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Nathan Marz gives an overview of Storm, a distributed computation system written in Clojure, then goes into detail on how it computes reach for Twitter URLs using distributed RPC. Source: https://vimeo.com/34001477 Uploader: Basho Technologies

Nathan Marz gives an overview of Storm, a distributed computation system written in Clojure, then goes into detail on how it computes reach for Twitter URLs using distributed RPC. Source: https://vimeo.com/34001477 Uploader: Basho Technologies

xviii,292p. ; 23 cm

The Beauty and Joy of Computing

The paper proposes a surprisingly simple characterization of a large class of models of distributed computing, via an agreement function: for each set of processes, the function determines the best level of set consensus these processes can reach. We show that the task computability of a large class of fair adversaries that includes, in particular superset-closed and symmetric one, is precisely captured by agreement functions.

The paper proposes a surprisingly simple characterization of a large class of models of distributed computing, via an agreement function: for each set of processes, the function determines the best level of set consensus these processes can reach. We show that the task computability of a large class of fair adversaries that includes, in particular superset-closed and symmetric one, is precisely captured by agreement functions.

The paper proposes a surprisingly simple characterization of a large class of models of distributed computing, via an agreement function: for each set of processes, the function determines the best level of set consensus these processes can reach. We show that the task computability of a large class of fair adversaries that includes, in particular superset-closed and symmetric one, is precisely captured by agreement functions.

This paper describes the Naval Ocean Systems Center (NOSC), Code 911 Digital Dynamics Processor (DDP). The DDP is a multiprocessor system designed for high speed numerical calculation. This system implements a new variation of common memory in order to allow a far greater number of processors than found currently on a TCDS. The conceptual design of the DDP was done in mid and late 1984 by Jack Zyphur. A variation of this design was implemented in hardware by Mitchell (1989) in early 1985. The first prototype was only two processor slaves, a repeater slave, and a master. Since the original goal of the DDP was to replace an EAI 8800 Analog computer, the first attempt at software for the DDP was a simulation language consisting of assembly language modules that would do the favor of direct equation implementation using a 'C' cross-compiler that run on the master. In early 1987 Murphy programmed in a quaternion algorithm and the DDP proved operational in the NOSC Hybrid-Simulator. The DDP has since been up graded to six processor slaves running MC68030 CPUs at 25 MHz.

Pseudo-bending is an algorithm for calculating seismic travel time through complex 3D velocity models. The algorithm was originally proposed by Um and Thurber (1987) and later extended by Zhao et al. (1992) to account for first order velocity discontinuities. We have modified Zhao's method of handling discontinuities by implementing a two-dimensional (2D) minimization algorithm that searches for the point on the velocity discontinuity surface where Snell's Law is satisfied. Further, our implementation reduces the likelihood that the pseudo-bending algorithm will return a local minimum by starting the ray calculation from several different starting rays. Specifically, interfaces are defined that include first order discontinuities plus additional interfaces at levels of the model where local minima might be generated. Rays are computed that are constrained to bottom in each layer between these interfaces. The computed rays might be reflected off the top of the layer, turn within the layer, or diffract along the interface at the bottom of the layer. The computed ray that is seismologically valid and that has the shortest travel time is retained. The modifications we have made to the algorithm have made it more accurate and robust but have also made it more computationally expensive. To mitigate this impact, we have implemented our software in a distributed parallel computing environment, which makes possible the calculation of many rays simultaneously.

This report presents the formulation and testing of a Feasible Sequential Quadratic Programming (FSQP-DIS) optimization algorithm customized to a Distributed Numerical Computing environment (DNC). DNC utilizes networking technology and an ensemble of loosely coupled processors to compute structural analyses concurrently. Each iterate of the FSQP-DIS is partitioned for concurrent computations in the direction calculation, and the steplength calculation. The prototype environment is tested on three applications a mathematical programming problem, the design of a two-story planar steel frame, and finally, the optimal design of a two-story three-dimensional steel frame.

The Distributed Computing and Collaboration Framework has been developed by the Space and Naval Warfare Systems Center, San Diego (a Naval research and development facility), under the sponsorship of the Office of Naval Research. The focus of the effort is to provide superior performance in low bandwidth-high latency network conditions, a hallmark of Naval operational environments. The software development includes a variety of mechanisms to manage and reduce latencies, with emphasis on ensuring effective, real-time collaboration at the operational user level and efficient use of limited bandwidth channels at the network level. This paper will describe an initial software development package of the peer-to-peer architecture design requirements, exploiting a transport layer (TCP/IP) protocol. This package will support information distribution and search across multiple enclaves using peer-to-peer data models, as well as models of redundancy for robustness across networks composed of a mix of wired and wireless channels. The software was tested in a ship-to-shore, ship-to-ship, and ship-to-submarine paradigm to verify that the initial design met documented Navy bandwidth standards. Results of the analysis showed this initial software to be within standards constraints. The authors provide a detailed presentation of their Collaboration Evaluation Laboratory (and methodology) that they have used to manage their development and transition efforts.

The Beauty and Joy of Computing Professor Dan Garcia Link to lecture notes: http://inst.eecs.berkeley.edu/~cs10/fa11/lec/19/

We examine how to program a system so that the software continues to work in the face of a variety of failures of parts of the system. The design presented uses the concept of transactions: collections of primitive actions that are indivisible. The indivisibility of transactions insures that consistent results are obtained even when requests are processed concurrently or failures occur during a request. Our design permits transactions to be nested. Nested transactions provide nested universes of synchronization and recovery from failures. The advantages of nested transactions over single-level transactions are that they provide concurrency control within transactions by serializing subtransactions appropriately, and that they permit parts of a transaction to fail without necessarily aborting the entire transaction. The method for implementing nested transactions described in this report is novel in that it uses locking for concurrency control. We present the necessary algorithms for locking, recovery, distributed commitment, and distributed deadlock detection for a nested transaction system. While the design has not been implemented, it has been simulated. The algorithms are described in a formal notation in an appendix, as well as narratively in the body of the report.

We examine how to program a system so that the software continues to work in the face of a variety of failures of parts of the system. The design presented uses the concept of transactions: collections of primitive actions that are indivisible. The indivisibility of transactions insures that consistent results are obtained even when requests are processed concurrently or failures occur during a request. Our design permits transactions to be nested. Nested transactions provide nested universes of synchronization and recovery from failures. The advantages of nested transactions over single-level transactions are that they provide concurrency control within transactions by serializing subtransactions appropriately, and that they permit parts of a transaction to fail without necessarily aborting the entire transaction. The method for implementing nested transactions described in this report is novel in that it uses locking for concurrency control. We present the necessary algorithms for locking, recovery, distributed commitment, and distributed deadlock detection for a nested transaction system. While the design has not been implemented, it has been simulated. The algorithms are described in a formal notation in an appendix, as well as narratively in the body of the report.

This report summarizes the activities under the Distributed Computing Design System program. The DCDS program was responsible for the support of the DCDS environment, developed under contract to USASDC. The DCDS environment is an integrated set of tools, languages, and methodologies designed to support the entire life-cycle of system/software development. This LOE contract provided technical assistance, training, distribution, configuration management, sustainment, and enhancement of DCDS.

The Isis Toolkit is a programming environment for building process- group structured distributed software. The system is widely used in settings requiring high reliability, strong distributed consistency guarantees, and high speed communication. In this paper, we describe experimental studies of Isis performance. Our work explores the impact of hardware support for multicast performance, with a focus on flow control mechanisms. The use of hardware multicast in Isis has not been discussed elsewhere. One conclusion of the paper is that although is performance is limited primarily by flow control considerations, this type of hardware support can lead to significant performance improvements for certain communication patterns. A second conclusion was that the Isis flow-control problem is surprisingly difficult. More work in this area, and on the underlying operating system communications layer (UDP), could have significant impact on the system.

Large-scale science and engineering are done through the interaction of people, heterogeneous computing resources, information systems, and instruments, all of which are geographically and organizationally dispersed. The overall motivation for Grids is to facilitate the routine interactions of these resources in order to support large-scale science and engineering. Multi-disciplinary simulations provide a good example of a class of applications that are very likely to require aggregation of widely distributed computing, data, and intellectual resources. Such simulations - e.g. whole system aircraft simulation and whole system living cell simulation - require integrating applications and data that are developed by different teams of researchers frequently in different locations. The research team's are the only ones that have the expertise to maintain and improve the simulation code and/or the body of experimental data that drives the simulations. This results in an inherently distributed computing and data management environment.

We start with a discussion of the relevant literature, including Nature Inspired Computing as a framework in which to understand this work, and the process of biomimicry to be used in mimicking the necessary biological processes to create Digital Ecosystems. We then consider the relevant theoretical ecology in creating the digital counterpart of a biological ecosystem, including the topological structure of ecosystems, and evolutionary processes within distributed environments. This leads to a discussion of the relevant fields from computer science for the creation of Digital Ecosystems, including evolutionary computing, Multi-Agent Systems, and Service-Oriented Architectures. We then define Ecosystem-Oriented Architectures for the creation of Digital Ecosystems, imbibed with the properties of self-organisation and scalability from biological ecosystems, including a novel form of distributed evolutionary computing.

http://uf.catalog.fcla.edu/uf.jsp?st=UF021975271&ix=pm&I=0&V=D&pm=1

http://uf.catalog.fcla.edu/uf.jsp?st=UF021975271&ix=pm&I=0&V=D&pm=1

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Cloud computing is the revolution in current generation IT enterprise displaces database and application software to the large data centers for IT services. In this paper, we designed and simulated an adaptable and efficient scheme to guarantee the correctness of user data stored in the cloud and also with some prominent features. Homomorphic token is used for distributed verification of erasure–coded data. By using this scheme, we can identify misbehaving servers. In spite of past works, our scheme supports effective and secure dynamic operations on data blocks such as data insertion, deletion and modification. In contrast to traditional solutions, where the IT services are under proper physical, logical and personnel controls, cloud computing moves the application software and databases to the large data centers, where the data management and services may not be absolutely truthful. This effective security and performance analysis describes that the proposed scheme is extremely flexible against malicious data modification, convoluted failures and server clouding attacks.

The D0 experiment faces many challenges enabling access to large datasets for physicists on four continents. The new concepts for distributed large scale computing implemented in D0 aim for an optimal use of the available computing resources while minimising the person-power needed for operation. The real live test of these concepts is of special interest for the LHC Computing GRID, LCG, which follows a similar strategy.

The D0 experiment faces many challenges enabling access to large datasets for physicists on four continents. The new concepts for distributed large scale computing implemented in D0 aim for an optimal use of the available computing resources while minimising the person-power needed for operation. The real live test of these concepts is of special interest for the LHC Computing GRID, LCG, which follows a similar strategy.

The D0 experiment faces many challenges enabling access to large datasets for physicists on four continents. The new concepts for distributed large scale computing implemented in D0 aim for an optimal use of the available computing resources while minimising the person-power needed for operation. The real live test of these concepts is of special interest for the LHC Computing GRID, LCG, which follows a similar strategy.

The problem of optimally assigning the modules of a parallel program over the processors of a multiple computer system is addressed. A Sum-Bottleneck path algorithm is developed that permits the efficient solution of many variants of this problem under some constraints on the structure of the partitions. In particular, the following problems are solved optimally for a single-host, multiple satellite system: partitioning multiple chain structured parallel programs, multiple arbitrarily structured serial programs and single tree structured parallel programs. In addition, the problems of partitioning chain structured parallel programs across chain connected systems and across shared memory (or shared bus) systems are also solved under certain constraints. All solutions for parallel programs are equally applicable to pipelined programs. These results extend prior research in this area by explicitly taking concurrency into account and permit the efficient utilization of multiple computer architectures for a wide range of problems of practical interest.

We examine how to program a system so that the software continues to work in the face of a variety of failures of parts of the system. The design presented uses the concept of transactions: collections of primitive actions that are indivisible. The indivisibility of transactions insures that consistent results are obtained even when requests are processed concurrently or failures occur during a request. Our design permits transactions to be nested. Nested transactions provide nested universes of synchronization and recovery from failures. The advantages of nested transactions over single-level transactions are that they provide concurrency control within transactions by serializing subtransactions appropriately, and that they permit parts of a transaction to fail without necessarily aborting the entire transaction. The method for implementing nested transactions described in this report is novel in that it uses locking for concurrency control. We present the necessary algorithms for locking, recovery, distributed commitment, and distributed deadlock detection for a nested transaction system. While the design has not been implemented, it has been simulated. The algorithms are described in a formal notation in an appendix, as well as narratively in the body of the report.

We examine how to program a system so that the software continues to work in the face of a variety of failures of parts of the system. The design presented uses the concept of transactions: collections of primitive actions that are indivisible. The indivisibility of transactions insures that consistent results are obtained even when requests are processed concurrently or failures occur during a request. Our design permits transactions to be nested. Nested transactions provide nested universes of synchronization and recovery from failures. The advantages of nested transactions over single-level transactions are that they provide concurrency control within transactions by serializing subtransactions appropriately, and that they permit parts of a transaction to fail without necessarily aborting the entire transaction. The method for implementing nested transactions described in this report is novel in that it uses locking for concurrency control. We present the necessary algorithms for locking, recovery, distributed commitment, and distributed deadlock detection for a nested transaction system. While the design has not been implemented, it has been simulated. The algorithms are described in a formal notation in an appendix, as well as narratively in the body of the report.

We examine how to program a system so that the software continues to work in the face of a variety of failures of parts of the system. The design presented uses the concept of transactions: collections of primitive actions that are indivisible. The indivisibility of transactions insures that consistent results are obtained even when requests are processed concurrently or failures occur during a request. Our design permits transactions to be nested. Nested transactions provide nested universes of synchronization and recovery from failures. The advantages of nested transactions over single-level transactions are that they provide concurrency control within transactions by serializing subtransactions appropriately, and that they permit parts of a transaction to fail without necessarily aborting the entire transaction. The method for implementing nested transactions described in this report is novel in that it uses locking for concurrency control. We present the necessary algorithms for locking, recovery, distributed commitment, and distributed deadlock detection for a nested transaction system. While the design has not been implemented, it has been simulated. The algorithms are described in a formal notation in an appendix, as well as narratively in the body of the report.

This project has established the foundations for developing a Distributed Middleware-based Architecture for Fault tolerant Computing Over Distributed Repositories . During this project, the sub problems and related issues were identified and the creation of an integrated solution was investigated. In this project, the contractor implemented proof principle systems to show the effectiveness of the proposed approaches. The simulator has been extended to incorporate features specific to this scenario and analysis has been performed. This effort is by no means complete. Furthermore, not all the problems in the proposed architecture have been addressed. There are a number of important problems that need to be addressed to obtain a complete solution. In each section of the final report, the contractor has articulated the need for extending proposed solutions to reach a practically useful approach/solution.

The paper proposes a novel distributed service discovery protocol for pervasive environments. The protocol is based on the concepts of peer-to-peer caching of service advertisements and group-based intelligent forwarding of service requests. It does not require a service to be registered with a registry or lookup server. Services are described using the Web Ontology Language (OWL). We exploit the semantic class/subClass hierarchy of OWL to describe service groups and use this semantic information to selectively forward service requests. OWL-based service description also enables increased flexibility in service matching. We present simulation results that show that our protocol achieves increased efficiency in discovering services (compared to traditional broadcast-based mechanisms) by efficiently utilizing bandwidth via controlled forwarding of service requests.

Partial interconnection, ring, and global bus topologies are examined for use in a real-time distributed computing network. Message lengths and capacity allocation strategies for network links are evaluated in determining system performance based on average message delay. The data suggest a network topology for the application under study. Processor delays at each of the nine nodes in the network are introduced in a simulation model of a global bus network. Thus, link traffic and processor delays are used with message arrival rate, network bandwidth, and processor capacity parameters to arrive at a satisfactory computer system network for a real-time application. A method is developed whereby software requirements are determined in terms of the number of instructions executed. The desired system response time is established and software and hardware specifications may then be defined.

This work, as an AASERT Augmentation to F49620-92-J-0546, has developed a powerful concept in evaluating formal specifications concurrently with distributed program execution for the purposes of error detection, fault tolerance, and security. This concept is realized in the CCSP evaluation system for axiomatic proofs, for interval temporal formulae, and for a security calculus. We have validated This concept through nontrivial examples of distributed programs including a dynamic group membership protocol, a distributed database scheduler, of a responsive system modeling railroad trains on intersecting tracks, and of a secure warehouse management system. Moreover, the spinoff technologies from this work, in of themselves have become useful. CCSP can also be used as a debugging tool for distributed programs. Properties used in CCSP can be visualized using abstract glyphs. Both of these achievements may help to bring more use of formal methods into the mainstream.

The Mine Warfare Command in Charleston, South Carolina has been converting its information systems architecture from a centralized mainframe based system to a decentralized network of personal computers over the past several years. This thesis analyzes the progress Of the evolution as of May of 1992. The building blocks of a distributed architecture are discussed in relation to the choices the Mine Warfare Command has made to date. Areas that need further attention and development are discussed based on the research findings. Finally, recommendation for future planning, procurement and improvements to the system are made. Lessons learned by this command during the conversion to a networked system are described.

Our main investigations are about underwater communications using acoustic waves. Electromagnetic and optical waves do not work well underwater due to the nature of the medium, especially in the case of seawater. Acoustic waves are used for underwater communication due to the relatively low attenuation (i.e., signal reduction) of sound in water, specially in thermally stable, deep water settings. With the current acoustic modem technology, underwater communications concentrate in the 5 to 80 kilo Hertz range. For instance, EvoLogics modems may operate, according to the model, from 7 to 78 kiloHertz. All Teledyne Benthos modems operate in three bands: 9-14, 16-21 or 22-27 kilo Hertz. More particularly, we focus on software emulation of underwater acoustic wave propagation and software modulation and demodulation of underwater acoustic digital data signals in presence of mobility, with integration with other protocol layers. For underwater operation, mobility is relevant because there are underwater vehicles and environmental conditions cause displacements of sensors.

Rapid increases in the complexity of algorithms for real-time signal processing applications have led to performance requirements exceeding the capabilities of conventional digital signal processor (DSP) architectures. Many applications, such as autonomous sonar arrays, are distributed in nature and amenable to parallel computing on embedded systems constructed from multiple DSPs networked together. However, to realize the full potential of such applications, a lightweight service for message-passing communication and parallel process coordination is needed that is able to provide high throughput and low latency while minimizing processor and memory utilization. This paper presents the design and analysis of such a service, based on the Message Passing Interface (MPI) specification, for unicast and collective communications.

Distributed Computing Environment (DCE) has been in development for about five years but has only been widely used in the last two years. It consists of a number of services that have been selected from current proprietary distributed facilities and integrated so that they work together. Together these services form an architecture for distributed computing that enables users to carry out the new, cheaper operations they require with the interoperability, reliability and security standards of mainframe computers. The facilities provided by DCE are often reviewed from either the perspective of reliability or the perspective of interoperability. This paper reviews the facilities of DCE from the perspective of change. An architecture is proposed which will support the evolution of information systems.

A task is a set of related operations which can be performed on some input data. An algorithm is a collection of tasks with an underlying structure defined in terms of precedence relationships among the tasks. Two models of processing systems are considered. A distributed processing system consists of separate processors, each one dedicated to perform a single task, and permits pipelined processing of consecutive requests, as well as concurrent processing of tasks for a given request. A centralized processing system consists of a single processor which performs all the tasks for a given request sequentially, and services the requests sequentially without pipelining. The performance of these two systems is compared in terms of average execution times, under the constraint that the capacity of the processor in the centralized system is equal to the sum of the capacities of individual processors in the distribution system.

Distributed Computing Principles, Algorithms, and Systems

A hand-drawn poster version of the  Fallacies of Distributed Computing , credited to L Peter Deutsch of Sun Microsystems

A hand-drawn poster version of the  Fallacies of Distributed Computing , credited to L Peter Deutsch of Sun Microsystems

Typically an IDS refers to a software application that monitors a network for intrusion or malicious activity. It signals an alarm once an intrusion is detected. In this paper, an IDS based on Distributed Machine Learning that detects phishing attacks and issues an alarm when the intrusion is detected has been discussed. This is done by using SVM as the base algorithm. More on why SVM is used and how the IDS can be applied to detect other types of intrusion has been discussed. 

This paper describes the use of a distributed cloud computing system for high-throughput computing (HTC) scientific applications. The distributed cloud computing system is composed of a number of separate Infrastructure-as-a-Service (IaaS) clouds that are utilized in a unified infrastructure. The distributed cloud has been in production-quality operation for two years with approximately 500,000 completed jobs where a typical workload has 500 simultaneous embarrassingly-parallel jobs that run for approximately 12 hours. We review the design and implementation of the system which is based on pre-existing components and a number of custom components. We discuss the operation of the system, and describe our plans for the expansion to more sites and increased computing capacity.

Quantum bits have technological imperfections. Additionally, the capacity of a component that can be implemented feasibly is limited. Therefore, distributed quantum computation is required to scale up quantum computers. This dissertation presents a new quantum computer architecture which takes into account imperfections, aimed to realize distributed computation by connecting quantum computers each of which consists of multiple quantum CPUs and memories. Quantum CPUs employ a quantum error correcting code which has faster logical gates and quantum memories employ a code which is superior in space resource requirements. This dissertation focuses on quantum error correcting codes, giving a practical, concrete method for tolerating static losses such as faulty devices for the surface code. Numerical simulation with practical assumptions showed that a yield of functional qubits of 90% is marginally capable of building large-scale systems, by culling the poorer 50% of lattices during post-fabrication testing. Yield 80% is not usable even when culling 90% of generated lattices. For internal connections in a quantum computer and for connections between quantum computers, this dissertation gives a fault-tolerant method that bridges heterogeneous quantum error correcting codes. Numerical simulation showed that the scheme, which discards any quantum state in which any error is detected, always achieves an adequate logical error rate regardless of physical error rates in exchange for increased resource consumption. This dissertation gives a new extension of the surface code suitable for memories. This code is shown to require fewer physical qubits to encode a logical qubit than conventional codes. This code achieves the reduction of 50% physical qubits per a logical qubit. Collectively, the elements to propose the distributed quantum computer architecture are brought together.

We describe a distributed processing cluster of inexpensive Linux machines developed jointly by the Astronomy and Computer Science departments at Haverford College which has been successfully used to search a large volume of data from a recent radio pulsar survey. Analysis of radio pulsar surveys requires significant computational resources to handle the demanding data storage and processing needs. One goal of this project was to explore issues encountered when processing a large amount of pulsar survey data with limited computational resources. This cluster, which was developed and activated in only a few weeks by supervised undergraduate summer research students, used existing decommissioned computers, the campus network, and a script-based, client-oriented, self-scheduled data distribution approach to process the data. This setup provided simplicity, efficiency, and "on-the-fly" scalability at low cost. The entire 570 GB data set from the pulsar survey was processed at Haverford over the course of a ten-week summer period using this cluster. We conclude that this cluster can serve as a useful computational model in cases where data processing must be carried out on a limited budget. We have also constructed a DVD archive of the raw survey data in order to investigate the feasibility of using DVD as an inexpensive and easily accessible raw data storage format for pulsar surveys. DVD-based storage has not been widely explored in the pulsar community, but it has several advantages. The DVD archive we have constructed is reliable, portable, inexpensive, and can be easily read by any standard modern machine.

The "IMP Science Gateway Portal" (http://scigate.imp.kiev.ua) for complex workflow management and integration of distributed computing resources (like clusters, service grids, desktop grids, clouds) is presented. It is created on the basis of WS-PGRADE and gUSE technologies, where WS-PGRADE is designed for science workflow operation and gUSE - for smooth integration of available resources for parallel and distributed computing in various heterogeneous distributed computing infrastructures (DCI). The typical scientific workflow with possible scenarios of its preparation and usage is considered. Several typical science applications (scientific workflows) are considered for molecular dynamics (MD) simulations of complex behavior of various nanostructures (nanoindentation of graphene layers, defect system relaxation in metal nanocrystals, thermal stability of boron nitride nanotubes, etc.). The advantages and drawbacks of the solution are shortly analyzed in the context of its practical applications for MD simulations in materials science, physics and nanotechnologies with available heterogeneous DCIs.

We consider networks of processes which interact with beeps. Various beeping models are used. The basic one, defined by Cornejo and Kuhn [CK10], assumes that a process can choose either to beep or to listen; if it listens it can distinguish between silence or the presence of at least one beep. The aim of this paper is the study of the resolution of paradigms such as collision detection, computation of the degree of a vertex, colouring, or 2-hop-colouring in the framework of beeping models. For each of these problems we present Las Vegas or Monte Carlo algorithms and we analyse their complexities expressed in terms of the number of slots. We present also efficient randomised emulations of more powerful beeping models on the basic one. We illustrate emulation procedures with an efficient degree computation algorithm in the basic beeping model; this algorithm was given initially in a more powerful model.