Introduction to XML in Flash
by senocular
Additional XML Content
As you work with XML, especially that which
is not of your own creation (if you're just
starting out), you may notice other bits of
information outside the XML document root element.
Such information can exist before (in the XML
Prolog) and/or after (the XML Epilog) the document
root.
Most XML documents come with declarations
that provide more information about the XML.
These include XML declarations as well as doctype
declarations.
The optional XML declaration specifies certain
properties about the XML page itself such as
version and character encoding used. This is
placed at the very beginning of an XML document
before anything else, including comments and
even white space. Most XML documents should
at least be declared with one of these that
at least specifies XML version, though Flash
typically doesn't care whether an XML file it
receives has one or not. An example of a XML
declaration would be:
<?xml version="1.0"?>
Doctype declarations give information about
how an XML document is defined. They usually
consist of the name of the document root of
the XML file, its availability and a url to
a DTD (Document Type Definition) file that defines
the file's vocabulary. An example would
be
<!DOCTYPE root PUBLIC "http://www.kirupa.com/root.dtd">
where root is the the name of the document
root element and root.dtd is the
DTDs and Schemas, a successor to the
DTD (usually saved as .xsd), are files or instructions
within the doctype that outline how an XML behaves
and what it means. They define the vocabulary
that an XML file (or any of many that use it)
must adhere to to become valid.
Processing Instructions can also be
used in XML. These can go in the prolog, epilog
or within the XML body within the document root.
These provide special instructions to the application
processing the XML and are typically defined
with <? and >. For example, a PHP tag
in HTML is a processing instruction and can
be placed anywhere within an HTML (or PHP, rather)
document.
- <HTML>
- <HEAD>
- <TITLE>My Page</TITLE>
- </HEAD>
- <BODY>
- <?php
- print "Welcome to my page!";
- ?>
- </BODY>
- </HTML>
Most of these are of no importance when it
comes to Flash, however. The Flash interpreter
for XML will, for the most part, ignore these
though not without giving you access to their
raw values (via some XML properties to be covered
shortly). So unless otherwise needed, you wouldn't
have to spend too much time worrying about what
they all mean. Plus, as an introduction
to XML in Flash, they are out of the scope of
what is to be covered here in the first place.
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