Web warehousing plays a key role in providing the managers with up-to-date and comprehensive information about their business domain. On the other hand, since XML is now a standard de facto for the exchange of semi-structured data, integrating XML data into web warehouses is a hot topic. In this paper we propose a semi-automated methodology for designing web warehouses from XML sources modeled by XML Schemas. In the proposed methodology, design is carried out by first creating a schema graph, then navigating its arcs in order to derive a correct multidimensional representation. Differently from previous approaches in the literature, particular relevance is given to the problem of detecting shared hierarchies and convergence of dependencies, and of modeling many-to-many relationships. The approach is implemented in a prototype that reads an XML Schema and produces in output the logical schema of the warehouse.

Designing web warehouses from XML schemas

On-Line Analytical Processing (OLAP) systems based on multidimensional databases are essential elements of decision support. However, most existing data is stored in ordinary relational OLTP databases, i.e., data has to be (re-) modeled as multidimensional cubes before the advantages of OLAP tools are available. In this paper we present an approach for the automatic construction of multidimensional OLAP database schemas from existing relational OLTP databases, enabling easy OLAP design and analysis for most existing data sources. This is achieved through a set of practical and effective algorithms for discovering multidimensional schemas from relational databases. The algorithms take a wide range of available metadata into account in the discovery process, including functional and inclusion dependencies, and key and cardinality information.

Discovering multidimensional structure in relational data

Developing a data warehouse for XML documents involves two major processes: one of creating it, by processing XML raw documents into a specified data warehouse repository; and the other of querying it, by applying techniques to better answer user's queries. The proposed methodology in our paper on building XML data warehouses covers processes such as data cleaning and integration, summarization, intermediate XML documents, and updating/linking existing documents and creating fact tables.

On building XML data warehouses

Intelligent unmanned mining is a key process in coal mine production, which has direct impact on the production safety, coal output, economic benefits and social benefits of coal mine enterprises. With the rapid development and popularization of 5G+ intelligent mines and coal mine intelligent equipment in China, the intelligentization of intelligent unmanned mining has become an important research topic. Especially with the promulgation of some Chinese policies and regulations, intelligent unmanned mining technology has become one of the key technologies of coal mine production. To understand the connotation, status quo and development trends of intelligent unmanned mining, this paper takes the relationship between key technologies and engineering application of intelligent unmanned mining in China as the perspective. It is proposed that the intelligent unmanned mining technology is in the whole process of working face mining. A research structure of unmanned follow-up operation and safe patrol is changing to the mode of intelligent adaptive mining, followed by the basic concepts and characteristics of intelligent unmanned mining. Relevant researches that maybe beneficial to the proposed research content are reviewed in four layers, which include basic theory, key technology, mining mode, and overall design system theory and technology. Finally, the current intelligent unmanned mining mode and future trends in this field in China are summarized.

/pdf/a-review-of-intelligent-unmanned-mining-current-situation-1y6ewk5k.pdf

A Review of Intelligent Unmanned Mining Current Situation and Development Trend

The Data Warehouse

XML – the Extensible Markup Language has recently emerged as a standard for information representation and exchange on the internet, because of its portability, versatility and extensibility. As the large increase in the availability of such data, there is a need of an appropriate storage and an integration solution for future analysis and decision-making. Data warehouses systems provide a suitable means to organise and manage XML data for decision-making. However, XML data warehouse has some special requirements such as mixed content and irregular structure of XML data sources, which make existing traditional data warehouse approaches and techniques unsuitable. In this paper, we give an overview of current state of the art concerning how XML technologies can be combined with data warehousing systems, by the presentation of the most relevant XML warehousing approaches proposed in the literature.

An overview of XML warehouse design approaches and techniques

In this paper, we present a mixed approach for building XML data warehouses from both XML data sources and user requirements. Our proposed approach aims at obtaining a unique multidimensional schema of theXML data warehouse. The approach follows three steps. During the first step, an intermediate SBVR model extended with template rules is used to accommodate a data warehousing system and to facilitate the automatic identification of facts and dimensions from the user requirements. After modelling XML data sources in UML, the second step corresponds to identifying candidate DW schemata from such data sources. The third step compares these candidate schemata with the reference model obtained from the user requirements. In this step, we propose to adapt similarity metric-extended Boolean models (BIR) and to use them in order to measure, rank and select the most appropriate data warehouse schema. Such a schema should best describe the data sources and exhaustively cover all the needed user requirements. To demonstrate our approach, we present a case study of the bibliographic database dblp.

AuMixDw: Towards an automated hybrid approach for building XML data warehouses

Traditionally, the multidimensional schema of the data warehouse is derived from data sources that are mainly the company's internal data, well-known and structured, by identifying facts, dimensions and numeric measurements through a manual analysis of the operational schemas. With the proliferation of new platforms of communication in today's information societies, there has been growing numbers of web-based applications such as online social networks that generate huge amounts of XML data on the web. Therefore, it is increasingly important to develop an appropriate warehousing approach for such ever-growing XML data sources. However, XML documents have a complex hierarchical structure. Moreover, designing and building DWs is tedious, timeconsuming, error-prone and expensive process. In this paper, we describe an approach for automatically generating and building the star schema for data warehouse from XML schema. This approach is extensively based on standards (UML, XML, QVT, and XSLT). First, we model the structure of XML (XML Schema) using the Unified Modeling Language, which is the standard language for object oriented analysis and design. Then, we provide an algorithm that automatically selects the multidimensional concepts. After that, a representation in an XML schema language as the XML data warehouse schema description is derived automatically from UML star schema. Furthermore, we choose Query/Views/ Transformation (QVT), which is also OMG standard transformation language for defining and formalizing transformations between models. Finally, a prototype tool is implemented for testing and evaluating our approach and its transformations.

http://dline.info/fpaper/jdim/v12i6/10.pdf

An Approach for Generating an XML Data Warehouse Schema using Model Transformation Language

Over the past few years XML has rapidly become a widely accepted data format for information interchange and representation of semi-structured data. As a result, huge amounts of interesting data are generated and distributed on the Web, prompting the need of new and automated approaches to store, organize and analyze such data. Data warehouses systems provide an efficient tool and integrated repository with a high level of consolidation and a multi-dimensional view of the data. Several studies address the issue for designing a conceptual and logical schema of XML Data Warehouses. Nevertheless, these approaches focus only on identifying multidimensional concepts in a semi-automatic fashion. In this paper we propose an automatic approach for designing the logical schema for a data mart starting from the XML schema describing XML sources using UML and QVT transformation language. Our focus is not only on automating an XML Data Warehouse design, but also on providing a simplification process and a set of rules that applies successive transformations to create the star schema which is the predominant logical multidimensional scheme. Finally, we discuss implementation issues and we present a graphical tool to help designers and engineers design without technical expertise in multi-dimensional data modeling.

Towards the automation of XML data warehouse logical design

the increasing amounts of interesting data stored in the XML format is the most challenging issue for BI community, thus it is desirable to successfully extract, store and integrate this large sources of information special purpose systems called “data warehouse” for further analysis and decision-making. However, compared with the well structured relational databases of a company, XML data presents a complex hierarchical structure, which renders inappropriate, existing traditional data warehouse approaches and techniques. In this paper, we propose a semi-automatic approach for XML data warehouse design starting from XML schemas as data sources. The first step consists in automatically generating the UML Class diagram from W3C XML Schema (XSD). However, the obtained diagram can be very large and hard to understand. To overcome this situation, we use a set of rules based on basic techniques for object oriented design quality to develop a simplification algorithm that efficiently generates high-quality diagrams with limited number of classes. Then, we propose a multi-dimensional (MD) element extraction algorithm to automatically identify facts, measures and their corresponding dimensions. We also present a new metric for ranking obtained MD schemas according to their relevance. The final step consists in automatically generating the star XML schema that corresponds to the XML Data warehouse schema. Finally, we have implemented our approach using JAVA and we have evaluated this tool on several XML schemas.

Zoubir Ouaret

Papers

An overview of XML warehouse design approaches and techniques

AuMixDw: Towards an automated hybrid approach for building XML data warehouses

An Approach for Generating an XML Data Warehouse Schema using Model Transformation Language

Towards the automation of XML data warehouse logical design

A global and comprehensive approach for XML data warehouse design