18 research outputs found

    Statistical Model Checking of Distributed Programs within SimGrid

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    International audienceIn this paper, we present an approach to perform statistical model-checking over stochastic distributed programs using the SimGrid framework. The distributed programs are modeled using SimGrid, a fast and lightweight framework for the simulation of distributed programs, which we have enhanced in three ways: a cleaner description of the probabilistic evolution of the capacities of resources, a centralized random number generator, and a protocol for the observation of the simulations. We also propose a toolset for the statistical model-checking of those simulated distributed programs, and in particular a prototype tool SimGridStatMC. The toolset is illustrated to evaluate various properties of an implementation of the peer to peer BitTorrent protocol

    OTS 2019 Advanced Information Technology and Services

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    Prispevki, zbrani v zborniku ĆŸe 24. strokovne konference Sodobne informacijske tehnologije in storitve, naslavljajo izjemno aktualne izzive, s katerimi se informatiki, programski inĆŸenirji, računalničarji, podatkovni znanstveniki, arhitekti, razvijalci ter upravljalci informacijskih reĆĄitev in storitev srečujemo pri svojem vsakdanjem delu. Avtorji predstavljajo inovativne reĆĄitve in skozi konkretne projekte pridobljene izkuĆĄnje s/z: vpeljavo tehnologij strojnega učenja in obogatene inteligence, uporabo tehnologij in platform veriĆŸenja blokov, razvojem ĆĄibko sklopljenih mikrostoritev, popolno virtualizacijo in izkoriơčanjem porazdeljenih infrastruktur, zagotavljanjem kibernetske varnosti, zaupnosti in zasebnosti, skaliranjem agilnih metod v porazdeljenih projektnih skupinah, vpeljavo agilnih pristopov v sklopu avtomatiziranih in neprekinjenih procesov razvoja, testiranja, integracije in dostave, posodobitvijo in nadgradnjo obstoječih informacijskih sistemov, razvojem uporabniĆĄko prijaznih spletnih in mobilnih reĆĄitev in uvajanjem sodobnih programskih jezikov in razvojnih okolij.The papers in the proceedings of the 24th Professional Conference on Advanced Information Technology and Services address the extremely topical challenges that we (IS/IT experts, Software Engineers, Computer Scientists, Data Scientists, software and solution architects, developers, IT managers, etc.) encounter in our daily work. The authors present the innovative solutions and rich experience gained by conducting real-life projects: Applying Augmented Intelligence and Machine Learning technologies, Using Blockchain technologies and platforms, Developing loosely coupled micro-services, Providing full virtualization and exploitation of distributed infrastructures, Ensuring cybersecurity, confidentiality and privacy, Applying large-scale agile methods in distributed teams, Introducing agile approaches that enable the rapid and efficient software development via automated processes, and continuous testing, integration, delivery & deployment Updating and upgrading existing Information Systems, Incorporating advanced programming languages and development environments, Developing user-friendly web and mobile solutions & services

    Data Plane Throughput vs Control Plane Delay: Experimental Study of BitTorrent Performance

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    In this paper, we address the trade-off between the data planeefficiency and the control plane timeliness for the BitTorrent performance.We argue that loss-based congestion control protocols can fill largebuffers, leading to a higher end-to-end delay, unlike low-priorityor delay-based congestion control protocols.We perform experiments for both the uTorrent and mainline BitTorrentclients, and we study the impact of uTP (a novel transport protocolproposed by BitTorrent) and several TCP congestion control algorithms(Cubic, New Reno, LP, Vegas and Nice) on the download completion time.Briefly, in case peers in the swarm all use the same congestioncontrol algorithm, we observe that the specific algorithm has only alimited impact on the swarm performance. Conversely, when a mix of TCPcongestion control algorithms coexists, peers employing a delay-basedlow-priority algorithm exhibit shorter completion time.</p

    UTPA Undergraduate Catalog 2013-2015

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    https://scholarworks.utrgv.edu/edinburglegacycatalogs/1077/thumbnail.jp

    User-centric power-friendly quality-based network selection strategy for heterogeneous wireless environments

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    The ‘Always Best Connected’ vision is built around the scenario of a mobile user seamlessly roaming within a multi-operator multi-technology multi-terminal multi-application multi-user environment supported by the next generation of wireless networks. In this heterogeneous environment, users equipped with multi-mode wireless mobile devices will access rich media services via one or more access networks. All these access networks may differ in terms of technology, coverage range, available bandwidth, operator, monetary cost, energy usage etc. In this context, there is a need for a smart network selection decision to be made, to choose the best available network option to cater for the user’s current application and requirements. The decision is a difficult one, especially given the number and dynamics of the possible input parameters. What parameters are used and how those parameters model the application requirements and user needs is important. Also, game theory approaches can be used to model and analyze the cooperative or competitive interaction between the rational decision makers involved, which are users, seeking to get good service quality at good value prices, and/or the network operators, trying to increase their revenue. This thesis presents the roadmap towards an ‘Always Best Connected’ environment. The proposed solution includes an Adapt-or-Handover solution which makes use of a Signal Strength-based Adaptive Multimedia Delivery mechanism (SAMMy) and a Power-Friendly Access Network Selection Strategy (PoFANS) in order to help the user in taking decisions, and to improve the energy efficiency at the end-user mobile device. A Reputation-based System is proposed, which models the user-network interaction as a repeated cooperative game following the repeated Prisoner’s Dilemma game from Game Theory. It combines reputation-based systems, game theory and a network selection mechanism in order to create a reputation-based heterogeneous environment. In this environment, the users keep track of their individual history with the visited networks. Every time, a user connects to a network the user-network interaction game is played. The outcome of the game is a network reputation factor which reflects the network’s previous behavior in assuring service guarantees to the user. The network reputation factor will impact the decision taken by the user next time, when he/she will have to decide whether to connect or not to that specific network. The performance of the proposed solutions was evaluated through in-depth analysis and both simulation-based and experimental-oriented testing. The results clearly show improved performance of the proposed solutions in comparison with other similar state-of-the-art solutions. An energy consumption study for a Google Nexus One streaming adaptive multimedia was performed, and a comprehensive survey on related Game Theory research are provided as part of the work

    Experimental Assessment of BitTorrent Completion Time in Heterogeneous TCP/uTP Swarms

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    Le contrĂŽle de congestion dans les applications Pair-Ă -Pair : le cas de LEDBAT

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    In the last years, Internet delays are considerably growing, causing a performance deterioration of interactive applications. This phenomenon is getting worse with the increasing popularity of bandwidth-intensive applications, as video streaming, remote backup and P2P systems. The cause of these delays has been identified with the excess buffering inside the network, called “bufferbloat”. Research efforts in this direction head toward active queue management techniques and end-to-end congestion control. In this context, we investigated LEDBAT, a low-priority delay-based transport protocol introduced by BitTorrent. This protocol is designed to transfer large amount of data without affecting the delay experienced by other applications or users. First we analysed transport-level performance of LEDBAT using experimental measurement, simulation and analytical model. Specifically, we evaluated LEDBAT as is, comparing its performance to standard TCP or to other low priority protocols. We then identified a later-comer advantage and we proposed fLEDBAT, which re-introduces intra-protocol fairness maintaining the original LEDBAT objectives. Finally we studied the impact of the LEDBAT protocol on BitTorrent performance. Through simulations and real network experiments, we analysed how BitTorrent impacts on the buffer occupancy of the access node. BitTorrent performance was evaluated in terms of completion time, the main metric to assess the user quality of experience. Results showed that LEDBAT decreases the completion time with respect to standard TCP and significantly reduces the buffer occupancy, that translates in lower delays experienced by competing interactive applications.Durant ces derniĂšres annĂ©es, les dĂ©lais de transmission sur Internet ont augmentĂ© de maniĂšre considĂ©rable, causant une dĂ©tĂ©rioration de performances des applications interactives. La cause de ces augmentations de dĂ©lais est l’excĂšs de mĂ©moire tampon Ă  l’intĂ©rieur du rĂ©seau, appelĂ© "bufferbloat". Les efforts de recherche dans cette direction vont vers des techniques de gestion des files d’attente actives et des techniques de contrĂŽle de congestion de bout-Ă -bout. Dans ce contexte, nous avons examinĂ© LEDBAT, un protocole introduit par BitTorrent qui se base sur le dĂ©lai au niveau transport, et conçu pour transfĂ©rer grandes quantitĂ©s de donnĂ©es sans affecter les dĂ©lais expĂ©rimentĂ©s par d’autres applications ou utilisateurs. Nous avons analysĂ© la performance de niveau de transport de LEDBAT avec de mesures expĂ©rimentales, de simulations et de modĂšles analytiques, en comparant ses performances au standard TCP ou Ă  d’autre protocoles de failbe prioritĂ©. Nous avons ensuite identifiĂ© un problĂšme d’iniquitĂ©, et nous avons proposĂ© fLEDBAT, qui rĂ©-introduit l’équitĂ© intra-protocole. Dans un deuxiĂšme temps, nous avons Ă©tudiĂ© l’impact du protocole LEDBAT sur la performance de BitTorrent. Par des simulations et des expĂ©rimentations sur rĂ©seaux rĂ©elles, nous avons analysĂ© les effets de LEDBAT sur le remplissage des tampons des noeuds d’accĂšs. Les performances de BitTorrent ont Ă©tĂ© Ă©valuĂ©es en termes de temps d’exĂ©cution, qui reflĂšte la qualitĂ© de l’expĂ©rience utilisateur. Dans les deux cas, les rĂ©sultats ont montrĂ© que LEDBAT diminue le temps de traitement par rapport Ă  TCP et rĂ©duit de maniĂšre significative l’utilisation de tampons, ce qui se traduit par une baisse des dĂ©lais

    A method for securing online community service: A study of selected Western Australian councils

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    Since the Internet was made publicly accessible, it has become increasingly popular and its deployment has been broad and global thereby facilitating a range of available online services such as Electronic Mail (email), news or bulletins, Internet Relay Chat (IRC) and World Wide Web (WWW). Progressively, other online services such as telephony, video conference, video on demand, Interactive Television (ITV) and Geographic Information System (GIS) have been integrated with the Internet and become publicly available. Presently, Internet broadband communication services incorporating both wired and wireless network technologies has seen the emergence of the concept of a digital community which has been growing and expanding rapidly around the world. Internet and the ever expanding online services to the wider digital community has raised the issue of security of these services during usage. Most local councils throughout Western Australia have resorted to delivering online services such as library, online payments and email accessibility. The provision and usage of these services have inherent security risks. Consequently, this study investigated the concept of a secure digital community in the secure provision and usage of these online services in selected local councils in Western Australia (WA). After an extensive review of existing literature, information security frameworks were derived from the adaptation of various resources, such as the OSSTMM 2.2 Section C: Internet Technology Security benchmark which was used as the main template. In addition, this template was enhanced into a framework model by incorporating other benchmarks such as NIST, CIS, ISSAF as well as other sources of information. These included information security related books, related ICT network and security websites such as CERT, CheckPoint, Cisco, GFI, Juniper, MS, NESSUS and NMAP together with journals and personal interviews. The proposed information security frameworks were developed to enhance the level of security strength of the email and online web systems as well as to increase the level of confidence in the system security within the selected local councils in WA. All the investigative studies were based upon the available selected local councils’ data and the associated analyses of the results as obtained from the testing software. In addition, the interpretive multiple-case study principles were used during the investigation to achieve or fulfil the purpose of this study. The findings from this study were then abstracted for use in a framework and made available for use as a model for possible adaptation and implementation to other similarly structured councils or organisations. As a result, the study confirmed that the proposed information security frameworks have the capability and potential to improve the level of security strength. In addition, the level of satisfaction and confidence of council staff of the selected local councils in WA in the system security would also be increased due to the application of these frameworks. Although these information security frameworks may be recommended as practical and supporting tools for local councils, the findings from this study were specific only to the selected local councils used in this study. Further research using other councils, may be necessary in order for the information security frameworks to be adopted within a wider range of councils or organisations in WA or elsewhere
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