115 research outputs found
Efficient service discovery in wide area networks
Living in an increasingly networked world, with an abundant number
of services available to consumers, the consumer electronics market
is enjoying a boom. The average consumer in the developed world may
own several networked devices such as games consoles, mobile phones,
PDAs, laptops and desktops, wireless picture frames and printers to
name but a few. With this growing number of networked devices comes
a growing demand for services, defined here as functions requested
by a client and provided by a networked node. For example, a client
may wish to download and share music or pictures, find and use
printer services, or lookup information (e.g. train times, cinema
bookings).
It is notable that a significant proportion of networked devices are
now mobile. Mobile devices introduce a new dynamic to the service
discovery problem, such as lower battery and processing power and
more expensive bandwidth. Device owners expect to access services
not only in their immediate proximity, but further afield (e.g. in
their homes and offices). Solving these problems is the focus of
this research.
This Thesis offers two alternative approaches to service discovery
in Wide Area Networks (WANs). Firstly, a unique combination of the
Session Initiation Protocol (SIP) and the OSGi middleware technology
is presented to provide both mobility and service discovery
capability in WANs. Through experimentation, this technique is shown
to be successful where the number of operating domains is small, but
it does not scale well.
To address the issue of scalability, this Thesis proposes the use of
Peer-to-Peer (P2P) service overlays as a medium for service
discovery in WANs. To confirm that P2P overlays can in fact support
service discovery, a technique to utilise the Distributed Hash Table
(DHT) functionality of distributed systems is used to store and
retrieve service advertisements. Through simulation, this is shown
to be both a scalable and a flexible service discovery technique.
However, the problems associated with P2P networks with respect to
efficiency are well documented.
In a novel approach to reduce messaging costs in P2P networks,
multi-destination multicast is used. Two well known P2P overlays are
extended using the Explicit Multi-Unicast (XCAST) protocol. The
resulting analysis of this extension provides a strong argument for
multiple P2P maintenance algorithms co-existing in a single P2P
overlay to provide adaptable performance. A novel multi-tier P2P
overlay system is presented, which is tailored for service rich
mobile devices and which provides an efficient platform for service
discovery
Next Generation Service Delivery Platforms and Service Overlay Networks
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively
Emerging research directions in computer science : contributions from the young informatics faculty in Karlsruhe
In order to build better human-friendly human-computer interfaces,
such interfaces need to be enabled with capabilities to perceive
the user, his location, identity, activities and in particular his interaction
with others and the machine. Only with these perception capabilities
can smart systems ( for example human-friendly robots or smart environments) become posssible. In my research I\u27m thus focusing on the
development of novel techniques for the visual perception of humans and
their activities, in order to facilitate perceptive multimodal interfaces,
humanoid robots and smart environments. My work includes research
on person tracking, person identication, recognition of pointing gestures,
estimation of head orientation and focus of attention, as well as
audio-visual scene and activity analysis. Application areas are humanfriendly
humanoid robots, smart environments, content-based image and
video analysis, as well as safety- and security-related applications. This
article gives a brief overview of my ongoing research activities in these
areas
Socially aware microcloud service overlay optimization in community networks
Community networks are a growing network cooperation effort by citizens to build and maintain Internet infrastructure in regions that are not available. Adding that, to bring cloud services to community networks (CNs), microclouds were started as an edge cloud computing model where members cooperate using resources. Therefore, enhancing routing for services in CNs is an attractive paradigm that benefits the infrastructure. The problem is the growing consumption of resources for disseminating messages in the CN environment. This is because the services that build their overlay networks are oblivious to the underlying workload patterns that arise from social cooperation in CNs. In this paper, we propose Select in Community Networks (SELECTinCN), which enhances the overlay creation for pub/sub systems over peer-to-peer (P2P) networks. Moreover, SELECTinCN includes social information based on cooperation within CNs by exploiting the social aspects of the community of practice. Our work organizes the peers in a ring topology and provides an adaptive P2P connection establishment algorithm, where each peer identifies the number of connections needed based on the social structure and user availability. This allows us to propagate messages using a reduced number of hops, thus providing an efficient heuristic to an NP-hard problem that maps the workload graph to the structured P2P overlays resulting in a number of messages close to the theoretical minimum. Experiments show that, by using social network information, SELECTinCN reduces the number of relay nodes by up to 89% using the community of practice information versus the state-of-the-art pub/sub notification systems given as baseline.Peer ReviewedPostprint (author's final draft
Cognitively-inspired Agent-based Service Composition for Mobile & Pervasive Computing
Automatic service composition in mobile and pervasive computing faces many
challenges due to the complex and highly dynamic nature of the environment.
Common approaches consider service composition as a decision problem whose
solution is usually addressed from optimization perspectives which are not
feasible in practice due to the intractability of the problem, limited
computational resources of smart devices, service host's mobility, and time
constraints to tailor composition plans. Thus, our main contribution is the
development of a cognitively-inspired agent-based service composition model
focused on bounded rationality rather than optimality, which allows the system
to compensate for limited resources by selectively filtering out continuous
streams of data. Our approach exhibits features such as distributedness,
modularity, emergent global functionality, and robustness, which endow it with
capabilities to perform decentralized service composition by orchestrating
manifold service providers and conflicting goals from multiple users. The
evaluation of our approach shows promising results when compared against
state-of-the-art service composition models.Comment: This paper will appear on AIMS'19 (International Conference on
Artificial Intelligence and Mobile Services) on June 2
Overview of OAI and its relation to scientific publishing in 2004
An introduction to OAI: what it means, what has been happening, and what implications there might be for the future of scientific publishing
Network Orchestration in Reliable 5G/NFV/SDN Infrastructures
In this paper, we elaborate an SDN orchestration solution aiming at the dynamic adaptation of service chain paths thereby addressing high-availability requirements of 5G applications. We present an SDN orchestrator that periodically monitors the availability of the network and, if necessary, promptly adapts service chain paths to recover from congestion events and to preserve network QoS performance of service data flows. A set of performance results are finally presented.This work has been partially supported by the EU H2020 5G Exchange (5GEx) innovation project (grant no. 671636) and by EU H2020 5G-Transformer Project (grant no. 761536
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