Abstract: We describe the design and implementation
of a secure and robust architectural data management
model suitable for cultural environments. Usage and exploitation
of the WorldWideWeb is a critical requirement
for a series of administrative tasks such as collecting, managing
and distributing valuable cultural and artistic information.
This requirement introduces a great number of
Internet threats for cultural organizations that may cause
huge data and/or financial losses, harm their reputation
and public acceptance as well as people’s trust on them.
Our model addresses a list of fundamental operational
and security requirements. It utilizes a number of cryptographic
primitives and techniques that provide data safety
and secure user interaction on especially demanding online
collaboration environments. We provide a reference
implementation of our architectural model and discuss
the technical issues. It is designed as a standalone solution
but it can be flexibly adapted in broader management
infrastructures.
Abstract: This paper addresses the efficient processing of
top-k queries in wide-area distributed data
repositories where the index lists for the attribute
values (or text terms) of a query are distributed
across a number of data peers and the
computational costs include network latency,
bandwidth consumption, and local peer work.
We present KLEE, a novel algorithmic
framework for distributed top-k queries,
designed for high performance and flexibility.
KLEE makes a strong case for approximate top-k
algorithms over widely distributed data sources.
It shows how great gains in efficiency can be
enjoyed at low result-quality penalties. Further,
KLEE affords the query-initiating peer the
flexibility to trade-off result quality and expected
performance and to trade-off the number of
communication phases engaged during query
execution versus network bandwidth
performance. We have implemented KLEE and
related algorithms and conducted a
comprehensive performance evaluation. Our
evaluation employed real-world and synthetic
large, web-data collections, and query
benchmarks. Our experimental results show that
KLEE can achieve major performance gains in
terms of network bandwidth, query response
times, and much lighter peer loads, all with small
errors in result precision and other result-quality
measures
Abstract: In this paper we examine the problem of searching for some information item in the nodes of a fully
interconnected computer network, where each node contains information relevant to some topic
as well as links to other network nodes that also contain information, not necessarily related to
locally kept information. These links are used to facilitate the Internet users and mobile software
agents that try to locate specific pieces of information. However, the links do not necessarily point
to nodes containing information of interest to the user or relevant to the aims of the mobile agent.
Thus an element of uncertainty is introduced. For example, when an Internet user or some search
agent lands on a particular network node, they see a set of links that point to information that is,
supposedly, relevant to the current search. Therefore, we can assume that a link points to relevant
information with some unknown probability p that, in general, is related to the number of nodes
in the network (intuitively, as the network grows, this probability tends to zero since adding more
nodes to the network renders some extant links less accurate or obsolete). Consequently, since there
is uncertainty as to whether the links contained in a node?s Web page are correct or not, a search
algorithm cannot rely on following the links systematically since it may end up spending too much
time visiting nodes that contain irrelevant information. In this work, we will describe and analyze
a search algorithm that is only allowed to transfer a fixed amount of memory along communication
links as it visits the network nodes. The algorithm is, however, allowed to use one bit of memory at
each node as an ?already visited? flag. In this way the algorithm has its memory distributed to the
network nodes, avoiding overloading the network links as it moves from node to node searching for
the information. We work on fully interconnected networks for simplicity reasons and, moreover,
because according to some recent experimental evidence, such networks can be considered to be a
good approximation of the current structure of the WorldWideWeb.
Abstract: Internet of Things technologies are considered the next big
step in Smart Building installations. Although such technologies have
been widely studied in simulation and experimental scenarios it is not so
obvious how problems of real world installations should be dealt with. In
this work we deploy IoT devices for sensing and control in a multi-office
space and employ technologies such as CoAP, RESTful interfaces and
Semantic Descriptions to integrate them with the Web. We report our
research goals, the challenges we faced, the decisions we made and the
experience gained from the design, deployment and operation of all the
hardware and software components that compose our system.
