Building autonomous mobile agents has been a major research effort for a while with cooperative mobile robotics receiving a lot of attention in recent times. Motion planning is a critical problem in deploying autonomous agents. In this research we have developed two novel global motion planning schemes for a group of mobile agents which eliminate some of the disadvantages of the current methods available. The first is the homotopy method in which the planning is done in polynomial space. In this method the position in local frame of each mobile agent is mapped to a complex number and a time varying polynomial contains information regarding the current positions of all mobile agents, the degree of the polynomial being the number of mobile agents and the roots of the polynomial representing the position in local frame of the mobile agents at a given time. This polynomial is constructed by finding a path parameterized in time from the initial to the goal polynomial (represent the initial and goal positions in local frame of the mobile agents) so that the discriminant variety or the set of polynomials with multiple roots is avoided in polynomial space. This is equivalent to saying that there is no collision between any two agents in going from initial position to goal position. The second is the homogeneous deformation method. It is based on continuum theory for motion of deformable bodies. In this method a swarm of vehicles is considered at rest in an initial configuration with no restrictions on the initial shape or the locations of the vehicles within that shape. A motion plan is developed to move this swarm of vehicles from the initial configuration to a new configuration such that there are no collisions between any vehicles at any time instant. It is achieved via a linear map between the initial and desired final configuration such that the map is invertible at all times. Both the methods proposed are computationally attractive. Also they facilitate motion coordination between groups of mobile agents with limited or no sensing and communication.

The last decade has seen an explosion in the growth and use of the Internet. Rapidly evolving network and computer technology, coupled with the exponential growth of services and information available on the Internet, is heralding in a new era of ubiquitous computing. Hundreds of millions of people will soon have pervasive access to a huge amount of information, which they will be able to access through a plethora of diverse computational devices. These devices are no longer isolated number crunching machines; rather they are on our desks, on our wrists, in our clothes, embedded in our cars, phones and even washing machines. These computers are constantly communicating with each other via LANs, Intranets, the Internet, and through wireless networks, in which the size and topology of the network is constantly changing. Over this hardware substrate we are attempting to architect new types of distributed system, ones that are able to adapt to changing qualities and location of service. Traditional theories and techniques for building distributed systems are being challenged. In this new era of massively distributed computing we require new paradigms for building distributed systems. This thesis is concerned with how we structure distributed systems. In Part I, we trace the emergence and evolution of computing abstractions and build a philosophical argument supporting mobile code, contrasting it with traditional distribution abstractions. Further, we assert the belief that the abstractions used in traditional distributed systems are flawed, and are not suited to the underlying hardware substrate on which contemporary global networks are built. In Part U, we describe the experimental work and subsequent evaluation that constitutes the first steps taken to validate the arguments of Part I.

Research Doctorate - Doctor of Philosophy (PhD) / Mobile agents are programs that travel autonomously through a computer network in order to perform some computation or gather information on behalf of a human user or an application. In the last several years numerous applications of mobile agents have emerged, including e-commerce. However, mobile agent paradigm introduces a number of security threats both to the agents themselves and to the servers that they visit. This thesis gives an overview of the main security issues related to the mobile agent paradigm. The first part of the thesis focuses on security of mobile agent itself. In this part, we propose a new coupling technique based on trust as a social control to work together with existing traditional security mechanisms. It relies on the “reputation” of the hosts in the itinerary and ensures that the agent succeeds in accomplishing its task with a high probability. Due to the fact that the coupling technique requires an agent’s itinerary to be known in advance, we introduce two new concepts: a “Scout mobile agent”, whose primary purpose is to determine the itinerary required for accomplishing a given task, and a “Routed mobile agent”, which operates with an itinerary known in advance. This enables the Routed agent to incorporate various security mechanisms, including our new coupling technique. Our Routed agent technique is also applicable independently of the Scout agent, whenever the itinerary and the trust values of the platforms in the itinerary are known. We also proposed a Petrol Station as an entity that would provide a service to other entities, in the form of certifying mobile agents and equipping them with safe itinerary based on trust score and applying the Routed agent. In the second part of the thesis, we shed some light on the security of mobile agent platforms as it is considered more critical than the security of agents. In particular, we consider a scenario where a platform hosts a database containing confidential individual information and allows mobile agentstoquery the data base. This mobile agent maybe behave maliciously which is similar to an intruder in the Statistical Disclosure Control(SDC), where measuring disclosure risk is still considered as a difficult and only partly solved problem[111]. We introduce a scenario that is not adequately covered by any of the previous discloser risk measures. Shannon’s entropy can be considered a satisfactory measure for the disclosure risk that is related to the exact compromise. However, in the case of approximate compromise, we argue that Shannon’s entropy does not express precisely the intruder’s knowledge about a particular confidential value. We introduce a novel disclosure risk measure that is based on Shannon’s entropy but covers both exact and approximate compromise. The main advantage of our measure over previously proposed measures that it gives careful consideration to the attribute values in addition to the probabilities with which the values occur. We use a dynamic programming algorithm to calculate the disclosure risk for various levels of approximate compromise. Importantly, our proposed measure is independent of the applied SDC technique. Finally, we show how this measure can be used to evaluate the security mechanisms for protecting privacy in statistical databases and data mining. We conduct extensive experiments and apply our proposed security measure to three different data sets protected by three different SDC techniques, namely Sampling, Query Restriction, and Noise Addition.

Research Doctorate - Doctor of Philosophy (PhD) / Mobile agents are programs that travel autonomously through a computer network in order to perform some computation or gather information on behalf of a human user or an application. In the last several years numerous applications of mobile agents have emerged, including e-commerce. However, mobile agent paradigm introduces a number of security threats both to the agents themselves and to the servers that they visit. This thesis gives an overview of the main security issues related to the mobile agent paradigm. The first part of the thesis focuses on security of mobile agent itself. In this part, we propose a new coupling technique based on trust as a social control to work together with existing traditional security mechanisms. It relies on the “reputation” of the hosts in the itinerary and ensures that the agent succeeds in accomplishing its task with a high probability. Due to the fact that the coupling technique requires an agent’s itinerary to be known in advance, we introduce two new concepts: a “Scout mobile agent”, whose primary purpose is to determine the itinerary required for accomplishing a given task, and a “Routed mobile agent”, which operates with an itinerary known in advance. This enables the Routed agent to incorporate various security mechanisms, including our new coupling technique. Our Routed agent technique is also applicable independently of the Scout agent, whenever the itinerary and the trust values of the platforms in the itinerary are known. We also proposed a Petrol Station as an entity that would provide a service to other entities, in the form of certifying mobile agents and equipping them with safe itinerary based on trust score and applying the Routed agent. In the second part of the thesis, we shed some light on the security of mobile agent platforms as it is considered more critical than the security of agents. In particular, we consider a scenario where a platform hosts a database containing confidential individual information and allows mobile agentstoquery the data base. This mobile agent maybe behave maliciously which is similar to an intruder in the Statistical Disclosure Control(SDC), where measuring disclosure risk is still considered as a difficult and only partly solved problem[111]. We introduce a scenario that is not adequately covered by any of the previous discloser risk measures. Shannon’s entropy can be considered a satisfactory measure for the disclosure risk that is related to the exact compromise. However, in the case of approximate compromise, we argue that Shannon’s entropy does not express precisely the intruder’s knowledge about a particular confidential value. We introduce a novel disclosure risk measure that is based on Shannon’s entropy but covers both exact and approximate compromise. The main advantage of our measure over previously proposed measures that it gives careful consideration to the attribute values in addition to the probabilities with which the values occur. We use a dynamic programming algorithm to calculate the disclosure risk for various levels of approximate compromise. Importantly, our proposed measure is independent of the applied SDC technique. Finally, we show how this measure can be used to evaluate the security mechanisms for protecting privacy in statistical databases and data mining. We conduct extensive experiments and apply our proposed security measure to three different data sets protected by three different SDC techniques, namely Sampling, Query Restriction, and Noise Addition.

This thesis undertakes to provide an architecture and understanding of the incorporation of trust into the paradigm of mobile multi-agent systems. Trust deliberation is a soft security approach to the problem of mobile agent security whereby an agent is protected from the malicious behaviour of others within the system. Using a trust approach capitalises on observing malicious behaviour rather than preventing it. We adopt an architectural approach to trust such than we do not provide a model in itself, numerous mathematical models for the calculation of trust based on a history of observations already exist. Rather we look to provide the framework enabling such models to be utilised by mobile agents. As trust is subjective we envisage a system whereby individual agents will use different trust models or different weighting mechanisms. Three architectures are provided. Centralised whereby the platform itself provides all of the services needed by an agent to make observations and calculate trust. Decentralised in which each individual agent is responsible for making observations, communicating trust and the calculation of its own trust in others. A hybrid architecture such that trust mechanisms are provided by the platform and additionally are embedded within the agents themselves. As an optimisation of the architectures proposed in this thesis, we introduce the notion of trust communities. A community is used as a means to represent the trust information in categorisations dependant upon various properties. Optimisation occurs in two ways; firstly with subjective communities and secondly with system communities. A customised implementation framework of the architectures is introduced in the form of our TEMPLE (Trust Enabled Mobile-agent PLatform Environment) and stands as the underpinning of a case-study implementation in order to provide empirical evidence in the form of scenario test-bed data as to the effectiveness of each architecture. The case study chosen for use in a trust based system is that of a fish market' as given the number of interactions, entities, and migration of agents involved in the system thus, providing substantial output data based upon the trust decisions made by agents. Hence, a good indicator of the effectiveness of equipping agents with trust ability using our architectures.

M.Sc.(Computer Science) / The dissertation investigates trust and reputation as a specialisation of agent technology. The research presented herein aims to establish and demonstrate how it is possible for one rational agent to trust another entity. Furthermore, the research presented herein aims to determine the extent of the limitations of trust and reputation models, and of the demonstrable solution in particular. To this end, the dissertation investigates theoretical aspects of trust. The dissertation investigates several existing trust models and establishes criteria for a qualitative analysis. Supplementary techniques aimed at enhancing trust evaluation are also investigated. The research also identifies architectural abstractions suitable for developing agents capable of intelligent trust evaluation. The main focus of the research is enhancing agent protection through a trust-based approach. A particular problem is the threats posed to mobile agents from malicious agent hosts. Therefore, a solution is sought that can be used to augment existing mechanisms aimed at mobile agent protection and agent protection in general. Thus, the research also examines mobile agents and mobile agent systems in an effort to produce a general trust-based solution that can be applied in most mobile agent systems. The solution presented in the dissertation proposes the concept of an evaluator agent as an add-on to existing mobile agent systems. The evaluator agent is presented as a rational agent with an embedded intelligent trust evaluation capability. The intelligent trust evaluation capability is provided via a set of reusable components. The solution demonstrates how a rational agent may evaluate the trustworthiness of other entities. The dissertation further analyses the strengths and limitations of the approach. The dissertation provides results that quantitatively demonstrate the extent of the limitations of the trust-based approach. The contribution of the dissertation partly lies in the service orientation of the evaluator agent approach. The service orientation of the solution provides an abstraction and a degree of heterogeneity suitable for handling the challenges of open environments. The solution can be deployed in most mobile agent systems to provide a trust evaluation service without the need to redesign existing mobile agent systems. More broadly, the research is another step towards the development of cognitive social agents.

With the advances of wireless communications and micro-electronic device technologies, wireless sensor networks have been applied in a wide spectrum of applications, including one of the killer applications--object tracking. Among numerous challenges in object tracking, one of the important issues is the energy management. One solution to the above issue is the mobile agent-based paradigm. Using the mobile agent in wireless sensor networks has many advantages over the client/server paradigm in terms of energy consumptions, networks band-width, etc. In this thesis, we adopt the mobile agent-based paradigm to support object track-ing in wireless sensor networks. Although using the mobile agents for object tracking can improve the overall perfor-mance, the hurdle is the determination of the mobile agent itinerary. The past studies on ob-ject tracking considered the object¡¦s movement behavior as randomness or the direction and the speed of the object remain constant for a certain period of time. However, in most real-world cases, the object movement behavior is often based on certain underlying events rather than randomness complete. With this assumption, the movements of objects are some-times predictable. Through the prediction, the mobile agent can determine which node to mi-grate in order to reduce energy consumption and increase the performance of object tracking. In this thesis, we develop a mining-based approach to discover the useful patterns from the object¡¦s movement behavior. This approach utilizes the discovered rules to choose the sensor node the mobile agent needs to migrate in order to reduce the number of wrong migration, to reduce total energy consumed by sensor nodes, and to prolong the lifetime of the wireless sensor network. Experimental results show the efficiency of the proposed approach.

Portable languages and distributed paradigms have driven a wave of new applications and processing models. One of the most promising, certainly from its early marketing, but disappointing (from its limited uptake)is the mobile agent execution and data processing model. Mobile agents are autonomous programs which can move around a heterogeneous network such as the Internet, crossing through a number of different security domains, and perform some work at each visited destination as partial completion of a mission for their agent user. Despite their promise as a technology and paradigm to drive global electronic services (i.e.any Internet-driven-and-delivered service, not solely e-commerce related activities), their up take on the Internet has been very limited. Chief among the reasons for the paradigm's practical under-achievement is there is no ubiquitous frame work for using Internet mobile agents, and non-trivial security concerns abound for the two major stake holders (mobile agent users and mobile agent platform owners). While both stake holders have security concerns with the dangers of the mobile agent processing model, most investigators in the field are of the opinion that protecting mobile agents from malicious agent platforms is more problematic than protecting agent platforms from malicious mobile agents. Traditional cryptographic mechanisms are not well-suited to counter the bulk of the threats associated with the mobile agent paradigm due to the untrusted hosting of an agent and its intended autonomous, flexible movement and processing. In our investigation, we identified that the large majority of the research undertaken on mobile agent security to date has taken a micro-level perspective. By this we mean research focused solely on either of the two major stakeholders, and even then often only on improving measures to address one security issue dear to the stake holder - for example mobile agent privacy (for agent users) or access control to platform resources (for mobile agent platform owners). We decided to take a more encompassing, higher-level approach in tackling mobile agent security issues. In this endeavour, we developed the beginnings of an infrastructural-approach to not only reduce the security concerns of both major stakeholders, but bring them transparently to a working relationship. Strategic utilisation of both existing distributed system trusted-third parties (TTPs) and novel mobile agent paradigm-specific TTPs are fundamental in the infrastructural framework we have devised. Besides designing an application and language independent frame work for supporting a large-scale Internet mobile agent network, our Mobile Agent Secure Hub Infrastructure (MASHIn) proposal encompasses support for flexible access control to agent platform resources. A reliable means to track the location and processing times of autonomous Internet mobile agents is discussed, withfault-tolerant handling support to work around unexpected processing delays. Secure,highly-effective (incomparison to existing mechanisms) strategies for providing mobile agent privacy, execution integrity, and stake holder confidence scores were devised - all which fit comfortably within the MASHIn framework. We have deliberately considered the interests - withoutbias -of both stake holders when designing our solutions. In relation to mobile agent execution integrity, we devised a new criteria for assessing the robustness of existing execution integrity schemes. Whilst none of the existing schemes analysed met a large number of our desired properties for a robust scheme, we identified that the objectives of Hohl's reference states scheme were most admirable - particularly real - time in - mission execution integrity checking. Subsequently, we revised Hohl's reference states protocols to fit in the MASHIn framework, and were able to overcome not only the two major limitations identified in his scheme, but also meet all of our desired properties for a robust execution integrity scheme (given an acceptable decrease in processing effiency). The MASHIn offers a promising new perspective for future mobile agent security research and indeed a new frame work for enabling safe and autonomous Internet mobile agents. Just as an economy cannot thrive without diligent care given to micro and macro-level issues, we do not see the security prospects of mobile agents (and ultimately the prospects of the mobile agent paradigm) advancing without diligent research on both levels.

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>NR 20140805</p>

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.