Working with data sources
Windows Media Services supports multiple data sources through the use of data source plug-ins. By default, Windows Media Services has the following data source plug-ins available:
- WMS File Data Source plug-in. When the source of the content streamed by your publishing point is a located on a Common Internet File System (CIFS) Windows Media Services uses the WMS File Data Source plug-in to access the content. This plug-in is able to read data from any CIFS file system, including the NTFS file system, file allocation table (FAT), or FAT32, and can use the address system. If you are storing your content by using an alternate file system, then you need to obtain a custom data source plug-in so that Windows Media Services can read the data.
- WMS Network Data Source plug-in. When the source of the content streamed by your publishing point is another computer on your network, such as an encoder or another Windows Media server, Windows Media Services uses the WMS Network Data Source plug-in to access the content. This plug-in is able to read streaming data packets from a network and uses a control protocol plug-in to negotiate a connection to the network source.
- WMS HTTP Download Data Source plug-in. When the source of the content streamed by your publishing point is a that is retrieved from a Web server, Windows Media Services uses the WMS HTTP Download Data Source plug-in to transfer the playlist file from the Web server to the Windows Media server.
- WMS Push Data Source plug-in. When the source of the content streamed by your publishing point originates from an encoder that is capable of pushing content, the encoder administrator has the option of broadcasting directly from the encoder or broadcasting through a Windows Media server. If the administrator chooses to broadcast through a Windows Media server, the encoder can initiate a connection to the Windows Media server, create a for its use, and send the stream over the network to the server. This series of events is commonly called an encoder push or push distribution, because the encoder initiates the connection to the server to broadcast the stream. In this situation, Windows Media Services uses the WMS Push Data Source plug-in to maintain the connection between the encoder and the server. This plug-in is able to accept incoming digital media data packets from an encoder.
If the encoder administrator chooses to broadcast directly from the encoder, Windows Media Services can still initiate a connection to the encoder using the encoder connection URL and can then broadcast the stream. This scenario is known as encoder pull or pull distribution. In this situation, the WMS Network Data Source plug-in is used.
These data source plug-ins provide support for the most common streaming scenarios. You can use the Windows Media Services Software Development Kit (SDK) to create custom data source plug-ins to handle more specific scenarios.
Notes
- Any data source accessed must have the appropriate permissions settings for Windows Media Services to retrieve the content from the location. By default, Windows Media Services uses the Network Service account when responding to network authentication and authorization requests. The Network Service account should be granted at least read access permissions for any data source you want to use with Windows Media Services. For more information see Understanding rights.
- Custom or third-party plug-ins should be located in a protected directory to prevent tampering. The protected directory can be any directory that has been set to deny write permissions to unauthorized users. For more information about restricting directory access, see the Windows Help and Support Center.
- If the content source for your publishing point is a computer running Windows 2000 Server you may have difficulty streaming the content because Windows 2000 Server and Windows Server 2003 handle user account authorization and privileges differently. If the two servers are members of the same domain, on-demand publishing points that have the WMS NTFS ACL Authorization plug-in enabled will cause remote clients to receive an "Access denied" error message when they attempt to retrieve content from the computer running Windows 2000 Server. Local clients, such as the Test stream feature of Windows Media Services, are not affected. If the two computers are not members of the same domain, see To access content on a computer running Windows 2000 Server.
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