XmlReaderSettings.DtdProcessing Property

Definition

Namespace:

System.Xml

Assembly:

System.Xml.ReaderWriter.dll

Gets or sets a value that determines the processing of DTDs.

public:
 property System::Xml::DtdProcessing DtdProcessing { System::Xml::DtdProcessing get(); void set(System::Xml::DtdProcessing value); };

public System.Xml.DtdProcessing DtdProcessing { get; set; }

member this.DtdProcessing : System.Xml.DtdProcessing with get, set

Public Property DtdProcessing As DtdProcessing

Property Value

DtdProcessing

One of the enumeration values that determines the processing of DTDs. The default is Prohibit.

Examples

The following example validates an XML file using a DTD file.

#using <System.Xml.dll>

using namespace System;
using namespace System::Xml;
using namespace System::Xml::Schema;
using namespace System::IO;

// Display any validation errors.
static void ValidationCallBack( Object^ /*sender*/, ValidationEventArgs^ e )
{
   Console::WriteLine( L"Validation Error: {0}", e->Message );
}

int main()
{
   // Set the validation settings.
   XmlReaderSettings^ settings = gcnew XmlReaderSettings;
   settings->DtdProcessing = DtdProcessing::Parse;
   settings->ValidationType = ValidationType::DTD;
   settings->ValidationEventHandler += gcnew ValidationEventHandler( ValidationCallBack );

   // Create the XmlReader object.
   XmlReader^ reader = XmlReader::Create( L"itemDTD.xml", settings );

   // Parse the file. 
   while ( reader->Read() )
      ;

   return 1;
}

using System;
using System.Xml;
using System.Xml.Schema;
using System.IO;

public class Sample {

  public static void Main() {

    // Set the validation settings.
    XmlReaderSettings settings = new XmlReaderSettings();
    settings.DtdProcessing = DtdProcessing.Parse;
    settings.ValidationType = ValidationType.DTD;
    settings.ValidationEventHandler += new ValidationEventHandler (ValidationCallBack);

    // Create the XmlReader object.
    XmlReader reader = XmlReader.Create("itemDTD.xml", settings);

    // Parse the file.
    while (reader.Read());
  }

  // Display any validation errors.
  private static void ValidationCallBack(object sender, ValidationEventArgs e) {
    Console.WriteLine("Validation Error: {0}", e.Message);
  }
}

Imports System.Xml
Imports System.Xml.Schema
Imports System.IO

public class Sample 

  public shared sub Main() 

    ' Set the validation settings.
    Dim settings as XmlReaderSettings = new XmlReaderSettings()
    settings.DtdProcessing = DtdProcessing.Parse
    settings.ValidationType = ValidationType.DTD
    AddHandler settings.ValidationEventHandler, AddressOf ValidationCallBack
 
    ' Create the XmlReader object.
    Dim reader as XmlReader = XmlReader.Create("itemDTD.xml", settings)

    ' Parse the file. 
    while reader.Read()
    end while
    
  end sub

  ' Display any validation errors.
  private shared sub ValidationCallBack(sender as object, e as ValidationEventArgs) 
    Console.WriteLine("Validation Error: {0}", e.Message)
  end sub
end class

Input

The example uses the itemDTD.xml file as input.

<!--XML file using a DTD-->
<!DOCTYPE store [
  <!ELEMENT store (item)*> 
  <!ELEMENT item (name,dept,price)>
  <!ATTLIST item type CDATA #REQUIRED>
  <!ELEMENT name (#PCDATA)>
  <!ELEMENT price (#PCDATA)>]>
<store>
  <item type="supplies"  ISBN="2-3631-4">
    <name>paint</name>
    <price>16.95</price>
  </item>
</store>

Remarks

Document type definition (DTD) validation is implemented by using the validity constraints defined in the W3C Extensible Markup Language (XML) 1.0 (fourth edition) recommendation. DTDs use a formal grammar to describe the structure and syntax of compliant XML documents; they specify the content and values allowed for the XML document.

This property can have one of the following values:

• DtdProcessing.Parse to enable DTD processing.

• DtdProcessing.Prohibit to throw an XmlException exception when a DTD is encountered.

• DtdProcessing.Ignore to disable DTD processing without warnings or exceptions.

To perform validation against a DTD, the XmlReader uses the DTD defined in the DOCTYPE declaration of an XML document. The DOCTYPE declaration can either point to an inline DTD or can be a reference to an external DTD file. To validate an XML file against a DTD:

• Set the XmlReaderSettings.DtdProcessing property to DtdProcessing.Parse.

• Set the XmlReaderSettings.ValidationType property to ValidationType.DTD.

• If the DTD is an external file stored on a network resource that requires authentication, pass an XmlResolver object with the necessary credentials to the Create method.

Important

If the DtdProcessing property is set to DtdProcessing.Ignore, the XmlReader will not report the DTDs. This means that the DTD/DOCTYPE will be lost on output.