Appendix B. XML: A Quick Tour

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Java APIs for XML Kick Start
By Aoyon Chowdhury, Parag Choudhary

Table of Contents
Part VI.  Appendixes


IN THIS APPENDIX

  • What Is XML?

  • A Sample XML Document

  • The XML Declaration

  • Comments

  • The Root Element

  • Processing Instructions

  • Elements

  • Attributes

  • Character References

  • Entity References

  • CDATA Section

  • Document Type Definition (DTD)

  • The Document Type Declaration

  • Declaring Elements

  • Declaring Attributes

The Internet and the World Wide Web have grown from a collection of HTML pages displaying static data to a complex environment that facilitates the exchange of data from heterogenous systems, databases, directory services, and sundry other applications. More often than not, these applications are server-side business components, hosted on heterogeneous platforms and environments, which consume and process the data without any human intervention whatsoever.

Another interesting development that is now taking place is the development of Web services. A Web service is essentially an environment that provides a mechanism for creating, deploying, finding, and working with applications that are hosted over the Web. These applications provide a variety of services, and technically you can create a new application by simply combining a bunch of separate Web services. This process is analogous to using a number of JavaBeans components to create an application.

For example, a fictitious company named WeAuthenticate Inc. can develop a Web service for authenticating users. Another company named InformationProviders can simply sign up with WeAuthenticate to use its Web service for authentication. The end user, which can be either human or another application, after connecting to the InformationProviders' Web site, is made to enter its login ID and password. This information is then sent to WeAuthenticate's Web service, and the authentication is done. The result of the authentication is then sent to the InformationProviders Web server, which might then enable the user to access information from InformationProviders' Web site.

This exchange of data and information between computers is possible only if there is a mechanism that is understood by machines and applications, regardless of the operating system or hardware that they run on. XML provides a mechanism for exchanging information in a format that is machine-neutral.

In this appendix, we will take a quick look at XML and explore the anatomy of an XML document. However, this is not by any means a complete reference of XML. If you want to learn more about XML, a very good reference is Sams Teach Yourself XML in 24 Hours by Michael Morrison.


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[0672324342/app02]

 
 


JavaT APIs for XML Kick Start
JAX: Java APIs for XML Kick Start
ISBN: 0672324342
EAN: 2147483647
Year: 2002
Pages: 133

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