Aplicación de técnicas activas para el control de restricciones en el desarrollo de bases de datos

En las metodologías de desarrollo de BD nos encontramos que los modelos conceptuales que aplicamos son cada vez más ricos y capaces de recoger con mayor precisión las especificaciones del dominio. El problema surge cuando queremos mantener esta semántica en la siguiente fase de la metodología, la fase lógica. La mayoría de estas metodologías utilizan el modelo relacional para transformar el esquema conceptual a un esquema lógico. Para ello, se aplican un conjunto de reglas de transformación. Estas reglas son, en general, muy básicas pues solo especifican la transformación de los elementos más simples y sencillos del modelo conceptual, esto implica una pérdida de semántica significativa, que lleva al diseñador a controlar y comprobar las restricciones de integridad del dominio fuera de la BD. Para representar las restricciones de integridad, el estándar SQL3 y la mayoría de los SGBDs comerciales proporcionan dos maneras: mecanismos declarativos y mecanismos procedimentales. Los mecanismos declarativos aportan una base fundamental y estrategia tradicional para reforzar las reglas básicas de negocio (Not Null, Default, Unique, Primary Key, Foreign Key , Check, Domain y Assertion). Sin embargo, estas cláusulas no son capaces de expresar todas las restricciones de integridad incluidas en un modelo conceptual, por eso, se utilizan mecanismos procedimentales como reglas activas/disparadores para poder controlar estas restricciones dentro del SGBD. En este trabajo de tesis doctoral se propone incorporar reglas activas para preservar todas las restricciones de integridad asociadas a un dominio dentro de la BD y proporcionar a los diseñadores herramientas que faciliten la generación automática de estas reglas, el análisis de su comportamiento teniendo en cuenta las interacciones con el resto de elementos de la BD y su visualización. El trabajo está enmarcado dentro del proyecto "Plataforma de gestión de procesos software: Modelado, reutilización y medición“. TIN2004/07083 ----------------------------------------Abstract: In database development methodologies, conceptual models are more abstract and concerned to express more accurately the semantics of the real world. A problem is produced when we want to maintain this semantics in the following phase of methodologies: the logical phase. Most of these methodologies are agree with the application of the relational model to transform the conceptual scheme into a logical scheme. To do that, a set of transformation rules is applied. These rules are basics and simples, they specify the transformation of the simplest conceptual elements and this implies a lost semantics. Therefore, databases developers must employ different mechanisms to enforce database consistency. To verify integrity constraints, the recent SQL standard and almost all commercial DBMSs support two ways: declaratively mechanisms and procedural mechanisms. Declarative mechanisms provide a fundamental base and traditional strategy to enforce business basic rules by using constraints such as: Not Null, Default, Unique, Primary Key, Foreign Key, Check, Domain, and Assertion. Because of these constructors are insufficient to express all integrity constraints, procedural mechanisms active rules/triggers are used in order to control these constraints inside the DBMS. In this doctoral thesis work, incorporating active rules into database are proposed to preserve all integrity constraints associated. Moreover, we provide some tools to facilitate: automatic rules generation, rules analysis, and rules behaviour visualization considering the interactions with the reminder of elements. This work is part of the project "Software Process Management Platform: modelling, reuse and measurement". TIN2004/0708

Applying a Fuzzy Approach to Relaxing Cardinality Constraints

9 pages, 3 figures.-- Contributed to: 15th International Conference on Database and Expert Systems Applications (DEXA 2004, Zaragoza, Spain, Aug 30 - Sep 3, 2004).In database applications the verification of cardinality constraints is a serious and complex problem that appears when the modifications operations are performed in a large cascade. Many efforts have been devoted to solve this problem, but some solutions lead to other problems such as the complex execution model or an impact on the database performance. In this paper a method to reducing and simplifying the complex verification of cardinality constraints by relaxing these constraints using fuzzy concepts is proposed.Publicad

OCL2Trigger: Deriving active mechanisms for relational databases using Model-Driven Architecture

16 pages, 10 figures.-- Issue title: "Best papers from the 2007 Australian Software Engineering Conference (ASWEC 2007), Melbourne, Australia, April 10-13, 2007, Australian Software Engineering Conference 2007".Transforming integrity constraints into active rules or triggers for verifying database consistency produces a serious and complex problem related to real time behaviour that must be considered for any implementation. Our main contribution to this work is to provide a complete approach for deriving the active mechanisms for Relational Databases from the specification of the integrity constraints by using OCL. This approach is designed in accordance with the MDA approach which consists of transforming the specified OCL clauses into a class diagram into SQL:2003 standard triggers, then transforming the standard triggers into target DBMS triggers. We believe that developing triggers and plugging them into a given model is insufficient because the behaviour of such triggers is invisible to the developers, and therefore not controllable. For this reason, a DBMS trigger verification model is used in our approach, in order to ensure the termination of trigger execution. Our approach is implemented as an add-in tool in Rational Rose called OCL2Trigger.This work is part of the "Software Process Management Platform: Modelling, reuse and measurement" TIN2004/07083 project.Publicad

Plugging active mechanisms to control dynamic aspects derived from the Multiplicity Constraint in UML

8 pages, 5 figures.-- Contributed to: 7th International Conference on the Unified Modeling Language (UML'2004, Lisbon, Portugal, Oct 11-15, 2004).Multiple efforts have been devoted to face the problem of database modelling. One of them is the automatization of database design process using CASE tools. Frequently, these tools do not completely support all phases of database analysis and the design methodology that they propose. Therefore, we propose to incorporate new features to these tools enhancing them and solving some of the modelling problems. In this paper we present an add-in module that aims to generate triggers for preserving the multiplicity constraints of a conceptual scheme in the transformation to a relational scheme. The module is integrated into the RATIONAL ROSE case tool.Publicad

Guidelines for representing complex cardinality constraints in binary and ternary relationships

Ternary relationships represent the association among three entities whose constraints database designers do not always know how to manage. In other words, it is very difficult for the designer to detect, represent and add constraints in a ternary relationship according to the domain requirements. To remedy the shortcomings in capturing the semantics required for the representation of this kind of relationship, the present paper discusses a practical method to motivate the designer's use of ternary relationships in a methodological framework. The method shows how to calculate cardinality constraints in binary and ternary relationships and to preserve the associated semantics until the implementation phase of the database development method.This work forms part of the ‘Thuban: Natural Interaction Platform for Virtual Attending in Real Environments’ project (TIN2008-02711), the Spanish Ministry of Industry, Tourism and Trade through the project Semants (TSI-020100-2009-419) and also by the Spanish research projects: MA2VICMR: Improving the access, analysis and visibility of the multilingual and multimedia information in web for the Region of Madrid (S2009/TIC-1542).Publicad

Using UML’s Sequence Diagrams for Representing Execution Models Associated to Triggers

11 pages, 3 figures.-- Contributed to: 23rd British National Conference on Databases (BNCOD 23, Belfast, Northern Ireland, UK, July 18-20, 2006).Using active rules or triggers to verify integrity constraints is a serious and complex problem because these mechanisms have behaviour that could be difficult to predict in a complex database. The situation is even worse as there are few tools available for developing and verifying them. We believe that automatic support for trigger development and verification would help database developers to adopt triggers in the database design process. Therefore, in this work we suggest a visualization add-in tool that represents and verifies triggers execution by using UML’s sequence diagrams. This tool is added in RATIONAL ROSE and it simulates the execution sequence of a set of triggers when a DML operation is produced. This tool uses the SQL standard to express the triggers semantics and execution.This work is part of the project "Software Process Management Platform: modelling, reuse and measurement". TIN2004/07083.Publicad

Combining Wikipedia and Newswire Texts for Question Answering in Spanish

4 pages, 1 figure.-- Contributed to: Advances in Multilingual and Multimodal Information Retrieval: 8th Workshop of the Cross-Language Evaluation Forum (CLEF 2007, Budapest, Hungary, Sep 19-21, 2007).This paper describes the adaptations of the MIRACLE group QA system in order to participate in the Spanish monolingual question answering task at QA@CLEF 2007. A system, initially developed for the EFE collection, was reused for Wikipedia. Answers from both collections were combined using temporal information extracted from questions and collections. Reusing the EFE subsystem has proven not feasible, and questions with answers only in Wikipedia have obtained low accuracy. Besides, a co-reference module based on heuristics was introduced for processing topic-related questions. This module achieves good coverage in different situations but it is hindered by the moderate accuracy of the base system and the chaining of incorrect answers.This work has been partially supported by the Regional Government of Madrid under the Research Network MAVIR (S-0505/TIC-0267) and projects by the Spanish Ministry of Education and Science (TIN2004/07083,TIN2004-07588-C03-02,TIN2007-67407-C03-01).Publicad

Pandora Case Tool: Generating Triggers for Cardinality Constraints in RDBMS

4 pages, 1 figure.-- Contributed to: IADIS International Conference WWW/Internet 2003 (ICWI 2003, Algarve, Portugal, Nov 5-8, 2003).The cardinality constraint is one of the most important constraints that can be established in a conceptual model. Nevertheless, not all CASE tools for developing database support the validation of this constraint due to the complexity associated to the referential integrity rules. So that, the contribution of this work concerns to provide PANDORA CASE (a tool used for learning and developing database in internet) algorithms which can be used to generate triggers for enforcing the cardinality constraints of a given database. These triggers are full compatible with the standard SQL3.Publicad