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XmlNode.BaseURI Property

Gets the base URI of the current node.

[Visual Basic]
Public Overridable ReadOnly Property BaseURI As String
public virtual string BaseURI {get;}
public: __property virtual String* get_BaseURI();
public function get BaseURI() : String;

Property Value

The location from which the node was loaded or String.Empty if the node has no base URI.


A networked XML document is comprised of chunks of data aggregated using various W3C standard inclusion mechanisms and therefore contains nodes that come from different places. The BaseURI tells you where these nodes came from.

The value of this property varies depending on the node type. For example, Document nodes return the location of the XmlDocument object. Nodes which are child nodes of external EntityReference nodes return the location of the entity itself. For example, consider the following XML document:

<!DOCTYPE item [
<!ENTITY xyz SYSTEM "a/b.xml">
<item num='123'>&xyz;</item>

where the external entity a/b.xml contains the XML text: <test>123</test>.

If the document is loaded from http://server/mydata.xml, BaseURI returns the following:

NodeType Name BaseURI
Attribute num http://server/mydata.xml
Document #document http://server/mydata.xml
DocumentType item http://server/mydata.xml
Entity xyz http://server/mydata.xml
Element item http://server/mydata.xml
EntityReference xyz http://server/mydata.xml
Element test http://server/a/b.xml
Text #text http://server/a/b.xml

BaseURI looks for entity reference boundaries, so if entities are expanded this information is not preserved and this property returns the location of the XmlDocument object in all cases.

As a second example, given the following XML document:

<!DOCTYPE Mydata SYSTEM "http://localhost/doctype.dtd">

where the DTD file contains the following:

<!ENTITY xyz <E1>My Data</E1>
<!ATTLIST baa attr1 "woof">

If the XML document is loaded from http://localhost/mydata.xml, BaseURI returns the following for each of the nodes:

NodeType Name BaseURI
Document #document http://localhost/mydata.xml
DocumentType Mydata http://localhost/mydata.xml

The XmlDocumentType.SystemId or XmlDocumentType.PublicId properties can be used to identify where the DTD file was loaded from.

Element baa http://localhost/mydata.xml
Entity xyz http://localhost/doctype.dtd
EntityReference xyz http://localhost/mydata.xml
Attribute woof http://localhost/mydata.xml
Note   The base URI of a default attribute is the same as the base URI of the element to which they belong.

This property is a Microsoft extension to the Document Object Model (DOM).


Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

See Also

XmlNode Class | XmlNode Members | System.Xml Namespace