IWMSEventAuthorizationCallback.OnAuthorizeEvent (Visual Basic .NET)

IWMSEventAuthorizationCallback.OnAuthorizeEvent (Visual Basic .NET)

The OnAuthorizeEvent method returns the result of the IWMSEventAuthorizationPlugin.AuthorizeEvent method call to the server.

Syntax

Parameters

hr

[in] Int32 containing the result of the call to AuthorizeEvent.

Context

Object containing a value defined by the server to identify which call to AuthorizeEvent the plug-in is responding to when it calls OnAuthorizeEvent. You must pass this value back unaltered.

Return Values

This method does not return a value. If the plug-in uses the IWMSEventLog object to log error information, it is recommended that it send NS_E_PLUGIN_ERROR_REPORTED (0xC00D157D) to the server in the hr parameter. Typically, the server attempts to make plug-in error information available to the server object model, the Windows Event Viewer, and the troubleshooting list in the details pane of the Windows Media Services MMC. However, if the plug-in uses the IWMSEventLog object to log custom error information to the Windows Event Viewer, sending NS_E_PLUGIN_ERROR_REPORTED stops the server from also logging to the event viewer. For more information about plug-in error information, see Identifying Plug-in Errors.

If this method fails, it throws an exception.

Example Code

The following example illustrates a possible implementation of the AuthorizeEvent method for an access control list (ACL) authorization plug-in. OnAuthorizeEvent is called at the bottom of the example.

Public Sub AuthorizeEvent( _
    ByRef pEvent As WMS_EVENT, ByVal pUserCtx As IWMSContext, _
    ByVal pPresentationCtx As IWMSContext, _
    ByVal pCommandCtx As IWMSCommandContext, _
    ByVal pCallback As IWMSEventAuthorizationCallback, _
    ByVal Context As Object) _
        Implements IWMSEventAuthorizationPlugin.AuthorizeEvent

        Dim wmsAccess As WMS_ACCESS_CONTROL = _
                         WMS_ACCESS_CONTROL.WMS_ACL_DENY_ALL
        Dim strUser As String = ""

        ' This variable uses numerical values to 
        ' represent HRESULT error codes.
        Dim hr As Integer = 0

        ' Switch on the event type.
        Select Case (pEvent.Type)
            Case WMS_EVENT_TYPE.WMS_EVENT_DESCRIBE, _
                 WMS_EVENT_TYPE.WMS_EVENT_OPEN, _
                 WMS_EVENT_TYPE.WMS_EVENT_GET_PARAMETER, _
                 WMS_EVENT_TYPE.WMS_EVENT_VALIDATE_PUSH_DISTRIBUTION
                Try
                    ' Retrieve the user name from the user context.
                    pUserCtx.GetStringValue(WMSDefines.WMS_USER_NAME, _
                                         WMSDefines.WMS_USER_NAME_ID, _
                                         strUser, _
                                         0)

                   If strUser <> "" Then

                        ' Determine whether the user is in the access 
                        ' control list, and what rights the user has.
                        ' The GetUserAccess funtion is user-defined.
                        m_AccessControl.GetUserAccess(strUser, ByRef _
                                                                wmsAccess)

                      If pEvent.Type = _
                         WMS_EVENT_TYPE.WMS_EVENT_OPEN Or _
                         pEvent.Type = WMS_EVENT_TYPE.WMS_EVENT_DESCRIBE _
                         Or pEvent.Type = _
                         WMS_EVENT_TYPE.WMS_EVENT_GET_PARAMETER Then

                            ' Check to see whether read access is 
                            ' permitted.
                          If WMS_ACCESS_CONTROL.WMS_ACL_DENY_READ = _
                                                            wmsAccess Then

                                ' User was denied read access.
                                ' Pass the callback method the integer
                                ' value of E_ACCESSDENIED.
                                hr = &H80070005
                          ElseIf WMS_ACCESS_CONTROL.WMS_ACL_ALLOW_READ = _
                                                            wmsAccess Then

                                ' User was granted read access.
                                hr = 0
                          Else

                                ' User was neither granted nor denied read 
                                ' access. Pass the callback method the 
                                ' integer value of E_FAIL.
                                hr = &H80004005
                          End If
                      End If
                   Else

                        ' Check whether write access is permitted.
                        If WMS_ACCESS_CONTROL.WMS_ACL_DENY_WRITE = _
                                                            wmsAccess Then

                                ' User was denied read access.
                                ' Pass the callback method the integer
                                ' value of E_ACCESSDENIED.
                                hr = &H80070005
                        ElseIf WMS_ACCESS_CONTROL.WMS_ACL_ALLOW_WRITE = _
                                                            wmsAccess Then
                            ' User was granted write access.
                            hr = 0
                        Else
                                ' User was neither granted nor denied read 
                                ' access. Pass the callback method the 
                                ' integer value of E_FAIL.
                                hr = &H80004005
                        End If
                    End If

                ' Null out string containing user name.
                strUser = ""

                Catch e As Exception
                    ' TODO: Handle exceptions.
                Finally
                    ' Report the results of the authorization
                    ' challenge back to the server.
                    pCallback.OnAuthorizeEvent(hr, Context)
                End Try
        End Select
    End Sub

Requirements

Reference: Add a reference to Microsoft.WindowsMediaServices.

Namespace: Microsoft.WindowsMediaServices.Interop.

Assembly: Microsoft.WindowsMediaServices.dll.

Library: WMSServerTypeLib.dll.

Platform: Windows Server 2003, Enterprise Edition; Windows Server 2003, Datacenter Edition; Windows Server 2008.

See Also

• IWMSEventAuthorizationCallback Object (Visual Basic .NET)