Proactive Mechanisms for Video-on-Demand Content Delivery

Video delivery over the Internet is the dominant source of network load all over the world. Especially VoD streaming services such as YouTube, Netflix, and Amazon Video have propelled the proliferation of VoD in many peoples' everyday life. VoD allows watching video from a large quantity of content at any time and on a multitude of devices, including smart TVs, laptops, and smartphones. Studies show that many people under the age of 32 grew up with VoD services and have never subscribed to a traditional cable TV service. This shift in video consumption behavior is continuing with an ever-growing number of users. satisfy this large demand, VoD service providers usually rely on CDN, which make VoD streaming scalable by operating a geographically distributed network of several hundreds of thousands of servers. Thereby, they deliver content from locations close to the users, which keeps traffic local and enables a fast playback start. CDN experience heavy utilization during the day and are usually reactive to the user demand, which is not optimal as it leads to expensive over-provisioning, to cope with traffic peaks, and overreacting content eviction that decreases the CDN's performance. However, to sustain future VoD streaming projections with hundreds of millions of users, new approaches are required to increase the content delivery efficiency. To this end, this thesis identifies three key research areas that have the potential to address the future demand for VoD content. Our first contribution is the design of vFetch, a privacy-preserving prefetching mechanism for mobile devices. It focuses explicitly on OTT VoD providers such as YouTube. vFetch learns the user interest towards different content channels and uses these insights to prefetch content on a user terminal. To do so, it continually monitors the user behavior and the device's mobile connectivity pattern, to allow for resource-efficient download scheduling. Thereby, vFetch illustrates how personalized prefetching can reduce the mobile data volume and alleviate mobile networks by offloading peak-hour traffic. Our second contribution focuses on proactive in-network caching. To this end, we present the design of the ProCache mechanism that divides the available cache storage concerning separate content categories. Thus, the available storage is allocated to these divisions based on their contribution to the overall cache efficiency. We propose a general work-flow that emphasizes multiple categories of a mixed content workload in addition to a work-flow tailored for music video content, the dominant traffic source on YouTube. Thereby, ProCache shows how content-awareness can contribute to efficient in-network caching. Our third contribution targets the application of multicast for VoD scenarios. Many users request popular VoD content with only small differences in their playback start time which offers a potential for multicast. Therefore, we present the design of the VoDCast mechanism that leverages this potential to multicast parts of popular VoD content. Thereby, VoDCast illustrates how ISP can collaborate with CDN to coordinate on content that should be delivered by ISP-internal multicast

Policies for Web Services

Web services are predominantly used to implement service-oriented architectures (SOA). However, there are several areas such as temporal dimensions, real-time, streaming, or efficient and flexible file transfers where web service functionality should be extended. These extensions can, for example, be achieved by using policies. Since there are often alternative solutions to provide functionality (e.g., different protocols can be used to achieve the transfer of data), the WS-Policy standard is especially useful to extend web services with policies. It allows to create policies to generally state the properties under which a service is provided and to explicitly express alternative properties. To extend the functionality of web services, two policies are introduced in this thesis: the Temporal Policy and the Communication Policy. The temporal policy is the foundation for adding temporal dimensions to a WS-Policy. The temporal policy itself is not a WS-Policy but an independent policy language that describes temporal dimensions of and dependencies between temporal policies and WS-Policies. Switching of protocol dependencies, pricing of services, quality of service, and security are example areas for using a temporal policy. To describe protocol dependencies of a service for streaming, real-time and file transfers, a communication policy can be utilized. The communication policy is a concrete WS-Policy. With the communication policy, a service can expose the protocols it depends on for a communication after its invocation. Thus, a web service client knows the protocols required to support a communication with the service. Therefore, it is possible to evaluate beforehand whether an invocation of a service is reasonable. On top of the newly introduced policies, novel mechanisms and tools are provided to alleviate service use and enable flexible and efficient data handling. Furthermore, the involvement of the end user in the development process can be achieved more easily. The Flex-SwA architecture, the first component in this thesis based on the newly introduced policies, implements the actual file transfers and streaming protocols that are described as dependencies in a communication policy. Several communication patterns support the flexible handling of the communication. A reference concept enables seamless message forwarding with reduced data movement. Based on the Flex-SwA implementation and the communication policy, it is possible to improve usability - especially in the area of service-oriented Grids - by integrating data transfers into an automatically generated web and Grid service client. The Web and Grid Service Browser is introduced in this thesis as such a generic client. It provides a familiar environment for using services by offering the client generation as part of the browser. Data transfers are directly integrated into service invocation without having to perform data transmissions explicitly. For multimedia MIME types, special plugins allow the consumption of multimedia data. To enable an end user to build applications that also leverage high performance computing resources, the Service-enabled Mashup Editor is presented that lets the user combine popular web applications with web and Grid services. Again, the communication policy provides descriptive means for file transfers and Flex-SwAs reference concept is used for data exchange. To show the applicability of these novel concepts, several use cases from the area of multimedia processing have been selected. Based on the temporal policy, the communication policy, Flex-SwA, the Web and Grid Service Browser, and the Service-enabled Mashup Editor, the development of a scalable service-oriented multimedia architecture is presented. The multimedia SOA offers, among others, a face detection workflow, a video-on-demand service, and an audio resynthesis service. More precisely, a video-on-demand service describes its dependency on a multicast protocol by using a communication policy. A temporal policy is then used to perform the description of a protocol switch from one multicast protocol to another one by changing the communication policy at the end of its validity period. The Service-enabled Mashup Editor is used as a client for the new multicast protocol after the multicast protocol has been switched. To stream single frames from a frame decoder service to a face detection service (which are both part of the face detection workflow) and to transfer audio files with the different Flex-SwA communication patterns to an audio resynthesis service, Flex-SwA is used. The invocation of the face detection workflow and the audio resynthesis service is realized with the Web and Grid Service Browser

Media Gateway : το μοντέλο μίας υπηρεσίας ηλεκτρονικού εμπορίου για τη διαχείριση κατανεμημένων πολυμεσικών (multimedia) εφαρμογών και δεδομένων

Η ηλεκτρονική υπηρεσία του ζωντανού παραδείγματος που εξετάζουμε σε αυτήν την εργασία, απαιτεί μεγάλη εγκατάσταση υπολογιστών εκτιθέμενους στο Διαδίκτυο. Συνεπώς, μία τέτοια εφαρμογή απειλείται από σοβαρούς κινδύνους μέσω του Διαδικτύου. Το βασικότερο όφελος που θα μπορούσαμε να προσφέρουμε στους χρήστες της υπηρεσίας αυτής είναι η ασφάλεια και η προστασία των προσωπικών τους δεδομένων. Μη λαμβάνοντας υπ όψιν αυτόν τον τομέα η λειτουργία της υπηρεσίας αυτής θα επηρεαζόταν αρνητικά. Το πρώτο βήμα στη διαμόρφωση μίας αρχιτεκτονικής ασφαλείας είναι η εύρεση και ο καθορισμός των στόχων ασφάλειας του συστήματος. Οι βασικότερες έννοιες που εξετάζονται στον τομέα της ασφάλειας είναι η διαθεσιμότητα των δεδομένων, που δίνει το πλεονέκτημα στο χρήστη να χρησιμοποιεί την υπηρεσία από οπουδήποτε και οποτεδήποτε, καθώς και η εμπιστευτικότητα και ακεραιότητα των δεδομένων, που αποτελούν σημαντικούς παράγοντες απόφασης χρήσης της νέας υπηρεσίας, αφού εξασφαλίζουν στο χρήστη ότι τα προσωπικά του δεδομένα δεν θα είναι προσβάσιμα και δεν θα μπορούν να τροποποιηθούν ή να υποκλαπούν από τρίτους, κακόβουλους χρήστες. Επιπρόσθετα, εξετάστηκαν και άλλες σημαντικές έννοιες που εγγυώνται στο χρήστη την ασφάλειά του κατά την πραγματοποίηση οποιασδήποτε ενέργειας στην υπηρεσία, όπως για παράδειγμα η αυθεντικοποίηση, η εξουσιοδότηση, η απόδοση ευθυνών και η μη-απάρνηση. Τέλος, για τη δημιουργία αρχιτεκτονικών ασφαλείας είναι απαραίτητο να εξετάσουμε περισσότερα αντίμετρα για τους κινδύνους που εγκυμονούν, μιας και ολοένα και περισσότεροι κίνδυνοι απειλούν τα συστήματα χρόνο με το χρόνο. Τα μέτρα ασφαλείας που θα πάρουμε θα πρέπει να μην περιορίζουν τις ενέργειες των χρηστών και τη συνεργασία μεταξύ τους, αλλά αντίθετα να τα υποστηρίζουν με τον αποτελεσματικότερο και ασφαλέστερο τρόπο προς αυτούς

Journal of Telecommunications and Information Technology, 2011, nr 3

kwartalni

Forestilte publikum : Casestudier av den norske film- og tv-bransjens strategier for sosiale medier (2015-2018)

Hvordan film- og tv-bransjen forestiller seg og tilnærmer seg publikum i nye sosiale medier får konsekvenser for hvordan de distribuerer og produserer sitt innhold. Medie- og kulturindustrienes mer eller mindre presise forestillinger og «konstruksjon» av publikum har tidligere vært analysert som et sentralt vilkår for produksjon og distribusjon i film- og tv-bransjen (Ang, 1991; Havens & Lotz, 2011: 5). Fremveksten av sosiale medier representerer noe nytt med tanke på hvordan publikum forestilles og tolkes innen medieproduksjon og distribusjon (Ang i Litt, 2012). Denne avhandlingen er en samling av caseanalyser av hvordan forestillingene om publikum reforhandles i lys av sosiale medier i perioden 2015-2018. Avhandlingen vektlegger å undersøke og beskrive hvordan uavhengige distributører i den norske film- og tv-bransjen jobber med å utvikle ny publikumspraksis for å synliggjøre norske nisjeproduksjoner i sosiale medier. Ved å vektlegge tilnærmingen til særlig de mindre, uavhengige distributørene i film- og tv-bransjen, beskriver avhandlingen et empirisk felt som det er lite forsket på innen produksjons- og distribusjonsstudier i en skandinavisk mediefaglig sammenheng. Hvis vi ønsker å forstå vilkårene for et kulturelt mangfold både på et strukturelt og representativt/innholdsmessig nivå, er det verdifullt for det mediefaglige forskningsfeltet å interessere seg for å undersøke denne delen av norsk kulturproduksjon og distribusjon. Medieprodusentene og distributørenes forestillinger om publikum – og deres metoder og strategier for å nå dem, og forstå dem via sosiale medier – skjer ikke i et sosialt eller institusjonelt vakuum. Denne avhandlingen beskriver derfor også hvordan deres omgivende institusjoner, som Norsk filminstitutt og NRK, spiller inn i rådende forståelser av hva sosiale medier til enhver tid «er», og hvordan publikum og nye målgrupper tolkes og forstås i nye digitale medier. Casestudiene i denne avhandlingen tilhører dermed en mediefaglig retning innenfor studiet av kulturfeltet og nye medier, der man ikke forsker på hva sosiale medier er i seg selv, men hva de representerer for aktører som jobber med distribusjon i kulturfeltet, og hvilke følger det får for hvordan de organiserer ny publikumspraksis. Avhandlingen viser at ulike forestillinger om sosiale medier aktiviserer forskjellige former for ny publikumspraksis. Det vil si forestillinger om sosiale medier som algoritmestyrte plattformer, som nye markedsføringsverktøy eller som semi-offentlige rom. Sosiale medieplattformer som Facebook, Instagram, Twitter, Snapchat og YouTube skaper en infrastruktur der mediebrukeren – det empiriske, virtuelle publikum – også videreformidles som et «mediert publikum». Med andre ord et «mediert publikum» som kan «segmenteres» via ulike markedsføringsverktøy, og hvis oppmerksomhet kan selges videre, til for eksempel profesjonelle medieprodusenter og distributører. Hvilken forståelse, fortolkning og innsikt disse sistnevnte aktørene har i verktøyene på sosiale medier for det «medierte publikum» er derfor overordnede for denne avhandlingens analytiske fokus

Blajburg i revizionizam: Između istorije i mita

Rad ima intenciju da polazeći od teorijsko-metodoloških postavki kritičke istoriografije objasni suštinu uzroka istorijskog revizionizma u savremenom hrvatskom društvu i delu istoriografije. Blajburški narativ, kao ključno mesto istorijsko-revizionističkih ukrštanja, postao je u novije vreme jedna od okosnica nacionalističke ideologije, pa i samog identiteta savremene Hrvatske. U takvim okolnostima sve je teže odvojiti ideološke, mitotvorne i martirološke konstrukcije od racionalne i naučno proverljive, ali i kontekstualno uobličene interpretacije zbivanja na kraju Drugog svetskog rata u Jugoslaviji

Multimedia-Streaming in Benutzergruppen

At the time being, multimedia services using IP technology like IPTV or video on-demand are a hot topic. Technically, they can be classified under the notion of streaming. A server sends media data in a continuous fashion to one or several clients, which consume and display data portions as soon as they arrive. Using a feedback channel customers may influence the play-back, watching programs time-shifted or pausing the program. An enhancement of such streaming services is to watch those movies with a group of people on several devices in parallel. Similar approaches have been developed using IP multicast. However, users cannot control the presentation: pausing or skipping of more unimportant parts is impossible. Moreover, members cannot be added to the session directly within the application. The costream architecture developed in this works offers a collaborative streaming service without these limitations: People may join others watching a movie or invite others to such a collaborative streaming session. Dependent on the desired course of the session the participants' control operations are executed for all users, or the group is split into subgroups to let watchers follow their own time-lines. A group management controls this by means of user roles. Separate from the group management, the so-called association service provides for streaming session control and synchronization among participants. This separation of duties is advantageous in the sense that standard components can be used: For group management, SIP conferencing servers are suitable, whereas session control can best be handled using RTSP proxies as already used for caching of media data. Eventually, the evaluation of this architecture shows that such a service offers both low latency for clients and an acceptable synchronization of media streams to different client devices. Moreover, the communication overhead compared to usual conferencing or streaming systems is very low.Mit Hilfe der IP-Technologie erbrachte Multimedia-Dienste wie IPTV oder Video-on-Demand sind zur Zeit ein gefragtes Thema. Technisch werden solche Dienste unter dem Begriff "Streaming" eingeordnet. Ein Server sendet Mediendaten kontinuierlich an Empfänger, welche die Daten sofort weiterverarbeiten und anzeigen. Über einen Rückkanal hat der Kunde die Möglichkeit der Einflussnahme auf die Wiedergabe. Eine Weiterentwicklung dieser Streaming-Dienste ist die Möglichkeit, gemeinsam mit anderen denselben Film auf mehreren Geräten anzusehen. Ähnliche Ansätze gibt es im Internet bereits durch IP-Multicast. Allerdings können Benutzer hierbei keinen Einfluss auf die Übertragung nehmen - das Überspringen von Teilen ist zum Beispiel nicht möglich. Andere Benutzer können nicht direkt zur Streaming-Sitzung eingeladen werden. Collaborative Streaming ohne solche Einschränkungen bietet die in dieser Arbeit entwickelte costream-Architektur: Sie erlaubt es, andere zum gemeinsamen Betrachten eines Filmes einzuladen oder sich selbst in eine Benutzergruppe einzuklinken. Abhängig vom gewünschten Ablauf der Sitzung wird die Steuerung für alle Teilnehmer durchgeführt oder die Gruppe aufgeteilt. Eine Gruppenverwaltung regelt dies mit Hilfe von Rollenzuweisungen. Davon getrennt sorgt eine weitere Komponente für die Steuerung der Streaming-Sitzungen und die Synchronisation zwischen Teilnehmern. Diese Aufteilung hat den Vorteil, dass von der IETF entwickelte Standardprotokolle eingesetzt werden können. Für die Gruppenverwaltung sind SIP-Konferenzsysteme geeignet, während für die Sitzungssteuerung ein RTSP-Zwischensystem benutzt wurde. Die Evaluierung dieser Architektur zeigt schließlich, dass ein solcher Dienst nicht nur geringe Wartezeiten aufweist, sondern eine akzeptable Synchronisation der Datenströme auf die verschiedenen Ausgabegeräte der Benutzer erreicht wird. Zudem ist der Zusatzaufwand verglichen mit üblichen Konferenz- oder Streaming-Systemen sehr gering

Jurnal Teknodik Vol.XIII No.1 Juni 2010

Wahana Penelitian, Pengembangan dan Pendayagunaan Teknologi Informasi dan Komunikasi Untuk Pendidikan/Pembelajaran. Jurnal Teknologi Pendidikan diterbitkan oleh Pusat Teknologi Informasi dan Komunikasi Pendidikan dan Kebudayaan Kementerian Pendidikan dan Kebudayaan