Chapter 1: Writing XML Documents

Summary

• A metalanguage that allows you to create markup languages specific to an industry or application
• Provides strict separation between content and structure.
• Enables powerful, automated manipulation of data.
• XML documents contain tags (elements) and text.

• Not predefined. Each application defines its tags.
• Syntax: <ElementName> ... </ElementName>
• Case sensitive.
• End tags required.
• Empty elements allowed: <ElementName/>
• Nesting allowed.

• A piece of information defined in an element.
• A name-value pair.
• Usage: <book used="yes">
• Value must be quoted.
• Types of attributes discussed in the next chapter.

• A piece of data with a name.
• Referred to with this syntax: &entity_name;
• May be an external file with text, graphics, video, etc.
• May be a shorthand for frequently-used phrases.
• Predefined entities: &amp; &lt; &gt; &quot; &apos;

• Just like HTML comments.
• Syntax: <!-- comment text -->

• Tell the processor what not to process.
• Syntax:
  <![CDATA[
    ... markup that shouldn't be processed ...
  ]]>

• Allows you to create and use "universal" tagnames recognized by applications in the Web.
• Syntax:
  <catalog xmlns:bk="http://www.keller.com/xml/books">
    <bk:book>
      ...
    </bk:book>
    ...
  </catalog>
• Namespaces are inherited by sub-elements.
• A document may use elements from multiple namespaces.