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
UNC 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 playlist 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 broadcast publishing point 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.
Notes