Advances in networking technologies will soon make it possible to use the global information infrastructure in a qualitatively different way—as a computational resource as well as an information resource. This idea for an integrated computation and information resource called the Computational Power Grid has been described by the recent book entitled The Grid: Blueprint for a New Computing Infrastructure [18]. The Grid will connect the nation’s computers, databases, instruments, and people in a seamless web, supporting emerging computation-rich application concepts such as remote computing, distributed supercomputing, tele-immersion, smart instruments, and data mining. To realize this vision, significant scientific and technical obstacles must be overcome. Principal among these is usability. Because the Grid will be inherently more complex than existing computer systems, programs that execute on the Grid will reflect some of this complexity. Hence, making Grid resources useful and accessible to scientists and engineers will require new software tools that embody major advances in both the theory and practice of building Grid applications. The goal of the Grid Application Development Software (GrADS) Project is to simplify distributed heterogeneous computing in the same way that the World Wide Web simplified information sharing

Data-intensive, interactive applications are an important class of metacomputing (Grid) applications. They are characterized by large dataflows between data providers and consumers, like scientific simulations and remote visualization clients of simulation output. Such dataflows vary at runtime, due to changes in consumers' data needs, changes in the nature of the data being transmitted, or changes in the availability of computing resources used by flows. The topic

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. ...

In this paper we present the Active Harmony automated runtime tuning system. We describe the interface used by programs to make applications tunable. We present the Library Specification Layer which helps program library developers expose multtple variations of the same API using different algorithms. The Library Specification Language helps to select the most appropriate program library to tune the overall performance. We also present the optimization algorithm that we used to adjust parameters in the application and the libraries. Finally, we present results that show how the system is able to tune several real applications. The automated tuning system is able to tune the application parameters to within a few percent of the best value after evaluating only 11 configurations out of over 1, 700possible combinations.

PAWS (Parallel Application WorkSpace) is a software infrastructure for use in connecting separate parallel applications within a component-like model. A central PAWS Controller coordinates the linking of serial or parallel applications across a network to allow them to share parallel data structures such as multidimensional arrays. Applications use the PAWS API to indicate which data structures are to be shared and at what points the data is ready to be sent or received. PAWS implements a general parallel data descriptor, and automatically carries out parallel layout remapping when necessary. Connections can be dynamically established and dropped, and can use multiple data transfer pathways between applications. PAWS uses the NEXUS communication library and is independent of the application’s parallel communication mechanism. 1.

At least three factors in the existing migrating systems make them less suitable in Grid systems especially when the goal is to improve the response times for individual applications - separate policies for suspension and migration of executing applications employed by these migration systems, the use of pre-defined conditions for suspension and migration and the lack of knowledge of the remaining execution time of the applications. In this paper we describe a migration framework for performance oriented Grid systems that implements tightly coupled policies for both suspension and migration of executing applications. The suspension and migration policies take into account both the load changes on systems as well the remaining execution times of the applications thereby taking into account both system load and application characteristics. The main goal of our migration framework is to improve the response times for individual applications. We also present some results that demonstrate the usefulness of our migrating system.

Optimizing a given software to exploit the features of the underlying system has been an area of research for many years. Recently, a number of self adapting software have been designed and developed for various computing environments. In this paper, we discuss the design and implementation of a software that dynamically adjusts the parallelism of applications executing on computational Grids in accordance to the changing load characteristics of the underlying resources. The migration framework implemented by our software is oriented towards performance oriented Grid systems and implements tightly coupled policies for both suspension and migration of executing applications. The suspension and migration policies take into account both the load changes on systems as well the remaining execution times of the applications thereby taking into account both system load and application characteristics. The main goal of our migration framework is to improve the response times for individual applications. We also present some results that demonstrate the usefulness of our migration framework.

The ability to produce malleable parallel applications that can be stopped and reconfigured during the execution can offer attractive benefits for both the system and the applications. The reconfiguration can be in terms of varying the parallelism for the applications, changing the data distributions during the executions or dynamically changing the software components involved in the application execution. In distributed and Grid computing systems, migration and reconfiguration of such malleable applications across distributed heterogeneous sites which do not share common file systems provides flexibility for scheduling and resource management in such distributed environments. The present reconfiguration systems do not support migration of parallel applications to distributed locations. In this paper, we discuss a framework for developing malleable and migratable MPI message-passing parallel applications for distributed systems. The framework includes a user-level checkpointing library called SRS and a runtime support system that manages the checkpointed data for distribution to distributed locations. Our experiment results indicate that the parallel applications, with instrumentation to SRS library, were able to achieve reconfigurability incurring about 15- 35% overhead.

In this paper we discuss problems and solutions pertaining to the interaction of components representing parallel applications. We introduce the notion of a collective port which is an extension of the Common Component Architecture (CCA) ports and allows collective components representing parallel applications to interact as one entity. We further describe a class of translation components, which translate between the distributed data format used by one parallel implementation to that used by another. A well known example of such components is the MxN component which translates between data distributed on M processors to data distributed on N processors. We describe its implementation in Parallel Application Work Space (PAWS), as well as the data structures PAWS uses to support it. We also present a mechanism allowing the framework to invoke this component on the programmer’s behalf whenever such translation is necessary, freeing the programmer from treating collective component interactions as a special case. In doing that we introduce framework-based, user-defined distributed type casts. Finally, we discuss our initial experiments in building optimized complex translation components out of atomic functionalities. 1.

Computational Steering is the ultimate goal of interactive simulation: researchers change parameters of their simulation and immediately receive feedback on the effect. We present a general and flexible graphics tool that is part of an environment for Computational Steering developed at CWI. It enables the researcher to interactively develop his own interface with the simulation. This interface is constructed with 3D Parametrized Geometric Objects. The properties of the objects are parametrized to output data and input parameters of the simulation. The objects visualize the output of the simulation while the researcher can steer the simulation by direct manipulation of the objects. Several applications of 3D Computational Steering are presented.