Database Reference
In-Depth Information
Organizations benefit in many ways from using the Web for database processing. They can transfer data
to and from their databases to suppliers, customers, and others outside the company; this provides current
information in a timely way to those needing the information. As another example, a company can allow cus-
tomers to place orders that directly update the organization
s database and trigger the processing required to
fulfill the orders. Additionally, Web clients can access an organization
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s Web pages at their convenience 24-7.
The tradeoffs for an organization using the Web for database processing include the increased complexities
and cost of maintaining an always available Web presence and reliance on the Internet with potential data
communication contention difficulties and increased security exposure.
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XML
Many different software languages, software products, computer hardware devices, and standards exist to
make e-commerce possible. As e-commerce evolves, these Web components are constantly changing and
improving with new components appearing frequently. Since 1994, the international World Wide Web Con-
sortium (W3C) has developed Web standards, specifications, guidelines, and recommendations, including
HTML standards. HTML is a text-based markup language, which means that it contains tags that describe a
document
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s content and appearance. HTML was created and first used in 1990 by Tim Berners-Lee, the
founder of the Web, the founder of W3C, and the person who wrote the software for the first Web browser
and for the first Web server. As the basis for creating HTML, Berners-Lee used Standard Generalized Markup
Language (SGML), which is a metalanguage (a language used to define another language) used to create
document markup languages; SGML became a standard in 1986. Languages based on the full SGML are used
to manage large, complex reports and technical specifications for a variety of computer platforms, printers,
and other devices. Berners-Lee borrowed the tagging concepts and some of the tags from SGML for the HTML
language, adding a few tags specifically for the processing of Web pages over the Internet.
HTML contains tags that describe the content and appearance of Web pages to Web browsers, but HTML
does not describe the structure and meaning of the data it contains. That is, you can
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t identify in an HTML
document which data elements are in the Web page, what each data elements means, and how those data
elements are related. This limitation is not a problem for Web pages that are intended to be used in the
traditional way, in which a user requests and works with Web pages using a Web browser. However,
e-commerce between organizations, called business to business (B2B), is an important part of communica-
tion across the Internet. Organizations send data from their databases to the databases of other organizations,
and those organizations that send data need to receive data in return. In these situations, the structure and
meaning of the transmitted data are of utmost importance because organizations structure common data,
such as product data and cost data, in their databases in different ways. Somehow the document containing
the data being transmitted between organizations must convey the structure and meaning of the data it
contains. To address the inability of HTML to specify the structure and meaning of data and to address
the need for the exchange of data between organizations, XML was developed and became a W3C
recommendation in 1998.
Extensible Markup Language (XML), a metalanguage derived from a restricted subset of SGML, is
designed for the exchange of data on the Web. Using XML, you can create text documents that follow simple,
specific rules for their content and you can define new tags that define the data in the document and the
structure of the data so that programs running on any platform can interpret and process the document.
Figure 9-9 shows the key portions of a file that was created by exporting the Rep table in the Premiere
Products database as an XML document using Access.
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