Streaming Media Supplement sa2150 and sa2250

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Chapter 4 Understanding Media-IXT and WMT
An example of WMT metafile rewriting
We have seen how Media-IXT caches WMT streaming media data. Now we can examine how Media-IXT
rewrites the URLs in a WMT metafile.
For our example, we assume that we have:
• An HTTP server whose hostname is movies.com.
• Links to WMT files pointing to this HTTP server.
• A Media-IXT with IP address 10.10.10.10.
• An origin Windows Media server with IP address 11.11.11.11
.
The URLs within the WMT metafiles point to media content on this server.
Let’s say that one of our media content URLs, as originally found in a WMT metafile, looks like this:
mms://11.11.11.11/movie300.asf
Media-IXT rewrites the WMT metafile so the media content URL becomes:
mms://10.10.10.10/ink/rhmovies.com/11.11.11.11/movie300.asf
This rewritten media content URL is called the host-embedded filename. The idea is that the original media
content URL is an ordinary filename or pathname, and the rewritten form has the hostname or IP address of
Media-IXT embedded within it. (In our example, what’s embedded is the IP address of our Media-IXT host,
namely 10.10.10.10.)
Now the rewritten URL has the characteristics we require, since:
• it points, first, to our Media-IXT (at IP address 10.10.10.10)
• next, it contains the hostname of the HTTP server where the WMT metafile resides (movies.com)
• finally, it points to the location of the media file on the origin Windows Media server (the file
movie300.asf at IP address 11.11.11.11)
Figure 4-5. WMT streaming with Media-IXT performing proxy caching (concluded)
Windows
Media Server
Cl i e n t b r o w se r
with Windows
Media Player
Web Server
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metadata
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udp
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mms
Windows Media Player contacts Media-IXT on the MMSport, passing the rewritten URL.
Media-IXT obtains metadata about the media content invoked by the URL from the origin
Windows Media Server.
Media-IXT tries to find a match between the origin Windows Media Server's metadata and
metadata in
Media-IXT'scache. Media-IXT findsan exact match, meaning the
content is in cache and fresh.
Media-IXT serves the content from cache.
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Me ia-IXTd