What are the uri's actually used for after the namespace?

Question

Do the URI's in lines ( 5,6,7 ) actually have to point to anything?

When I point them at duff urls it still seems to work to validate my xml, so what is the point?

<?xml version="1.0" encoding="utf-8"?>
<xs:schema id="UploadXSD"
    targetNamespace="UploadXSD"
    elementFormDefault="qualified"
    xmlns="http://tempuri.org/UploadXSD.xsd"
    xmlns:mstns="http://tempuri.org/UploadXSD.xsd"
    xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <xs:element name="Video">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="Title" minOccurs="1" type="xs:string"></xs:element>
        <xs:element name="Description" minOccurs="1" type="xs:string"></xs:element>
        <xs:element name="Contributor" minOccurs="1" type="xs:string"></xs:element>
        <xs:element name="Subject" minOccurs="1" type="xs:string"></xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

</xs:schema>

TToni TToni · Accepted Answer · 2010-11-29T15:54:45

The point of using URNs as namespace is that they are unique. You could also use a GUID for example, but this way they are more readable.

Of course, using URNs gives you the possibility to point them to an actual resource, like a xsd file, but that's an added bonus and not necessary.

The "tempuri" things are just default names ("temp"+"uri"), which you should replace with a real URN to avoid namespace collisiions.

The XMLSchema namespace actually points to a website that contains information about XML-Schema.

If you use XML-Documents and Schemas regurlarly, read at least the primer, to get an idea about the possibilities of XML-Schema. More info about XML Namespaces is here.

What are the uri's actually used for after the namespace?

2 Answers