Introduction to XML in Flash
       by senocular

Element Nodes
Elements are the actual XML tags (or folders). Each letter, to, from and body are all XML elements.

<letter>
<to>Sandy</to>
<from>Peter</from>
<body>I love you!</body>
</letter>

The letter element represents the XML document root element. There should only be one root element tag for every XML document (though, actually, Flash specifically could care less). All other elements should be placed within this root element to define the entire contents of the document.

When one node is in another node, it is said to be a child of that node. A node with children is considered to be the parent of its children - almost like we're dealing with a family tree. The letter element has 3 children, to, from and body. The parent node of each of those three is letter.

All element nodes in XML must have a beginning and an end - an opening and closing tag. Elements with no content within an opening or closing tag, or having no children, like <to></to> for example, are called "empty elements" and can be alternatively written as <ELEMENTNAME /> or in the case of to, <to />, where you have one tag basically closing itself. Having just <to> without any closing would be incorrect. The following is the same example from before, just without any text within the to element making it empty.

<letter>
<to />
<from>Peter</from>
<body>I love you!</body>
</letter>

Apparently Peter just got dumped.

When naming elements, there are certain rules you should follow. Element names must contain valid only characters. These include letters, numbers, underscores (_), hyphens (-), periods (.), and colons (:). Colons are typically only used as a namespace delimiter, a topic which won't be covered here. Though the characters just mentioned are all valid, element names can only start with letters or underscores (or colons). On top of that, you should not begin element names with "xml" as it is also, technically, restricted. Naming is also case sensitive. So if you start a non-empty element with <tag> it must end in </tag> to properly close it and not, for instance, </Tag>. Typically XML tags are written in lowercase, and should you place HTML within XML, the HTML is often uppercase.

Unlike folders in a directory on your computer, elements can exist within the same parent element and share the same name. It is quite ok to have more than one to element in the letter example. Each element still remains unique in its own right even though it's name is shared among one or others within the parent (or document for that matter). This makes it much easier to send a letter to more than one person!

<letter>
<to>Lisa</to>
<to>Jenna</to>
<to>Karen</to>
<from>Peter</from>
<body>I love you!</body>
</letter>

 


 




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