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FromXml Method

DnsPermission.FromXml Method

Reconstructs a DnsPermission instance from an XML encoding.

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

'Declaration
Public Overrides Sub FromXml ( _
	securityElement As SecurityElement _
)

Parameters

securityElement
Type: System.Security.SecurityElement

The XML encoding to use to reconstruct the DnsPermission instance.

Implements

ISecurityEncodable.FromXml(SecurityElement)

ExceptionCondition
ArgumentNullException

securityElement is Nothing.

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

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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