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LicenseAcquirer.OnAcquireLicense Method

Silverlight

The default implementation of this method calls into the MediaElement to acquire a license. You should override this method if you want to handle the license acquisition yourself.

Namespace:  System.Windows.Media
Assembly:  System.Windows (in System.Windows.dll)

protected internal virtual void OnAcquireLicense(
	Stream licenseChallenge,
	Uri licenseServerUri
)

Parameters

licenseChallenge
Type: System.IO.Stream
The PlayReady license acquisition challenge, which is to be sent to a PlayReady Server instance.
licenseServerUri
Type: System.Uri
The URI of the License Server. If the LicenseServerUriOverride property is set, then this parameter will contain the value of the LicenseServerUriOverride. If not set, then this parameter will return the value of the License Server URI found inside the WRMHeader header. In the case of WMDRM packaged content, the License Server URI will always be reset to null.

If the LicenseAcquirer is created on demand (from the media element), the OnAcquireLicense method is called when the Media pipeline is building a topology and is raised before MediaOpened is raised for a particular Source or entry of a Source. If the LicenseAcquirer is being used in license pre-acquisition mode (prior to attempting playback), the OnAcquireLicense method is called, but no media element events are raised.

You should override the OnAcquireLicense method if you want to handle the license acquisition yourself. When overridden, this method is called by using the PlayReady license acquisition challenge as the argument. Within this method, you should set up your WebRequest and WebResponse callback and return.

If you override this method and call the base class implementation, processing will be performed automatically. (In those cases, there can be no custom protocol for the response. The response has to be the PlayReady license server response.) If you do not call the base method, you must call the SetLicenseResponse method. Otherwise, the license acquisition processing will be stalled. If the LicenseAcquirer object is attached to a MediaElement then the MediaElement will remain in the AcquiringLicense state.

The LicenseAcquirer class is used by the MediaElement to handle acquiring licenses for DRM encrypted content from a PlayReady License Server. You can create a derived class from the LicenseAcquirer class and add custom logic like adding your own custom authentication scheme to the license request.

The following example shows how to override the LicenseAcquirer class (named "ManualLicenseAcquirer") and have a MediaElement use it to acquire the license.

<StackPanel x:Name="LayoutRoot" Background="Gray" Orientation="Vertical">
   <MediaElement x:Name="myME" Height="100"/>
</StackPanel>
public partial class Page : UserControl
{

    public Page()
    {
      InitializeComponent();
      this.Loaded += new RoutedEventHandler(Page_Loaded);
    }

    void Page_Loaded(object sender, RoutedEventArgs e)
    {
      // Test a full fledged manual acquirer

      // Set the LicenseAcquirer of the MediaElement to the custom License Acquirer
      // defined in this sample.
      myME.LicenseAcquirer = new ManualLicenseAcquirer(myME.Name);

      // Set the License URI to proper License Server address.
      myME.LicenseAcquirer.LicenseServerUriOverride = new Uri("http://contoso.com/myLicenseServer.asmx", UriKind.Absolute);
      myME.MediaFailed += new EventHandler<ExceptionRoutedEventArgs>(myME_MediaFailed);

      // Set the source of the MediaElement to the URL of the media encrypted with WMDRM.
      myME.Source = new Uri("http://contoso.com/wmdrm_url.wmv", UriKind.Absolute);
    }

    void myME_MediaFailed(object sender, ExceptionRoutedEventArgs e)
    {
      string errorMessage = "";
      if (e.ErrorException.ToString().Contains(" 6001 "))
      {
          errorMessage = "The individualization component software failed to" +
                         " download to the user’s computer. This error would" +
                         " come up when the MediaElement is in the Individualizing" +
                         " MediaElementState. One possible reason for this error is" +
                         " that the Silverlight client cannot connect the Microsoft" +
                         " Individualization Server.";
      }
      else if (e.ErrorException.ToString().Contains(" 6004 "))
      {
          errorMessage = " The installation of Silverlight on the client is" +
                         " out of date and needs to be updated.";  
      }
      else
      {
          errorMessage = "MediaFailed: " + e.ErrorException.Message + ".";
      }
      System.Windows.Browser.HtmlPage.Window.Alert(errorMessage);
    }

    // makes license request explicitly
    public class ManualLicenseAcquirer : LicenseAcquirer
    {
      private string challengeString;
      string _mediaElementName;

    public ManualLicenseAcquirer(string mediaElementName)
    {
      _mediaElementName = mediaElementName;
    }

    // The default implementation of OnAcquireLicense calls into the MediaElement to acquire a
    //  license. It is called when the Media pipeline is building a topology and will be raised
    // before MediaOpened is raised.
    protected override void OnAcquireLicense(System.IO.Stream licenseChallenge, Uri licenseServerUri)
    {
      StreamReader sr = new StreamReader(licenseChallenge);
      challengeString = sr.ReadToEnd();

      // Need to resolve the URI for the License Server -- make sure it is correct
      // and store that correct URI as resolvedLicenseServerUri.
      Uri resolvedLicenseServerUri;
      if (LicenseServerUriOverride == null)
        resolvedLicenseServerUri = licenseServerUri;
      else
        resolvedLicenseServerUri = LicenseServerUriOverride;

      // Make a HttpWebRequest to the License Server.
      HttpWebRequest request = WebRequest.Create(resolvedLicenseServerUri) as HttpWebRequest;
      request.Method = "POST";

      // Set ContentType through property    
      request.ContentType = "application/xml";

      //  ADD REQUIRED HEADERS.
      // The headers below are necessary so that error handling and redirects are handled 
      // properly via the Silverlight client.
      request.Headers["msprdrm_server_redirect_compat"] = "false";
      request.Headers["msprdrm_server_exception_compat"] = "false";

      //  Initiate getting request stream  
      IAsyncResult asyncResult = request.BeginGetRequestStream(new AsyncCallback(RequestStreamCallback), request);
    }

    // This method is called when the asynchronous operation completes.
    void RequestStreamCallback(IAsyncResult ar)
    {
      HttpWebRequest request = ar.AsyncState as HttpWebRequest;

      // populate request stream  
      request.ContentType = "text/xml";
      Stream requestStream = request.EndGetRequestStream(ar);
      StreamWriter streamWriter = new StreamWriter(requestStream, System.Text.Encoding.UTF8);

      streamWriter.Write(challengeString);
      streamWriter.Close();

      // Make async call for response  
      request.BeginGetResponse(new AsyncCallback(ResponseCallback), request);
    }

    private void ResponseCallback(IAsyncResult ar)
    {
      HttpWebRequest request = ar.AsyncState as HttpWebRequest;
      WebResponse response = request.EndGetResponse(ar);
      SetLicenseResponse(response.GetResponseStream());
    }
  }
}

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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