Zugl.: Aachen, Techn. Hochsch., Diss., 2010

Zugl.: Potsdam, Univ., Diss., 2009

Thesis (Ph. D. in Computer Science)--Vanderbilt University, Dec. 2005. / Title from title screen. Includes bibliographical references.

Middleware has become a key enabler for the development of distributed applications. Unfortunately, conventional middleware technologies do not yet offer sufficient functionality to make them suitable for mobile environments. This dissertation proposes a novel middleware approach termed opportunistic overlays and its dynamically reconfigurable support framework for building efficient mobile applications. Specifically, we address the inefficiency of content delivery introduced by node mobility and by dynamically changing system loads, in the context of publish/subscribe systems. In response to changes in physical network topology, in nodes' physical locations, and in network node behaviors, the opportunistic overlay approach dynamically adapts event dissemination structures (i.e., broker overlays) with the goal of optimizing end-to-end delays in event delivery. Adaptation techniques include the dynamic construction of broker overlay networks, runtime changes of mobile clients' assignments to brokers, and dynamic broker load balancing. Essentially, opportunistic overlays implement a middleware-level analogue of the networking routing protocols used in wireless communications (i.e., Mobile IP, AODV, DSR and DSDV). By thus coordinating network- with middleware-level routing, opportunistic overlays can attain substantial performance improvements over non-adaptive event systems. Such improvements are due to their use of shorter network paths and better balancing of loads across event brokers. Opportunistic overlays and the adaptive methods they use are realized by a set of distributed protocols implemented in a Java-based publish/subscribe infrastructure. Comprehensive performance evaluations are performed via simulation, emulation, and with two representative applications on actual networks. Experimental results demonstrate that the opportunistic overlay approach is practically applicable and that the performance advantages attained from the use of opportunistic overlays can be substantial, in both infrastructure-based mobile environments and mobile ad hoc networks.

The reliability of RFID systems depends on a number of factors including: RF interference, deployment environment, configuration of the readers, and placement of readers and tags. While RFID technology is improving rapidly, a reliable deployment of this technology is still a significant challenge impeding wide-spread adoption. This research investigates system software solutions for achieving a highly reliable deployment that mitigates inherent unreliability in RFID technology. We have considered two different problem domains for large scale RFID deployment. One is item tracking and the other is guidance-monitoring. Item tracking considers applications that have statically placed RFID readers to observe the RFID tagged objects in motion. An airport scenario to observe the tagged baggage or warehouse scenarios to track the tagged goods are examples of item tracking applications. A self guided tour, search and rescue scenario or a visually impaired person looking for direction and guidance in a tagged environment are examples of item location applications. It is observed that there is a notion of path that follows the direction and flow of the mobile items in the item tracking applications and a path gets created along the direction and flow of the mobile object in item location applications. A system level knowledge of the data flow can benefit the system in different aspects such as improved reliability, resource management and real time response. We have designed and implemented an RFID middleware for item tracking: RF²ID (Reliable Framework for Radio Frequency Identification) to organize and support queries over data streams in an efficient manner. We have developed (1) a virtual reader abstraction to improve the potentially error-prone nature of reader generated data (2) a novel path abstraction to capture the logical flow of information among virtual readers. Prototype implementation using both RFID readers and simulated readers using an empirical model of RFID readers show that RF²ID is able to provide high reliability, support path-based object detection and use efficient resource management techniques. We propose a middleware solution that takes into account the data flow information for item location application that requires real time response. The guidance-monitoring scenario considers mobile RFID readers that traverse in a tagged environment. We consider the scenario of an Assisted Living Center for elderly residents as a motivating guidance-monitoring application. The solution for guidance-monitoring system is called GuardianAngel. The application scenario considers a tagged indoor environment with residents having their own RFID readers to provide them with adequate information about the surroundings. The guidance and monitoring requirement can be conflicting. The guidance information requires very fine grain information about the environment to make proper decisions. On the other hand, the monitoring system must not have a fine grain knowledge which can introduce concerns such as privacy concerns. We consider this aspect during the design and implementation. The system is a two layered infrastructure that has the upper layer which is the monitoring layer. This layer is in charge of monitoring of the actors in the environment. The monitoring layer is physically a set of distributed virtual stations that have the knowledge about the environment. The environment itself is equipped with RFID tags. The residents of the environment have the mobile object that has a sensing element and a computing element (e.g., handhold device with a portable RFID reader) - the guidance server runs on this mobile object. The guidance server is in charge of making local decisions to the users. It is resource limited and asks for new information from the virtual stations as needed. The guidance server also provides the monitoring server with the information regarding the status of the mobile object. But the status information is not fine grain information - the guidance server wraps up the information over a period of time and over a larger region to hide the detailed information of the users.The system uses the logical path based abstraction to guide the users. We have implemented the real testbed using grid structured RFID devices along with scalability study using emulated RFID readers. The basic contribution of our work is based on providing novel middleware solution that is able to serve the application taking into account the inherent unreliability of RFID technology. Our path abstraction that uses the physical flow of data as an ally to generate a logical system level flow enhances the performance in many ways.

Made available in DSpace on 2015-04-11T14:03:07Z (GMT). No. of bitstreams: 1 Pericles Silva de Oliveira.pdf: 1419309 bytes, checksum: a94fd2a3db41a5f73beca4ba46071af0 (MD5) Previous issue date: 2006-04-13 / In directories implementation is common the use of LDAP (Lightweight Directory Access Protocol) protocol. In these directories are stored objects that obey the LDAP schema. The queries effected on the directories use protocol specification, where the client effects queries with filters using parameters. In LDAP version 3 not possible queries without the knowledge of the LDAP schema. Our proposal is a LDAP system, named Flex-LDAP, that to be possible keywords-based queries. That LDAP system use Information Retri eval Model (vectorial model) to queries processing. To evaluate ours LDAP was implemented a server that running on two environments: the first with only LDAP server in version 3 and other with the Flex-LDAP between LDAP client and LDAP Server in version 3. The tests result shows better performance in throughput and flexible queries (only keywords in queries filter). / Em implementações de sistemas constituídos por diretórios é comum a utilização do LDAP (Lightweight Directory Access Protocol ). Nestes diretórios são armazenados objetos que obedecem á esquemas. As consultas efetuadas sobre os diretórios obedecem a uma especificação de protocolo, onde o cliente efetua consultas representadas através de parâmetros. Na versão 3 do suíte LDAP não é possível a realização de consultas, sem o conhecimento prévio do esquema. Nossa proposta é uma especificação de um sistema composto de um suíte LDAP que permita consultas em formato menos rígido, liberando o usuário final da necessidade de conhecer (ou referir-se) previamente o esquema da base para realizar consultas. Em nossa especificação utilizamos uma técnica da área de Recuperação de Informação, denominada de modelo vetorial, incorporada a um servidor LDAP. Para avaliarmos nossa especificação, foi implementado um servidor que denominamos de Flex-LDAP. Nos experimentos utilizamos dois ambientes: um basea do no servidor LDAP tradicional, e outro utilizando nosso servidor Flex-LDAP. Os resultados obtidos mostraram significativas vantagens do uso do Flex-LDAP sob o servidor LDAP tradicional. Tanto na questão da flexibilização das consultas, quanto no aspecto do desempenho do sistema.

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / To ensure range interoperability and range resource reuse are available and promoted across the DoD Test and Training range community, the Central Test and Evaluation Investment Program (CTEIP) has developed and continues to refine the Test and Training Enabling Architecture (TENA). TENA provides the architecture and software implementation to enable range interoperability, to foster range asset reuse, to provide composability, and to enable simulation‐based system engineering/acquisition. TENA has proven to be a critical enabler of major distributed live military exercises but has expanded to embrace other usage. Inclusive of new technologies, TENA developers are actively involved with the integrated Network Enhanced Telemetry (iNET), a CTEIP program which will provide wireless connectivity over which a variety of users will run applications and exchange data.

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / The Foundation Initiative 2010 (FI 2010) project, sponsored by the Office of the Secretary of Defense (OSD) Central Test and Evaluation Investment Program (CTEIP), has developed and is continuing to refine a common architecture and requisite software used to integrate testing, training, and simulation systems distributed across many DoD test and training range facilities. The Test and Training Enabling Architecture (TENA), has been successfully implemented on DoD and commercial range instrumentation systems, used as a reusable enabler of distributed, live United States Joint Forces Command (USJFCOM) and Joint National Training Capability (JNTC) exercises.

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

<p>In this diploma thesis we have aimed to identify metrics that accommodate two chosen system quality factors and implementing the selected metrics in a metrics tool. The metrics chosen should measure change in the system quality factors reusability and maintainability for the middleware system COS at Telenor Mobile and similar systems. The metrics tool should support the aspect-oriented programming language AspectJ, and is planned to be a plugin to the open source code analysis framework XRadar. Changes due to introduction of aspects are of particular interest.</p><p>We have through a GQM process identified the following subcharacteristics for the chosen system quality factors: modularity, testability, analyzability, changeability and stability. Questions are formulated to analyze these sub factors, and metrics that can answer the questions are chosen.</p><p>We have implemented the tool AspectMetrics, which calculate metrics on Java and AspectJ code and generates an XML report containing the measurement results. A transformation from XML to HTML web pages is also provided. The metrics tool can measure size metrics, like the number of statements and the number of classes, coupling, fan-in/fan-out, cohesion and advice-in/advice-out. Advice-in and advice-out are two new metrics which respectively measures how many advice a class (or aspect) is affected by and how many joinpoints an advice hits on. These metrics are inspired by the concept for the fan-in and fan-out metrics.</p><p>The tool has been used to analyze two versions of the system DIAS v.2.0, which is a part of a diploma study in 2000. We have in our preparation project in 2003 added aspects to the DIAS system while keeping the system functionally equal to the original version. We have used our metrics tool to calculate the differences between the system with and the system without aspects. The introduction of aspects gave a positive change in coupling, fan-in/fan-out and size measures, while cohesion was negatively affected. The metrics thus, overall, indicated a positive change to the subcharacteristics testability, analyzability, changeability and stability and both the main quality factors. There was no indication of a positive change to modularity.</p><p>The analysis of the measurement results indicates that most of the metrics perform as intended. The size metrics, coupling, fan-in/fan-out, and advice-in/advice-out all gave results that corresponded to what we had expected. However, the cohesion measure did not behave in a way that could be correlated to the actual changes performed on the code. A closer analysis showed that moving and merging of functionality could result in either an increase or a decrease in cohesion. Thus we find that cohesion, at least in its current form, is not a suitable metric when using aspect-oriented programming. Further, this gave reason to reinvestigate the disappointing modularity results. With a reworked set of criteria we also found indication of improved modularity.</p>