The retailing giant Wal-Mart owes its success to the efficient use of information technology in its operations. One of the noteworthy advances made by Wal-Mart is the development of the data warehouse which gives the company a strategic advantage over its competitors. In this chapter, the planning and implementation of the Wal-Mart data warehouse is described and its integration with the operational systems is discussed. The chapter also highlights some of the problems encountered in the developmental process of the data warehouse. The implications of the recent advances in technologies such as RFID, which is likely to play an important role in the Wal-Mart data warehouse in future, is also detailed in this chapter.
TopIntroduction
With advances in the structural and functional complexity of XML, a standardized method for designing and visually presenting XML structures is becoming necessary.
XML modeling techniques can be generally classified based on the chosen approach into one of the following three major categories: (1) Entity Relationship (ER), (2) Unified Modeling Language (UML), and (3) Structured Hierarchical Model. Literature reveals the existence of several methodologies for modeling XML that are derived from these three categories. Several proprietary commercial tools that can be adapted to design and model XML structures have been introduced in recent years. In this chapter, we present six such academic tools and four commercial methodologies relevant in modeling XML structures and provided an overview of the same is provided by making use of appropriate examples. In order for the survey to be more comparative, a common working example is chosen and equivalent conceptual models are developed to illustrate a model’s capabilities. To conclude, a discussion summarizing the capabilities of each of the methods and their suitability as a conceptual model for XML is analysed to help answer the question posed by the chapter: Is developing a conceptual model for XML a Myth or a Reality?
Several business situations arise where a conceptual model is necessary. A good conceptual model can help planners by providing a framework for developing architectures, assigning project responsibilities, and selecting technology (Mohr, 2001). For XML in particular, the verbose and syntax-heavy nature of the schema languages makes them unsuitable for providing this type of framework. As an illustration, consider the typical business problem of data interchange between different organizations. These type of applications, often used with the term EDI (Electronic Data Interchange), is already being moved to XML (Kay, 2000; Ogbuji, 1999). The non-proprietary nature of XML and its descriptive markup make it suitable for exchange of information between organizations. Ogbuji (1999) uses a purchase order example to illustrate how the interchange process can be facilitated with XML. However, a quick look at the illustration reveals that XML data and structure syntax, although more generalized and more descriptive than the EDI notation used by the article (ANSI X12 Transaction set), it is not going to be suitable for use in the presentation of the data to its potential users. A conceptual model of this purchase order, shown in Figure 1, reveals the internal structure of the order and items, and is more suited for understanding the conceptual structure of the application, and this is exactly the aim of this chapter.
Figure 1. A conceptual model for the purchase order application
In the rest of this chapter, we intend to demonstrate how conceptual models can in fact handle the complexities of XML, and the advances of such models in current literature as well as commercial applications. Toward that goal, we first further motivate the problem in the second section, and then discuss the interesting problems that arise when creating a conceptual model for XML in the third section. We then discuss six research-based methods in the fourth section, followed by four commercial tools in the fifth section. Finally, we compare these various tools in the sixth section and draw conclusions on the state of the current development in conceptual modeling for XML in the seventh section.
TopMotivation
Since its introduction in 1996, the use of XML has been steadily increasing, and it can be considered as the “format of choice” for data with mostly textual content. XML is widely used as the data format for a variety of applications, encompassing data from financial business transactions to satellite and scientific information. In addition, XML is also used to represent data communication between disparate applications. The two leading Web application development platforms .NET (Microsoft, 2003) and J2EE (Sun, 2004) both use XML Web Services (a standard mechanism for communication between applications, where the format for the exchange of data, and the specification of the services are modeled using XML).