Wojtek Furmanski

WebFlow – a visual programming paradigm for Web/Java based coarse grain distributed computing

We present here recent work at NPAC aimed at developing WebFlow – a general purpose Web-based visual interactive programming environment for coarse grain distributed computing. We follow the 3-tier architecture with the central control and integration WebVM layer in tier-2, interacting with the visual graph editor applets in tier-1 (front-end) and the legacy systems in tier-3. WebVM is given by a mesh of Java Web servers such as Jeeves from JavaSoft or Jigsaw from MIT/W3C. All system control structures are implemented as URL-addressable servlets which enable Web browser-based authoring, monitoring, publication, documentation and software distribution tools for distributed computing. We view WebFlow/WEbVM as a promising programming paradigm and co-ordination model for the exploding volume of Web/Java software, and we illustrate it in a set of ongoing application development activities.

WebFlow - High-Level Programming Environment and Visual Authoring Toolkit for High Performance Distributed Computing

We developed a platform independent, three-tier system, called WebFlow. The visual authoring tools implemented in the front end integrated with the middle tier network of servers based on the industry standards and following distributed object paradigm, facilitate seamless integration of commodity software components. We add high performance to commodity systems using GLOBUS metacomputing toolkit as the backend. We have explained these ideas in general before, and here for the first time we describe a fully operational example which is expected to be deployed in an NCSA Alliance Grand Challenge.

Load balancing loosely synchronous problems with a neural network

Hopfield and Tank have introduced the use of neural networks for the solution of optimization problems such as the traveling salesman problem. Here we show how to generalize this method to decompose loosely synchronous problems onto parallel machines and in particular the hypercube. In this case, decomposition or load balancing can be formulated graph theoretically in terms of optimal partitioning of the computational graph into N = 2d subgraphs. The algorithm has a suggestive spin system interpretation, with the ferromagnetic interaction minimizing the communication and the long range paramagnetic force balancing the load. The optimal fixed point of the network is in the Higgs phase of the magnet, with the domains of constant spontaneous magnetization representing the optimal decomposition map. The method is fast, reliable and admits various simple implementations: sequential, concurrent on the hypercube, analog on the neural network with adaptive weights (“learning”). We analyze the sequential performance of various mean field based network algorithms and we compare the network approach with the statistical Monte Carlo technique of simulated annealing.

Java for parallel computing and as a general language for scientific and engineering simulation and modeling

We discuss the role of Java and Web technologies for general simulation. We classify the classes of concurrency typical in problems and analyze separately the role of Java in user interfaces, coarse grain software integration, and detailed computational kernels. We conclude that Java could become a major language for computational science, as it potentially o ers good performance, excellent user interfaces, and the advantages of object-oriented structure.

Petaops and Exaops: supercomputing on the Web

There are large-scale computation problems that could benefit from the power of the Web. The authors have chosen the year 2007 to set a hardware scenario where petaflops performance could be obtained by a variety of architectures, including an ATM-connected corporate intranet. They classify the kinds of parallelism found in different applications, arguing that the Web has advantages in the expression of general forms of parallelism that make it suitable as the software environment of choice for these applications on all hardware platforms. They conclude by analyzing Web software approaches in some detail, taking an inevitably nearer term perspective. Their purpose is to show how the Web and MPP can be advanced synergistically to solve different problems.

The software architecture of a virtual distributed computing environment

The requirements of grand challenge problems and the deployment of gigabit networks makes the network computing framework an attractive and cost effective computing environment with which to interconnect geographically distributed processing and storage resources. Our project, Virtual Distributed Computing Environment (VDCE), provides a problem-solving environment for high-performance distributed computing over wide area networks. VDCE delivers well-defined library functions that relieve end-users of tedious task implementations and also support reusability. In this paper we present the conceptual design of VDCE software architecture, which is defined in three modules: (a) the Application Editor, a user-friendly application development environment that generates the Application Flow Graph (AFG) of an application; (b) the Application Scheduler, which provides an efficient task-to-resource mapping of AFG; and (c) the VDCE Runtime System, which is responsible for running and managing application execution and monitoring the VDCE resources.

Web based metacomputing

Abstract Programming tools that are simultaneously sustainable, highly functional, robust and easy to use have been hard to come by in the HPCC arena. This is partially due to the difficulty in developing sophisticated customized systems for what is a relatively small part of the worldwide computing enterprise. Thus, we have developed a new strategy – termed High Performance Commodity Computing (HPCC) [G. Fox, W. Furmanski, HPCC as high performance commodity computing, in: I. Foster, C. Kesselman (Eds.), Building National Grid, http://www.npac.syr.edu/users/gcf/HPcc/HPcc.html ] – which builds HPCC programming tools on top of the remarkable new software infrastructure being built for the commercial web and distributed object areas. We add high performance to commodity systems using multi-tier architecture with Globus metacomputing toolkit as the backend of a middle-tier of commodity web and object servers. We have demonstrated the fully functional prototype of WebFlow during Alliance’98 meeting.

Optimal communication algorithms for regular decompositions on the hypercube

We discuss optimal communication and decomposition algorithms for a class of regular problems on concurrent computers with a hypercube topology, using a general technique we call the method of cube geodesics. We address the calculation of various transformations ( convolutions, functionals etc. ) of data distributed over the hypercube; examples are the Fast Fourier Transform, matrix algorithms, global scalar products and vector sums, sorting. These all involve long distance inter-node interactions and require more intricate communication that the simple local problems with static spatial decomposition such as partial differential equations. We believe that our library of optimal communication routines is applicable to these and many other problems. The simple example of a database application is sketched. We implement the algorithms on the Caltech/JPL Mark II hypercube and present a detailed performance analysis.

The use of the national information infrastructure and high performance computers in industry

We divide potential NII (National Information Infrastructure) services into five broad areas: Collaboration and televirtuality; InfoVISiON (Information, Video, Imagery, and Simulation on Demand), and digital libraries; commerce; metacomputing; WebTop productivity services. The latter denotes the broad suite of tools we expect to be offered on the Web in a general environment we term WebWindous. We review current and future World Wide Web technologies, which could underlie these services. In particular we suggest an integration framework WebWork for high performance (parallel and distributed) computing and the NII. We point out that pervasive WebWork and WebWindows technologies will enable, facilitate and substantially accelerate such complex software processes on the NII. We briefly analyze seven broad application areas: society; business enterprises; health care; defense command and control, and crisis management; education; collaboratory; manufacturing. We contrast their use of NII services with a more detailed examination of the manufacture of complex systems, such as aircraft and automobiles. This application stresses the NII but there is a remarkable opportunity to develop new manufacturing practices that offer cost savings and reduced time to market.

Optimal matrix algorithms on homogeneous hypercubes

This paper describes a set of concurrent algorithms for matrix algebra, based on a library of collective communication routines for the hypercube. We show how a systematic application of scattering reduces load imbalance. A number of examples are considered (Gaussian elimination, Gauss-Jordan matrix inversion, the power method for eigenvectors, and tridiagonalisation by Householders method), and the concurrent efficiencies are discussed.