DSS from an RE perspective: A systematic mapping

Decision support systems (DSS) provide a unified analytical view of business data to better support decision-making processes. Such systems have shown a high level of user satisfaction and return on investment. However, several surveys stress the high failure rate of DSS projects. This problem results from setting the wrong requirements by approaching DSS in the same way as operational systems, whereas a specific approach is needed. Although this is well-known, there is still a surprising gap on how to address requirements engineering (RE) for DSS.; To overcome this problem, we conducted a systematic mapping study to identify and classify the literature on DSS from an RE perspective. Twenty-seven primary studies that addressed the main stages of RE were selected, mapped, and classified into 39 models, 27 techniques, and 54 items of guidance. We have also identified a gap in the literature on how to design the DSS main constructs (typically, the data warehouse and data flows) in a methodological manner from the business needs. We believe this study will help practitioners better address the RE stages of DSS projects.Peer ReviewedPostprint (author's final draft

A unified view of data-intensive flows in business intelligence systems : a survey

Data-intensive flows are central processes in today’s business intelligence (BI) systems, deploying different technologies to deliver data, from a multitude of data sources, in user-preferred and analysis-ready formats. To meet complex requirements of next generation BI systems, we often need an effective combination of the traditionally batched extract-transform-load (ETL) processes that populate a data warehouse (DW) from integrated data sources, and more real-time and operational data flows that integrate source data at runtime. Both academia and industry thus must have a clear understanding of the foundations of data-intensive flows and the challenges of moving towards next generation BI environments. In this paper we present a survey of today’s research on data-intensive flows and the related fundamental fields of database theory. The study is based on a proposed set of dimensions describing the important challenges of data-intensive flows in the next generation BI setting. As a result of this survey, we envision an architecture of a system for managing the lifecycle of data-intensive flows. The results further provide a comprehensive understanding of data-intensive flows, recognizing challenges that still are to be addressed, and how the current solutions can be applied for addressing these challenges.Peer ReviewedPostprint (author's final draft

Model-driven development of Data Vault based data warehouses.

U tezi je razmatrano više problema vezanih za projektovanje i razvoj skladišta podataka, kao što su: - neusaglašenost skladišta podataka sa izvorima podataka, nastala kao rezultat permanentnih promena strukture izvora, - nekompletnost podataka u skladištu podataka, - heterogenost modela izvora i njihova semantička neusaglašenost - nepostojanje standardnog konceptualnog modela i modela strukture skladišta podataka...Several issues, related to the design and development of data warehouses, are analyzed in this thesis: - inconsistency between the data warehouse and data sources due to the permanent changes in the structure of the data sources, - incompleteness of the stored data, - heterogeneity of data source models and their semantic inconsistency, - absence of standardized conceptual or structural data warehouse models..

Analyse en ligne (OLAP) de documents

Thèse également disponible sur le site de l'Université Paul Sabatier, Toulouse 3 : http://thesesups.ups-tlse.fr/160/Data warehouses and OLAP systems (On-Line Analytical Processing) provide methods and tools for enterprise information system data analysis. But only 20% of the data of a corporate information system may be processed with actual OLAP systems. The rest, namely 80%, i.e. documents, remains out of reach of OLAP systems due to the lack of adapted tools and processes. To solve this issue we propose a multidimensional conceptual model for representing analysis concepts. The model rests on a unique concept that models both analysis subjects as well as analysis axes. We define an aggregation function to aggregate textual data in order to obtain a summarised vision of the information extracted from documents. This function summarises a set of keywords into a smaller and more general set. We introduce a core of manipulation operators that allow the specification of analyses and their manipulation with the use of the concepts of the model. We associate a design process for the integration of data extracted from documents within an OLAP system that describes the phases for designing the conceptual schema, for analysing the document sources and for the loading process. In order to validate these propositions we have implemented a prototype.Les entrepôts de données et les systèmes d'analyse en ligne OLAP (On-Line Analytical Processing) fournissent des méthodes et des outils permettant l'analyse de données issues des systèmes d'information des entreprises. Mais, seules 20% des données d'un système d'information est constitué de données analysables par les systèmes OLAP actuels. Les 80% restant, constitués de documents, restent hors de portée de ces systèmes faute d'outils ou de méthodes adaptés. Pour répondre à cette problématique nous proposons un modèle conceptuel multidimensionnel pour représenter les concepts d'analyse. Ce modèle repose sur un unique concept, modélisant à la fois les sujets et les axes d'une analyse. Nous y associons une fonction pour agréger des données textuelles afin d'obtenir une vision synthétique des informations issues de documents. Cette fonction résume un ensemble de mots-clefs par un ensemble plus petit et plus général. Nous introduisons un noyau d'opérations élémentaires permettant la spécification d'analyses multidimensionnelles à partir des concepts du modèle ainsi que leur manipulation pour affiner une analyse. Nous proposons également une démarche pour l'intégration des données issues de documents, qui décrit les phases pour concevoir le schéma conceptuel multidimensionnel, l'analyse des sources de données ainsi que le processus d'alimentation. Enfin, pour valider notre proposition, nous présentons un prototype

Formal design of data warehouse and OLAP systems : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Information Systems at Massey University, Palmerston North, New Zealand

A data warehouse is a single data store, where data from multiple data sources is integrated for online business analytical processing (OLAP) of an entire organisation. The rationale being single and integrated is to ensure a consistent view of the organisational business performance independent from different angels of business perspectives. Due to its wide coverage of subjects, data warehouse design is a highly complex, lengthy and error-prone process. Furthermore, the business analytical tasks change over time, which results in changes in the requirements for the OLAP systems. Thus, data warehouse and OLAP systems are rather dynamic and the design process is continuous. In this thesis, we propose a method that is integrated, formal and application-tailored to overcome the complexity problem, deal with the system dynamics, improve the quality of the system and the chance of success. Our method comprises three important parts: the general ASMs method with types, the application tailored design framework for data warehouse and OLAP, and the schema integration method with a set of provably correct refinement rules. By using the ASM method, we are able to model both data and operations in a uniform conceptual framework, which enables us to design an integrated approach for data warehouse and OLAP design. The freedom given by the ASM method allows us to model the system at an abstract level that is easy to understand for both users and designers. More specifically, the language allows us to use the terms from the user domain not biased by the terms used in computer systems. The pseudo-code like transition rules, which gives the simplest form of operational semantics in ASMs, give the closeness to programming languages for designers to understand. Furthermore, these rules are rooted in mathematics to assist in improving the quality of the system design. By extending the ASMs with types, the modelling language is tailored for data warehouse with the terms that are well developed for data-intensive applications, which makes it easy to model the schema evolution as refinements in the dynamic data warehouse design. By providing the application-tailored design framework, we break down the design complexity by business processes (also called subjects in data warehousing) and design concerns. By designing the data warehouse by subjects, our method resembles Kimball's "bottom-up" approach. However, with the schema integration method, our method resolves the stovepipe issue of the approach. By building up a data warehouse iteratively in an integrated framework, our method not only results in an integrated data warehouse, but also resolves the issues of complexity and delayed ROI (Return On Investment) in Inmon's "top-down" approach. By dealing with the user change requests in the same way as new subjects, and modelling data and operations explicitly in a three-tier architecture, namely the data sources, the data warehouse and the OLAP (online Analytical Processing), our method facilitates dynamic design with system integrity. By introducing a notion of refinement specific to schema evolution, namely schema refinement, for capturing the notion of schema dominance in schema integration, we are able to build a set of correctness-proven refinement rules. By providing the set of refinement rules, we simplify the designers's work in correctness design verification. Nevertheless, we do not aim for a complete set due to the fact that there are many different ways for schema integration, and neither a prescribed way of integration to allow designer favored design. Furthermore, given its °exibility in the process, our method can be extended for new emerging design issues easily

Modélisation des bases de données multidimensionnelles : analyse par fonctions d'agrégation multiples

Le résumé en français n'a pas été communiqué par l'auteur.Le résumé en anglais n'a pas été communiqué par l'auteur

Modélisation des bases de données multidimensionnelles : analyse par fonctions d'agrégation multiples

Le résumé en français n'a pas été communiqué par l'auteur.Le résumé en anglais n'a pas été communiqué par l'auteur

Intégration holistique et entreposage automatique des données ouvertes

Statistical Open Data present useful information to feed up a decision-making system. Their integration and storage within these systems is achieved through ETL processes. It is necessary to automate these processes in order to facilitate their accessibility to non-experts. These processes have also need to face out the problems of lack of schemes and structural and sematic heterogeneity, which characterize the Open Data. To meet these issues, we propose a new ETL approach based on graphs. For the extraction, we propose automatic activities performing detection and annotations based on a model of a table. For the transformation, we propose a linear program fulfilling holistic integration of several graphs. This model supplies an optimal and a unique solution. For the loading, we propose a progressive process for the definition of the multidimensional schema and the augmentation of the integrated graph. Finally, we present a prototype and the experimental evaluations.Les statistiques présentes dans les Open Data ou données ouvertes constituent des informations utiles pour alimenter un système décisionnel. Leur intégration et leur entreposage au sein du système décisionnel se fait à travers des processus ETL. Il faut automatiser ces processus afin de faciliter leur accessibilité à des non-experts. Ces processus doivent pallier aux problèmes de manque de schémas, d'hétérogénéité structurelle et sémantique qui caractérisent les données ouvertes. Afin de répondre à ces problématiques, nous proposons une nouvelle démarche ETL basée sur les graphes. Pour l'extraction du graphe d'un tableau, nous proposons des activités de détection et d'annotation automatiques. Pour la transformation, nous proposons un programme linéaire pour résoudre le problème d'appariement holistique de données structurelles provenant de plusieurs graphes. Ce modèle fournit une solution optimale et unique. Pour le chargement, nous proposons un processus progressif pour la définition du schéma multidimensionnel et l'augmentation du graphe intégré. Enfin, nous présentons un prototype et les résultats d'expérimentations