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In computational grids, performance-hungry applications need to simultaneously tap the computational power of multiple, dynamically available sites. The crux of designing grid programming environments stems exactly from the dynamic availability of compute cycles: grid programming environments (a) need to be portable to run on as many sites as possible, (b)(More)
LOFAR, the LOw-Frequency ARray, is a new-generation radio interferometer constructed in the north of the Netherlands and across europe. Utilizing a novel phased-array design, LOFAR covers the largely unexplored low-frequency range from 10–240 MHz and provides a number of unique observing capabilities. Spreading out from a core located near the village of(More)
Divide-and-conquer programs are easily parallelized by letting the programmer annotate potential parallelism in the form of <italic>spawn</italic> and <italic>sync</italic> constructs. To achieve efficient program execution, the generated work load has to be balanced evenly among the available CPUs. For single cluster systems, <italic>Random(More)
The MPJ programming interface has been defined by the Java Grande forum to provide MPI-like message passing for Java applications. In this paper, we present MPJ/Ibis, the first implementation of MPJ based on our Ibis programming environment for cluster and grid computing. By exploiting both flexibility and efficiency of Ibis, our MPJ implementation delivers(More)
Computational grids have an enormous potential to provide compute power. However, this power remains largely unexploited today for most applications, except trivially parallel programs. Developing parallel grid applications simply is too difficult. Grids introduce several problems not encountered before, mainly due to the highly heterogeneous and dynamic(More)
Invited Paper Core Grid technologies are rapidly maturing, but there remains a shortage of real Grid applications. One important reason is the lack of a simple and high-level application programming toolkit, bridging the gap between existing Grid middleware and application-level needs. The Grid Application Toolkit (GAT), as currently developed by the(More)
Grid programming environments need to be both portable and efficient to exploit the computational power of dynamically available resources. In previous work, we have presented the divide-and-conquer based Satin model for parallel computing on clustered wide-area systems. In this paper, we present the Satin implementation on top of our new Ibis platform(More)
The Distributed ASCI Supercomputer (DAS) is a homogeneous wide-area distributed system consisting of four cluster computers at different locations. DAS has been used for research on communication software, parallel languages and programming systems, schedulers, parallel applications, and distributed applications. The paper gives a preview of the most(More)
Java offers interesting opportunities for parallel computing. In particular, Java Remote Method Invocation (RMI) provides a flexible kind of remote procedure call (RPC) that supports polymorphism. Sun's RMI implementation achieves this kind of flexibility at the cost of a major runtime overhead. The goal of this article is to show that RMI can be(More)