在機會網路上，傳遞資料遠比一般網路困難。運用行動代理人於機會網路上， 可大幅提升機會網路的功能，其中的行動代理人平台，需要一個代理人的搜尋 機制，方能實現對代理人的控制。本篇論文以「山文誌登山資訊系統」為背景，探討行動代理人在機會網路上的應用。在此登山客追蹤與環境監控系統中，每個登山客都攜帶一個配備有 GPS 功能的小型設備，此設備會在登山客的移動過程中，自動收集位置資訊，並使用短程無線電來和鄰近的登山客交換彼此的資訊。由於行動代理人是附屬於登山客所攜帶的設備上，而且當靠近其他登山客時，才可藉此轉移到另一個設備，故其行動力受制於登山客的移動行為。因登山客行走速率差異不大、所在位置分佈不均，使得行動代理人的轉移極為緩慢且需仰賴不確定的碰面機會，導致行動代理人之搜尋效率極低，無法支援緊急任務。為此，我們提出控制網路的方法，及一個簡單的搜尋演算法，讓搜尋代理人藉此高速網路來快速移動，以提高目標代理人的搜尋效率。在不同的考量及目標下，我們提出幾個控制網路的建置模型，並在證明其為 NP-complete問題後，提出有效的啟發式演算法來解決此控制點選擇問題。 / Transmitting data on an opportunistic network is much more difficult than that on a general network. The communication capability of an opportunistic network can be greatly enhanced via mobile agent functionality. A mobile agent platform demands a search mechanism to locate and control its agents. In this thesis, we investigate the adoption of mobile agent to opportunistic networks using "CenWits" system as reference model. In CenWits system, each hiker carries a GPS enabled sensor node to collect and exchange movement statistics with its fellow hikers using a short range wireless links. Since mobile agents will be attached to the sensor nodes that hikers carry with, mobile agents can hop from one host to another only when two hosts (hikers) meet together such that their mobility is restrained by the moving behavior of hikers. The little difference in walking speed and the uneven distribution of hikers make the hopping of mobile agents extremely slow and opportunistic. As a consequence, the search of mobile agents is slow and inefficient crippling agility of urgent agent functionality. Therefore, we propose to construct a control network using high speed network for search agents to travel in high speed. Under different objectives and constraints, we propose several control point placement models. After proving them to be NP-Complete, we propose few efficient heuristic algorithms to solve the placement problem. We also propose a simple search algorithm for search agents to search target agents quickly by using a control network.

Mobile agent planning (MAP) is increasingly viewed as an important technique of information retrieval systems to provide location aware services of minimum cost in mobile computing environment. Although Hopfield-Tank neural network has been proposed for solving the traveling salesperson problem, little attention has been paid to the time constraints on resource validity for optimizing the cost of the mobile agent. Consequently, we hypothesized that Hopfield-Tank neural network can be used to solve the MAP problem. To test this hypothesis, we modify Hopfield-Tank neural network and design a new energy function to not only cope with the dynamic temporal features of the computing environment, in particular the server performance and network latency when scheduling mobile agents, but also satisfy the location-based constraints such as the starting and end node of the routing sequence must be the home site of the traveling mobile agent. In addition, the energy function is reformulated into a Lyapunov function to guarantee the convergent stable state and existence of the valid solution. The connection weights between the neurons and the activation function of state variables in the dynamic network are devised in searching for the valid solutions. Moreover, the objective function is derived to estimate the completion time of the valid solutions and predict the optimal routing path. Simulations study was conducted to evaluate the proposed model and algorithm for different time variables and various coefficient values of the energy function. The experimental results quantitatively demonstrate the computational power and speed of the proposed model by producing solutions that are very close to the minimum costs of the location-based and time-constrained distributed MAP problem rapidly. The spatio-temporal technique proposed in this work is an innovative approach in providing knowledge applicable to improving the effectiveness of solving optimization problems.

Annealed neural network combines the characteristics of both simulation annealing and Hopfield-Tank neural network, which are high quality solutions and fast convergence. Mobile agent planning is an important technique of information retrieval systems to provide the minimum cost of the location-aware services in mobile computing environment. By taking the time constraints of effective resources into account and the mobile agent to explore the cost optimization, we modify annealing neural network to design a new energy function and control the annealing temperature in order to deal with the dynamic temporal feature of computing environments. We not only consider the server performance and network latency when scheduling mobile agents, but also investigate the location-based constraints, such as the home site of routing sequence of the traveling mobile agent must be the start and end node. To guarantee the convergent stable state and existence of the valid solution, the energy function is reformulated into a Lyapunov function which is combined with the annealing temperature to form an activation function. The connection weights between the neurons and the activation function of state variables in the dynamic network are devised in searching for the valid solutions. Simulation of different coefficients assess the proposed model and algorithm. Furthermore, Taguchi method is used to obtain the optimal combination factors of annealing neural network. The results show that this research presents the feature of both simulated annealing and Hopfield neural network by providing fast convergence and highly quality. In addition with a larger number of sites, the experimental results demonstrate the benefits of the annealed neural network. This innovation would be applicable to improve the effectiveness of solving optimization problems.

<p>Internet Telephony defined as real time voice or multimediacommunications over packet switched networks dates back to theearly days of the Internet. ARPA's Network SecureCommunications project had implemented, as early as December1973, an infrastructure for local and transnet real time voicecommunication. Two main sets of standards have emerged: H. 323from the ITU-T and the session initiation protocol (SIP) fromthe Internet Engineering Task Force (IETF). Both includespecifications for value added services. Value added services,or more simply services, are critical to service providers'survival and success. Unfortunately, the service architecturesthat come with the ITU-T and the IETF sets of standards arerather weak. Although they are constantly evolving,alternatives and complements need to be researched. This thesiswhich is made up of a formal dissertation and 6 appendices,proposes a novel mobile agent based service architecture forInternet Telephony. The architecture addresses the issues noneof the existing architectures solves in a satisfactory manner.Furthermore it adds mobile agents to the panoply of servicecreation tools. The appendices are reprints of articlespublished in refereed magazines/journals or under considerationfor publication. The formal dissertation is a summary of thepublications. A consistent and comprehensive set ofrequirements are derived. They are TINA-C flavored, but adaptedto Internet Telephony. They are used to critically reviewrelated work and also used to motivate the use of mobile agentsas the pillars of a novel architecture. The components of thisnovel architecture are identified. The key component is themobile service agent. It acts as a folder and carriesservice(s) to which the end-user has subscribed. Mobile serviceagents need to be upgraded when new versions of service logicare available and when end-users make changes to service data.This thesis proposes a novel upgrading framework. The currentInternet infrastructure comprises a wide range of hosts. Mobileagent platforms are now available for most of thesehosts/clients including memory/processing power constrainedPDAs. Our mobile service agents need to adapt to hostvariability when roaming. A novel adaptivity framework is alsoproposed. These two frameworks are general and can be appliedto any other mobile agent which meets a basic set ofassumptions. A key advantage of a mobile agent based servicearchitecture is that it enables the developement of mobileagent based services. The thesis proposes a novel mobile agentbased multi-party session scheduler. The feasibility and theadvantages of the architecture proposed by this thesis havebeen demonstrated by a prototype on which measurements havebeen made. Future work includes the addition of a securityframework to the architecture, and refinenements to theupgrading and adaptivity frameworks. More mobile agent basedservices, especially mobile multi agent based services willalso be developed.</p>

Mobility occurs naturally in many distributed system applications such as telecommunications and electronic commerce. Mobility may reduce bandwidth consumption and coupling and increase flexibility. However, it seems that relatively little work has been done to support quality assurance techniques such as testing and verification of mobile systems. This thesis describes an approach for checking the conformance of a mobile, distributed application with respect to an executable model at runtime. The approach is based on kiltera -- a novel, high-level language supporting the description and execution of models of concurrent, mobile, distributed, and timed computation. The approach allows distributed, rather than centralized, monitoring. However, it makes very few assumptions about the platform that the mobile agent system is implemented in. We have implemented our approach and validated it using four case studies. Two of them are examples of mobile agent systems, the two others are implementations of distributed algorithms. Our approach was able to detect seeded faults in the implementations. To check the effectiveness and the efficiency of our approach more comprehensively a mutation-based evaluation framework has been implemented. In this framework a set of a new mutation operators for mobile agent systems has been identified in order to automatically generate and run a number of mutants programs and then evaluate the ability of our approach to detect these mutants. We found that our approach is very effective and efficient in killing the non-equivalent mutants. / Thesis (Ph.D, Computing) -- Queen's University, 2010-04-27 12:35:47.996

Thesis (Ph. D.)--University of Florida, 2004. / Title from title page of source document. Document formatted into pages; contains 168 pages. Includes vita. Includes bibliographical references.

The mobility attribute of a mobile agent implies deployment thereof in untrustworthy environments, which introduces malicious host threats. The research question deals with how a security framework could be constructed to address the mentioned threats without introducing high costs or restraining the mobile agent's autonomy or performance. Available literature have been studied, analysed and discussed. The salient characteristics as well as the drawbacks of current solutions were isolated. Through this knowledge a dynamic mobile agent security framework was defined. The framework is based on the definition of multiple security levels, depending on type of deployment environment and type of application. A prototype was constructed and tested and it was found to be lightweight and efficient, giving developers insight into possible security threats as well as tools for maximum protection against malicious hosts. The framework outperformed other frameworks / models as it provides dynamic solutions without burdening a system with unnecessary security gadgets and hence paying for it in system cost and performance / Computing / D.Phil.

The mobility attribute of a mobile agent implies deployment thereof in untrustworthy environments, which introduces malicious host threats. The research question deals with how a security framework could be constructed to address the mentioned threats without introducing high costs or restraining the mobile agent's autonomy or performance. Available literature have been studied, analysed and discussed. The salient characteristics as well as the drawbacks of current solutions were isolated. Through this knowledge a dynamic mobile agent security framework was defined. The framework is based on the definition of multiple security levels, depending on type of deployment environment and type of application. A prototype was constructed and tested and it was found to be lightweight and efficient, giving developers insight into possible security threats as well as tools for maximum protection against malicious hosts. The framework outperformed other frameworks / models as it provides dynamic solutions without burdening a system with unnecessary security gadgets and hence paying for it in system cost and performance / Computing / D.Phil.

Agentes móveis são programas que podem ser disparados de um computador (cliente) e transmitidos através de uma rede de comunicação para uma outra maquina (servidor) com o objetivo de executar tarefas a eles designadas. Esta dissertação apresenta uma avaliação de plataformas de desenvolvimento e servidores para agentes móveis. A tecnologia de agentes móveis tem sido alvo de grandes pesquisas, inclusive nos setores de Segurança da Informação e Comércio Eletrônico. Foram executados testes e com as informações foi feita uma análise comparativa, levando-se em consideração questões como características de desempenho dos agentes, desempenho e segurança. Para efetuar os testes foram necessários o entendimento do funcionamento do servidor e o desenvolvimento de seus agentes. Os testes de desempenho serviram para definir quais agentes são mais ágeis e quais são os gastos de processamento dos servidores. Já o teste de segurança teve a finalidade de classificar os servidores quanto à segurança. Os resultados obtidos serviram para indicar qual a melhor plataforma a ser utilizada no desenvolvimento do Sistema de Detecção de Intrusão (SDI) do ICMC. As plataformas que obtiveram destaques nos testes foram o ASDK 1.1 e Grasshopper. A plataforma escolhida para o SDI foi o ASDK 1.1. / Mobile agents are programs able to migrate from a client computer to a server computer through communication networks. There are several mobile agent technologis application, includind Information Security and Eletronic Commerce. This work describes the valuation of mobile agent plataforms. A test environment was desired and 5 plataforms were compared in terms of the security and performance provided. To make the assessment it was necessary to understand the server functionality an the methodologies to develop the agents. The test of performace helped to define which agents are more agile and what are their processing needs while in the server. The security test aimed to classify the servers in them security. The results were used to determine which is better mobile agente plataform to be used in the on going ICMC’s Intrusion Detection System (IDS). The best performance plataforms were the ASDK 1.1 and the Grasshopper. The chosen plataform for the IDS was the ASDK 1.1.

In last few years, the use of wireless sensor networks and cell phones has become ubiquitous; fusing these technologies in the field of business will open up new possibilities. To fill this lacuna, I propose a novel idea where the combination of these will facilitate companies to receive feedback on their products and services. System's unobtrusive sensors will not only collect shopping, mobile usage data from consumers but will also make effective use of this information to increase revenue, cut costs, etc.; the use of mobile agent based data mining allows analyzing the data from different dimensions, categorizing it on factors such as product positioning, promotion of goods, etc. as in the case of a shopping store. Additionally, because of the dynamic mining system the companies get on-the-scene recommendation of products rather than off-the-scene. In this thesis, a novel distributed pervasive mining system is proposed to get dynamic shopping information and mobile device usage of the customers.