IWMSCacheProxyServerCallback.OnDownloadContentProgress (C#)

The OnDownloadContentProgress method is called by the server to respond when a cache plug-in calls IWMSCacheProxyServer::DownloadContent. The OnDownloadContentProgress method is called every time content is downloaded. Therefore, it is called every time an entry in a playlist has been downloaded. However, it is not guaranteed to be called in the order of the entries.

void IWMSCacheProxyServerCallback.OnDownloadContentProgress(
  int lHr,
  WMS_RECORD_PROGRESS_OPCODE opCode,
  IWMSContext pArchiveContext,
  object varContext
);

Arguments

	[in] int indicating whether the call to IWMSCacheProxyServer.DownloadContent.
	[in] Member of the WMS_RECORD_PROGRESS_OPCODE enumeration type indicating the state of the download. This must be one of the following values.

Value	Description
WMS_RECORD_PROGRESS_ARCHIVE_STARTED	The requested content is being saved.
WMS_RECORD_PROGRESS_ARCHIVE_FINISHED	The archiving process has been completed.

	[in] IWMSContextIWMSContext Object (C#) containing a pointer to an INSSBufferINSSBuffer Object (C#) that contains the serialized metadata for the media item being downloaded. The metadata must be persisted by the plug-in. For more information, see Downloading Content.
	[in] object containing a value defined by the plug-in when it called IWMSCacheProxyServer.DownLoadContent. For example, your plug-in can use this parameter to persist state information. The server does not alter this value and passes it back when calling OnDownloadContentProgress.

Return Value

This method does not return a value. To report an error, the plug-in can throw a COMException object to the server. If the plug-in uses the IWMSEventLogIWMSEventLog Object (C#) to log error information, it is recommended that it throw NS_E_PLUGIN_ERROR_REPORTED (0xC00D157D). 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 send custom error information to the Windows Event Viewer, throwing 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.

Example

using Microsoft.WindowsMediaServices.Interop;
using System.Runtime.InteropServices;

void IWMSCacheProxyServerCallback.OnDownloadContentProgress(
                                    int lHr,
                                    WMS_RECORD_PROGRESS_OPCODE opCode,
                                    IWMSContext pArchiveContext,
                                    object varContext)
{
  try
  {
    // The call to IWMSCacheProxyServer.DownloadContentProgress
    // succeeded.
    if(lHr==0)
    {
      // The archive has been started.
      if(opCode==WMS_RECORD_PROGRESS_OPCODE.WMS_RECORD_PROGRESS_ARCHIVE_STARTED)
      {
        // Retrieve the name of the download file.
        INSSBuffer NSBuffer=null;
        Guid guid = typeof(INSSBuffer).GUID;
        Object obj;
        pArchiveContext.GetAndQueryIUnknownValue(WMSDefines.WMS_ARCHIVE_CONTENT_DESCRIPTION_LIST_BUFFER,
                                                 WMSDefines.WMS_ARCHIVE_CONTENT_DESCRIPTION_LIST_BUFFER_ID,
                                                 ref guid,
                                                 out obj ,
                                                 0);
        NSBuffer = (INSSBuffer)obj;
        string CacheFile;
        pArchiveContext.GetStringValue(WMSDefines.WMS_ARCHIVE_FILENAME,
                                       WMSDefines.WMS_ARCHIVE_FILENAME_ID,
                                       out CacheFile,
                                       0);

        // Retrieve the user-defined ContentInfo object
        // from the varContext parameter.
        ContentInfo ci = (ContentInfo)varContext;

        // If this is not a playlist, assign the file
        // name to the cache URL.                    
        string s = GetStringFromNSSBuffer(NSBuffer);
        if((ci.ContentType & 2)==0) // not a playlist
        {
          ci.CDLData = s;
          ci.CacheUrl = CacheFile;
        }
        // This is a playlist.
        else
        {
          PlaylistItem Item = new PlaylistItem();
          Item.CacheUrl = CacheFile;
          Item.CDLData = s;
          ci.CDL.Add((object)Item);
        }
      }
    }
  }

  catch(Exception e)
  {
    throw new COMException();
  }

  return;
}

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

Concepts

IWMSCacheProxyServerCallback Object (C#)