The thesis deals with the study of the computer worm meeting several criteria (it should be fully distributed, decentralized and stealthy). These conditions lead to anonymity, longevity and better security of our worm. After presenting the recently used architectures and new technologies we analyse the known implementations. We propose the solutions with the new design together with the possible ways of improvements. In the next chapter we study biological concepts suitable for the new replication mode, where we implement the key concepts of functionality in a higher programming language. At design we have considered as important to be platform independent, so it is possible for the worm to spread in almost every computer environment, in dependence of implementation of the required modules. Powered by TCPDF (www.tcpdf.org)

M.Sc. / Grid computing is a technology concerned with harvesting idle resources of geographically distributed and interconnected computers. It solves problems regarded as too complex or large to be solved by a single computer. Furthermore, economic grid computing is becoming the most dominant form of grid computing. It enables some form of payment to occur between resource producers and resource consumers in grid computing. Mobile devices and mobile telecommunication services, a relatively new field of technology, are rapidly increasing in popularity, size, strength and application. At the end of 2006, there were approximately 2.7 billion global active mobile users utilising mobile devices and mobile telecommunication services [Aho07]. At the end of 2007 this number had grown to 3.3 billion mobile users, more than half a billion additional mobile users in a period of one year [McN07]. With such large numbers, grid computing can benefit from the clustering of mobile devices forming a mobile grid computing model. However, there are many inherent disadvantages concerning mobile devices, such as low processing capabilities, unpredictable network connections and battery utilisation. Such hurdles must be addressed and solved if a mobile computing infrastructure or architecture is ever to be considered. This dissertation proposes the implementation of an economic mobile computing solution: Mobile Agents for Global Mobile Device Grid Infrastructure Enterprises, or MAGGIE. MAGGIE is concerned with harvesting idle mobile device resources by implementing the supply and demand economic model, aiming to create a healthy competitive economic market environment. MAGGIE implements agent and mobile agent technology to compensate for the hurdles introduced by mobile devices and mobile device software development platforms. It is targeted at both Sun Microsystems’s J2ME MIDP 2.0 and Microsoft’s .NET Compact Framework, enabling lower-end and higher-end mobile devices to contribute mobile computing services and resources for utilisation by other mobile device users. The primary goal of MAGGIE is to produce an architecture as generic as possible regarding the development and implementation of MAGGIE services. MAGGIE allows third-party application developers to seamlessly implement an array of MAGGIE services, without indepth prior knowledge of the architecture and technical aspects of MAGGIE. Finally, MAGGIE’s capabilities are demonstrated by implementing a distributed mobile chess service known as the MAGGIE Chess Service. The MAGGIE Chess Service enables a collection of distributed mobile devices in determining the best move originating from a chessboard position.

Autonomic Computing (AC) aims at solving the problem of managing the rapidly-growing complexity of Information Technology systems, by creating self-managing systems. In this thesis, we have surveyed the progress of the AC field, and studied the requirements, models and architectures of AC. The commonly recognized AC requirements are four properties - self-configuring, self-healing, self-optimizing, and self-protecting. The recommended software architecture is the MAPE-K model containing four modules, namely - monitor, analyze, plan and execute, as well as the knowledge repository. In the modern software marketplace, Java Management Extensions (JMX) has facilitated one function of the AC requirements - monitoring. Using JMX, we implemented a package that attempts to assist programming for AC features including socket management, logging, and recovery of distributed computation. In the experiments, we have not only realized the powerful Java capabilities that are unknown to many educators, we also illustrated the feasibility of learning AC in senior computer science courses.

This report describes a distributed approach to social filtering based on the agent metaphor. Firstly, previous approaches are described, such as cognitive filtering and social filtering. Then a couple of previously implemented systems are presented and then a new system design is proposed. The main goal is to give the requirements and design of an agent-based system that recommends web-documents. The presented approach combines cognitive and social filtering to get the advantages from both techniques. Finally, a prototype implementation called WebCondor is described and results of testing the system are reported and discussed.

[pt] Sistemas multi-agentes são sociedades com agentes autônomos e heterogêneos que podem trabalhar em conjunto para alcançar objetivos similares ou totalmente diferentes. Quando falhas acontecem enquanto algum agente de software tenta alcançar seus objetivos, torna-se importante entender porque tais falhas acontecem e o que pode ser feito para remediar tais problemas. Considerando o ambiente distribuído, dinâmico e a natureza dos sistemas multi-agentes, é importante definir os requisitos necessários para realizar diagnósticos das falhas e recomendações de planos alternativos para agentes que desejam alcançar seus objetivos. Assim, esta dissertação propõe soluções para os principais desafios de criar um sistema que realize diagnósticos e proveja recomendações sobre execuções de agentes. Além disso, o trabalho propõe um framework híbrido de diagnóstico e recomendação que provê suporte para tais desafios. A partir do framework, instâncias de diferentes domínios podem ser criadas, como, por exemplo, aplicações baseadas em computação ubíqua e diferentes diagnósticos e recomendações podem ser providas. / [en] Multi-agent systems are societies with autonomous and heterogeneous agents that can work together to achieve similar or different goals. Agents executing in such systems may not be able to achieve their goals due to failures during system execution. When an agent tries to achieve its desired goals, but faces failures during execution, it becomes important to understand why such failures occurred and what can be done to remedy the problem. The distributed, dynamic and nature of multi-agent systems calls for a new form of failure handling approach to address its unique requirements, which involves both diagnosing specific failures and recommending alternative plans for successful agent execution and goal attainment. We discuss solutions to the main challenges of creating a system that can perform diagnoses and provide recommendations about agent executions to support goal attainment, and propose a hybrid diagnostic-recommendation framework that provides support for methods to address such challenges. From the framework, instances of different domains can be created, such as, applications based on ubiquitous computing and different diagnoses and recommendations can be provided.

[pt] A complexidade e a distribuição de sistemas multiagentes tornam seu desenvolvimento muito sujeito a falhas. Ao mesmo tempo, poucas iniciativas procuram resolver o problema através de teste automatizado da mesma maneira que no desenvolvimento orientado a objetos. Este trabalho apresenta um framework para o desenvolvimento de aplicações de teste automatizado através de agentes Stubs para o middleware M-Law. O middleware implementa um interpretador para a linguagem XMLaw, atuando como mediador da comunicação dos agentes segundo a definição das leis de interação. / [en] Complexity and distribution of multi-agent systems make the development of such systems failure prone. In this context, few solutions try to solve the problem through automated tests as we see in object oriented development. This work presents a framework for test automated applications development through the use of Stub agents for the middleware M-Law. This middleware implements the law-enforcement mechanism for regulating OMAS specified by the description language XMLaw which implements a law definition language, called XMLaw, for agent interaction in open multi-agent systems.

[pt] Os últimos anos têm sido marcados pelo significativo crescimento em todo o mundo da demanda por serviços de telecomunicações. Tal cenário de expansão de redes e da necessidade de coexistência e interoperabilidade de diferentes tecnologias de forma economicamente viável proporciona grandes desafios para a gerência, operação e manutenção de redes de telecomunicações. O presente trabalho apresenta alguns dos principais modelos e paradigmas de gerência de redes tradicionalmente empregados em redes de telecomunicações e que ainda hoje são amplamente utilizados pela indústria. Muitos dos modelos apresentados foram significativamente influenciados por conceitos e técnicas oriundos da área de engenharia de software. Uma grande ênfase é dada particularmente ao uso de técnicas baseadas em agentes de software para gerência de redes. Para tanto, importantes conceitos sobre agentes de software são apresentados, assim como exemplos de trabalhos em que agentes de software são utilizados no domínio de gerência de redes. Por fim, é proposta uma arquitetura baseada em agentes de software para gerência de falhas em redes legadas de telecomunicações, que são comumente gerenciadas por sistemas centralizados. O objetivo principal desta arquitetura é permitir o diagnóstico e a correção de falhas de rede de forma a não sobrecarregar o sistema centralizado de gerência. Para tanto, são utilizados agentes de software que distribuem informações mantidas no sistema centralizado para outros agentes do sistema. Desta forma, é possível que os agentes responsáveis por executar os procedimentos de diagnóstico e correção de falhas desempenhem suas atividades sem a necessidade de uma comunicação direta com o sistema centralizado. / [en] The last few years have been marked by a significant and worldwide growth in the demand for telecommunications services. Such scenery of network expansion and the need for coexistence and interoperability of different technologies in an economically viable way provides great challenges for the management, operation and maintenance of telecommunications networks. This work presents some of the main network management models and paradigms traditionally employed in telecommunications networks and that still count with wide adoption in the industry as of this day. Many of the presented models have been significantly influenced by concepts and techniques originated in the software engineering field. A great emphasis is particularly given to the use of network management techniques based on software agents. To this end, important concepts of software agents are presented, as well as examples of works where software agents are used in the network management domain. Finally, an architecture based on software agents used for fault management in legacy telecommunications networks, which are usually managed by centralized systems, is proposed. The main objective of this architecture is to allow the diagnosis and the correction of network faults in a way not to overload the centralized management system. To this end, the architecture uses software agents that distribute information maintained in the centralized management system to other agents of the system. In such way, it is possible for the agents responsible for executing the fault diagnosis and correction procedures to perform their activities without the necessity for direct communication with the centralized system.

Nous nous intéressons dans cette thèse à la planification pour les problèmes de prise de décision décentralisée séquentielle dans l'incertain. Dans le cadre centralisé, l'utilisation des formalismes MDP et POMDP a permis d'élaborer des techniques de planification efficaces. Le cadre Dec-POMDP permet de formaliser les problèmes décentralisés. Ce type de problèmes appartient à une autre classe de complexité que les problèmes centralisés. Pour cette raison, jusqu'à récemment, seuls de très petits problèmes pouvaient être résolus et uniquement pour des horizons très faibles. Des algorithmes heuristiques ont récemment été proposés pour traiter des problèmes de taille plus conséquente mais n'ont pas de preuve théorique de qualité de solution. Nous montrons comment une information heuristique sur le problème à résoudre représentée par une distribution de probabilité sur les croyances centralisées permet de guider la recherche approchée de politique. Cette information heuristique permet de formuler chaque étape de la planification comme un problème d'optimisation combinatoire. Cette formulation conduit à des politiques de meilleure qualité que les approches existantes. / In this thesis, we focus on planning in decentralised sequentialdecision taking in uncertainty. In the centralised case, the MDP andPOMDP frameworks leads to efficient planning algorithms. The Dec-POMDPframework is used to model decentralised problems. This kind ofproblems is in a higher class of complexity than the centralisedproblem. For this reason, until recently, only very small problem could be solved and only for very small horizons. Recently, some heuristic algorithms have been proposed to handle problem of higher size but there is no theoretic proof of the solution quality. In this thesis, we show how to use a heuristic information in the problem, modelled as a probability distribution on the centralised beliefs, to guide the search for a good approximate policy. Using this heuristic information, we formulate each time step of the planning procedure as a combinatorial optimisation problem. This formulation leads to policies of better quality than previously existing approaches.

[pt] Esta dissertação propõe um framework de sistemas multi- agentes para aplicações do domínio de Radio Frequency Identification (RFID). Esta tecnologia de identificação automática de objetos vem se desenvolvendo rapidamente e promete substituir brevemente a tecnologia atual de identificação de produtos: código de barras. Além de promover o desenvolvimento de hardware para etiquetas e leitoras RFID, novos padrões de identificação estão sendo propostos, desafiando os desenvolvedores de software a produzirem novas soluções para lidar com o novo e maior volume de dados e com a natureza distribuída das leitoras e leituras de objetos. Esta dissertação propõe um framework projetado utilizando-se a abordagem de sistemas multi-agentes (SMA) capaz de instanciar SMA distribuídos que: - Interagem com a infra-estrutura RFID existente (leitoras, etiquetas e middlewares); - Facilitam a geração de informações com semântica de negócios a partir de dados crus gerados por esta infra-estrutura, e; - Facilitam a implementação de novas funcionalidades decorrentes do leque de aplicações vislumbradas pelo surgimento de RFID. / [en] Radio Frequency Identification (RFID) technology along with the Electronic Product Code (EPC) created a new complex environment for warehouses systems and supply chain systems in general. The EPC specification created one more level of identification: the product instance. This new level of identification had blown the volume of data being managed by applications. That fact, along with the deployment of distributed RFID readers, causes the necessity of new applications capable of interacting with this infrastructure and capable of processing, filtering and interpreting these new data. This work proposes a framework for distributed multi-agent systems capable of interacting with a deployed RFID infrastructure.

Este trabalho apresenta o projeto e arquitetura de uma plataforma para execução de Agentes com funções implementadas em hardware, tomando vantagem do uso de hardware reconfigurável. Os Agentes em hardware são implementados utilizando dispositivos FPGA (Field-programmable Gate Array). O trabalho estende trabalhos anteriores semelhantes na área, com o diferencial de adicionar suporte às funcionalidades de reconfiguração parcial do hardware, suportar aplicações que demandam alto desempenho em hardware – como processamento de sinais e imagens – e redução de recursos de hardware necessários para execução da interface em software. A plataforma proposta utiliza o framework JADE (Java Agent Development Framework), que é um dos frameworks mais populares no estado da arte de desenvolvimento de Agentes e compatível com outros frameworks de Agentes através da conformidade aos padrões FIPA (Foundation for Intelligent Physical Agents). Com o uso do JADE, a plataforma possibilita a comunicação entre Agentes com funções implementadas em hardware e Agentes puramente implementados em software dentro de um mesmo SMA (Sistema Multi-Agente). Uma funcionalidade notável do JADE é a possibilidade de migração de Agentes entre plataformas de um mesmo SMA. Através do uso da reconfiguração parcial de hardware em conjunto com o JADE, a plataforma permite a migração de Agentes de software para hardware e vice-versa, além de suportar reconfiguração de múltiplos Agentes em hardware com um único FPGA. A plataforma faz uso de um único chip através do uso de um processador soft core implementado na lógica programável. O uso deste processador é um diferencial neste trabalho, e mostra que é possível utilizar o JADE em sistemas embarcados com recursos de processamento limitados. Ou seja, em um Agente cuja principal função é implementada em hardware, basta um processador bastante simples para atuar como uma interface entre o hardware e o framework de Agentes. O uso do processador dentro do FPGA tem também o benefício de oferecer formas de acesso mais integrado ao hardware, permitindo maior desempenho na transmissão de dados ao hardware. A plataforma foi validada através de estudos de caso de Agentes com implementações em hardware e em software, incluindo um estudo de caso aplicado de processamento de imagem embarcado utilizando VANTs (Veículos Aéreos Não-Tripulados). O estudo também apresenta comparações de desempenho entre a execução dos Agentes em hardware e em outras plataformas embarcadas de prateleira. Os experimentos realizados mostram um ganho significativo de desempenho nas implementações em FPGA, especialmente considerando processamento de imagens de alta resolução, mesmo considerando que o FPGA executa em frequências consideravelmente reduzidas em comparação às outras plataformas testadas. / This work described the design and architecture of a platform for execution of Agents whose functions are implemented in hardware, by leveraging the use of reconfigurable hardware. The hardware Agents are implemented using FPGA (Field-programmable Gate Array) devices. This work extends previous similar work in this field, while adding the features of hardware partial reconfiguration, supporting applications which require high performance in hardware – such as image or signal processing – and reducing the hardware resource for the software interface execution. The proposed platform makes use of the JADE (Java Agent Development Framework) framework, which is one of the most popular frameworks in state-of-the-art Agent development, and is also compatible with other Agent development frameworks due to compliance with FIPA (Foundation for Intelligent Physical Agents) standards. With the use of JADE, the platform enables communication among Agents which are implemented in hardware and Agents purely implemented in software, inside the same MAS (Multi-Agent System). One notable feature of JADE is the possibility of migrating Agents among platforms inside a single MAS. Through the use of hardware partial reconfiguration along with JADE, the platform enables the migration of Agents from software to hardware and viceversa, in addition to supporting múltiple hardware Agents in a single FPGA. The platform makes use of a single chip, by using a MicroBlaze soft core processor implemented in programmable logic. The use of this processor is a distinction on this work, and it shows that it is possible to use JADE on embedded systems with limited processing power. That is, in an Agent whose main function is implemented in hardware, a very simple processor to act as an interface between hardware and the Agent framework is enough. The use of the soft core processor inside the FPGA also has the benefit of offering more integrated ways of accessing hardware, enabling higher performance for transferring data to hardware. The platform was validated through case studies of hardware and software Agent implementation, including a case study applied to image processing using UAVs (Unmanned Aerial Vehicles). The study also shows performance comparisons between the Agent execution in hardware and in other off-the-shelf embedded platforms. The performed experiments report a significative performance increase in the FPGA implementations, particularly in high resolution image processing, even considering that the FPGA runs in considerably lower clock frequency than the other tested platforms.