188,611 research outputs found
Semi-automatic semantic enrichment of raw sensor data
One of the more recent sources of large volumes of generated data is sensor devices, where dedicated sensing equipment is used to monitor events and happenings in a wide range of domains, including monitoring human biometrics. In recent trials to examine the effects that key moments in movies have on the human body, we fitted fitted with a number of biometric sensor devices and monitored them as they watched a range of dierent movies in groups. The purpose of these experiments was to examine the correlation between humans' highlights in movies as observed from biometric sensors, and highlights in the same movies as identified by our automatic movie analysis techniques. However,the problem with this type of experiment is that both the analysis of the video stream and the sensor data readings are not directly usable
in their raw form because of the sheer volume of low-level data values generated both from the sensors and from the movie analysis. This work describes the semi-automated enrichment of both video analysis and sensor data and the mechanism used to query the data in both centralised
environments, and in a peer-to-peer architecture when the number of sensor devices grows to large numbers. We present and validate a scalable means of semi-automating the semantic enrichment of sensor data, thereby providing a means of large-scale sensor management
Understanding the Properties of the BitTorrent Overlay
In this paper, we conduct extensive simulations to understand the properties
of the overlay generated by BitTorrent. We start by analyzing how the overlay
properties impact the efficiency of BitTorrent. We focus on the average peer
set size (i.e., average number of neighbors), the time for a peer to reach its
maximum peer set size, and the diameter of the overlay. In particular, we show
that the later a peer arrives in a torrent, the longer it takes to reach its
maximum peer set size. Then, we evaluate the impact of the maximum peer set
size, the maximum number of outgoing connections per peer, and the number of
NATed peers on the overlay properties. We show that BitTorrent generates a
robust overlay, but that this overlay is not a random graph. In particular, the
connectivity of a peer to its neighbors depends on its arriving order in the
torrent. We also show that a large number of NATed peers significantly
compromise the robustness of the overlay to attacks. Finally, we evaluate the
impact of peer exchange on the overlay properties, and we show that it
generates a chain-like overlay with a large diameter, which will adversely
impact the efficiency of large torrents
The state of peer-to-peer network simulators
Networking research often relies on simulation in order to test and evaluate new ideas. An important requirement of this process is that results must be reproducible so that other researchers can replicate, validate and extend existing work. We look at the landscape of simulators for research in peer-to-peer (P2P) networks by conducting a survey of a combined total of over 280 papers from before and after 2007 (the year of the last survey in this area), and comment on the large quantity of research using bespoke, closed-source simulators. We propose a set of criteria that P2P simulators should meet, and poll the P2P research community for their agreement. We aim to drive the community towards performing their experiments on simulators that allow for others to validate their results
Storytelling Security: User-Intention Based Traffic Sanitization
Malicious software (malware) with decentralized communication infrastructure, such as peer-to-peer botnets, is difficult to detect. In this paper, we describe a traffic-sanitization method for identifying malware-triggered outbound connections from a personal computer. Our solution correlates user activities with the content of outbound traffic. Our key observation is that user-initiated outbound traffic typically has corresponding human inputs, i.e., keystroke or mouse clicks. Our analysis on the causal relations between user inputs and packet payload enables the efficient enforcement of the inter-packet dependency at the application level.
We formalize our approach within the framework of protocol-state machine. We define new application-level traffic-sanitization policies that enforce the inter-packet dependencies. The dependency is derived from the transitions among protocol states that involve both user actions and network events. We refer to our methodology as storytelling security.
We demonstrate a concrete realization of our methodology in the context of peer-to-peer file-sharing application, describe its use in blocking traffic of P2P bots on a host. We implement and evaluate our prototype in Windows operating system in both online and offline deployment settings. Our experimental evaluation along with case studies of real-world P2P applications demonstrates the feasibility of verifying the inter-packet dependencies. Our deep packet inspection incurs overhead on the outbound network flow. Our solution can also be used as an offline collect-and-analyze tool
Swarming Overlay Construction Strategies
Swarming peer-to-peer systems play an increasingly instrumental role in
Internet content distribution. It is therefore important to better understand
how these systems behave in practice. Recent research efforts have looked at
various protocol parameters and have measured how they affect system
performance and robustness. However, the importance of the strategy based on
which peers establish connections has been largely overlooked. This work
utilizes extensive simulations to examine the default overlay construction
strategy in BitTorrent systems. Based on the results, we identify a critical
parameter, the maximum allowable number of outgoing connections at each peer,
and evaluate its impact on the robustness of the generated overlay. We find
that there is no single optimal value for this parameter using the default
strategy. We then propose an alternative strategy that allows certain new peer
connection requests to replace existing connections. Further experiments with
the new strategy demonstrate that it outperforms the default one for all
considered metrics by creating an overlay more robust to churn. Additionally,
our proposed strategy exhibits optimal behavior for a well-defined value of the
maximum number of outgoing connections, thereby removing the need to set this
parameter in an ad-hoc manner
Autonomic Management of Maintenance Scheduling in Chord
This paper experimentally evaluates the effects of applying autonomic
management to the scheduling of maintenance operations in a deployed Chord
network, for various membership churn and workload patterns. Two versions of an
autonomic management policy were compared with a static configuration. The
autonomic policies varied with respect to the aggressiveness with which they
responded to peer access error rates and to wasted maintenance operations. In
most experiments, significant improvements due to autonomic management were
observed in the performance of routing operations and the quantity of data
transmitted between network members. Of the autonomic policies, the more
aggressive version gave slightly better results
Mesmerizer: A Effective Tool for a Complete Peer-to-Peer Software Development Life-cycle
In this paper we present what are, in our experience, the best
practices in Peer-To-Peer(P2P) application development and
how we combined them in a middleware platform called Mesmerizer. We explain how simulation is an integral part of
the development process and not just an assessment tool.
We then present our component-based event-driven framework for P2P application development, which can be used
to execute multiple instances of the same application in a
strictly controlled manner over an emulated network layer
for simulation/testing, or a single application in a concurrent
environment for deployment purpose. We highlight modeling aspects that are of critical importance for designing and
testing P2P applications, e.g. the emulation of Network Address Translation and bandwidth dynamics. We show how
our simulator scales when emulating low-level bandwidth
characteristics of thousands of concurrent peers while preserving a good degree of accuracy compared to a packet-level
simulator
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