309 research outputs found

    An Overlay Architecture for Personalized Object Access and Sharing in a Peer-to-Peer Environment

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    Due to its exponential growth and decentralized nature, the Internet has evolved into a chaotic repository, making it difficult for users to discover and access resources of interest to them. As a result, users have to deal with the problem of information overload. The Semantic Web's emergence provides Internet users with the ability to associate explicit, self-described semantics with resources. This ability will facilitate in turn the development of ontology-based resource discovery tools to help users retrieve information in an efficient manner. However, it is widely believed that the Semantic Web of the future will be a complex web of smaller ontologies, mostly created by various groups of web users who share a similar interest, referred to as a Community of Interest. This thesis proposes a solution to the information overload problem using a user driven framework, referred to as a Personalized Web, that allows individual users to organize themselves into Communities of Interests based on ontologies agreed upon by all community members. Within this framework, users can define and augment their personalized views of the Internet by associating specific properties and attributes to resources and defining constraint-functions and rules that govern the interpretation of the semantics associated with the resources. Such views can then be used to capture the user's interests and integrate these views into a user-defined Personalized Web. As a proof of concept, a Personalized Web architecture that employs ontology-based semantics and a structured Peer-to-Peer overlay network to provide a foundation of semantically-based resource indexing and advertising is developed. In order to investigate mechanisms that support the resource advertising and retrieval of the Personalized Web architecture, three agent-driven advertising and retrieval schemes, the Aggressive scheme, the Crawler-based scheme, and the Minimum-Cover-Rule scheme, were implemented and evaluated in both stable and churn environments. In addition to the development of a Personalized Web architecture that deals with typical web resources, this thesis used a case study to explore the potential of the Personalized Web architecture to support future web service workflow applications. The results of this investigation demonstrated that the architecture can support the automation of service discovery, negotiation, and invocation, allowing service consumers to actualize a personalized web service workflow. Further investigation will be required to improve the performance of the automation and allow it to be performed in a secure and robust manner. In order to support the next generation Internet, further exploration will be needed for the development of a Personalized Web that includes ubiquitous and pervasive resources

    Efficient Peer-to-Peer Content Sharing for Learning in Virtual Worlds

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    Virtual world technologies provide new and immersive space for learning, training, and education. They are enabled by the content creation and content sharing function for allowing users to create and interoperate various learning objects. Unfortunately, virtual world content sharing based on persistent virtual world content storage, to the best of our knowledge, does not exist. In this paper, we address this problem by proposing a content sharing scheme based on Virtual Net, a virtual world persistency framework. For efficient content retrieval, three strategies have been proposed to reduce communication overhead and content load delay.By integrating these strategies, a virtual world content search and retrieval algorithm has been devised. The experiment results verify the effectiveness of the algorithm

    CHORUS Deliverable 2.1: State of the Art on Multimedia Search Engines

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    Based on the information provided by European projects and national initiatives related to multimedia search as well as domains experts that participated in the CHORUS Think-thanks and workshops, this document reports on the state of the art related to multimedia content search from, a technical, and socio-economic perspective. The technical perspective includes an up to date view on content based indexing and retrieval technologies, multimedia search in the context of mobile devices and peer-to-peer networks, and an overview of current evaluation and benchmark inititiatives to measure the performance of multimedia search engines. From a socio-economic perspective we inventorize the impact and legal consequences of these technical advances and point out future directions of research

    WP3 Deliverable 3: A Grid Service Framework for Self e-Learning Networks

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    In this report we propose a set of services that are applicable in the case of SeLeNe in alignment to the Open Grid Services Architecture (OGSA). In general, a service-based architecture is proposed that allows a user to submit requests to the SeLeNe Network, viewed as a whole, for the completion of some specific task. At this point, the SeLeNe project concentrates on providing services for the utilization of Learning Objects ' (LO) metadata based on the RDF/S standards. Service placement produces a number of possible architectural alternatives. Finally, we present issues not extensively covered by the SeLeNe project but constitute basic challenges for future work

    Discovery and Push Notification Mechanisms for Mobile Cloud Services

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    Viimase viie aasta jooksul on mobiilsed seadmed nagu sülearvutid, pihuarvutid, nutitelefonid jmt. tunginud peaaegu kõigisse inimeste igapäevaelu tegevustesse. Samuti on põhjalik teadus- ja arendustegevus mobiilsete tehnoloogiate vallas viinud märkimisväärsete täiustusteni riistvara, tarkvara ja andmeedastuse alal. Tänapäeval on mobiilsed seadmed varustatud sisseehitatud sensorite, kaamera, puutetundliku ekraani, suurema hulga mäluga, kuid ka tõhusamate energiatarbemehhanismidega. Lisaks on iOS ja Android operatsioonisüsteemide väljalaske tõttu suurenenud nii mobiilirakenduste arv kui keerukus, pakkudes arvukamalt kõrgetasemelisi rakendusi. Sarnaselt on toimunud olulised arengud ja standardiseerimisele suunatud jõupingutused veebiteenusete valdkonnas ja elementaarsetele veebiteenuste ligipääsu kasutatakse laialdaselt nutitelefonidest. See on viinud loogilise järgmise sammuna veebiteenuste pakkumiseni nutitelefonidest. Telefonidest veebiteenuste pakkumise kontseptsioon ei ole uus ning seda on põhjalikult uurinud Srirama, kes pakkus välja Mobile Host (Mobiilne Veebiteenuse Pakkuja) kontseptsiooni. Algne realisatsioon kasutas aga aegunud tehnoloogiaid nagu JMEE, PersonalJava, SOAP arhitektuur jne. See töö uuendab Mobile Host'i kasutades uusimaid tehnoloogiad, nagu Android OS ja REST arhitektuur, ning pakub välja teenusemootori, mis põhineb Apache Felix'il - OSGi platvormi realisatsioonil piiratud ressurssidega seadmetele. Hämmastava kiirusega toimunud arengud mobiilsete arvutuste vallas võimaldavad uue põlvkonna veebirakenduste loomist valdkondades nagu keskkonnateadlikkus, sotsiaalvõrgustikud, koostöövahendid, asukohapõhised teenused jne. Sellised rakendused saavad ära kasutada Mobile Host'i võimalusi. Selle tulemusena on klientidel ligipääs väga suurele hulgale teenustele, mistõttu tekib vajadus efektiivse teenuste avastamise mehhanismi järele. See töö pakub välja kataloogipõhise avastusmehhanismi võrgu ülekatte toega suurtele, kõrge liikuvusega võrgustikele. See mehhanism toetub OWL-S'le, mis on ontoloogia veebiteenuseid pakkuvate ressursside avastamiseks, väljakutseks, koostamiseks ja jälgimiseks. Töö kirjeldab ka Srirama välja pakutud algupärast teenuste avastamise mehhanismi, mis toetub peer-to-peer võrkudele ja Apache Lucene võtmesõna otsingumootorile. Uurimuse käigus uuendatakse teenuseotsing kasutama Apache Solr'i, Apache Lucene'i viimast versiooni. Teenuste avastust testiti põhjalikult ja tulemused on töös kokkuvõtvalt välja toodud. Mobiilsete tehnoloogiate vallas uuritakse ka võimalust kasutada pilvetehnolologiat laiendamaks mobiilseadmete salvestusmahtu ja töökoormust edastades pilve andme- ja arvutusmahukad ülesanded. See soodustab keerulisemate ja võimalusrohkemate mobiilirakenduste arendust. Pilve delegeeritavate toimingute aeganõudva iseloomu tõttu aga on vajalik asünkroonne mehhanism teavitamaks kasutajat, millal töömahukad tegevused on lõpetatud. Mobiilsete pilveteenuste pakkujad ja vahevara lahendused võivad kasu saada Mobile Host'ist ja selle asünkroonsete teavituste võimekusest. Uurimus esitleb nelja teavitusmehhanismi: AC2DM, APNS, IBM MQTT ja Mobile Host'i põhine teavitus. Töö võtab kokku kvantitatiivse analüüsi tulemused ja toob välja nelja teavitamise lähenemise tugevused ja nõrkused. Lisaks kirjeldatakse CroudSTag rakenduse realisatsiooni - CroudSTag on mobiilirakendus, mille eesmärgiks on sotsiaalsete gruppide moodustamine kasutades näotuvastustehnoloogiat. CroudSTag-i realisatsioon kasutab mobiilseid pilveteenuseid ja Mobile Host'i, et pakkuda oma funktsionaalsust kasutajale.In the last lustrum the mobile devices such as laptops, PDAs, smart phones, tablets, etc. have pervaded almost all the environments where people perform their day-to-day activities. Further, the extensive Research and Development in mobile technologies has led to significant improvements in hardware, software and transmission. Similarly, there are significant developments and standardization efforts in web services domain and basic web services have been widely accessed from smart phones. This has lead to the logical next step of providing web services from the smart phones. The concept of the web service provisioning from smart phones is not new and has been extensively explored by Srirama who proposed the concept of Mobile Host. However, the original implementation considered aged technologies such as JMEE, PersonalJava, SOAP architecture among others. This work updates the Mobile Host to the latest technologies like Android OS and REST architecture and proposes a service engine based on Apache Felix, and OSGI implementation for resource constraint devices. Moreover, the astonishing speed in developments in mobile computing enable the new generation of applications from domains such as context-awareness, social network, collaborative tools, location based services, etc., which benefit from the Mobile Host service provisioning capabilities. As a result the clients have access to a huge number of services available; therefore, an efficient and effective service discovery mechanism is required. The thesis proposes a directory-based with network overlay support discovery mechanism for large networks with high mobility. The proposed discovery mechanism relies in OWL-S, an ontology for service discovery, invocation, composition, and monitoring of web resources. The work also considers the original service discovery mechanism proposed by Srirama relying in peer-to-peer networks and Apache Lucene, a keyword search engine. The study updates the service search to Apache Solr, the latest development for Apache Lucene. The service discovery was extensively tested and the results are summarized in this work. Mobile technologies are looking into the clouds for extending their capabilities in storage and processing by offloading data and process intensive tasks. This fosters the development of more complex and rich mobile applications. However, due to the time-consuming nature of the tasks delegated to the clouds, an asynchronous mechanism is necessary for notifying the user when the intensive tasks are completed. Mobile cloud service providers and Middleware solutions might benefit from Mobile Host and its asynchronous notification capabilities. The study presents four push notification mechanisms being AC2DM, APNS, IBM MQTT and Mobile Host based push notification. The work summarizes the results of a quantitative analysis and highlights the strengths and weakness of the four notifications approaches. In addition, it explains CroudSTag realization, a mobile application that aims the social group formation by means of facial recognition that relies in mobile cloud services and Mobile Host to provide its functionality to the user

    Large-Scale Time-Shifted Streaming Delivery

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    An attractive new feature of connected TV systems consists in allowing users to access past portions of the TV channel. This feature, called time-shifted streaming, is now used by millions of TV viewers. We address in this paper the design of a large-scale delivery system for time-shifted streaming. We highlight the characteristics of time-shifted streaming that prevent known video delivery systems to be used. Then, we present two proposals that meet the demand for two radically different types of TV operator. First, the Peer-Assisted Catch-Up Streaming system, namely PACUS, aims at reducing the load on the server of a large TV broadcasters without losing the control of the TV delivery. Second, the turntable structure, is an overlay of nodes that allow an independent content delivery network or a small independent TV broadcaster to ensure that all past TV programs are stored and as available as possible. We show through extensive simulations that our objectives are reached, with a reduction of up to three quarters of the traffic for PACUS and a 100\% guaranteed availability for the turntable structure. We also compare our proposals to the main previous works in the area

    A Transparent, Reputation-Based Architecture for Semantic Web Annotation

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    New forms of conceiving the web such as web 2.0 and the semantic web have emerged for numerous purposes ranging from professional activities to leisure. The semantic web is based on associating concepts with web pages, rather than only identifying hyperlinks and repeated literals. ITACA is a project whose aim is to add semantic annotations to web pages, where semantic annotations are Wikipedia URLs. Therefore, users can write, read and vote on semantic annotations of a webpage. Semantic annotations of a webpage are ranked according to users' votes. Building upon the ITACA project, we propose a transparent, reputation-based architecture. With this proposal, semantic annotations are stored in the users' local machines instead of web servers, so that web servers transparency is preserved. To achieve transparency, an indexing server is added to the architecture to locate semantic annotations. Moreover, users are grouped into reputation domains, providing accurate semantic annotation ranking when retrieving annotations of a web page. Cache copies of semantic annotations in annotation servers are done to improve eficiency of the algorithm, reducing the number of sent messages

    Systems Applications of Social Networks

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    The aim of this article is to provide an understanding of social networks as a useful addition to the standard tool-box of techniques used by system designers. To this end, we give examples of how data about social links have been collected and used in di erent application contexts. We develop a broad taxonomy-based overview of common properties of social networks, review how they might be used in di erent applications, and point out potential pitfalls where appropriate. We propose a framework, distinguishing between two main types of social network-based user selection-personalised user selection which identi es target users who may be relevant for a given source node, using the social network around the source as a context, and generic user selection or group delimitation, which lters for a set of users who satisfy a set of application requirements based on their social properties. Using this framework, we survey applications of social networks in three typical kinds of application scenarios: recommender systems, content-sharing systems (e.g., P2P or video streaming), and systems which defend against users who abuse the system (e.g., spam or sybil attacks). In each case, we discuss potential directions for future research that involve using social network properties.Comment: Will appear in ACM computing Survey
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