The need for increased computational power is growing faster than our ability to produce faster computers. Already researchers are proposing systems that require peta-flop capable super computers, a far cry from what is currently capable. To meet such high computational requirements, networks of computers will be required. While it is possible to network together computers to achieve a single task, making that network more flexible to handle a multitude of different tasks is the promise of grid computing. <p>Grid systems are slowly appearing that are designed to run many independent tasks, and provide the ability for programs to migrate between machines before completion. However, these systems lack coordination capabilities. Many grid systems/environments allow multiple tasks to communicate/coordinate with each other based on various paradigms, but don't provide migration capabilities. <p>This thesis proposes a system, called JOLTS, that attempts to fill a gap by providing both checkpointing and coordination capabilities. The coordination model offered by JOLTS is based on the Objective Linda coordination language, with some additions. This thesis will show that the object space model is an effective form of coordination and communication, and can effectively be combined with checkpointing capabilities inside the same grid system.

The need for increased computational power is growing faster than our ability to produce faster computers. Already researchers are proposing systems that require peta-flop capable super computers, a far cry from what is currently capable. To meet such high computational requirements, networks of computers will be required. While it is possible to network together computers to achieve a single task, making that network more flexible to handle a multitude of different tasks is the promise of grid computing. <p>Grid systems are slowly appearing that are designed to run many independent tasks, and provide the ability for programs to migrate between machines before completion. However, these systems lack coordination capabilities. Many grid systems/environments allow multiple tasks to communicate/coordinate with each other based on various paradigms, but don't provide migration capabilities. <p>This thesis proposes a system, called JOLTS, that attempts to fill a gap by providing both checkpointing and coordination capabilities. The coordination model offered by JOLTS is based on the Objective Linda coordination language, with some additions. This thesis will show that the object space model is an effective form of coordination and communication, and can effectively be combined with checkpointing capabilities inside the same grid system.

The purpose of this project is to update the tool of Network Traffic Recognition System (NTRS) which is proprietary software of Ericsson AB and Tsinghua University, and to implement the updated tool to finish SIP/VoIP traffic recognition. Basing on the original NTRS, I analyze the traffic recognition principal of NTRS, and redesign the structure and module of the tool according to characteristics of SIP/VoIP traffic, and then finally I program to achieve the upgrade. After the final test with our SIP data trace files in the updated system, a satisfactory result is derived. The result presents that our updated system holds a rate of recognition on a confident level in the SIP session recognition as well as the VoIP call recognition. In the comparison with the software of Wireshark, our updated system has a result which is extremely close to Wireshark’s output, and the working time is much less than Wireshark. In the aspect of practicability, the memory overflow problem is avoided, and the updated system can output the specific information of SIP/VoIP traffic recognition, such as SIP type, SIP state, VoIP state, etc. The upgrade fulfills the demand of this project.

This thesis reports research conducted into a character recognition system suitable for use in a reading aid for the blind. A brief review of blind reading aids is given, showing the need for a device which is cheap, simple and effective. The structure of a proposed reading aid fulfilling these needs is outlined, with a list of the desired characteristics of each of its subsystems. The remainder of the thesis is concerned with research into just two of these subsystems: the input device and the character recognizer. A detailed review of pattern recognition by the n-tuple method is presented, followed by a description of the experimental techniques used in obtaining real data from a camera system, and in simulating various recognizer structures. The camera system and computer programs developed specifically for the research are described in detail. Several series of experiments are reported, concerned mainly with investigating problems associated directly with the blind reading aid, namely accommodation of multifont printed text and of the tracking errors inherent in data from a hand-held probe. A further series of experiments, aimed at improving the performance of the recognizer within fixed size constraints, i. e., optimisation, has a wider field of application. Finally suggestions are made as to how the recognizer might be implemented in a reading aid, using RAMs, ROMs, or PLAs as the main storage elements.

Mobile applications are deployed in highly dynamic environments. Devices have limited resources available and the user context changes frequently. This introduces new requirements for applications, and requires that applications are able to adapt during runtime. In addition, developers must be able to incrementally add new behaviour to applications as required by unanticipated situations. Current approaches to mobile application development and architectures do not properly address these requirements of mobile applications. This work proposes a framework, based on coordination principles, which is able to facilitate the required methods of adaptation. The framework incorporates a methodology and an architecture. The architecture provides significant advantages over previous work in terms of adaptation support. The methodology provides developers with a development process and guidelines whereby adaptive applications may be specified. As new requirements of existing applications emerge, developers can build and deploy additions to applications during runtime. The research has been evaluated through the design of application prototypes. These were built through the use of an implemented toolkit for application development, which is based on the specified methodology. The architecture, methodology and toolkit provide a unifying framework for mobile applications. The work presented in this thesis closes a gap in existing knowledge in the design and execution of distributed mobile applications.

The Generative Communication (GC) paradigm was introduced in the early 1980s in the form of the Linda coordination and communication language (Gelernter & Bernstein, 1982). The goal of the language was to provide an elegant, intuitive alternative to the state-of-the-art in parallel and distributed processing languages at that time, namely remote procedure calls; message passing systems; and shared memory systems (Gelernter, 1985). Despite the longevity of the Linda coordination language and the GC paradigm, in general, the literature is devoid of meaningful research into the construction and manipulation of dynamic, pointer-based data structures within the context of the GC paradigm. This document motivates the need for such data structures in GC. In addition, this document explores the reasons for the lack literature regarding dynamic pointer-based data structures in GC. Finally, we develop solutions to address the lack of support, within the GC paradigm, for such data structures. / Ph. D.

Este trabalho explora a gerência de segurança e cooperação de aplicações em sistemas distribuídos móveis. Neste contexto, é feito um estudo sobre os diferentes middlewares para ambientes móveis (mobile middleware): suas capacidades de enfrentar os desafios da mobilidade e da segurança. As análises do estudo mostram que esses middlewares devem possuir características que lhes permitem uma melhor adaptação às necessidades das aplicações e à natureza dos ambientes móveis. Os middlewares existentes pouco abordam a questão da segurança. A segurança ainda é um problema complexo que deve ser gerido em todos os níveis de um sistema distribuído móvel, incluindo novos mecanismos. Com base nessa análise, foi desenvolvido um modelo de gerência de segurança que implementa um mecanismo de autenticação mútua, confidencialidade, detecção de intruso e controle de acesso em ambientes móveis. O objetivo é garantir a confiabilidade, a disponibilidade de serviços e a privacidade do usuário através da tecnologia PET - Privacy-Enhancing Tecnologies. A idéia é fundamentada em agentes interceptadores e autoridades de segurança que distribuem tíquetes de segurança e controlam o acesso a recursos e espaços de tuple do ambiente. O estudo de caso apresentou resultados satisfatórios que permitem julgar a pertinência do modelo proposto. O modelo será integrado a um sistema de e-saúde. / The work exploits the security management and the cooperation of applications in mobile distributed systems. In this context a study of different mobile middleware is made. The study examines their capacities to face the challenges of mobility and security issues. The analysis shows that the existing middleware has very few approaches on security problems; security is still a complex issue to be managed in all the levels of mobile distributed system including new mechanisms. Based on this analysis, a security management model is developed that implements a mechanism for mutual authentication, confidentiality, intrusion detection, access control of mobile agents in mobile environments, ensures services availability and user privacy, through technology PET (Privacy-Enhancing Technologies). The idea is based on interceptor agents and security authorities that distribute security tickets and control the access to resources and Tuple spaces in mobile environment. The proposed model presents good performance and is integrated to an e-health system: Relationship Management with Chronic Patient GRPC.

Este trabalho explora a gerência de segurança e cooperação de aplicações em sistemas distribuídos móveis. Neste contexto, é feito um estudo sobre os diferentes middlewares para ambientes móveis (mobile middleware): suas capacidades de enfrentar os desafios da mobilidade e da segurança. As análises do estudo mostram que esses middlewares devem possuir características que lhes permitem uma melhor adaptação às necessidades das aplicações e à natureza dos ambientes móveis. Os middlewares existentes pouco abordam a questão da segurança. A segurança ainda é um problema complexo que deve ser gerido em todos os níveis de um sistema distribuído móvel, incluindo novos mecanismos. Com base nessa análise, foi desenvolvido um modelo de gerência de segurança que implementa um mecanismo de autenticação mútua, confidencialidade, detecção de intruso e controle de acesso em ambientes móveis. O objetivo é garantir a confiabilidade, a disponibilidade de serviços e a privacidade do usuário através da tecnologia PET - Privacy-Enhancing Tecnologies. A idéia é fundamentada em agentes interceptadores e autoridades de segurança que distribuem tíquetes de segurança e controlam o acesso a recursos e espaços de tuple do ambiente. O estudo de caso apresentou resultados satisfatórios que permitem julgar a pertinência do modelo proposto. O modelo será integrado a um sistema de e-saúde. / The work exploits the security management and the cooperation of applications in mobile distributed systems. In this context a study of different mobile middleware is made. The study examines their capacities to face the challenges of mobility and security issues. The analysis shows that the existing middleware has very few approaches on security problems; security is still a complex issue to be managed in all the levels of mobile distributed system including new mechanisms. Based on this analysis, a security management model is developed that implements a mechanism for mutual authentication, confidentiality, intrusion detection, access control of mobile agents in mobile environments, ensures services availability and user privacy, through technology PET (Privacy-Enhancing Technologies). The idea is based on interceptor agents and security authorities that distribute security tickets and control the access to resources and Tuple spaces in mobile environment. The proposed model presents good performance and is integrated to an e-health system: Relationship Management with Chronic Patient GRPC.

Humans are creatures of habit, often developing a routine for their day-to-day life. We propose a way to identify routine as regularities extracted from the context data of mobile phones. We choose Lecroq et al.'s existing state of the art algorithm as basis for a set of modifications that render it suitable for the task. Our approach searches alignments in sequences of n-tuples of context data, which correspond to the user traces of routine activity. Our key enhancements to this algorithm are exploiting the sequential nature of the data an early maximisation approach. We develop a generator of context-like data to allow us to evaluate our approach. Additionally, we collect and manually annotate a mobile phone context dataset to facilitate the evaluation of our algorithm. The results allow us to validate the concept of our approach.

Ontological database management systems are a powerful tool that combine traditional database techniques with ontological reasoning methods. In this setting, a classical extensional database is enriched with an ontology, or a set of logical assertions, that describe how new, intensional knowledge can be derived from the extensional data. Conjunctive queries are therefore answered against this combined knowledge base of extensional and intensional data. Many languages that represent ontologies have been introduced in the literature. In this thesis we will focus on existential rules (also called tuple-generating dependencies or Datalog^&plusmn; rules), and three established languages in this area, namely guarded-based rules, sticky rules and weakly-acyclic rules. The main goal of the thesis is to enrich these languages with non-deterministic constructs (i.e. disjunctions) and investigate the complexity of the answering conjunctive queries under these extended languages. As is common in the literature, we will distinguish between combined complexity, where the database, the ontology and the query are considered as input, and data complexity, where only the database is considered as input. The latter case is relevant in practice, as usually the ontology and the query can be considered as fixed, and are usually much smaller than the database itself. After giving appropriate definitions to extend the considered languages to disjunctive existential rules, we establish a series of complexity results, completing the complexity picture for each of the above languages, and four different query languages: arbitrary conjunctive queries, bounded (hyper-)treewidth queries, acyclic queries and atomic queries. For the guarded-based languages, we show a strong 2EXPTIME lower bound for general queries that holds even for fixed ontologies, and establishes 2EXPTIME-completeness of the query answering problem in this case. For acyclic queries, the complexity can be reduced to EXPTIME, if the predicate arity is bounded, and the problem even becomes tractable for certain restricted languages, if only atomic queries are used. For ontologies represented by sticky disjunctive rules, we show that the problem becomes undecidable, even in the case of data complexity and atomic queries. Finally, for weakly-acyclic rules, we show that the complexity increases from 2EXPTIME to coN2EXPTIME in general, and from tractable to coNP in case of the data complexity, independent of which query language is used. After answering the open complexity questions, we investigate applications and relevant consequences of our results for description logics and give two generic complexity statements, respectively, for acyclic and general conjunctive query answering over description logic knowledge bases. These generic results allow for an easy determination of the complexity of this reasoning task, based on the expressivity of the considered description logic.