MessageHeaderAttribute.MustUnderstand Property
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Specifies whether the node acting in the Actor role must understand this header. This is mapped to the mustUnderstand SOAP header attribute.
public:
property bool MustUnderstand { bool get(); void set(bool value); };public bool MustUnderstand { get; set; }member this.MustUnderstand : bool with get, setPublic Property MustUnderstand As BooleanProperty Value
true if the node acting in the Actor role must understand this header; otherwise, false.
Examples
The following code example shows the use of the MessageHeaderAttribute to create a SOAP header for the response message with the Name, Namespace and MustUnderstand properties set to values appropriate for this header. The code example is followed by an example of the message when sent.
[MessageContract]
public class HelloResponseMessage
{
private string localResponse = String.Empty;
private string extra = String.Empty;
[MessageBodyMember(
Name = "ResponseToGreeting",
Namespace = "http://www.examples.com")]
public string Response
{
get { return localResponse; }
set { localResponse = value; }
}
[MessageHeader(
Name = "OutOfBandData",
Namespace = "http://www.examples.com",
MustUnderstand=true
)]
public string ExtraValues
{
get { return extra; }
set { this.extra = value; }
}
/*
The following is the response message, edited for clarity.
<s:Envelope>
<s:Header>
<a:Action s:mustUnderstand="1">http://HelloResponseMessage/Action</a:Action>
<h:OutOfBandData s:mustUnderstand="1" xmlns:h="http://www.examples.com">Served by object 13804354.</h:OutOfBandData>
</s:Header>
<s:Body>
<HelloResponseMessage xmlns="Microsoft.WCF.Documentation">
<ResponseToGreeting xmlns="http://www.examples.com">Service received: Hello.</ResponseToGreeting>
</HelloResponseMessage>
</s:Body>
</s:Envelope>
*/
}
<MessageContract> _
Public Class HelloResponseMessage
Private localResponse As String = String.Empty
Private extra As String = String.Empty
<MessageBodyMember(Name := "ResponseToGreeting", Namespace := "http://www.examples.com")> _
Public Property Response() As String
Get
Return localResponse
End Get
Set(ByVal value As String)
localResponse = value
End Set
End Property
<MessageHeader(Name := "OutOfBandData", Namespace := "http://www.examples.com", MustUnderstand:=True)> _
Public Property ExtraValues() As String
Get
Return extra
End Get
Set(ByVal value As String)
Me.extra = value
End Set
End Property
'
' The following is the response message, edited for clarity.
'
' <s:Envelope>
' <s:Header>
' <a:Action s:mustUnderstand="1">http://HelloResponseMessage/Action</a:Action>
' <h:OutOfBandData s:mustUnderstand="1" xmlns:h="http://www.examples.com">Served by object 13804354.</h:OutOfBandData>
' </s:Header>
' <s:Body>
' <HelloResponseMessage xmlns="Microsoft.WCF.Documentation">
' <ResponseToGreeting xmlns="http://www.examples.com">Service received: Hello.</ResponseToGreeting>
' </s:Body>
' </s:Envelope>
'
End Class
Remarks
For more information, see the Remarks section of MessageHeaderAttribute for details.
Important
It is important to remember that if the MustUnderstand property is true in a message being sent and the application on the receiving side does not understand the header a fault is generated. Conversely, if a header with the mustUnderstand SOAP header attribute set to true is received by Windows Communication Foundation (WCF), it must be a part of the message contract (or must be processed by one of the Windows Communication Foundation (WCF) channels); otherwise, it is assumed that the header is not understood and an exception is thrown.
