Faouzi Boufarès

Constraints checking in UML class diagrams: SQL vs OCL

Numerous CASE tools are used for applications analysis and design. These tools often do not take into account all the information (structures and constraints) given in a conceptual level. So, the elements obtained at the physiccal level do not completely coincide with the conceptual elements. Consequently, some semantics are lost. Our goal, in this paper, is to give rules to translate some constraints not taken into account in the processes used to translate the conceptual schema. In object databases, these constraints are expressed in OCL while they are expressed, in relational databases, using active mechanisms. Consequently, these constraints are checked during databases updates.

A Massively Parallel Processing for the Multiple Linear Regression

The amount of data generated by traditional business activities, has resulted data warehouses with a size up to petabytes. The ability to analyze this torrent of data will become the basis of competition and growth for individual firms by ever-narrower segmentation of customers, improvement of decision-making and unearth valuable insights that would otherwise remain hidden. For this purpose, the large size of data to be processed requires the use of high-performance analytical systems running on distributed environments. Because the data is so big it affects the types of algorithms we are willing to consider. Then standard analytics algorithms need to be adapted to take advantage of cloud computing models which provide scalability and flexibility. This work illustrates an implementation of a parallel version of the multiple linear regression. It can extract coefficients from large amounts of data, based on MapReduce Framework with large scale. Parallel processing of multiple linear regression will be based on the QR decomposition and the ordinary least squares method adapted to Map Reduce. Our platform in deployed on Cloud Amazon EMR. Experimental results demonstrate that the our parallel version of the multiple linear regression can efficiently handle very large datasets on commodity hardware with a good performance on different evaluation criterions, including number, size and structure of machines in the cluster.

Constraints satisfaction problems in data modeling

We present a new approach to study the global coherence of constraints in data modeling. Unlike most of other approaches, we take a best part of these constraints into account during modeling processing. Thus, it is useless to generate the database - which may be partially or totally empty - if the constraints are in conflict. To this end, we formalize the constraints in mathematical inequalities form combined with expressions in first-order logic. We propose two approaches to detect and localize conflicts. In the first one, an algorithm, based on Fourier-Motzkin elimination, is suggested. In the second approach, the conceptual schema is formalized using a knowledge base.

On the integration of heterogeneous methods for complex applications

An approach towards harmonization of the large variety of existing information system modeling and specification techniques rather than standardization of single techniques is proposed. This approach provides a framework relating meta models in an open ordering and transformation scheme by means of a set of basic transformations.

Relational Implementation of Object Oriented Information System Design Using a Generic Model

The emergence of the object philosophy in the new software development techniques gave birth to many object models. In this paper, Our aim, is to use a generic object-oriented model, to generate an optimized relational environment. This optimization concerns the best choice to implement, in the relational model, the structural links between classes using the set of treatments expressed on the information system studied. This approach presents the advantage, comparing to the classical structural methods, to choose a relational schema which will not be reconsidered later in the implementation stage.

Semantic of Data Dependencies to Improve the Data Quality

Data quality in databases is a critical challenge because the cost of anomalies may be very high, especially for large databases. Therefore, the correction of these anomalies represents an issue that has become more and more important both in enterprises and in academia. In this work, we address the problems of intra-column and inter-columns anomalies in big data. We propose a new approach for data cleaning that takes into account the semantic dependencies between the columns of a data source. The novelty of our proposal is the reduction of the size of the search space in the process of functional dependency discovery based on data semantics. In this paper, we present the first steps of our work. They allow recognizing the semantics of data and correct intra-column anomalies.

A new tool to analyze ER-schemas

Cardinality constraints as well as key constraints and functional dependencies are among the most popular classes of constraints in database models. While each constraint class is now well understood, little is done about their interaction. Today, cardinality constraints and key constraints are embedded in most CASE tools, which are usually based on the entity-relationship model. However, these tools do not offer intelligent consistency checking routines for cardinality constraints and they do not consider the global coherence. Conflicts among the constraints are not detected. Our aim is then, to propose a tool for reasoning about a set of cardinality constraints, key and certain functional dependencies in order to help in database design. We treat the global coherence of cardinality constraints. We propose two steps: a syntactical analysis according to our ER Meta-schema and a semantic analysis in order to verify the cardinality constraints and their interactions.

From Object-Oriented Design Towards Object-Oriented Programming

The emergence of the object philosophy in the new software development techniques gave birth to many object models. The object-oriented approach enables the improvement of software quality, the reduction of future maintenance requirements, the reuse and the adaptation of specification and developments. However the difficulty lies in the transition between the conceptual specification and the implementation because of the disparity of the formalism proper to each level. To resolve the problem, we propose an object oriented interface supported by a software tool and based on a pivot model and a set of mapping rules.

An efficient detection of conflicting XML updates

As the amount of XML documents on the Web is constantly increasing, and since their contents can change over time, updating these documents with concurrency control becomes an interesting issue. The main problem is to detect conflicts between transactions. In this paper, we present an approach to detect conflicts between transactions. Our approach is based on path expressions associated with operations. This make our approach scalable in the majority of cases since it is independent from the database size as well as from the number of modified fragments. We give here the global architecture of our concurrency control mechanism in which our algorithm, to detect conflicts, is improved. Finally, we describe an experimental evaluation of