code: public static String getRequiredAttributeValue(
          Node node, String attributeName)
      {
          NamedNodeMap attributes = node.getAttributes();
          Node attributeNode = attributes.getNamedItem(attributeName);
          if (attributeNode == null)
          {
              throw new XmlException(
                  "No attribute with name \""+attributeName+"\" found");
          }
          String value = attributeNode.getNodeValue();
          if (value == null)
          {
              throw new XmlException(
                  "Attribute with name \""+attributeName+"\" has no value");
          }
          return value;
      }
docs: Returns the attribute with the given name from the given node.
  
  @param node The node to obtain the attribute from
  @param attributeName The name of the attribute
  @return The value of the attribute
  @throws XmlException If no value of the attribute with the given
  name could be obtained.