In what context are you expecting to find something there?
Ordinarily, a URI in an XML namespace declaration doesn't necessarily point to a web-accessible resource. From http://www.architag.com/architag/Tag/Ar ... =8&p=1&s=1
You will see lots of namespace declarations as you look at XML documents. Many, if not most, of them look like URLs. That is, they have the form "http://...something... " . This is misleading, as you would expect that you could type the string into your Web browser and go somewhere useful. This is a natural tendency, as we were all genetically programmed to do such a thing. Type in a URL and the faithful server responds with something you can use. You want to get a schema, or a software specification, or a listing of the tags, or even just a phone number of the person who can help us with more information.
However, you will be lucky to get anything at that "address " . That's because the XML namespace declaration is not a URL. It is a URI. "URI " stands for "Uniform Resource Identifier " . If an XML document has a namespace declaration, then the string that follows is sent to the application as a namespace. The string means nothing to the parser. That's right, it's just a string to the parser. The parser does not go out to any resource to check and see if there is a schema there. Since it is a string, its only requirement is that it be well-formed.
... Having said all of that, you might be comforted to know that there are conventions that people are doing to help you get information on a document that is identified with a namespace. Quite often, if a namespace looks like a URL, there will be something at that endpoint that will give you, the human, some guidance in how to interpret the namespace. The important thing to understand, however, is that this is not official according to the XML namespaces specification, and just as often, you might just get a 404 error.