DnsPermission.FromXml Method (SecurityElement)

 

Reconstructs a DnsPermission instance from an XML encoding.

Namespace:   System.Net
Assembly:  System (in System.dll)

Public Overrides Sub FromXml (
	securityElement As SecurityElement
)

Parameters

securityElement
Type: System.Security.SecurityElement

The XML encoding to use to reconstruct the DnsPermission instance.

Exception Condition
ArgumentNullException

securityElement is null.

ArgumentException

securityElement is not a DnsPermission element.

The FromXml method reconstructs a DnsPermission instance from an XML encoding defined by the SecurityElement class.

Use the ToXml method to XML-encode the DnsPermission instance, including state information.

The following example reconstructs a DnsPermission instance from an XML encoding.

Public Sub ConstructDnsPermission()
    Try
        ' Create a DnsPermission instance.
        Dim permission As New DnsPermission(PermissionState.None)
        ' Create a SecurityElement instance by calling the ToXml method on the
        ' DnsPermission instance and print its attributes, 
        ' which hold the  XML encoding of the DnsPermission instance.
        Console.WriteLine("Attributes and Values of 'DnsPermission' instance :")
        PrintKeysAndValues(permission.ToXml().Attributes)

        ' Create a SecurityElement instacnce .
        Dim securityElementObj As New SecurityElement("IPermission")
        ' Add attributes and values of the SecurityElement instance corresponding to
        ' teh permission instance.
        securityElementObj.AddAttribute("version", "1")
        securityElementObj.AddAttribute("Unrestricted", "true")
        securityElementObj.AddAttribute("class", "System.Net.DnsPermission")

        ' Reconstruct a DnsPermission instance from an XML encoding.
        Dim permission1 As New DnsPermission(PermissionState.None)
        permission1.FromXml(securityElementObj)

        ' Print the attributes and values of the constructed DnsPermission object.
        Console.WriteLine("After reconstruction Attributes and Values of new DnsPermission instance :")
        PrintKeysAndValues(permission1.ToXml().Attributes)
    Catch e As NullReferenceException
        Console.WriteLine("NullReferenceException caught!!!")
        Console.WriteLine(("Source : " + e.Source))
        Console.WriteLine(("Message : " + e.Message))
    Catch e As SecurityException
        Console.WriteLine("SecurityException caught!!!")
        Console.WriteLine(("Source : " + e.Source))
        Console.WriteLine(("Message : " + e.Message))
    Catch e As ArgumentNullException
        Console.WriteLine("ArgumentNullException caught!!!")
        Console.WriteLine(("Source : " + e.Source))
        Console.WriteLine(("Message : " + e.Message))
    Catch e As Exception
        Console.WriteLine("Exception caught!!!")
        Console.WriteLine(("Source : " + e.Source))
        Console.WriteLine(("Message : " + e.Message))
    End Try
End Sub 'ConstructDnsPermission


Private Sub PrintKeysAndValues(myList As Hashtable)
    ' Get the enumerator that can iterate through the hash table.
    Dim myEnumerator As IDictionaryEnumerator = myList.GetEnumerator()
    Console.WriteLine(ControlChars.Tab + "-KEY-" + ControlChars.Tab + "-VALUE-")
    While myEnumerator.MoveNext()
        Console.WriteLine(ControlChars.Tab + "{0}:" + ControlChars.Tab + "{1}", myEnumerator.Key, myEnumerator.Value)
    End While
    Console.WriteLine()
End Sub 'PrintKeysAndValues

.NET Framework
Available since 1.1
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