406 research outputs found

    Isolation in XML Bases

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    The eXtensible Markup Language (XML) is well accepted in many different application areas. As a consequence, there is an increasing need for persistently storing XML documents. As soon as many users and applications work concurrently on the same collection of XML documents - i.e. an XML base - isolating accesses and modifications of different transactions becomes an important issue. We discuss six different core protocols for synchronizing access to and modifications of XML document collections. These core protocols synchronize structure traversals and modifications. They are meant to be integrated into a native XML base management System (XBMS). Four of the six core protocols are based on two phase locking, one uses time stamps, and the last one uses a novel dynamic commit-ordering approach. The latter two protocols achieve a higher degree of concurrency by a novel implicit representation of multiple versions. We also discuss extensions of these core protocols to full-fledged protocols. Further, we show how the two phase locking based protocols can achieve a higher degree of concurrency by exploiting the semantics expressed in Document Type Definitions (DTDs)

    Lock-based Protocols for Cooperation on XML Documents

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    The eXtensible Markup Language (XML) is well accepted in several different Web application areas. As soon as many users and applications work concurrently on the same collection of XML documents - e.g. on an XML database via a Web interface - isolating accesses and modifications of different transactions becomes an important issue. We discuss four different core protocols for synchronizing access to and modifications of XML document collections. These core protocols synchronize structure traversals and modifications. They are meant to be integrated into a native XML base management System (XBMS) and are based on two phase locking. We also demonstrate the different degrees of cooperation that are possible with these protocols by various experimental results. Furthermore, we also discuss extensions of these core protocols to full-fledged protocols. Further, we show how to achieve a higher degree of concurrency by exploiting the semantics expressed in Document Type Definitions (DTDs)

    NVIDIA Bug Services: Synchronization & Statistics

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    The NVIDIA ChromeOS team works with NVIDIA’s internal bug database and Google’s partner bugs database. Project Managers currently manually copy-paste bugs from the Google database to the NVIDIA database so that NVIDIA engineers can work on those bugs. To track the progress of projects, NVIDIA’s Project Managers manually tabulate data and generate bug trend visualizations. Both these manual operations are time-intensive and prone to human error. We developed a service to automate the synchronization of Google bugs, guaranteeing timely and automatic Google partner bug updates. We also developed a tool to automate the generation of bug statistics, providing an easy manner of periodically visualizing bug trends

    Breaking Fitness Records without Moving: Reverse Engineering and Spoofing Fitbit

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    Tens of millions of wearable fitness trackers are shipped yearly to consumers who routinely collect information about their exercising patterns. Smartphones push this health-related data to vendors' cloud platforms, enabling users to analyze summary statistics on-line and adjust their habits. Third-parties including health insurance providers now offer discounts and financial rewards in exchange for such private information and evidence of healthy lifestyles. Given the associated monetary value, the authenticity and correctness of the activity data collected becomes imperative. In this paper, we provide an in-depth security analysis of the operation of fitness trackers commercialized by Fitbit, the wearables market leader. We reveal an intricate security through obscurity approach implemented by the user activity synchronization protocol running on the devices we analyze. Although non-trivial to interpret, we reverse engineer the message semantics, demonstrate how falsified user activity reports can be injected, and argue that based on our discoveries, such attacks can be performed at scale to obtain financial gains. We further document a hardware attack vector that enables circumvention of the end-to-end protocol encryption present in the latest Fitbit firmware, leading to the spoofing of valid encrypted fitness data. Finally, we give guidelines for avoiding similar vulnerabilities in future system designs

    XML-aware data synchronization for mobile devices

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    In everyday life, and when using computer systems in particular, it is sometimes the case that a logical datum is replicated into multiple copies, such as when we send a document by electronic mail, or inform interested parties of a new address of residence. If the datum for some reason changes, we would then also like the changes to be reflected in the copies. The problem of keeping the copies up-to-date with respect to each other is studied under the heading of data synchronization. In this thesis, we address data synchronization for mobile devices with limited energy resources and limited connectivity to the Internet, such as mobile phones. The importance of data synchronization is emphasized here, as it becomes infeasible to communicate continuously and in high volumes about the current state of each copy. The established conventions of the Internet and mobile computing environments on such matters as storage interfaces and data formats define an overall system architecture, into which we as seamlessly as possible want to incorporate our proposal. By focusing on interoperability we lower the threshold for utilizing our research in practice. We present a comprehensive approach to data synchronization for mobile devices that is optimistic and state-based, and which targets opaque and XML files on a standard file system. We consider how to use the available connectivity in an economical manner, and so that existing sources of data on the Internet can be utilized. We focus on XML synchronization, where we identify an opportunity to utilize the structure of the data the format exposes. Specifically, we present an algorithm for merging concurrent changes to XML documents which supports subtree moves, an efficient heuristic algorithm for computing tree-level changes between two XML documents, and an overall architecture and algorithms to support the use of lazily instantiated XML documents. Our data synchronization approach is evaluated quantitatively in several experiments, as well as qualitatively by constructing applications that build on top of the approach. One of our applications is an editor that processes 1 GB XML files on a mobile phone

    File Tracking For Mobile Devices

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    Since 2010, the smart device has become an integral part of people’s daily lives. The popularity of smart devices has increased dramatically. However, as the number of devices owned by an individual user increases, so does the risk of data leakage and loss. This problem has started to draw attention because the data contained on smart devices tends to be personal or sensitive in nature. Many people have so much data on their devices that they have no idea as to what they are missing when a device is lost. Although there are already some solutions for data recovery, a data backup system on a remote server, these solutions are not accessible in the non-Internet environment. Development of a data recovery system that is accessible in the non-Internet environment is essential because of the constraints of mobile devices, such as unreliable network. This research proposes an architecture that allows the data recovery in both Internet (cloud) and Non-Internet (local) network by using different connection technologies. A data tracking mechanism has also been designed to monitor data flow among multiple devices, such as the cloud server, mobile devices, and tablets. Additionally, a synchronization system has been developed to ensure the consistency of tracking information. By designing and implementing this architecture, the two problems regarding to the data: "what is where" and "who has what" are resolved

    ebXML: Global Standard for Electronic Business

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    Business-to-business integration is transforming the market and has already begun to increase the efficiency of those companies involved. EDI (Electronic Document Interchange) became very popular during 1970’s; Today EDI transactions total about $750 billion year. EDI is being used by 90% of Fortune 1000 companies. It has indeed become a dominant technology for the largest companies, on the other hand it has been adopted by less than 5% of small and medium sized companies in general and, of these, many use EDI only because their larger customers require it. The reason behind is that EDI is a difficult, complex technology to implement usually comes with high transactional cost. Hence it is suitable for large companies with large volume of transactions. EDI uses fixed, rigid and compressed data format that is difficult to decipher and debug. The data exchange in EDI happens in proprietary VAN (value added network) which is an expensive solution. EbXML (Electronic Business XML) envisioned creating a single global electronic marketplace where enterprises of any size and in any geographic location can meet and conduct business with each other through exchange of xml based messages. The XML (the Extensible Markup Language) has rapidly imposed itself as a popular format for exchange of information on the web. The very nature of XML is that it is a structured document format, in that it represents not only the information to be exchanged, but the metadata encapsulating its meaning. XML technology has potential to solve the existing problems in current EDI systems. Using ebXML, companies have a standard method to exchange business messages, conduct trading relationships, communicate data in common terms and define and register business processes. EbXML is designed to provide a simple way for companies to find one another and conduct business over the Web, allowing those with different platforms to speak a common language. EbXML targets to provide low cost solutions for small and medium enterprises as well as complex solution for large enterprises. This project attempts to implement a prototype of ebXML messaging service as per ebXML specification to obtain the insight look of feasibility and suitability of XML solution for EDI

    Tiedon synkronointi sosiaalisen verkostopalvelun ja RFD -varaston välillä käyttäen julkaisu / tilaus -viestintää

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    Tämä diplomityö esittelee julkaisu/tilaus -välittäjäsovelluksen tiedon synkronointiin Nokia Smart-M3:n, RDF-pohjaisen henkilökohtaisen Smart Space:n ja Aalto Social Interfacen (ASI), Googlen OpenSocial -tyylisen REST-pohjaisen web servicen välillä. Hyödyllinen tieto on usein hajallaan monen eri internet-resurssin takana, jolloin tiedon yhteen kokoaminen ja tarjoaminen yhteisen rajapinnan kautta on oleellista. Semanttisen webin teknologiat tarjoavat dynaamisesti laajennettavan alustan yhdisteltyjen palvelujen tarjoamiseen. Tällä hetkellä kuitenkin tarvittavien työkalujen puute hankaloittaa tiedon jakamista semanttisten tietokantojen ja perinteisten web-palvelujen välillä. Tätä ongelmaa lähestyttiin ensin kirjallisuustutkimuksella nykyisistä teknologioista. Tuloksia hyödynnettiin synkronointiagentin toteuttamisessa Smart-M3:n ja ASI:n välille, joista jälkimmäinen sisältää olemassa olevaa käyttäjädataa. Python valittiin ohjelmointikieleksi sen monipuolisuuden ja Smart-M3:n tarjoaman kirjastotuen takia. Funktio kirjoitettiin ASI:n hierarkkisen ontologian muuntamiseen RDF-verkoksi, ja molemmat osapuolet yhdistettiin välittäjäagenttisovelluksella. Lopuksi sovelluksen toiminnallisuutta ja suorituskykyä arvioitiin. Tämän työn päätuloksena syntyi Smart-M3:n ja ASI:n välillä synkronointia varten virheensietokykyinen agenttisovellus, sekä sen arviointi. Sovellusta voi käyttää sellaisenaan, ja se tarjoaa myös pohjan uusien Aalto-palveluita hyödyntävien agenttien yhdistämiseen Smart-M3:een tai muuhun semanttiseen tietokantaan. Tämä helpottaa henkilökohtaisen Smart Space -käsitteen hyödyntämistä älykkääseen ja tiedon jakamiseen olemassa olevien internet-resurssien välillä, vaatimatta muutoksia niiden toteutukseen.This Thesis presents a publish/subscribe mediator application for synchronizing data between an RDF-based personal Smart Space, provided by Nokia Smart-M3, and Aalto Social Interface (ASI), a Google OpenSocial inspired RESTful Web Service. As useful information is scattered over a multitude of different internet resources, aggregating data to enable accessing them through a single interface becomes essential. The Semantic Web technologies provide a dynamically extensible platform for building composite services. However, currently there is a lack of necessary tools to enable sharing data between semantic databases and traditional Web Services in practice. This problem was approached by first conducting a literature study about the current technologies. The results were used in implementing a synchronization agent between Smart-M3 and ASI, which provides existing user data. Python was chosen as the programming language for its flexibility and the provided Smart-M3 Python knowledge processor library. Functions for mapping ASI's hierarchical ontology and data to an RDF graph were written, and both sides were connected with the mediator agent application. Finally, the application's functionality and performance were evaluated. The main result of this Thesis is a fault-tolerant agent software for synchronizing between Smart-M3 and ASI, and an evaluation of the software and its future possibilities. The agent can be used as such, and it also provides a basis for implementing further agents that connect other Aalto services to Smart-M3 or some other semantic database. This will facilitate wider adoption of the personal Smart Space concept as a framework for intelligently and non-intrusively sharing data between existing internet resources
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