Silent license acquisition not working
There are two kinds of license acquisition mechanism in MS DRM: silent and non-silent. If content providers implement both of them in DRM license server application, Windows Media Player should go silent mode first as long as automatically downloads usage rights option is enabled. It switches to non-silent mode when silent mode gets failed.
If you’re content provider and gets some complains from the users which is about silent mode does not work, you might want to check two things:
1. When you package the content, make sure you use a correct URL string of license server. The URL string is a HTTP address (http://xxxx), sometimes, the string may be changed to “http:\\xxx” by mistake or other reasons. This will make silent license acquisition failed but non-silent will still be working. WMP's non-silent related module internally checks the string format and corrects it if it’s incorrect. This is a good and makes application robust, but it makes troubleshooting become hard. Because non-silent mode works, people may not suspect the license server URL string is incorrect, and pay more attention to other stuff. Checking the license server URL string is pretty easy, you could review code or just open a DRM’d file in ASFViewer, you can find the string in the head.
2. If the license server application is developed by ASP.NET, ASP.NET may add some HTML tags in HTTP response string. These tags are invisible to developers and will confuse WMP9’s XML parser. To get around it, you might want to write code like below:
Response.Clear();
Response.Write(liccenseresponse);
Response.Flush();
Response.End();
Windows Media Player 10/11 do not have this issue because of the XML parser is different.
