Streaming Media Supplement sa2150 and sa2250

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Chapter 1
Live passthrough.
When Media-IXT simply passes live content through from the origin server to the client.
See “Live content” .
Live splitting.
When Media-IXT splits one live stream from the origin server into several streams to different
clients. See “Live content” .
Lower level.
Part of hierarchy closer to client.
Management-only clustering.
Media-IXT cluster nodes share configuration information, so that all nodes can
be administered at once as a single system image of the cluster.
Media content URL.
(Applies to WMT) The URL that locates the actual streaming media content on an origin
Windows Media server. See “Host-embedded filename” .
Media-IXT.
HP Media eXtension Technology.
MMS.
(applies to WMT) Microsoft Media Services. The MediaPlayer control protocol, similar in spirit to
RTSP. MMS has the well-known port of 1755; uses either MMST or MMSU as the data transfer protocol. TCP
is the underlying transport protocol for the MMST data transfer protocol. UDP is the underlying transport
protocol for the MMSU data transfer protocol.
On-demand content.
When an origin server begins playing a clip in response to a client request, the content
being streamed is on-demand content. See “Live content” .
Parent.
Node closer to originator of the content in a hierarchical deployment. Child and parent communicate
directly. See “Child” .
PNA.
(Applies to RealNetworks) A proprietary RealNetworks protocol that has been replaced by RTSP. PNA
URLs have a scheme of.pnm. See “RTSP” below.
Preloading.
The placing of content which no client has requested into the cache. Preloading can be done either
by pulling from an upstream server, or pushing to a Media-IXT. See “CDS” .
Pristine content.
Content exactly as it is stored on an origin server.
Proxy.
A system that acts on behalf of an origin server, positioned between the origin server and its clients.
Pull splitting.
(applies to RealNetworks) Host contacts upstream host and tells upstream host to send payload
data. (As opposed to push splitting, where upstream host takes initiative and sends data to downstream host with
no prior request by the downstream host.)
Push splitting.
(applies to RealNetworks) Upstream host sends payload data to downstream host with no prior
request from the downstream host.
QuickTime.
A streaming media format from Apple; the client is QuickTime Player and the origin server is
QuickTime server. There is also a QuickTime file format. See “RTSP” and “RDT” .
RDT.
(Applies to RealNetworks) A data transfer protocol used by the RealNetworks streaming format. This is
a proprietary protocol of RealNetworks corporation. Formerly known as RDP.
RealNetworks.
A streaming media format from the company of the same name; the client is RealPlayer and
the origin server is RealServer. See “RTSP” and “PNA” .
Reverse proxy caching.
Proxy caching of whatever client requests are directed to a particular origin server
or group of origin servers. The proxy cache answers to the advertised name of the origin server, acting for and
hiding the origin server. See “Forward proxy caching” .
RTP.
(Applies to QuickTime) A data transfer protocol used by the QuickTime streaming format. Real Time
Protocol is based on RFCs 2326 and 1889.
RTSP.
(Applies to RealNetworks, QuickTime) A control protocol, used by the RealNetworks and QuickTime
streaming formats. Real Time Streaming Protocol is based RFC 2326.
Streaming media.
Audio and video that play over the Web without prior downloading of the complete files
that contain them.
Streaming media format.
A technology encompassing its own media players, its own origin servers, and its
own chosen protocols and ways of handling streaming media data. RealNetworks, Windows Media
Technologies, and QuickTime are streaming media formats. See “Control protocol” , “Data transfer protocol”
and “Underlying transport protocol” .