William E. Johnston

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We have implemented and deployed an access control mechanism that uses digitally-signed certificates to define and enforce an access policy for a set of distributed resources that have multiple, independent and geographically dispersed stakeholders. The stakeholders assert their access requirements in use-condition certificates and designate those trusted(More)
We describe a methodology that enables the real-time diagnosis of performance problems in complex high-performance distributed systems. The methodology includes tools for generating precision event logs that can be used to provide detailed end-to-end application and system level monitoring; a Java agent-based system for managing the large amount of logging(More)
Information Power Grid (IPG) is the name of NASA's project to build a fully distributed computing and data management environment – a Grid. The IPG project has near, medium, and long-term goals that represent a continuum of engineering, development, and research topics. The overall goal is to provide the NASA scientific and engineering communities a(More)
With the advent of service sensitive applications such as remote controlled experiments, time constrained massive data transfers, and video-conferencing, it has become apparent that there is a need for the setup of dynamically provisioned, quality of service enabled virtual circuits. The ESnet on-demand secure circuits and advance reservation system(More)
In widely distributed systems generally, and in science-oriented Grids in particular, software, CPU time, storage, etc., are treated as " services " – they can be allocated and used with service guarantees that allows them to be integrated into systems that perform complex tasks. Network communication is currently not a service – it is provided, in general,(More)
We have designed, built, and analyzed a distributed parallel storage system that will supply image streams fast enough to permit multi-user, “real-time”, video-like applications in a wide-area ATM network-based Internet environment. We have based the implementation on user-level code in order to secure portability; we have characterized the(More)
As the practice of science moves beyond the single investigator due to the complexity of the problems that now dominate science, large collaborative and multi-institutional teams are needed to address these problems. In order to support this shift in science, the computing and data handling infrastructure that is essential to most of modern science must(More)
We describe an approach to the analysis of the performance of distributed applications in high-speed wide-area networks. The approach is designed to identify all of the issues that impact performance, and isolate the causes due to the related hardware and software components. We also describe the use of a distributed parallel data server as a network load(More)