What is XML?
 | XML = EXtensible Markup Language |
| XML is not a programming language like Java or C. |
| It is a markup language much like HTML with origins in SGML. |
| Like HTML, XML requires a "user agent" to properly retrieve and
process XML documents. |
| It is completely text based. |
| It was designed to describe and store data. |
| XML tags are not predefined in XML - they are defined by the user making
XML - self-describing. |
| Like SGML, XML can use a DTD (= Document Type Definition) to formally describe the
data. |
HTML v. XML
| XML is not a replacement for HTML. |
| XML and HTML were designed with different goals:
 | XML was designed to describe data and to focus on what data is. |
| HTML was designed to display data and to focus on how data looks. |
| HTML is about displaying information, XML is about describing
information. |
|
| XML is extensible...
| The tags used to markup HTML documents and the structure of HTML documents
are predefined. |
| The author of HTML documents can only use tags that are
defined in the HTML standard. |
| XML allows the author to define his own tags and his own document
structure. |
|
| XML is a complement to HTML
| Most experts agree that the future development of the Web will most likely
focus on XML being used to
structure and describe the web data... |
| While HTML will be used to format and
display that data. |
|
| XML in the future of the Web
| The HTML community has been participating in XML development since its creation. |
| The XML standard has been developed quickly, and a large number of software vendors have adopted the standard. |
|
How can XML be used?
XML can...
| Keep data separated from your HTML |
| Be used to store data inside HTML documents |
| Be used as a format to exchange information |
| Be used to store data in files or in databases |
XML can keep data separated from HTML
| HTML pages are used to display data. |
| Data is often stored inside HTML pages. |
|
With XML this data can now be stored in a separate XML file. |
| With XML, you concentrate on using HTML for formatting and display,
knowing that changes
in the underlying data will not force changes to any of your HTML code. |
XML can also store data inside HTML documents
| XML data can also be stored inside HTML pages as "Data Islands". |
| Therefore, you can focus on using HTML for formatting and displaying the
data. |
XML can be used to exchange data
| In the business and information world, computer systems and databases contain data in
incompatible formats. |
| One of the most time-consuming challenges for developers
has been to exchange data between such systems over the Internet and
various networks. |
| Converting the
data to XML can greatly reduce this complexity and create data that can be read
by different types of applications. |
XML can be used to store data
| XML can also be used to store, exchange, import and export data in files or in
databases. |
| Applications can
be written to store and retrieve information from the store, and generic
applications can be used to display the data. |
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