XML is designed to enable the use of SGML on the web
It is extensible because it is not a fixed format like HTML
It is a metalanguage (because it's written in SGML) which lets you design your own markup language.
XML will allow groups of people or organizations to create their own customized markup languages for exchanging information in their own domain
The goal of XML is allow generic SGML to be served, received, and processed on the Web in the way that is now possible with HTML
XML lets you define your own customized markup languages for many classes of documents
It is an advance because it:
Does not depend on a single, inflexible document type (HTML);Allows the complexity of full SGML, whose syntax allows many powerful but complex options
According to Stall (1998):It has been said that XML provides 80% of the benefit of SGML with 20% of the effort.
It provides a much richer linking functionality, including complex link relationships, such as links with multiple targets, multi-directional links, and automatically updated link databases
Why is XML a useful addition (adapted from the XML FAQ):
Authors can design their own document types using XML, instead of being stuck with HTML
Document types can be explicitly tailored to an audience, eliminating the workarounds that have to take place with HTML to achieve special effectsAuthors and designers will be free to invent their own markup elements
Information content can be richer and easier to use, because the hypertext linking abilities of XML are much greater than those of HTML.
XML can provide more and better facilities for browser presentation and performance;
It removes many of the underlying complexities of SGML in favor of a more flexible model, so writing programs to handle XML will be much easier than doing the same for full SGML.
Information will be more accessible and reusable, because XML can be used by any XML software instead of being restricted to specific manufacturers as has become the case with HTML.
Valid XML files are valid SGML, so they can be used outside the Web as well, in an SGML environment.
XML is not intended to replace HTML
It provides a higher level of functionality that is expected to have wide utlilty in environments using structured document exchange
Using XML
To construct your own XML language (also called a "vocabulary"), you begin with a specific Document Type Definition (DTD)
A DTD provides the rules that define the elements and structure of your new language.To create LML (Librarian Markup Language), the DTD would include a rule that states that the <NAME> element consists of three other elements called <FIRST>, <MIDDLE>, and <LAST>, in that order.The rule would also indicate if any of the nested elements is optional, can be repeated, and/or has a default value.
| This page prepared by Howard Rosenbaum | Last update: 11.12.98 |
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| You are here: http://memex.lib.indiana.edu/hrosenba/www/Pres/IULOG/tech2.html | |
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Onwards! | |