Abdellah Boukerram

COSABuilder AND COSAInstantiator: AN EXTENSIBLE TOOL FOR ARCHITECTURAL DESCRIPTION

As software systems grow, their complexity augments rapidly. In consequence their understandability and evolvability are becoming a difficult task. To address this issue, we have previously defined COSA (Component-Object based Software Architecture), which is a software architecture model that describes systems as a collection of components and connectors. However, COSA has been undertaken with academic rather than commercial goals. This paper presents a modeling tool (called COSABuilder) and instantiating tool (called COSAInstantiator) for COSA metamodel and describes their various features. Our contribution is not only offering MDA-based tools but also automatic instantiation and automatic verification of software architecture specifications. The goal is to preserve architecture traceability features in the modeling space and to create accurate architectures.

A survey of DHT solutions in fixed and mobile networks

Peer-to-peer P2P networks had experienced a great acceptance in recent years in the area of distributed computing, mainly attributed to their inherent management of some interests such as scaling, dynamic nature and heterogeneity that are required by the current network infrastructure. Specifically, structured P2P systems that have shown a great performance since their appearance due to the organisation they offer to the logical topology and objects placement according to specific algorithms. This survey presents a comprehensive and a critical study of research related to enhanced distributed hash tables DHTs, by presenting a classification according to the used methods and a comparison based on some important points as the routing tables, maintenance cost, lookup process, etc. We discuss the strengths and the weaknesses of existing approaches, and then we highlight the research issues that still to be lacked in order to serve as a guide for interested researchers.

Context-aware quality model driven approach: a new approach for quality control in pervasive computing environments

This paper presents extension of MDA called Context-aware Quality Model Driven Architecture (CQ-MDA) which can be used for quality control in pervasive computing environments. The proposed CQ-MDA approach based on ContextualArchRQMM (Contextual ARCHitecture Quality Requirement MetaModel), being an extension to the MDA, allows for considering quality and resources-awareness while conducting the design process. The main idea of presented extension consists in three abstractions levels: PIM (Platform Independent Model), CPIM (Contextual Platform Independent Model) and CPSM (Contextual Platform Specific Model). At the PIM level, a model decomposed into a two interrelated models: software architecture artifacts, which reflect functional requirements and quality model. At the CPIM level a simultaneous transformation of these two models with contextual information details is elaborated and then refined to a specific platform at the CPSM level. Such a procedure ensures that the transformation decisions should be based on the quality assessment of the created models.

A survey of locality-awareness solutions in mobile DHT systems

Structured peer-to-peer (P2P) systems showed over time a high performance to P2P users since their appearance. They are no longer restricted to wired networks but they are also applied on mobile devices in some recent researches in which the characteristics of mobility and wireless networks must be taken into account. The existing P2P protocols are experienced by the nonconsideration of the physical topology in the construction of the overlay, i.e. the overlay is not aware of its underlying physical networks which results a redundant traffic and high end-to-end latency. The solution of this problem called locality-awareness. In this paper, we discuss and compare available works on locality-awareness in DHT-Based mobile systems, mentioning its methods and advantages provided to both MANET (Mobile Ad-hoc Network) and cellular networks.

A Limited Energy Consumption Model for P2P Wireless Sensor Networks

One of the most critical and challenging issues when developing wireless sensor networks (WSNs) is how to extend the network lifetime. Sensors are energy-constrained devices that require developing minimization techniques and mechanisms in order to exploit perfectly the energy and to prolong as long as possible the overall network lifetime. In this paper, we propose a limited energy consumption model for P2P wireless sensor networks, which takes a benefit of the Chord assets and adapts this last one so that it will be suitable for P2P WSNs. Chord in its basic form optimizes the path length by minimizing the number of hops, but it does not optimize the energy, since it was designed for wired networks. The key idea of our proposal is to optimize both the number of hops and the energy consumption to provide an energy-efficient routing scheme for P2P WSNs. The proposed enhanced Chord scheme makes a use of only Cluster-Heads (with the strongest level of energy) to construct the ring, which reduces the Chord topology while preserving the network connectivity. In the enhanced Chord scheme, Cluster-Heads are elected automatically and dynamically over the time, which helps to extend the network longevity. Simulation results show that the proposed scheme proves good performances in terms of hops number, alive nodes over the time and energy efficiency.

Discovering Interest Based Mobile Communities

Human mobility has attracted lots of attention in the domain of wireless communication technologies and behavioral sciences. Exploring and analyzing human movements that are changing over time, relating to user habits and depending on spacial aspect is a challenging problem. In this paper, we are interested in discovering communities of mobile users and studying how do communities provide accurate knowledge to analysis the different forms of human mobility. The basic idea of our work is to model the behaviour of users with strong social characteristics regarding the context of their location histories to explore a similar interest of people by mining their mobiles communities. The proposed analysis illustrates in what way a common interest of a group of individuals can create better understanding of human mobility. Realistic models based on these interest based communities can be the basis for applications as recommendation system or wireless networks management.

Locality-Awareness and Replication for an Adaptive CHORD to MANet

Structuredpeer-to-peer(P2P)systemshaveshownovertimeahighperformancetoP2Pusers.Theyare typicallyappliedonInternetandwirednetworks.Ontheotherhand,theevolutionofmobiledevices andthepopularityofinfrastructure-lesswirelessnetworksasmobilead-hocnetworks(MANET), makeofthemaninterestingunderlayforP2Poverlays.However,theirenergyconsumptionstillsa criticalelementwithlimited-energybatteries,andthemostprincipalcauseofenergyconsumption istheimmenseoverhead.TheaimofthisworkistoapplytheChordprotocolonMANETunderlay, inordertobenefitfromtheefficientcontent-sharingprocessandtheinfrastructure-lessmobility.At thesametime,thisworkaimstoconserveagoodlevelofenergyconsumptionandnetworklifetime. Therefore,itproposesanovelmechanismoflocalityawarenessandreplicationofdatathatattempts toimprovethelookupefficiencyandreducethetrafficoverhead. KeywORDS Distributed Hash Table, Energy, Locality Awareness, Mobile Network, Replication, Structured P2P Systems

RepMChord: A novel replication approach for mobile Chord with reduced traffic overhead

Summary Structured peer-to-peer systems based on distributed hash table (DHT) have known a great popularity and performance since their appearance. They have experienced multiple improvements to increase the efficiency, like replication mechanism with different used methods and different objectives like increasing data availability or fitting to churn. Besides their benefits, these methods suffer from the excessive generated overhead in maintenance process. On the other side, we have the interest deployment of DHT overlay on mobile ad hoc network, which benefits from the infrastructure-less architecture, but presents some shortcomings because of the limited bandwidth and energy batteries, what require a reduced overhead. Therefore, the aim of this work is to improve the lookup efficiency of DHT-based Chord on mobile ad hoc network underlay. For that, we propose a novel replication mechanism based on data structure to determine the replica nodes, while avoiding the excessive generated overhead in maintenance process to cope with the problem of limited energy batteries. To evaluate the proposed method, we present an extensive simulation study that compares the work to another efficient replication method and to mobile basic Chord. The results show the efficiency of our approach in decreasing the lookup path, the maintenance overhead, and the energy consumption.

Can we recognize the next user’s mobile community?

Accurate location prediction is central for the current and future location based services. We propose here an approach based on a new definition of community, which is centered on individual interests, and open for a novel prediction approach that exploits the properties of these communities. We show on real traces that the proposed approach is very efficient and allows to achieve high performances.

Energy-efficient data collection in grid-based Wireless Sensor Networks using a mobile sink

To save energy in Wireless Sensor Networks (WSNs) and prolong the network lifetime, many works investigate the use of one or more mobile sinks. These solutions are mainly based on organizing the network within a grid to simplify the computation of the sink trajectory. However, existing solutions do not take into account energy consumption during grid construction and do not scale when the sink has to visit every cell of the network grid. To overcome this drawback, we propose an energy-based cell-head selection combined with two sink mobility algorithms to minimize energy consumption of sensor nodes and optimize data collection. Experimentation results confirm the efficiency of our algorithms compared to two basics schemes, i.e. static sink and random sink mobility and also to the related work.