You can use a playlist created on a Web server by either an ASP page or by a Web script as the source for an on-demand publishing point or broadcast publishing point. Because this custom playlist can be dynamically created each time the server accesses it, it is referred to as a dynamic source.
When you generate a playlist from a dynamic source, Windows Media Services must first retrieve the playlist from the Web server to the Windows Media server and then parse the playlist into a collection of digital media content which is then streamed to the client. Windows Media Services uses the WMS HTTP Download Data Source plug-in to download the playlist from the Web server. The playlist is then parsed by the WMS SMIL Playlist Parser plug-in and the content is streamed to the user.
The dynamic playlist is downloaded from the Web server using the Hypertext Transfer Protocol (HTTP). It can also be downloaded from a secure Web server that uses Secure Sockets Layer (SSL) to transfer data. If you are sourcing from a dynamic source, you must specify the source location by using the URL of the Web server. You can use the following formats to specify the URL, replacing Web_server_name with the name of your server, and replacing dynamic_playlist.asp with the name of the script file that creates the playlist being downloaded:
The "d" is appended to either the http or https prefixes to specify that the WMS HTTP Download Data Source plug-in be used with this content.