XML is international. XML is based on Unicode. Unicode allows for a larger amount of storage space for each character, which in turn makes it possible for Unicode to include characters for foreign alphabets. SGML and HTML are based on ASCII, which does not work well with many foreign languages.
XML can be structured. Using DTDs, XML can be structured so that both the content and syntax can be easily validated. This enhanced structure will enable you to create standardized valid XML documents.
XML documents can be built using composition. Using the more powerful linking methods of XML, documents can be created from a composite of other documents. This enhanced linking system will enable you to create customized documents by selecting only the pieces of other documents you need.
XML can be a data container. XML is ideally suited to be a container for data. Using DTDs, you can efficiently represent almost any data so that it can be read by humans, computer parsers, and applications.
XML offers flexibility. XML allows you either to not use a DTD (a default one will be used) or to define the structure of your document to the smallest detail using a DTD. With a DTD, you can define the exact structure of your document so that both the structure of the data and the content can be easily validated.
XML is easy to use. XML is only slightly more complicated than HTML. As more browsers support XML and more tools are available for working with XML, it is likely that more developers will take advantage of XML.
XML has standard formats. Standard formats for XML documents can be easily produced.
With these advantages, XML can be used to cater to the more complex corporate needs.
Summary
HTML was well suited for the birth of the Internet, but the Internet has become a center for commerce and information and a central focus of business operations, and HTML is no longer capable of meeting its needs. The failure of Internet browsers to meet the HTML standards, the difficulty of validating HTML documents, a poor linking system, and a lack of international support has made HTML a poor choice for the future. SGML is an excellent, powerful tool capable of documenting complex systems, but unfortunately, SGML is far too complex for the current needs of the Internet.
XML is ideally suited for the next generation of Internet applications, for ecommerce, and for the corporate DNS. XML is a simpler, lighter markup language, which is flexible, is easy to use, and can be used for international documents. XML is ideal for storing data and sending messages, and XML documents can be validated.
The XML 1.0 specification, defining the syntax of the XML language and XML DTDs, is well accepted and is not likely to change in the near future. Other elements of XML are still evolving, including schemas, which are similar to DTDs, and XML Path Language (XPath), which is a replacement for some of the current XML linking mechanisms. Over the next few years, XML will be refined to become an incredibly powerful tool that will create the next evolution of the Internet. This tutorial will present both the current XML standard and a glimpse into the XML, and applications, of the future.
