We present the design, implementation and application of SCIRun, a scientific programming environment that allows the interactive construction, debugging, and steering of large-scale scientific computations. Using this "computational workbench," a scientist can design and modify simulations interactively via a dataflow programming model. SCIRun enables scientists to design and modify model geometry, interactively change simulation parameters and boundary conditions, and interactively visualize geometric models and simulation results. We discuss the ubiquitous roles SCIRun plays as a computational tool (e.g. resource manager, thread scheduler, development environment), and how we have applied an object oriented design (implemented in C++) to the scientific computing process. Finally, we demonstrate the application of SCIRun to large scale problems in computational medicine. 1.1 Introduction 1.1.1 Visual Computing and Interactive Steering In recent years, the scientific computing commu...

Advances in high performance computing, communications, and user interfaces enable developers to construct increasingly interactive high performance applications. The Falcon system presented in this paper supports such interactivity by providing runtime libraries, tools, and user interfaces that permit the on-line monitoring and steering of large-scale parallel codes. The principal aspects of Falcon described in this paper are its abstractions and tools for capture and analysis of application-specific program information, performed on-line, with controlled latencies and scalable to parallel machines of substantial size. In addition, Falcon provides support for the on-line graphical display of monitoring information, and it allows programs to be steered during their execution, by human users or algorithmically. This paper presents our basic research motivation, outlines the Falcon system's functionality, and includes a detailed evaluation of its performance characteristics in light of i...

SCIRun is a scientific programming environment that allows the interactive construction, debugging, and steering of large-scale scientific computations. We review related systems and introduce a taxonomy that explores different computational steering solutions. Considering these approaches, we discuss why a tightly integrated problem solving environment, such as SCIRun, simplifies the design and debugging phases of computational science applications and how such an environment aids in the scientific discovery process. I. Introduction Since the introduction of computers, scientists and engineers have attempted to harness their power to simulate complex physical phenomena. Today, the computer is an almost universal tool used in a wide range of scientific and engineering domains. Computational science and engineering is the field that has grown out of the widespread use of computers to numerically simulate the physical phenomena associated with many problems in science and engineering. ...

Interactive program steering permits researchers to monitor and guide their applications during runtime. Interactive steering can help make end users more effective in addressing the scientific or engineering questions being solved with these programs, and it may be used to improve the performance of complex parallel and distributed codes. Progress is a toolkit for developing steerable applications. Users instrument their applications with library calls and then steer parallel applications with Progress' runtime system. Progress provides steerable objects which encapsulate program abstractions for monitoring and steering during program execution. Once created, steering objects are known to and manipulated by Progress' two components: (1) a server executing in the same memory space as the target program and capable of inspecting and manipulating program state, and (2) a potentially remote client providing command and graphical interfaces. Developers instrument their applications with t...

Distributed laboratories are environments where scientists and engineers working in geographically separated locations share access to interactive visualization tools and large-scale simulation computations, share information generated by such instruments, and collaborate across time and space to evaluate and discuss their results. The intent is to permit scientists, engineers, and managers at geographically distinct locations (including individuals telecommuting from home) to combine their expertise in solving shared problems by allowing them to simultaneously view, interact with, and steer sophisticated computation instruments executing on high performance distributed platforms. This paper reports on research efforts being undertaken at Georgia Tech that address the topic of distributed laboratories: -- Steering and monitoring tools and infrastructure used in the online observation and manipulation of two scientific computations developed jointly with end users. -- Middleware...

This paper describes a parallel implementation of a grand challenge problem: global atmospheric modeling. The novel contributions of our work include: (1) a detailed investigation of opportunities for parallelism in atmospheric transport based on spectral solution methods, (2) the experimental evaluation of overheads arising from load imbalances and data movement for alternative parallelization methods, and (3) the development of a parallel code that can be monitored and steered interactively based on output data visualizations and animations of program functionality or performance. Code parallelization takes advantage of the relative independence of computations at different levels in the earth's atmosphere, resulting in parallelism of up to 40 processors, each independently performing computations for different atmospheric levels and requiring few communications between different levels across model time steps. Next, additional parallelism is attained within each level by taking adva...

steering lets researchers investigate, calibrate, and control long-running, resource-intensive applications at runtime. Magellan, a prototype computational steering system, uses ACSL to intelligently control multithreaded, asynchronous steering servers that cooperatively steer applications.

Since the introduction of computers, scientists and engineers have attempted to harness their power to simulate complex physical phenomena. Today, the computer is an almost universal tool used in a wide range of scientific and engineering domains. Currently, organizing, running and visualizing a new large-scale simulation still requires hours or days of a researcher's time. Time and effort required for data input, output and conversion further slows and complicates process. We present the design and application of SCIRun, a Problem Solving Environment (PSE), and a computational steering software system. SCIRun allows a scientist or engineer to interactively steer a computation, changing parameters, recomputing, and then revisualizing all within the same programming environment. The tightly integrated modular environment provided by SCIRun allows computational steering to be applied to a broad range of advanced scientific computations. This dissertation demonstrates that computationa...

We describe a computational steering model which allows users to interactively change boundary conditions, model geometry, and computational parameters via a graphical user interface. To replace the typical simulation mode -- in which the researcher manually sets input parameters, computes results, stores data off to disk, visualizes the results via a separate visualization package, then starts again at the beginning -- we have designed software to "close the loop" and allow the visualization to help guide (steer) the design and computation phases of the simulation. We have applied the computational steering model to problems in medicine, specifically to applications in bioelectric field phenomena and biomedical device design. Introduction The current computational engineering and science modeling process is a familiar one -- create, or make modifications to, a geometric model, input initial conditions and/or boundary conditions, numerically approximate solutions to the governing equ...

Advances in networking, visualization and parallel computing signal the end of the days of batchmode processing for computationally intensive applications. The ability to control and interact with these applications in real-time offers both opportunities and challenges. This paper examines two computationally intensive scientific applications and discusses the ways in which more interactivity in their computations presents opportunities for gain. It briefly examines the requirements for systems trying to exploit these opportunities and discusses Falcon, a system that attempts to fulfill these requirements. 1 Introduction The world of computationally intensive computing is moving away from the batch-oriented style of processing. Users accustomed to spreadsheets and WYSIWYG word processing are not satisfied with the traditional hands-off, you'll-get-your-data-when-the-batch-queue-empties mode of running parallel programs. At the same time, high-speed network interfaces and the prolifera...