3,586 research outputs found
Towards Autonomic Service Provisioning Systems
This paper discusses our experience in building SPIRE, an autonomic system
for service provision. The architecture consists of a set of hosted Web
Services subject to QoS constraints, and a certain number of servers used to
run session-based traffic. Customers pay for having their jobs run, but require
in turn certain quality guarantees: there are different SLAs specifying charges
for running jobs and penalties for failing to meet promised performance
metrics. The system is driven by an utility function, aiming at optimizing the
average earned revenue per unit time. Demand and performance statistics are
collected, while traffic parameters are estimated in order to make dynamic
decisions concerning server allocation and admission control. Different utility
functions are introduced and a number of experiments aiming at testing their
performance are discussed. Results show that revenues can be dramatically
improved by imposing suitable conditions for accepting incoming traffic; the
proposed system performs well under different traffic settings, and it
successfully adapts to changes in the operating environment.Comment: 11 pages, 9 Figures,
http://www.wipo.int/pctdb/en/wo.jsp?WO=201002636
6G Mobile-Edge Empowered Metaverse: Requirements, Technologies, Challenges and Research Directions
The Metaverse has emerged as the successor of the conventional mobile
internet to change people's lifestyles. It has strict visual and physical
requirements to ensure an immersive experience (i.e., high visual quality, low
motion-to-photon latency, and real-time tactile and control experience).
However, the current communication systems fall short to satisfy these
requirements. Mobile edge computing (MEC) has been indispensable to enable low
latency and powerful computing. Moreover, the sixth generation (6G) networks
promise to provide end users with high-capacity communications to MEC servers.
In this paper, we bring together the primary components into a 6G mobile-edge
framework to empower the Metaverse. This includes the usage of heterogeneous
radios, intelligent reflecting surfaces (IRS), non-orthogonal multiple access
(NOMA), and digital twins (DTs). We also discuss novel communication paradigms
(i.e., semantic communication, holographic-type communication, and haptic
communication) to further satisfy the demand for human-type communications and
fulfil user preferences and immersive experiences in the Metaverse
Transparent and scalable client-side server selection using netlets
Replication of web content in the Internet has been found to improve service response time, performance and reliability offered by web services. When working with such distributed server systems, the location of servers with respect to client nodes is found to affect service response time perceived by clients in addition to server load conditions. This is due to the characteristics of the network path segments through which client requests get routed. Hence, a number of researchers have advocated making server selection decisions at the client-side of the network. In this paper, we present a transparent approach for client-side server selection in the Internet using Netlet services. Netlets are autonomous, nomadic mobile software components which persist and roam in the network independently, providing predefined network services. In this application, Netlet based services embedded with intelligence to support server selection are deployed by servers close to potential client communities to setup dynamic service decision points within the network. An anycast address is used to identify available distributed decision points in the network. Each service decision point transparently directs client requests to the best performing server based on its in-built intelligence supported by real-time measurements from probes sent by the Netlet to each server. It is shown that the resulting system provides a client-side server selection solution which is server-customisable, scalable and fault transparent
Secure, reliable and dynamic access to distributed clinical data
An abundance of statistical and scientific data exists in the area of clinical and epidemiological studies. Much of this data is distributed across regional, national and international boundaries with different policies on access and usage, and a multitude of different schemata for the data often complicated by the variety of supporting clinical coding schemes. This prevents the wide scale collation and analysis of such data as is often needed to infer clinical outcomes and to determine the often moderate effect of drugs. Through grid technologies it is possible to overcome the barriers introduced by distribution of heterogeneous data and services. However reliability, dynamicity and fine-grained security are essential in this domain, and are not typically offered by current grids. The MRC funded VOTES project (Virtual Organisations for Trials and Epidemiological Studies) has implemented a prototype infrastructure specifically designed to meet these challenges. This paper describes this on-going implementation effort and the lessons learned in building grid frameworks for and within a clinical environment
A Taxonomy of Data Grids for Distributed Data Sharing, Management and Processing
Data Grids have been adopted as the platform for scientific communities that
need to share, access, transport, process and manage large data collections
distributed worldwide. They combine high-end computing technologies with
high-performance networking and wide-area storage management techniques. In
this paper, we discuss the key concepts behind Data Grids and compare them with
other data sharing and distribution paradigms such as content delivery
networks, peer-to-peer networks and distributed databases. We then provide
comprehensive taxonomies that cover various aspects of architecture, data
transportation, data replication and resource allocation and scheduling.
Finally, we map the proposed taxonomy to various Data Grid systems not only to
validate the taxonomy but also to identify areas for future exploration.
Through this taxonomy, we aim to categorise existing systems to better
understand their goals and their methodology. This would help evaluate their
applicability for solving similar problems. This taxonomy also provides a "gap
analysis" of this area through which researchers can potentially identify new
issues for investigation. Finally, we hope that the proposed taxonomy and
mapping also helps to provide an easy way for new practitioners to understand
this complex area of research.Comment: 46 pages, 16 figures, Technical Repor
Fault-Tolerant Real-Time Streaming with FEC thanks to Capillary Multi-Path Routing
Erasure resilient FEC codes in off-line packetized streaming rely on time
diversity. This requires unrestricted buffering time at the receiver. In
real-time streaming the playback buffering time must be very short. Path
diversity is an orthogonal strategy. However, the large number of long paths
increases the number of underlying links and consecutively the overall link
failure rate. This may increase the overall requirement in redundant FEC
packets for combating the link failures. We introduce the Redundancy Overall
Requirement (ROR) metric, a routing coefficient specifying the total number of
FEC packets required for compensation of all underlying link failures. We
present a capillary routing algorithm for constructing layer by layer steadily
diversifying multi-path routing patterns. By measuring the ROR coefficients of
a dozen of routing layers on hundreds of network samples, we show that the
number of required FEC packets decreases substantially when the path diversity
is increased by the capillary routing construction algorithm
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