30 research outputs found

    Cacheability study for web content delivery

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    Master'sMASTER OF SCIENC

    Adaptive Caching of Distributed Components

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    Die Zugriffslokalität referenzierter Daten ist eine wichtige Eigenschaft verteilter Anwendungen. Lokales Zwischenspeichern abgefragter entfernter Daten (Caching) wird vielfach bei der Entwicklung solcher Anwendungen eingesetzt, um diese Eigenschaft auszunutzen. Anschliessende Zugriffe auf diese Daten können so beschleunigt werden, indem sie aus dem lokalen Zwischenspeicher bedient werden. Gegenwärtige Middleware-Architekturen bieten dem Anwendungsprogrammierer jedoch kaum Unterstützung für diesen nicht-funktionalen Aspekt. Die vorliegende Arbeit versucht deshalb, Caching als separaten, konfigurierbaren Middleware-Dienst auszulagern. Durch die Einbindung in den Softwareentwicklungsprozess wird die frühzeitige Modellierung und spätere Wiederverwendung caching-spezifischer Metadaten gewährleistet. Zur Laufzeit kann sich das entwickelte System außerdem bezüglich der Cachebarkeit von Daten adaptiv an geändertes Nutzungsverhalten anpassen.Locality of reference is an important property of distributed applications. Caching is typically employed during the development of such applications to exploit this property by locally storing queried data: Subsequent accesses can be accelerated by serving their results immediately form the local store. Current middleware architectures however hardly support this non-functional aspect. The thesis at hand thus tries outsource caching as a separate, configurable middleware service. Integration into the software development lifecycle provides for early capturing, modeling, and later reuse of cachingrelated metadata. At runtime, the implemented system can adapt to caching access characteristics with respect to data cacheability properties, thus healing misconfigurations and optimizing itself to an appropriate configuration. Speculative prefetching of data probably queried in the immediate future complements the presented approach

    Modeling and acceleration of content delivery in world wide web

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    Ph.DDOCTOR OF PHILOSOPH

    Measurement and Analysis of Mobile Web Cache Performance

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    The Web browser is a killer app on mobile devices such as smartphones. However, the user experience of mobile Web browsing is undesirable because of the slow resource loading. To improve the performance of Web resource loading, caching has been adopted as a key mechanism. However, the existing passive measurement studies cannot comprehensively characterize the performance of mobile Web caching. For example, most of these studies mainly focus on client-side implementations but not server-side configurations, suffer from biased user behaviors, and fail to study 'miscached' resources. To address these issues, in this paper, we present a proactive approach for a comprehensive measurement study on mobile Web cache performance. The key idea of our approach is to proactively crawl resources from hundreds of websites periodically with a fine-grained time interval. Thus, we are able to uncover the resource update history and cache configurations at the server side, and analyze the cache performance in various time granularities. Based on our collected data, we build a new cache analysis model and study the upper bound of how high percentage of resources could potentially be cached and how effective the caching works in practice. We report detailed analysis results of different websites and various types of Web resources, and identify the problems caused by unsatisfactory cache performance. In particular, we identify two major problems - Redundant Transfer and Miscached Resource, which lead to unsatisfactory cache performance. We investigate three main root causes: Same Content, Heuristic Expiration, and Conservative Expiration Time, and discuss what mobile Web developers can do to mitigate those problems.EI691-70

    Towards Soft Circuit Breaking in Service Meshes via Application-agnostic Caching

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    Service meshes factor out code dealing with inter-micro-service communication, such as circuit breaking. Circuit breaking actuation is currently limited to an "on/off" switch, i.e., a tripped circuit breaker will return an application-level error indicating service unavailability to the calling micro-service. This paper proposes a soft circuit breaker actuator, which returns cached data instead of an error. The overall resilience of a cloud application is improved if constituent micro-services return stale data, instead of no data at all. While caching is widely employed for serving web service traffic, its usage in inter-micro-service communication is lacking. Micro-services responses are highly dynamic, which requires carefully choosing adaptive time-to-life caching algorithms. We evaluate our approach through two experiments. First, we quantify the trade-off between traffic reduction and data staleness using a purpose-build service, thereby identifying algorithm configurations that keep data staleness at about 3% or less while reducing network load by up to 30%. Second, we quantify the network load reduction with the micro-service benchmark by Google Cloud called Hipster Shop. Our approach results in caching of about 80% of requests. Results show the feasibility and efficiency of our approach, which encourages implementing caching as a circuit breaking actuator in service meshes

    Principles of Security and Trust: 7th International Conference, POST 2018, Held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2018, Thessaloniki, Greece, April 14-20, 2018, Proceedings

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    authentication; computer science; computer software selection and evaluation; cryptography; data privacy; formal logic; formal methods; formal specification; internet; privacy; program compilers; programming languages; security analysis; security systems; semantics; separation logic; software engineering; specifications; verification; world wide we

    Data integrity for active web intermediaries

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    Master'sMASTER OF SCIENC

    A visualization service for Parkinson’s disease motoric measurements

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    Abstract. In the era of affordable sensors and smart devices, medical self measurements are increasingly common. Currently, powerful mobile phones and different sensor systems facilitate a variety of use cases for patients, enthusiasts and experts alike to measure their bodily condition. Visualizing the results of these measurements is not always a certainty, as the data could be complex or difficult to interpret in some other way. We design and develop a web application to visualize measurement data collected with an existing self-measurement application called STOP. STOP collects acceleration and gyroscopic data about hand tremor with parkinson’s disease patients. Our application, Medidash, draws dynamic temporal cartesian graphs from these measurements. Medidash consists of an existing AWARE-database and a Python-Dash based web application.Visualisointipalvelu Parkinsonin taudin oireiden mittausten kuvaamiseen. Tiivistelmä. Edullisen kuluttajaelektroniikan ja älylaitteiden aikakaudella lääketieteellinen mittaaminen yleistyy voimakkaasti. Nykyiset tehokkaat matkapuhelimet ja erilaiset sensorijärjestelmät mahdollistavat erilaisia käyttötarkoituksia terveyden mittaamiseen niin potilaille, ammattilaisille kuin harrastajillekin. Näiden mittausten visualisointi ei aina ole itsestäänselvyys, sillä kerätty data saattaa olla monimutkaista tai muuten hankalasti tulkittavaa. Suunnitelemme ja kehitämme verkkosovelluksen jo olemassa olevalla kehonmittausta tekevällä STOP-applikaatiolla kerätyn datan visualisointiin. STOP kerää kiihtyvyysanturilla ja gyroskoopilla dataa Parkinsonin taudin potilaiden käsien tärinästä. Kehittämämme sovellus, Medidash, piirtää dynaamisia kuvaajia mitatun datan visualisoimiseksi. Medidash koostuu jo olemassaolevasta AWARE-tietokannasta sekä Python-Dash-pohjaisesta verkkoapplikaatiosta
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