. We report on our experiences in building a computational environment for tomographic image analysis for marine seismologists studying the structure and evolution of mid-ocean ridge volcanism. The computational environment is determined by an evolving set of requirements for this problem domain and includes needs for high-performance parallel computing, large data analysis, model visualization, and computation interaction and control. Although these needs are not unique in scientific computing, the integration of techniques for seismic tomography with tools for parallel computing and data analysis into a computational environment was (and continues to be) an interesting, important learning experience for researchers in both disciplines. For the geologists, the use of the environment led to fundamental geologic discoveries on the East Pacific Rise, the improvement of parallel ray tracing algorithms, and a better regard for the use of computational steering in aiding model convergence. ...

Data- and task-parallelism are two important parallel programming models. Object-oriented paradigm in parallelism provides a good way of abstracting out various aspects of computations and computing resources. Using an object-oriented language like C++, one can compose data and control representations into a single active object. We propose a thread model of parallelism that addresses both data and task parallelism. Computation and communication can be overlapped by suspending a thread of computation which is waiting for an event and running an eligible thread of computation in its place. Threads naturally subsume taskparallelism. Threads are encapsulated into thread objects may be grouped into rope objects [22, 20], that span the parallel machine domain, for collective computation and communication. Thus data-parallelism can be supported. Since rope objects are parallel objects, they can be customized, interestingly, in a serial or a parallel manner. Spatial transparency of objects is...

This article presents an overview of on-line monitoring and dynamic analysis tools that support the design and testing of distributed computing systems. Software tools are based on the needs of users to observe and control system performance. Of growing importance are the integration of domain-specific and commercial, off-the-shelf (COTS) tools and the rapid-prototyping of application-specific tools. To focus the discussion of tools, we introduce two contemporary examples of complex distributed systems and present a comprehensive definition. Application areas include transaction processing and control. The overview of software tools for these types of complex distributed systems emphasizes various functionalities across the system lifecycle and tool integration technologies. The overview is intended to be broad and selective, but representative, so as to give the reader a "wide-angle view" of the application of software tools in this area. Finally, we summarize the PG RT integrated t...