277 research outputs found
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
User-Relative Names for Globally Connected Personal Devices
Nontechnical users who own increasingly ubiquitous network-enabled personal
devices such as laptops, digital cameras, and smart phones need a simple,
intuitive, and secure way to share information and services between their
devices. User Information Architecture, or UIA, is a novel naming and
peer-to-peer connectivity architecture addressing this need. Users assign UIA
names by "introducing" devices to each other on a common local-area network,
but these names remain securely bound to their target as devices migrate.
Multiple devices owned by the same user, once introduced, automatically merge
their namespaces to form a distributed "personal cluster" that the owner can
access or modify from any of his devices. Instead of requiring users to
allocate globally unique names from a central authority, UIA enables users to
assign their own "user-relative" names both to their own devices and to other
users. With UIA, for example, Alice can always access her iPod from any of her
own personal devices at any location via the name "ipod", and her friend Bob
can access her iPod via a relative name like "ipod.Alice".Comment: 7 pages, 1 figure, 1 tabl
RDF Querying
Reactive Web systems, Web services, and Web-based publish/
subscribe systems communicate events as XML messages, and in
many cases require composite event detection: it is not sufficient to react
to single event messages, but events have to be considered in relation to
other events that are received over time.
Emphasizing language design and formal semantics, we describe the
rule-based query language XChangeEQ for detecting composite events.
XChangeEQ is designed to completely cover and integrate the four complementary
querying dimensions: event data, event composition, temporal
relationships, and event accumulation. Semantics are provided as
model and fixpoint theories; while this is an established approach for rule
languages, it has not been applied for event queries before
Transparent network-assisted flow mobility for multimedia applications in IMS environments
Cellular network operators are striving to solve the problem caused by the increasing volume of traffic over their networks. Given the proliferation of multi-interface devices, offloading part of the traffic to available access networks (e. g., WiFi or 3G access networks, even from other operators) seems to be a promising alternative. Here, we propose an IMS-compatible solution for flow mobility between access networks that exhibits two key features: flow mobility is transparent to both local applications at mobile nodes and their communication peers (e. g., multimedia content servers), and mobility operations are assisted by the network, so the home network supports the terminal in the process of access network discovery, and provides the terminal with policies that meet visited and home operators' roaming agreements while optimizing the use of their networks. The proposed solution has been validated using a real IMS testbed with Ethernet and WiFi access networks, where the mobility of UDP and TCP flows has been tested.The work in this article has been partially granted
by the Madrid Community through the MEDIANET
project (S-2009/TIC-1468) and by the
Celtic UP-TO-US project (TSI-020400-2010-114)Publicad
Survey over Existing Query and Transformation Languages
A widely acknowledged obstacle for realizing the vision of the Semantic Web is the inability
of many current Semantic Web approaches to cope with data available in such diverging
representation formalisms as XML, RDF, or Topic Maps. A common query language is the first
step to allow transparent access to data in any of these formats. To further the understanding
of the requirements and approaches proposed for query languages in the conventional as well
as the Semantic Web, this report surveys a large number of query languages for accessing
XML, RDF, or Topic Maps. This is the first systematic survey to consider query languages from
all these areas. From the detailed survey of these query languages, a common classification
scheme is derived that is useful for understanding and differentiating languages within and
among all three areas
Translation techniques for distributed-shared memory programming models
This thesis argues that a modular, source-to-source translation system for distributed-shared memory programming models would be beneficial to the high-performance computing community. It goes on to present a proof-of-concept example in detail, translating between Global Arrays (GA) and Unified Parallel C (UPC). Some useful extensions to UPC are discussed, along with how they are implemented in the proof-of-concept translator
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