Abstract. A basic prerequisite for parallel programming is a good communication API. The recent i n terest in using Java for scienti c and engineering application has led to several international e orts to produce a message passing interface to support parallel computation. In this paper we describe and then discuss the syntax, functionality and performance of one such i n terface, mpiJava, an object-oriented Java i n terface to MPI. We rst discuss the design of the mpiJava API and the issues associated with its development. We then move on to brie y outline the steps necessary to 'port' mpiJava onto a range of operating systems, including Windows NT, Linux and Solaris. In the second part of the paper we present and then discuss some performance measurements made of communications bandwidth and latency to compare mpiJava on these systems. Finally, we summarise our experiences and then brie y mention work that we plan to undertake.

Several Java bindings of the Message Passing Interface standard, MPI, have been developed recently. Message buffers have usually been restricted to arrays with elements of primitive type. We discuss use of the Java object serialization model for marshalling general communication data in MPI. This approach is compared with a Java transcription of the standard MPI derived datatype mechanism.We describe an implementation of the mpiJaua interface to MPI incorporating automatic object serialization.Benchmark results show that the current JDK implementation of serialization is (not unexpectedly)probably not fast. enough for high performance applications.Means of solving this problem are discussed.

We describe an information system architecture for the ACES (Asia-Pacific Cooperation for Earthquake Simulation) community. It addresses several key features of the fieldsimulations at multiple scales that need to be coupled together; real-time and archival observational data, which needs to be analyzed for patterns and linked to the simulations; a variety of important algorithms including partial differential equation solvers, particle dynamics, signal processing and data analysis; a natural three dimensional space (plus time) setting for both visualization and observations; the linkage of field to real-time events both as an aid to crisis management and to scientific discovery. We also address the need to support education and research for a field whose computational sophistication is increasing rapidly and spans a broad range. The information system assumes that all significant data is defined by an XML layer which could be virtual but whose existence ensures that all data is object-based and can be accessed and searched in this form. The various capabilities needed by ACES are defined as Grid Services, which are conformant with emerging standards and implemented with different levels of fidelity and performance appropriate for the application. Grid Services can be composed in a hierarchical fashion to address complex problems. The real-time needs of the field are addressed by high performance implementation of data transfer and simulation services; further the environment is linked to real-time collaboration to support interactions between scientists in geographically distant locations. ACES Grid and .opennet Grid ArchitectureWe consider an ACES [1] computational environment (ACESCE) built in terms of a web-based user interfaces accessing services, which are built in a broker-based fashion [2]. The client machine contacts a server that acts as an intermediary to back-end resources and also as a conduit for clients to access services. One can also view the brokers as middleware wrappers that allow a heterogeneous collection of resources to be accessed in a relatively uniform fashion. In the simplest technology, these brokers or wrappers would be implemented as a Perl CGI program running on a web server. As discussed later, there are more sophisticated approaches but the basic model is correct;

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Abstract:The importance of network-ready personal