brupp.com

As defined by the W3C , an XML namespace is a collection of XML elements and attributes identified by an Internationalized Resource Identifier (IRI); this collection is often referred to as an XML “vocabulary.”

IRI is usually an URI e.g. http://www.brupp.com. Let’s understand this concept briefly. Take this example:

<root xmlns:brupp="http://brupp.com/">
     <data>
          <title>Title</title>
          <link>http://foofoo.com</link>
          <brupp:link href="http://brupp.com/somelink">Some Data</brupp:link>
          <description>description data</description>
          ...
    </data>
...
...
</root>

The XML above has no default namespace. Now lets suppose the XML demands need of reuse of some other existing namespace “http:/brupp.com”  which also has a <link> node. To avoid any ambiguity between the <link> node of both vocabulary XML namespace are added.

Why namespace? As described above it helps in leveraging different vocabulary of XML with same element and attribute name. Understand this way; you created a XML structure for a “Product” and “Customer”. Now you want to utilize these XML structure in a new “Database” XML. The problem: Both “Product” and “Customer” uses <id> node. Solution: Place them in different namespace (simply a unique string) and then use them as shown above xmlns:prod=”some namespace”.

In actionscript 3.0 you can access both< link> node without much hassle. See below a simple example created in Flex:

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" width="732" height="434"
     creationComplete="onCreationComplete()">
     <mx:Script>
     <![CDATA[
          namespace brupp = "http://brupp.com/";
          use namespace brupp;
          private var _objXML:XML =
                     <root xmlns:brupp="http://brupp.com/">
                       <data>
                         <title>Title</title>
                         <link>http://foo.com</link>
                         <brupp:link href="http://brupp.com/somelink" >some</brupp:link>
                         <description>description data</description>
                       </data>
                     </root>;

         private function onCreationComplete():void
         {
             trace("default link  " + _objXML.data.link);

         }
    ]]>
    </mx:Script>
</mx:Application>

The trace above will show both <link> nodes because we have told the compiler to “use namespace” brupp. If you comment the code line:

use namespace brupp;

and then run the application again; the “brupp” namespace <link> will not appear.

To add, if you only want to access the “brupp” namespace <link>, do this:

trace("brupp link  " + _objXML.data.brupp::link);

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