170 research outputs found
JooFlux: Hijacking Java 7 InvokeDynamic To Support Live Code Modifications
Changing functional and non-functional software implementation at runtime is
useful and even sometimes critical both in development and production
environments. JooFlux is a JVM agent that allows both the dynamic replacement
of method implementations and the application of aspect advices. It works by
doing bytecode transformation to take advantage of the new invokedynamic
instruction added in Java SE 7 to help implementing dynamic languages for the
JVM. JooFlux can be managed using a JMX agent so as to operate dynamic
modifications at runtime, without resorting to a dedicated domain-specific
language. We compared JooFlux with existing AOP platforms and dynamic
languages. Results demonstrate that JooFlux performances are close to the Java
ones --- with most of the time a marginal overhead, and sometimes a gain ---
where AOP platforms and dynamic languages present significant overheads. This
paves the way for interesting future evolutions and applications of JooFlux
Performance Comparison of Contention- and Schedule-based MAC Protocols in Urban Parking Sensor Networks
Network traffic model is a critical problem for urban applications, mainly
because of its diversity and node density. As wireless sensor network is highly
concerned with the development of smart cities, careful consideration to
traffic model helps choose appropriate protocols and adapt network parameters
to reach best performances on energy-latency tradeoffs. In this paper, we
compare the performance of two off-the-shelf medium access control protocols on
two different kinds of traffic models, and then evaluate their application-end
information delay and energy consumption while varying traffic parameters and
network density. From the simulation results, we highlight some limits induced
by network density and occurrence frequency of event-driven applications. When
it comes to realtime urban services, a protocol selection shall be taken into
account - even dynamically - with a special attention to energy-delay tradeoff.
To this end, we provide several insights on parking sensor networks.Comment: ACM International Workshop on Wireless and Mobile Technologies for
Smart Cities (WiMobCity) (2014
How to Choose the Relevant MAC Protocol for Wireless Smart Parking Urban Networks?
Parking sensor network is rapidly deploying around the world and is regarded
as one of the first implemented urban services in smart cities. To provide the
best network performance, the MAC protocol shall be adaptive enough in order to
satisfy the traffic intensity and variation of parking sensors. In this paper,
we study the heavy-tailed parking and vacant time models from SmartSantander,
and then we apply the traffic model in the simulation with four different kinds
of MAC protocols, that is, contention-based, schedule-based and two hybrid
versions of them. The result shows that the packet interarrival time is no
longer heavy-tailed while collecting a group of parking sensors, and then
choosing an appropriate MAC protocol highly depends on the network
configuration. Also, the information delay is bounded by traffic and MAC
parameters which are important criteria while the timely message is required.Comment: The 11th ACM International Symposium on Performance Evaluation of
Wireless Ad Hoc, Sensor, and Ubiquitous Networks (2014
Semantic Service Substitution in Pervasive Environments
A computing infrastructure where everything is a service offers many new
system and application possibilities. Among the main challenges, however, is
the issue of service substitution for the application execution in such
heterogeneous environments. An application would like to continue to execute
even when a service disappears, or it would like to benefit from the
environment by using better services with better QoS when possible. In this
article, we define a generic service model and describe the equivalence
relations between services considering the functionalities they propose and
their non functional QoS properties. We define semantic equivalence relations
between services and equivalence degree between non functional QoS properties.
Using these relations we propose semantic substitution mechanisms upon the
appearance and disappearance of services that fits the application needs. We
developed a prototype as a proof of concept and evaluated its efficiency over a
real use case
Router deployment of Streetside Parking Sensor Networks in Urban Areas
The deployment of urban infrastructure is very important for urban sensor
applications. In this paper, we studied and introduced the deployment strategy
of wireless on-street parking sensor networks. We defined a multiple-objective
problem with four objectives, and solved them with real street parking map. The
results show two sets of Pareto Front with the minimum energy consumption,
sensing information delay and the amount of deployed routers and gateways. The
result can be considered to provide urban service roadside unit or be taken
into account while designing a deployment algorithm.Comment: UM - Urban Modelling Symposium, Oct 2014, Lyon, France.
\<http://urbanmodelling.sciencesconf.org/\&g
Opportunities for a Truffle-based Golo Interpreter
Golo is a simple dynamically-typed language for the Java Virtual Machine.
Initially implemented as a ahead-of-time compiler to JVM bytecode, it leverages
invokedy-namic and JSR 292 method handles to implement a reasonably efficient
runtime. Truffle is emerging as a framework for building interpreters for JVM
languages with self-specializing AST nodes. Combined with the Graal compiler,
Truffle offers a simple path towards writing efficient interpreters while
keeping the engineering efforts balanced. The Golo project is interested in
experimenting with a Truffle interpreter in the future, as it would provides
interesting comparison elements between invokedynamic versus Truffle for
building a language runtime
Calendrier prévisionnel du déroulement d'une thèse
Manuel destiné aux thésards et encadrants de thèse.Différents guides apportent une aide précieuse au bon déroulement d'une thèse [3, 1, 2]. Après les avoir examinés, aucun ne propose de planification temporelle des tâches à réaliser dans la thèse. Ce mini-guide essaie de donner quelques éléments de réponse à cette demande. Il s'appuie sur un ensemble d'expériences collectées dans les domaines de l'informatique et du traitement du signal, et n'est donc évidemment pas exhaustif
Adding Network Coding Capabilities to the WSNet Simulator
This technical report presents the implementation of a Network Coding module
in WSNet - a Wireless Sensor Network simulator. This implementation provides a
generic programming interface to allow an easy specialization of different
coding strategies: random, source/destination-oriented, intra/inter-flow, etc
Bayesian Semiparametric Multi-State Models
Multi-state models provide a unified framework for the description of the evolution of discrete phenomena in continuous time. One particular example are Markov processes which can be characterised by a set of time-constant transition intensities between the states. In this paper, we will extend such parametric approaches to semiparametric models with flexible transition intensities based on Bayesian versions of penalised splines. The transition intensities will be modelled as smooth functions of time and can further be related to parametric as well as nonparametric covariate effects. Covariates with time-varying effects and frailty terms can be included in addition. Inference will be conducted either fully Bayesian using Markov chain Monte Carlo simulation techniques or empirically Bayesian based on a mixed model representation. A counting process representation of semiparametric multi-state models provides the likelihood formula and also forms the basis for model validation via martingale residual processes. As an application, we will consider human sleep data with a discrete set of sleep states such as REM and Non-REM phases. In this case, simple parametric approaches are inappropriate since the dynamics underlying human sleep are strongly varying throughout the night and individual-specific variation has to be accounted for using covariate information and frailty terms
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