Global Grids and Software Toolkits: A Study of Four Grid Middleware Technologies

Grid is an infrastructure that involves the integrated and collaborative use of computers, networks, databases and scientific instruments owned and managed by multiple organizations. Grid applications often involve large amounts of data and/or computing resources that require secure resource sharing across organizational boundaries. This makes Grid application management and deployment a complex undertaking. Grid middlewares provide users with seamless computing ability and uniform access to resources in the heterogeneous Grid environment. Several software toolkits and systems have been developed, most of which are results of academic research projects, all over the world. This chapter will focus on four of these middlewares--UNICORE, Globus, Legion and Gridbus. It also presents our implementation of a resource broker for UNICORE as this functionality was not supported in it. A comparison of these systems on the basis of the architecture, implementation model and several other features is included.Comment: 19 pages, 10 figure

DEFINING DIGITAL PRESERVATION WORK: A CASE STUDY OF THE DEVELOPMENT OF THE REFERENCE MODEL FOR AN OPEN ARCHIVAL INFORMATION SYSTEM

I report on a multi-method case study of the development of a standard called the Reference Model for an Open Archival Information System (OAIS), which describes components and services required to develop and maintain archives in order to support long-term access and understanding of the information in those archives. The development of the OAIS took place within a standards development organization called the Consultative Committee for Space Data Systems (CCSDS), whose formal purview is the work of space agencies, but the effort reached far beyond the traditional CCSDS interests and stakeholders. It has become a fundamental component of digital archive research and development in a variety of disciplines and sectors. Through document analysis, social network analysis and qualitative analysis of interview data, I explain how and why the OAIS development effort, which took place within a space data standards body, was transformed into a standard of much wider scope, relevant to a diverse set of actors. The OAIS development process involved substantial enrollment of resources from the environment, including skills and expertise; social ties; documentary artifacts; structures and routines; physical facilities and proximity; and funding streams. Enrollment from the environment did not occur automatically. It was based on concerted efforts by actors who searched for relevant literature, framed the process as open, and promoted it at professional events. Their acts of participation also helped to enroll resources, contributing to what structuration theory calls the signification and legitimation of the Reference Model, i.e. enactment of what the document means, and why and to whom it is important. Documentary artifacts were most successfully incorporated into the OAIS when they were perceived to support modularity and to be at an appropriate level of abstraction. The content of the Reference Model was subject to stabilization over time, making changes less likely and more limited in scope. A major factor in the success of the OAIS was the timing of its development. Actors within several streams of activity related to digital preservation perceived the need for a highlevel model but had not themselves developed one. At the same time, several actors now felt they had knowledge from their own recent digital archiving efforts, which could inform the development of the OAIS. This study has important implications for research on standardization, and it provides many lessons for those engaged in future standards development efforts.Ph.D.InformationUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/39372/2/dissertation_callee.pd

Image-space decomposition algorithms for sort-first parallel volume rendering of unstructured grids

Ankara : Department of Computer Engineering and Information Science and the Institute of Engineering and Science of Bilkent University, 1997.Thesis (Master's) -- Bilkent University, 1997.Includes bibliographical references leaves 96-100.Kutluca, HüseyinM.S