Converting XML DTDs to UML diagrams for conceptual data integration

Extensible Markup Language (XML) is fast becoming the new standard for data representation and exchange on the World Wide Web, e.g., in B2B e-commerce. Modern enterprises need to combine data from many sources in order to answer important business questions, creating a need for integration of web-based XML data. Previous web-based data integration efforts have focused almost exclusively on the logical level of data models, creating a need for techniques that focus on the conceptual level in order to communicate the structure and properties of the available data to users at a higher level of abstraction. The most widely used conceptual model at the moment is the Unified Modeling Language (UML).

This paper presents algorithms for automatically constructing UML diagrams from XML DTDs, enabling fast and easy graphical browsing of XML data sources on the web. The algorithms capture important semantic properties of the XML data such as precise cardinalities and aggregation (containment) relationships between the data elements. As a motivating application, it is shown how the generated diagrams can be used for the conceptual design of data warehouses based on web data, and an integration architecture is presented. The choice of data warehouses and On-Line Analytical Processing as the motivating application is another distinguishing feature of the presented approach.     

An architecture for automatically developing secure OLAP applications from models

ContextDecision makers query enterprise information stored in Data Warehouses (DW) by using tools (such as On-Line Analytical Processing (OLAP) tools) which use specific views or cubes from the corporate DW or Data Marts, based on the multidimensional modeling. Since the information managed is critical, security constraints have to be correctly established in order to avoid unauthorized accesses.ObjectiveIn previous work we have defined a Model-Driven based approach for developing a secure DWs repository by following a relational approach. Nevertheless, is also important to define security constraints in the metadata layer that connects the DWs repository with the OLAP tools, that is, over the same multidimensional structures that final users manage. This paper defines a proposal to develop secure OLAP applications and incorporates it into our previous approach.MethodOur proposal is composed of models and transformations. Our models have been defined using the extension capabilities from UML (conceptual model) and extending the OLAP package of CWM with security (logical model). Transformations have been defined by using a graphical notation and implemented into QVT and MOFScript. Finally, this proposal has been evaluated through case studies.ResultsA complete MDA architecture for developing secure OLAP applications. The main contributions of this paper are: improvement of a UML profile for conceptual modeling; definition of a logical metamodel for OLAP applications; and definition and implementation of transformations from conceptual to logical models, and from logical models to the secure implementation into a specific OLAP tool (SSAS).ConclusionOur proposal allows us to develop secure OLAP applications, providing a complete MDA architecture composed of several security models and automatic transformations towards the final secure implementation. Security aspects are early identified and fitted into a most robust solution that provides us a better information assurance and a saving of time in maintenance.     

一种OLAP概念建模的研究与实现

OLAP已成为决策支持的一种重要工具。鉴于对多种数据源集成和易用性的要求越来越高,文中提出了一种轻型OLAP的框架,它能利用XML在表示维度数据的优势,提供对XML数据源的集成,最终利用UML类图提供概念上的建模。从而让用户以统一、透明的方式从概念上完成建模,方便使用OLAP。     

XML加密的研究

随着互联网技术的发展,网络的数据交换越来越频繁。寸扩展标记语言（XML）作为一种描述数据的标记语言,具有对数据进行统一描述的强大功能,成为网络数据传输和交换的主要载体。由于在XML规范中不提供对数据的保密措施,所以它的安全性也受到了越来越多的关注。通过演示1个简单的数据交换,用XML加密确保安全,然后增加安全性需求的复杂程度,解释XML加密模式及其不同元素的使用。     

BOX: Browsing objects in XML

The latest Internet markup languages support the representation of structured information and vector graphics. In this paper we describe how these languages can be used to publish software engineering diagrams on the Internet. We introduce BOX, a portable, distributed and interoperable approach to browsing UML models with off‐the‐shelf technology. Our approach to browsing UML models leverages XML and related specifications, such as the Document Object Model (DOM), the XML Metadata Interchange (XMI) and the Vector Markup Language (VML). BOX translates a UML model that is represented in XMI into VML. VML can be directly displayed in Internet browsers, such as Microsoft's Internet Explorer 5. BOX enables software engineers to access and review UML models without the need to purchase licenses of tools that produced the models. BOX has been successfully evaluated in two industrial case studies. The case studies used BOX to make extensive domain and enterprise object models available to a large number of stakeholders over corporate intranets and the Internet. We show how XML and the BOX architecture can be applied to other software engineering notations. We also argue that the approach taken in BOX can be applied to other domains that have already started to adopt XML and have a need for graphic representation of XML information. These include browsing gene sequences, chemical molecule structures and conceptual knowledge representations. Copyright © 2000 John Wiley & Sons, Ltd.     

基于XML数据立方的面向对象扩展

本文是对基于XML的数据立方数据模型的面向对象的实现，通过对数据仓库技术，面向对象技术和XML技术的结合的探讨，扩展了XML Schema，从而为基于WEB数据仓库的应用提供了一种新的表示和实现方法，解决了数据仓库中模式演化所带来的重组问题，通过与面向对象技术的结合使用，把数据仓库变成为数据立方和OLAP方法的仓库，这种数据仓库的实现方案，保证了数据仓库系统的稳定性，灵活性和可扩展性，适应了新一代WEB应用的需要。     

基于XML技术的数据仓库多维数据模型

本文介绍了一种基于关系数据库、利用 XML技术实现多维数据模型方法 .首先讨论了在关系数据库之上构建数据仓库的系统结构 ,利用面向对象的技术构建一个逻辑多维数据模型 ,通过 XML 文档保存多维数据模型的元数据 .配合数据仓库的数据抽取工具、汇总工具可以实现数据仓库的基本功能 .对于实现关系数据库之上 OL AP和数据挖掘有一定的参考价值 .     

A Formal Object Approach to the Design of ZML

This paper addresses two issues: how formal object modeling techniques facilitate the XML application development and how XML technology helps formal/graphical software design process. In particular, the paper presents a XML/XSL approach to the development of a web environment for Z family languages (Z/Object-Z/TCOZ). The projection techniques and tools from object-oriented Z (in XML) to UML (in XMI) are developed using XSL Transformations (XSLT). Furthermore, object-oriented Z is used to specify and design the essential functionalities of the web environment and the projection tools to UML. In a sense, the paper also demonstrates a formal object approach to modeling XML applications.     

Conceptual modelling of web sites for end-users

Internet and the WWW more and more play an important role in our information society. It is now one of the major sources of information in every rank of our society. The overwhelming accessibility to data, on a global scale, does not necessarily translate to widespread utility of data. We often find that we are drowning in data, with few tools to help managing relevant data for our various activities. In this paper, we argue that the WWW and its end-users could benefit from the existence of a conceptual web site schema. We propose such a conceptual web site schema that describes what information is available in a web site and how this information is structured into pages and links. To allow to communicate this information through the web, we developed an XML Document Type Definition (DTD) for this conceptual web site schema. We also illustrate the feasibility of the approach by a simple application program developed using the XML Document Object Model (DOM). This revised version was published online in August 2006 with corrections to the Cover Date.     

Improving the performance and functionality of Mondrian open‐source OLAP systems

For a long time, the design of relational databases has focused on the optimization of atomic transactions (insert, select, update or delete). Currently, relational databases store tactical information of data warehouses, mainly for select‐like operations. However, the database paradigm has evolved, and nowadays on‐line analytical processing (OLAP) systems handle strategic information for further analysis. These systems enable fast, interactive and consistent information analysis of data warehouses, including shared calculations and allocations. OLAP and data warehouses jointly allow multidimensional data views, turning raw data into knowledge. OLAP allows ‘slice and dice’ navigation and a top‐down perspective of data hierarchies. In this paper, we describe our experience in the migration from a large relational database management system to an OLAP system on top of a relational layer (the data warehouse), and the resulting contributions in open‐source ROLAP optimization. Existing open‐source ROLAP technologies rely on summarized tables with materialized aggregate views to improve system performance (in terms of response time). The design and maintenance of those tables are cumbersome. Instead, we intensively exploit cache memory, where key data reside, yielding low response times. A cold start process brings summarized data from the relational database to cache memory, subsequently reducing the response time. We ensure concurrent access to the summarized data, as well as consistency when the relational database updates data. We also improve the OLAP functionality, by providing new features for automating the creation of calculated members. This makes it possible to define new measures on the fly using virtual dimensions, without re‐designing the multidimensional cube. We have chosen the XML/A de facto standard for service provision. Copyright © 2008 John Wiley & Sons, Ltd.     

A UML profile for multidimensional modeling in data warehouses

The multidimensional (MD) modeling, which is the foundation of data warehouses (DWs), MD databases, and On-Line Analytical Processing (OLAP) applications, is based on several properties different from those in traditional database modeling. In the past few years, there have been some proposals, providing their own formal and graphical notations, for representing the main MD properties at the conceptual level. However, unfortunately none of them has been accepted as a standard for conceptual MD modeling.

In this paper, we present an extension of the Unified Modeling Language (UML) using a UML profile. This profile is defined by a set of stereotypes, constraints and tagged values to elegantly represent main MD properties at the conceptual level. We make use of the Object Constraint Language (OCL) to specify the constraints attached to the defined stereotypes, thereby avoiding an arbitrary use of these stereotypes. We have based our proposal in UML for two main reasons: (i) UML is a well known standard modeling language known by most database designers, thereby designers can avoid learning a new notation, and (ii) UML can be easily extended so that it can be tailored for a specific domain with concrete peculiarities such as the multidimensional modeling for data warehouses. Moreover, our proposal is Model Driven Architecture (MDA) compliant and we use the Query View Transformation (QVT) approach for an automatic generation of the implementation in a target platform. Throughout the paper, we will describe how to easily accomplish the MD modeling of DWs at the conceptual level. Finally, we show how to use our extension in Rational Rose for MD modeling.     

一种基于XML的Web数据集成方案

介绍了Web环境下异构数据集成技术产生的背景和研究目的以及相关的概念、技术和方法,针对XML作为合适的数据交换格式的特点介绍了基于XML的信息集成的关键因素,提出了一种基于XML的Web数据集成操作模型,并讨论了该模型在Web数据集成时数据交换和共享过程,给出了集成构架的结构及组成。     

Dimensional enrichment of statistical linked open data

On-Line Analytical Processing (OLAP) is a data analysis technique typically used for local and well-prepared data. However, initiatives like Open Data and Open Government bring new and publicly available data on the web that are to be analyzed in the same way. The use of semantic web technologies for this context is especially encouraged by the Linked Data initiative. There is already a considerable amount of statistical linked open data sets published using the RDF Data Cube Vocabulary (QB) which is designed for these purposes. However, QB lacks some essential schema constructs (e.g., dimension levels) to support OLAP. Thus, the QB4OLAP vocabulary has been proposed to extend QB with the necessary constructs and be fully compliant with OLAP. In this paper, we focus on the enrichment of an existing QB data set with QB4OLAP semantics. We first thoroughly compare the two vocabularies and outline the benefits of QB4OLAP. Then, we propose a series of steps to automate the enrichment of QB data sets with specific QB4OLAP semantics; being the most important, the definition of aggregate functions and the detection of new concepts in the dimension hierarchy construction. The proposed steps are defined to form a semi-automatic enrichment method, which is implemented in a tool that enables the enrichment in an interactive and iterative fashion. The user can enrich the QB data set with QB4OLAP concepts (e.g., full-fledged dimension hierarchies) by choosing among the candidate concepts automatically discovered with the steps proposed. Finally, we conduct experiments with 25 users and use three real-world QB data sets to evaluate our approach. The evaluation demonstrates the feasibility of our approach and shows that, in practice, our tool facilitates, speeds up, and guarantees the correct results of the enrichment process.     

利用JTidy和XML实现Web数据信息的批量提取

为了有效地在Web上进行数据信息的提取,实现Web数据的清理与集成,针对发布批量格式化数据的网页类型,提出了利用XML和JTidy自动从Web页面批量提取数据信息的方法.根据该类网页的特点,基于开发一种通用程序的思想,对页面标签结构进行分析与分类,讨论了识别数据元素和对数据元素进行分组等提取过程中的难点,在此基础上建立了总体扫描与提取的算法.实验结果表明了批量提取信息方法的可行性与有效性.     

On Using a Warehouse to Analyze Web Logs

Analyzing Web Logs for usage and access trends can not only provide important information to web site developers and administrators, but also help in creating adaptive web sites. While there are many existing tools that generate fixed reports from web logs, they typically do not allow ad-hoc analysis queries. Moreover, such tools cannot discover hidden patterns of access embedded in the access logs. We describe a relational OLAP (ROLAP) approach for creating a web-log warehouse. This is populated both from web logs, as well as the results of mining web logs. We discuss the design criteria that influenced our choice of dimensions, facts and data granularity. A web based ad-hoc tool for analytic queries on the warehouse was developed. We present some of the performance specific experiments that we performed on our warehouse.     

XStorM: A Scalable Storage Mapping Scheme for XML Data

With the increasing ubiquity of XML, an eXtensible Markup Language, the industry is racing to provide XML infrastructure for e–commerce, information interchange, effective query of diverse sources and yet more integration of diverse data. It is anticipated that large volumes of XML data will be created manually from HTML documents or generated using some WWW tools and electronic data interchange (EDI). In this paper, we examine how large amounts of XML data can be stored in a relational database. Our scheme considers the unique irregular features of XML, including missing elements or multiple occurrences of the same element, and elements which may have atomic values in some data items and structured values in others. A detailed experimental study demonstrates good query performance, effective space utilization and scalability.     

Logical Representation of a Conceptual Model for Spatial Data Warehouses

The MultiDimER model is a conceptual model used for representing a multidimensional view of data for Data Warehouse (DW) and On-Line Analytical Processing (OLAP) applications. This model includes a spatial extension allowing spatiality in levels, hierarchies, fact relationships, and measures. In this way decision-making users can represent in an abstract manner their analysis needs without considering complex implementation issues and spatial OLAP tools developers can have a common vision for representing spatial data in a multidimensional model. In this paper we propose the transformation of a conceptual schema based on the MultiDimER constructs to an object-relational schema. We based our mapping on the SQL:2003 and SQL/MM standards giving examples of commercial implementation using Oracle 10g with its spatial extension. Further we use spatial integrity constraints to ensure the semantic equivalence of the conceptual and logical schemas. We also show some examples of Oracle spatial functions, including aggregation functions required for the manipulation of spatial data. The described mappings to the object-relational model along with the examples using a commercial system show the feasibility of implementing spatial DWs in current commercial DBMSs. Further, using integrated architectures, where spatial and thematic data is defined within the same DBMS, facilitates the system management simplifying data definition and manipulation.

CRM系统中基于ASP.NET的OLAP的设计与实现

介绍了客户关系管理（customer relationship management,CRM）、数据仓库和联机分析处理（on-line analytical processing,OLAP）服务,分析了基于数据仓库的CRM系统中OLAP设计的系统架构.基于ASP.NET和SQL Server2000,并综合运用OWC（office web components）、可扩展标记语言（extensible markup language,XML）等相关技术,提出了拓宽OLAP服务域,实现OLAP报表在Web上显示的一个解决方案.说明了系统的部署配置方法和应用程序的构建过程,给出了实现通过内嵌OWC的Web客户端页面,调用XML Web Service,与OLAP服务器建立连接并进行访问的具体方法.     

A relational–XML data warehouse for data aggregation with SQL and XQuery

Integrating information from multiple data sources is becoming increasingly important for enterprises that partner with other companies for e‐commerce. However, companies have their internal business applications deployed on diverse platforms and no standard solution for integrating information from these sources exists. To support business intelligence query activities, it is useful to build a data warehouse on top of middleware that aggregates the data obtained from various heterogeneous database systems. Online analytical processing (OLAP) can then be used to provide fast access to materialized views from the data warehouse. Since extensible markup language (XML) documents are a common data representation standard on the Internet and relational tables are commonly used for production data, OLAP must handle both relational and XML data. SQL and XQuery can be used to process the materialized relational and XML data cubes created from the aggregated data. This paper shows how to handle the two kinds of data cubes from a relational–XML data warehouse using extract, transformation and loading. Copyright © 2008 John Wiley & Sons, Ltd.     

Self-maintaining web pages

Data-intensive web-based information systems usually employ database systems to store the contents forming the basis for web page construction. Generating web pages on the fly, especially in peak times, can lead to severe performance problems. Thus, pre-generation of web pages has been suggested to be ready for prime time, allowing to reliably deliver several hundred pre-generated pages per second. Maintaining the consistency of these web pages with respect to changes within the database in an efficient way, however, represents a major challenge. This paper presents a novel approach for “self-maintaining” web pages that is, different to previous approaches, characterized by a simple (and thus, easy to maintain) database-to-web page mapping and very low page re-generation costs. This is achieved by utilizing fragmentation techniques from distributed databases, by allocating parameterized fragment classes to web page classes (rather than individual fragments to single web pages), and using the Extensible Markup Language (XML) as an intermediate layer between the database and the final web pages.