Grid computing enables computers on different networks to share their resources in an organized way. Authorized users can deploy the resources as if they were in the same organization. This resource sharing environment is called a Virtual Organization (VOs). To enable an open Grid to support resource sharing between multiple heterogeneous VOs, an authorization policy management framework is required to support authorization for VOs using heterogeneous authorization systems. The challenges include dynamic Grid memberships, VO trust relationships, and heterogeneous authorization systems. / To solve these problems in a loose-coupling way, we propose a dynamic, distributive and heterogeneous authorization policy management framework. The framework is called Dynamic Policy Management Framework (DPMF). DPMF groups VOs of the same authorization systems to form a virtual cluster. Authorization policy management is divided into inter-cluster heterogeneous policy management, and intra-cluster homogeneous policy management. Inside a virtual cluster, the workloads of policy management can be distributed among the VOs according to their trust relationships. The Conflict Analysis with Partial Information (CAPI) mechanism is developed to make authorization decisions in open environments without complete policy information. A Heterogeneous Policy Management mechanism is developed for DPMF to support inter-cluster heterogeneous policy management. / Traditional authorization policy management frameworks work well in authorization for a single VO where the participating hosts agree to follow a global authorization system. However, they are not capable of authorization policy management for multiple VOs which deploys heterogeneous authorization systems. / Yu, Chiu Man. / "April 2007." / Adviser: Ng Kam Wing. / Source: Dissertation Abstracts International, Volume: 69-01, Section: B, page: 0447. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 200-206). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Wong, Sze Wing. / Thesis submitted in: October 2007. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 176-180). / Abstracts in English and Chinese. / Abstract --- p.i / 論文摘要 --- p.iii / Acknowledgements --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Contributions of this thesis --- p.3 / Chapter 1.2 --- Thesis structure --- p.4 / Chapter 2 --- Background --- p.6 / Chapter 2.1 --- Web Services --- p.6 / Chapter 2.2 --- Grid Computing --- p.8 / Chapter 2.2.1 --- Open Grid Services Architecture (OGSA) --- p.9 / Chapter 2.2.2 --- Grid Services --- p.9 / Chapter 2.3 --- Globus Toolkit --- p.10 / Chapter 2.3.1 --- Components of Globus Toolkit 4 --- p.11 / Chapter 2.3.2 --- Grid Security Infrastructure (GSI) --- p.13 / Chapter 2.4 --- Mobile Agent --- p.13 / Chapter 2.4.1 --- Foundation for Intelligent Physical Agents (FIPA) --- p.14 / Chapter 2.5 --- Java Agent Development Framework (JADE) --- p.15 / Chapter 2.5.1 --- JADE-S --- p.17 / Chapter 3 --- Research Issues in Mobile Grid Services --- p.18 / Chapter 3.1 --- Mobile Grid Services --- p.18 / Chapter 3.2 --- Service Migration --- p.20 / Chapter 3.2.1 --- Using Mobile Agent with Weak Mobility --- p.20 / Chapter 3.2.2 --- Using Mobile Agent with Strong Mobility --- p.21 / Chapter 3.2.3 --- Using Snapshots --- p.22 / Chapter 3.2.4 --- Summary --- p.23 / Chapter 3.3 --- Service Sharing and Discovery --- p.24 / Chapter 3.3.1 --- Centralized Model --- p.24 / Chapter 3.3.2 --- Division into clusters --- p.25 / Chapter 3.3.3 --- Using Web Services Protocols --- p.26 / Chapter 3.3.4 --- Summary --- p.27 / Chapter 3.4 --- Security --- p.28 / Chapter 3.4.1 --- Resource control and accounting --- p.28 / Chapter 3.4.2 --- Using delegation document --- p.30 / Chapter 3.4.3 --- Summary --- p.31 / Chapter 4 --- Mobile Grid Service Framework --- p.32 / Chapter 4.1 --- Proposed Framework Overview --- p.32 / Chapter 4.1.1 --- Service Migration --- p.33 / Chapter 4.1.2 --- Service Sharing and Discovery --- p.34 / Chapter 4.1.3 --- Security --- p.34 / Chapter 4.2 --- Overall architecture --- p.35 / Chapter 4.3 --- Components of Mobile Grid Services --- p.36 / Chapter 4.3.1 --- Agent Manager --- p.37 / Chapter 4.3.2 --- Task Agent --- p.38 / Chapter 4.3.3 --- Monitor Agent --- p.39 / Chapter 4.4 --- Resource Information Service --- p.40 / Chapter 4.5 --- Scenario of Mobile Grid Service Execution --- p.41 / Chapter 5 --- MGSAPI --- p.43 / Chapter 5.1 --- API design --- p.43 / Chapter 5.2 --- API Implementation --- p.45 / Chapter 5.2.1 --- Overview --- p.45 / Chapter 5.2.2 --- Agent Manager Class --- p.46 / Chapter 5.2.3 --- Task Agent Templates --- p.52 / Chapter 5.2.4 --- Configurable Monitor Agent --- p.57 / Chapter 5.2.5 --- Resource Information Service --- p.61 / Chapter 5.2.6 --- Example Application --- p.66 / Chapter 6 --- Security Support for Mobile Grid Services --- p.68 / Chapter 6.1 --- Overview --- p.68 / Chapter 6.2 --- Authentication and Authorization --- p.70 / Chapter 6.3 --- Message Integrity and Confidentiality --- p.72 / Chapter 6.4 --- Permissions on Agents --- p.74 / Chapter 6.5 --- Security facilities in MGS API --- p.76 / Chapter 6.5.1 --- Major modifications for MGS components --- p.77 / Chapter 6.5.2 --- MGS Security Libraries --- p.79 / Chapter 6.5.3 --- MGS Security Configuration --- p.81 / Chapter 7 --- Agent Protection for Mobile Grid Services --- p.83 / Chapter 7.1 --- Overview --- p.83 / Chapter 7.2 --- Major modifications --- p.86 / Chapter 7.2.1 --- Exempting checking for executions on home host --- p.86 / Chapter 7.2.2 --- New definition of stage --- p.87 / Chapter 7.2.3 --- Extra operations in Task Agent and Agent Manager --- p.88 / Chapter 7.2.4 --- Handling of attack --- p.88 / Chapter 7.3 --- Implementation details --- p.91 / Chapter 7.3.1 --- Agent Manager --- p.91 / Chapter 7.3.2 --- Task Agent --- p.97 / Chapter 7.3.3 --- Monitor Agent --- p.101 / Chapter 7.3.4 --- Checker --- p.102 / Chapter 7.4 --- Discussions --- p.108 / Chapter 7.4.1 --- Against modification of code and data --- p.108 / Chapter 7.4.2 --- Against masquerade --- p.108 / Chapter 7.4.3 --- Against fake information in trace --- p.109 / Chapter 7.4.4 --- Against escape from re-execution --- p.109 / Chapter 7.4.5 --- Against collaboration of different hosts --- p.109 / Chapter 7.4.6 --- Detection of malicious host --- p.110 / Chapter 7.4.7 --- Weaknesses --- p.110 / Chapter 8 --- Performance Evaluation --- p.111 / Chapter 8.1 --- Experimental Setup --- p.111 / Chapter 8.2 --- MGS Performance --- p.117 / Chapter 8.2.1 --- Experiment details --- p.112 / Chapter 8.2.2 --- Experiment results --- p.113 / Chapter 8.2.3 --- Discussions --- p.116 / Chapter 8.3 --- MGS Overheads --- p.117 / Chapter 8.3.1 --- Experiment details --- p.117 / Chapter 8.3.2 --- Experiment results --- p.119 / Chapter 8.3.3 --- Discussions --- p.123 / Chapter 8.4 --- Agent Protection Overheads --- p.124 / Chapter 8.4.1 --- Experiment details --- p.124 / Chapter 8.4.2 --- Experiment results --- p.125 / Chapter 8.4.3 --- Discussions --- p.128 / Chapter 9 --- Conclusion and Future Works --- p.130 / Appendix A Administrator Guide for MGS API --- p.132 / Chapter A.l --- Installation of MGS API --- p.132 / Chapter A.1.1 --- Installation of pre-requisites --- p.132 / Chapter A.1.2 --- Installation of MGS API library --- p.135 / Chapter A.2 --- Setup of MGS platform --- p.135 / Chapter A.2.1 --- Setup of JADE platform --- p.135 / Chapter A.2.2 --- Setup of Globus containers --- p.136 / Appendix B Developer Guide for MGS API --- p.137 / Chapter B.1 --- Steps of developing a Mobile Grid Service --- p.137 / Chapter B.1.1 --- Design Mobile Grid Service --- p.137 / Chapter B.1.2 --- Define WSDL --- p.138 / Chapter B.1.3 --- Implement the service --- p.138 / Chapter B.1.4 --- Configure deployment in WSDD --- p.138 / Chapter B.1.5 --- Compile and deploy the service --- p.139 / Chapter B.2 --- Mobile Grid Service Implementation --- p.140 / Chapter B.2.1 --- Implement Task Agent --- p.140 / Chapter B.2.2 --- Implement Monitor Agent (optional) --- p.143 / Chapter B.2.3 --- Implement Agent Manager --- p.144 / Chapter B.3 --- Convert tool --- p.146 / Chapter B.4 --- Service configuration --- p.147 / Chapter B.4.1 --- TaskSetting object --- p.147 / Chapter B.4.2 --- MonitorSetting object --- p.147 / Chapter B.4.3 --- MGS Configuration file --- p.148 / Chapter B.4.4 --- Configuration for Resource Information Service --- p.149 / Chapter B.4.5 --- Globus-side security configuration of the service --- p.151 / Chapter B.5 --- MGS Configuration Helper --- p.151 / Chapter B.5.1 --- “Main Container´ح Panel --- p.152 / Chapter B.5.2 --- “Container´ح Panel --- p.154 / Chapter B.5.3 --- “Service´ح Panel --- p.156 / Chapter B.6 --- Interface details --- p.158 / Chapter B.6.1 --- Package mgs.manager --- p.158 / Chapter B.6.2 --- Package mgs.monitor --- p.165 / Chapter B.6.3 --- Package mgs.task --- p.167 / Chapter B.6.4 --- Package mgs.ftsFramework --- p.174 / Bibliography --- p.176 / Publications --- p.181

This thesis presents a study of applications and techniques for molecular dynamics simulations. Three studies are presented that are intended to improve our ability to simulate larger systems more realistically. A comparison study of two- and three-body potential models for liquid and amorphous Si0��� is presented. The structural, vibrational, and dynamic properties of the substance are compared using two- and three-body potential energy models against experimental results. The three-body interaction does poorly at reproducing the experimental phonon density of states, but better at reproducing the Si-O-Si bond angle distribution. The three-body interaction also produces much higher diffusivities than the two-body interactions. A study of tabulated functions in molecular dynamics is presented. Results show that the use of tabulated functions as a method for accelerating the force and potential energy calculation can be advantageous for interactions above a certain complexity level. The decrease in precision due to the use of tabulated functions is negligible when the tables are sufficiently large. Finally, an investigation into the benefits of multi-threaded programming for molecular dynamics is presented. / Graduation date: 1999

Thesis (Ph. D.)--University of Texas at Dallas, 2006. / Includes vita. Includes bibliographical references (leaves 231-251).

Grid computing is a virtualized distributed computing environment aimed at enabling the sharing of geographically distributed resources. Grid resources have traditionally consisted of dedicated supercomputers, clusters, or storage units. With the present ubiquitous network connections and the growing computational and storage capabilities of modem everyday-use computers, more resources such as PCs, devices (e.g., PDAs and sensors), applications, and services are on grid networks. Grid is expected to evolve from a computing and data management facility to a pervasive, world-wide resource-sharing infrastructure. To fully utilize the wide range of grid resources, effective resource discovery mechanisms are required. However, resource discovery in a global-scale grid is challenging due to the considerable diversity, large number, dynamic behavior, and geographical distribution of the resources. The resource discovery technology required to achieve the ambitious global grid vision is still in its infancy, and existing applications have difficulties in achieving both rich searchability and good scalability. In this thesis, we investigate the resource discovery problem for open-networked global-scale grids. In particular, we propose a distributed semantics-based discovery framework. We show how this framework can be used to address the discovery problem in such grids and improve three aspects of performance: expressiveness, scalability, and efficiency. Expressiveness is the first characteristic that a grid resource-searching mechanism should have. Most existing search systems use simple keyword-based lookups, which limit the searchability of the system. Our framework improves search expressiveness from two directions: First, it uses a semantic metadata scheme to provide users with a rich and flexible representation mechanism, to enable effective descriptions of desired resource properties and query requirements. Second, we employ ontological domain knowledge to assist in the search process. The system is thus able to understand the semantics of query requests according to their meanings in a specific domain; this procedure helps the system to locate only semantically related results. The more expressive the resource description and query request, however, the more difficult it is to design a scalable and efficient search mechanism. We ensure scalability by reconfiguring the network with respect to shared ontologies. This reconfiguration partitions the large unorganized search space into multiple well-organized semantically related sub-spaces that we call semantic virtual organizations. Semantic virtual organizations help to discriminatively distribute resource information and queries to related nodes, thus reducing the search space and improving scalability. To further improve the efficiency of searching the virtual organizations, we propose two semantics-based resource-integrating and searching systems: GONID and OntoSum. These two systems address searching problems for applications based on different network topologies: structured and unstructured peer-to-peer overlay networks. Queries in the search systems are processed in a transparent way, so that users accessing the data can be insulated from the fact that the information is distributed across different sources and represented with different formats. In both systems, ontological knowledge is decomposed into different coarse-grained elements, and then these elements are indexed with different schemes to fit the requirements of different applications. Resource metadata reasoning, integrating, and searching are based on the index. A complex query can be evaluated by performing relational operations such as select, project, and join on combinations of the indexing elements. We evaluate the performance of our system with extensive simulation experiments, the results of which confirm the effectiveness of the design. In addition, we implement a prototype that incorporates our ontology-based virtual organization formation and semantics-based query mechanisms. Our deployment of the prototype verifies the system's feasibility and its applicability to real-world applications.

No description available.

Certain scientific application domains, such as High-Energy Physics or Earth Observation, are expected to produce several Petabytes (220 Gigabyes) of data that is analyzed and evaluated by the scientists all over the world. In the context of data grid technology, data replication is mostly used to reduce access latency and bandwidth consumption. In this thesis, we adopt the typical Data Grid architecture, three kinds of nodes: server, cache, and client nodes. A server node represents a main storage site. A client node represents a site where data access requests are generated, and a cache node represents an intermediate storage site. However, the access latency of the hierarchical storage system may be of the order of seconds up to hours. The static replication strategy can be used to improve such long delay; however, it cannot adapt to changes of users¡¦ behaviors. Therefore, the dynamic data replication strategy is used in Data Grids. Three fundamental design issues in a dynamic replication strategy are: (1) when to create the replicas, (2) which files to be replicated, and (3) where the replicas to be placed. Two of well known replication strategies are Fast-Spread and Cascading, which can work well for different kinds of access patterns individually. For example, the Fast-Spread strategy works well for random access patterns, and the Cascading strategy works well for the patterns with the properties of localities. However, for so many different access patterns, if we use a strategy for one kind of access patterns and another strategy for another kind of access patterns, the system may become too complex. Therefore, in this thesis, we propose one strategy which can work for any kind of access patterns. We propose a replication approach, a Different Threshold (DT) approach to data replication in Data Grids, which can be dynamically adapted to several kinds of access patterns and provide even better performance than Cascading and Fast-Spread strategies. In our approach, there are different thresholds for different layers. Based on this approach, first, we propose a static DT strategy in which the threshold at each layer is fixed. So, by carefully adjusting the difference between the thresholds Ti, where i is the i-th layer of the tree structure, we can even provide the better performance than the above two well-known strategies. Moreover, among large amount of different data files, there may exist some hot data files. Those files which have been mostly requested are hot data files. To reduce the number of requests for the hot files, next, we propose the dynamic DT strategy. In the dynamic DT strategy, each data file even has its own threshold. We let data replication of hot files occur earlier than others by decreasing the thresholds of hot files earlier than the normal ones. From our simulation results, we show that the response time in our static DT strategy is less than that in the Cascading and the Fast-Spread strategies. Moreover, we can show that the performance of the dynamic DT strategy is better than that of the static DT strategy.

Thesis (D. Phil.(Computer Science))--University of Pretoria, 2008. / Includes bibliographical references (leaves 166-183).

Thesis (Ph.D.) -- University of Texas at Arlington, 2009.

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.