3,409 research outputs found
Operating-system support for distributed multimedia
Multimedia applications place new demands upon processors, networks and operating systems. While some network designers, through ATM for example, have considered revolutionary approaches to supporting multimedia, the same cannot be said for operating systems designers. Most work is evolutionary in nature, attempting to identify additional features that can be added to existing systems to support multimedia. Here we describe the Pegasus project's attempt to build an integrated hardware and operating system environment from\ud
the ground up specifically targeted towards multimedia
SHStream: Self-Healing Framework for HTTP Video-Streaming
HTTP video-streaming is leading delivery of video
content over the Internet. This phenomenon is explained by the
ubiquity of web browsers, the permeability of HTTP traffic
and the recent video technologies around HTML5. However,
the inclusion of multimedia requests imposes new requirements
on web servers due to responses with lifespans that can reach
dozens of minutes and timing requirements for data fragments
transmitted during the response period. Consequently, web-
servers require real-time performance control to avoid playback
outages caused by overloading and performance anomalies. We
present
SHStream
, a self-healing framework for web servers
delivering video-streaming content that provides (1) load admit-
tance to avoid server overloading; (2) prediction of performance
anomalies using online data stream learning algorithms; (3)
continuous evaluation and selection of the best algorithm for
prediction; and (4) proactive recovery by migrating the server
to other hosts using container-based virtualization techniques.
Evaluation of our framework using several variants of
Hoeffding
trees
and
ensemble algorithms
showed that with a small number of
learning instances, it is possible to achieve approximately 98% of
recall
and 99% of
precision
for failure predictions. Additionally,
proactive failover can be performed in less than 1 secon
Scalable Storage for Digital Libraries
I propose a storage system optimised for digital libraries. Its key features are its heterogeneous scalability; its integration and exploitation of rich semantic metadata associated with digital objects; its use of a name space; and its aggressive performance optimisation in the digital library domain
Video streaming with quality adaption using collaborative active grid networks
Due to the services and demands of the end
users, Distributed Computing (Grid Technology,
Web Services, and Peer-to-Peer) has been
developedrapidJy in thelastyears. Theconvergence
of these architectures has been possible using
mechanisms such as Collaborative work and
Resources Sharing. Grid computing is a platform to
enable flexible, secure, controlled, scalable,
ubiquitous and heterogeneous services. On the
other hand, Video Streaming applications demand
a greater deployment over connected Internet users.
The present work uses the Acti ve Grid technology
as a fundamental platform to give a solution of
multimediacontentrecovery. This solution takes
into account the following key concepts:
collaborative work, multi-source recovery and
adapti ve quality. A new archi tecture is designed to
deliver video content over a Grid Network. The
acti ve and passi ve roles of the nodes are important
to guarantee a high quality and efficiency for the
video streaming system. The acti ve sender nodes
are the content suppliers, while the passive sender
nodes wiU perform the backup functions, based on
global resource control policies. The aim of the
backup node is minirnize the time to restore the
systemin caseoffailures. In this way, all participant
peers work in a collaborati ve manner following a
mul ti -source recovery scheme.
Furthermore, Video La yered Encoding is used
to manage the video data in a high scalable way,
di viding the video in multiple layers. This video
codification scheme enables thequality adaptation
according to the availability of system resources. In
addition, a buffer by sender peer and by layer is
needed for an effecti ve control ofthe video retrieve.
The QoS will fit considering the state of each buffer
and the measurement tools provide by the Acti ve
Grid on the network nodes. Ke ywords: Peer -to-Peer Grid Architecture,
Services for Active Grids, Streaming Media,
Layered Coding, Quality Adaptation, CoUaborative
Work.Peer Reviewe
Video streaming with quality adaption using collaborative active grid networks
Due to the services and demands of the end
users, Distributed Computing (Grid Technology,
Web Services, and Peer-to-Peer) has been
developedrapidJy in thelastyears. Theconvergence
of these architectures has been possible using
mechanisms such as Collaborative work and
Resources Sharing. Grid computing is a platform to
enable flexible, secure, controlled, scalable,
ubiquitous and heterogeneous services. On the
other hand, Video Streaming applications demand
a greater deployment over connected Internet users.
The present work uses the Acti ve Grid technology
as a fundamental platform to give a solution of
multimediacontentrecovery. This solution takes
into account the following key concepts:
collaborative work, multi-source recovery and
adapti ve quality. A new archi tecture is designed to
deliver video content over a Grid Network. The
acti ve and passi ve roles of the nodes are important
to guarantee a high quality and efficiency for the
video streaming system. The acti ve sender nodes
are the content suppliers, while the passive sender
nodes wiU perform the backup functions, based on
global resource control policies. The aim of the
backup node is minirnize the time to restore the
systemin caseoffailures. In this way, all participant
peers work in a collaborati ve manner following a
mul ti -source recovery scheme.
Furthermore, Video La yered Encoding is used
to manage the video data in a high scalable way,
di viding the video in multiple layers. This video
codification scheme enables thequality adaptation
according to the availability of system resources. In
addition, a buffer by sender peer and by layer is
needed for an effecti ve control ofthe video retrieve.
The QoS will fit considering the state of each buffer
and the measurement tools provide by the Acti ve
Grid on the network nodes. Ke ywords: Peer -to-Peer Grid Architecture,
Services for Active Grids, Streaming Media,
Layered Coding, Quality Adaptation, CoUaborative
Work.Peer Reviewe
Dynamicity and Durability in Scalable Visual Instance Search.
Visual instance search involves retrieving from a collection of images the
ones that contain an instance of a visual query. Systems designed for visual
instance search face the major challenge of scalability: a collection of a few
million images used for instance search typically creates a few billion
features that must be indexed. Furthermore, as real image collections grow
rapidly, systems must also provide dynamicity, i.e., be able to handle on-line
insertions while concurrently serving retrieval operations. Durability, which
is the ability to recover correctly from software and hardware crashes, is the
natural complement of dynamicity. Durability, however, has rarely been
integrated within scalable and dynamic high-dimensional indexing solutions.
This article addresses the issue of dynamicity and durability for scalable
indexing of very large and rapidly growing collections of local features for
instance retrieval. By extending the NV-tree, a scalable disk-based
high-dimensional index, we show how to implement the ACID properties of
transactions which ensure both dynamicity and durability. We present a detailed
performance evaluation of the transactional NV-tree: (i) We show that the
insertion throughput is excellent despite the overhead for enforcing the ACID
properties; (ii) We also show that this transactional index is truly scalable
using a standard image benchmark embedded in collections of up to 28.5 billion
high-dimensional vectors; the largest single-server evaluations reported in the
literature
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