解ＴＣＰ／ＩＰ的网络开发界面。并通过一个具体实例及其源程序，使读者了解如何实现在ＴＣＰ／ＩＰ协议网络中任务间的数据通讯。本文最后指出，由此用户可在网络应用层上进行许多网络开发工作，如远地过程调用（ＲＰＣ）等。     

基于消息的分布式通信平台的设计与实现

本文介绍了在ＴＣＰ／ＩＰ上利用进程间通信机制——消息实现对用户透明的分布式通信平台的设计方案与思想以及具体实现。     

基于STREAMS机制的IP／X.25软件的设计与实现

ＳＴＲＥＡＭＳ机制是ＵＮＩＸ系统为开发通信服务而提供的一套通用、灵活的开发工具。，ＩＰ／Ｘ．２５软件则是ＴＣＰ／ＩＰ网络与Ｘ．２５公用数据网互连以及通过Ｘ．２５公用数据网实现ＴＣＰ／ＩＰ网络之间的互连的重要途径。文中在介绍基于ＳＴＲＥＡＭＳ机制的通信软件开发的一般思路后，着重叙述了ＩＰ／Ｘ．２５软件的功能和结构以及基于ＳＴＲＥＡＭＳ机制的设计与实现，并对基于ＳＴＲＥＡＭＳ机制的通信软件开发方法作了     

WWW文档协同写作系统中写作服务器的设计与实现

ＷＷＷＤＯＣ是一个基于ＴＣＰ／ＩＰ协议的分布式协同写作系统采用Ｃ／Ｓ结构。其中写作服务器是整个系统的关键,它响应客户机的请求,在协同控制机制下实现对目录树的操作管理和文档数据库的管理。本文介绍了写作服务器的设计与实现,包括它的数据模型和功能,详细介绍了协同机制。     

Visual Basic中的TCP程序设计

ＴＣＰ／ＩＰ是国际互连网络的标准通信协议，也是用来开发Ｃ／Ｓ应用的主要协议。如何进行基于ＴＣＰ／ＩＰ协议的软件开发，是开发Ｃ／Ｓ应用和其它网络应用的基础上。本文向读者介绍Ｖｉｓｕａｌ Ｂａｓｉｃ中的Ｗｉｎｓｏｃｋ控制和利用Ｗｉｎｓｏｃｋ控件进行ＴＣ程序设计的方法。     

异构环境下的文件传输服务系统（FTS）

本文介绍了一种异构环境下（异种网络协议、异种机）的多功能文件传输服务系统（ＦＴＳ）的设计和实现原理、系统提供的服务，以及系统的应用范围等。ＦＴＳ系统基于ＩＳＯ／ＯＳＩ的ＦＴＡＭ标准，采用了标准软件集成、队列管理技术和协议迁移技术，为用户提供了不同机型、不同操作系统、不同网络和协议（ＯＳＩ，ＳＮＡ，ＴＣＰ／ＩＰ等）之间的文件传输服务，并为用户进一步开发网络上的应用业务提供了良好的操作平台。     

容错系统中文件状态的保存与恢复算法

在机群计算环境中实现容错是人们日益关心的热点。许多著名的机群计算环境都使用检查点实现了容错的功能。但目前的检查点算法在使程序卷回执行的同时，不能相应地恢复文件系统的状态，因而对应用程序访问文件系统有较多的限制。本文在原子操作和并发控制的基础上，提出了能够恢复文件系统状态的ＳＣＲ算法，进一步发展了文件系统可恢复性的概念，ＳＣＲ算法与检查点机制结合使用，便可支持分布式应用程序在容错运行时对文件系统的任     

SFT: A consistent checkpointing algorithm with short freezing time

A consistent checkpointing algorithm with short freezing time(SFT) is presented in this paper.It supports fault-tolerance in distributed systems,The algorithm has shorter freezing time,lower overhead,and simplicity of recovery.To make checkpoint time shorter,a special control message(Munblock)is used to ensure that a process can respond the checkpoint event quickly at any given time.Moreover,main memory algorithm is used to improve the concurrency of checkpointing.By using SFT,the freezing time resulted by checkpointing is less than 0.03s.Furthermore,the control message number of SFT is only O(n).     

Application-level load migration and its implementation on top of PVM

The development and experiment of a load (process) migration scheme conceptually similar to moving house is described. The basic idea is to migrate a process by starting a new process on another processor with checkpoint data prepared by the old process itself but transferred automatically by the migration system. The new process will then unpack the data and resume the computation. The migration mechanism of our facility is implemented by a set of library calls on top of PVM. It performs functions such as freezing and unfreezing communications, checking load conditions, selecting destination processors, starting new processes and receiving migrated data. Before migrating, a process needs to freeze communication, handle pending messages in the receive buffer and pack checkpoint data. Besides the usual merits of concurrency, location transparency and the absence of residual dependency, our scheme solves the incoming message problem at the application level and is portable and easy to use in a heterogeneous environment. Our experiment shows that our facility can help to utilize 74% of idle CPU cycles of a network of workatations with less than 6% overhead on their normal operations. © 1997 by John Wiley & Sons, Ltd.     

Continuous Delivery Message Dissemination Problems under the Multicasting Communication Mode

We consider the Continuously Delivery Message Dissemination (CDMD) problem over the n processor single-port complete (all links are present and are bi-directional) static network with the multicasting communication primitive. This problem has been shown to be NP-complete even when all messages have equal length. For the CDMD problem we present an efficient approximation algorithm to construct a message routing schedule with total communication time at most 3.5d, where d is the total length of the messages that each processor needs to send or receive. The algorithm takes O(qn) time, where n is the number of processors and q is the total number of messages that the processors receive.     

基于改进Inver-over算子的并行TSP演化算法

设计了基于近邻点初始化和改进Inver-over(反序杂交)算子求解旅行商问题的并行演化算法.该算法执行时,主进程每当收集到各个种群的最好个体并形成精英种群时,就对该种群执行一次Inver-over算子,然后将其中最好的个体发送给各个种群.在PVM(并行虚拟机)并行环境下的实验结果表明,并行后能取得更好的解,并且在主进程中建立精英种群的演化有助于更好更快的收敛.     

An optimistic checkpointing and message logging approach for consistent global checkpoint collection in distributed systems

Checkpointing and rollback recovery are widely used techniques for achieving fault-tolerance in distributed systems. In this paper, we present a novel checkpointing algorithm which has the following desirable features: A process can independently initiate consistent global checkpointing by saving its current state, called a tentative checkpoint. Other processes come to know about a consistent global checkpoint initiation through information piggy-backed with the application messages or limited control messages if necessary. When a process comes to know about a new consistent global checkpoint initiation, it takes a tentative checkpoint after processing the message (not before processing the message as in existing communication-induced checkpointing algorithms). After a process takes a tentative checkpoint, it starts logging the messages sent and received in memory. When a process comes to know that every other process has taken a tentative checkpoint corresponding to current consistent global checkpoint initiation, it flushes the tentative checkpoint and the message log to the stable storage. The tentative checkpoints together with the message logs stored in the stable storage form a consistent global checkpoint. Two or more processes can concurrently initiate consistent global checkpointing by taking a new tentative checkpoint; in that case, the tentative checkpoints taken by all these processes will be part of the same consistent global checkpoint. The sequence numbers assigned to checkpoints by a process increase monotonically. Checkpoints with the same sequence number form a consistent global checkpoint. We also present the performance evaluation of our algorithm.     

Parallel Algorithms for Dynamic Shortest Path Problems

The development of intelligent transportation systems (ITS) and the resulting need for the solution of a variety of dynamic traffic network models and management problems require faster‐than‐real‐time computation of shortest path problems in dynamic networks. Recently, a sequential algorithm was developed to compute shortest paths in discrete time dynamic networks from all nodes and all departure times to one destination node. The algorithm is known as algorithm DOT and has an optimal worst‐case running‐time complexity. This implies that no algorithm with a better worst‐case computational complexity can be discovered. Consequently, in order to derive algorithms to solve all‐to‐one shortest path problems in dynamic networks, one would need to explore avenues other than the design of sequential solution algorithms only. The use of commercially‐available high‐performance computing platforms to develop parallel implementations of sequential algorithms is an example of such avenue. This paper reports on the design, implementation, and computational testing of parallel dynamic shortest path algorithms. We develop two shared‐memory and two message‐passing dynamic shortest path algorithm implementations, which are derived from algorithm DOT using the following parallelization strategies: decomposition by destination and decomposition by transportation network topology. The algorithms are coded using two types of parallel computing environments: a message‐passing environment based on the parallel virtual machine (PVM) library and a multi‐threading environment based on the SUN Microsystems Multi‐Threads (MT) library. We also develop a time‐based parallel version of algorithm DOT for the case of minimum time paths in FIFO networks, and a theoretical parallelization of algorithm DOT on an ‘ideal’ theoretical parallel machine. Performances of the implementations are analyzed and evaluated using large transportation networks, and two types of parallel computing platforms: a distributed network of Unix workstations and a SUN shared‐memory machine containing eight processors. Satisfactory speed‐ups in the running time of sequential algorithms are achieved, in particular for shared‐memory machines. Numerical results indicate that shared‐memory computers constitute the most appropriate type of parallel computing platforms for the computation of dynamic shortest paths for real‐time ITS applications.     

Efficient communication using message prediction for clusters of multiprocessors

With the increasing uniprocessor and symmetric multiprocessor computational power available today, interprocessor communication has become an important factor that limits the performance of clusters of workstations/multiprocessors. Many factors including communication hardware overhead, communication software overhead, and the user environment overhead (multithreading, multiuser) affect the performance of the communication subsystems in such systems. A significant portion of the software communication overhead belongs to a number of message copying operations. Ideally, it is desirable to have a true zero‐copy protocol where the message is moved directly from the send buffer in its user space to the receive buffer in the destination without any intermediate buffering. However, due to the fact that message‐passing applications at the send side do not know the final receive buffer addresses, early arrival messages have to be buffered at a temporary area. In this paper, we show that there is a message reception communication locality in message‐passing applications. We have utilized this communication locality and devised different message predictors at the receiver sides of communications. In essence, these message predictors can be efficiently used to drain the network and cache the incoming messages even if the corresponding receive calls have not yet been posted. The performance of these predictors, in terms of hit ratio, on some parallel applications are quite promising and suggest that prediction has the potential to eliminate most of the remaining message copies. We also show that the proposed predictors do not have sensitivity to the starting message reception call, and that they perform better than (or at least equal to) our previously proposed predictors. Copyright © 2002 John Wiley & Sons, Ltd.     

Concurrent checkpoint initiation and recovery algorithms on asynchronous ring networks

Checkpointing with rollback recovery is a well-known method for achieving fault-tolerance in distributed systems. In this work, we introduce algorithms for checkpointing and rollback recovery on asynchronous unidirectional and bi-directional ring networks. The proposed checkpointing algorithms can handle multiple concurrent initiations by different processes. While taking checkpoints, processes do not have to take into consideration any application message dependency. The synchronization is achieved by passing control messages among the processes. Application messages are acknowledged. Each process maintains a list of unacknowledged messages. Here we use a logical checkpoint, which is a standard checkpoint (i.e., snapshot of the process) plus a list of messages that have been sent by this process but are unacknowledged at the time of taking the checkpoint. The worst case message complexity of the proposed checkpointing algorithm is O(kn) when k initiators initiate concurrently. The time complexity is O(n). For the recovery algorithm, time and message complexities are both O(n).     

基于PVM的准同步检查点设置方法

检查点是并行系统中实现容错的重要手段，同步检查点方法已广泛应用在工作站机群系统中。PVM所提供的消息传递机制支持高效的异构网络计算，但不支持客错功能。为了降低同步检查点设置的时间开销，提出了一种基于PVM的准同步检查点设置方法，它吸取了同步检查点方法的优点，又通过消息记录方式实现各节点间独立进行状态保存，大大降低了检查点的同步开销，提高了检查点操作效率，该方法在PVM环境下得以实现，实验结果表明所提出的方法具有较好的客错性能。     

一种低费用的协调检查点算法

检查点算法作为一种有效的故障技术及容错手段,已广泛地运用在网格、分布式和云计算系统中。该文提出了一种非阻塞协调检查点算法,该算法增加了系统的可靠性,并允许检查点灵活设置,充分缩减了同步信息数量,加速了检查点形成时间。和典型的相关算法比较,该文提出的算法使用更少的同步控制消息,具有更低的费用,引入同步控制消息的时间复杂度由一般的O（n2）降到O（n）,且同步消息数仅仅为n-1。