Abderrahim Ait Wakrime

Ontological approach for Data WareHouse design

Waste management is a major concern of the various policy makers, economic and social. It is present each time he comes to launching development projects and / or development of urban infrastructure. The implementation of Data Warehousing assisting in decision making in this context, proves very useful, but at the same time a very complex task. We provide a solution to support Data Warehouse design. Our solution combines the two classical approaches to design, it is both oriented and need-oriented data. It is based on ontology representation languages an the results of work on the alignment. Our Data Warehouse design process has two stages. The first one which is interactive and semi-automatic, transforms user requirements into ontologies, the second step that is fully automatic, aligns the resulting ontologies from the first step and produces an ontology associated to the multidimensional data model. The waste management field will be our guideline to illustrate our approach.

Place-Liveness of ComSA Applications

Interactive scientific visualization applications are based on heterogeneous codes to implement simulation, visualization and interaction parts. These different parts need to be precisely assembled to construct high performance applications allowing efficient interactions. Thanks to their programming paradigm, component-based approaches are suitable to construct this kind of applications. However, building a correct application using this paradigm is a difficult task. Even starting up such an application may be a difficult problem since the composition may lead to deadlocks. This paper defines a sufficient condition that ensures place-liveness of a subclass of FIFO nets. This result is used to provide tools that help a user to analyze his application. Especially, this analysis aims at avoiding deadlocks and starting the application up in a way that ensures its liveness i.e. all its components are active.

A MaxSAT based approach for QoS cloud services

ABSTRACT Web Services technologies are operated to build Software as a Service (SaaS) layer in the Cloud Computing. It happens that a single Web Service does not respond to customers request. In this case, one needs to compose several distributed Web Services in order to achieve the customers goal and allow interaction between heterogeneous applications. In this paper, a new approach for QoS Web Services problem is proposed. It is based on an original encoding using satisfiability problem. To minimise the composition and also take into account user preferences, an objective function is used leading to the known Maximum Satisfiability problem (MaxSAT). Such formulation is flexible and allows to introduce constraints in order to seek for specified Web Services Composition. Experimental evaluation on some generated instances shows the feasibility of our proposed approach.

Formal Approach for QoS-Aware Cloud Service Composition

Cloud Computing based Software as a Service (SaaS) combines multiple Web Services to satisfy a SaaS request. SaaS is based on Service-Oriented Architecture and Web Service technology which are popular paradigm to design new generation of applications. One of the advantages of Web Services technology is to building distributed application on demand using existing service oriented application. Web Services Composition (WSC) in Cloud Computing is necessary when a single service is unable to satisfy all the customers requirements. WSC is a complex task in the SaaS which involves several steps like discovery, compatibility checking, selection and deployment. To reduce the complexity of WSC, we model Web Services and their composition using Boolean satisfiability problem so that a specific property of their structures is looked into behavioral compatibility. The aim of this work is the modelling and verification of Web Services Composition using a formal method based on Satisfiability (SAT). However, in some cases it may be preferable to use variations of the general SAT problem. Specifically, using the Minimally Unsatisfiable Subformula (MUS), we formally define a Web Services Composition and its validation. When we have a multiple Web Services Compositions that meet the users needs, a QoS of the resulting WSC is maximized or, in some cases, minimized.

On QoS web service composition using satisfiability

Cloud Computing based Software as a Service (SaaS) combines multiple Web Services in order to satisfy a SaaS request. SaaS is based on Service Oriented Architectures and Web Service technology which are popular paradigm to design new generation of applications. These functionalities are published on the Internet, but exploiting rigorously a large data stream in order to use Web Services is a complicated and laborious task which may involve error prone. In this paper we investigate the problem of SaaS Web Service Composition. We present a new technique that translates the problem of minimum SaaS Web Services composition into MaxSAT problem. We extend this encoding to take int account the QoS by proposing a weighted MaxSAT version.

On the fly reconfiguration of interactive scientific visualization applications

An interactive scientific visualization application is constructed from different codes to implement simulation, data treatment, visualization and interaction parts. The application construction requires support for the assembly of the different parts considering their heterogeneity in the one hand and the need to achieve an efficient application to be run in real time on the other hand. Component-based approach is an interesting paradigm to handle such applications. Moreover in a context of visual analytics, some applications need to be dynamically reconfigured since some components as analysis steps are not persistent and need to be restarted or stopped on the fly. This paper describes a reconfiguration process for ComSA applications, a component based approach dedicated to interactive scientific visualization applications that relies on an exogenous coordination model. This process enables the reconfiguration of running applications. It aims to minimize the number of stopped components during the reconfiguration phase while avoiding the application to crash. It uses the properties of the coordination model to circumscribe the part of the application impacted by the reconfiguration. This region is safely paused, then modified and finally restarted.

Minimum Unsatisfiability based QoS Web Service Composition over the Cloud Computing

Cloud Computing based Software as a Service (SaaS) combines multiple Web Services in order to satisfy a SaaS request. SaaS is based on Service Oriented Architectures and Web Service technology which are popular paradigm to design new generation of applications. These functionalities are published on the Internet, but exploiting rigorously a large data stream in order to use Web Services is a complicated and laborious task which may involve error prone. In this paper we investigate the problem of SaaS Web Service Composition. We present a new technique that combines an encoding into SAT and a Minimal Unsatisfiability Subformulas extraction to obtain the minimum SaaS Web Service Composition. Furthermore, we generalize this approach to take into account the quality of SaaS Web Service.