Streaming Media Supplement sa2150 and sa2250

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Chapter 9 Configuring Media-IXT for QuickTime
dest_host=music.com scheme=rtsp action=standard-cache tag=RNI
dest_domain=. suffix=.rm action=never-cache
Differences between forward and reverse proxy selective caching
For a reverse proxy deployment, selective caching rules must be written differently than for a forward proxy
deployment. That is because rules must be based on requested URLs after remapping has been applied. In a
forward proxy clients request the origin server hostname. In reverse proxy clients request the advertised name
of the website, which Media-IXT then remaps to the origin server hostname. Observe the differences in the two
examples that follow.
A forward proxy cache.config example
Here is an example rule:
dest_host=foo.bar.com scheme=rtsp action=never-cache tag=QT
This rule prevents Media-IXT from caching QuickTime content hosted on the origin server foo.bar.com.
A reverse proxy cache.config example
Here is an example rule:
dest_host=back.door.com scheme=rtsp action=never-cache tag=QT
Let us assume that:
• the advertised name of the website is foo.bar.com
• Media-IXT answers requests for foo.bar.com
• Media-IXT performs reverse proxy for the origin server back.door.com
What happens to make this rule work?
1. The QuickTime player client sends a request for content at the advertised website name, foo.bar.com;
2. Media-IXT answers the request, remapping foo.bar.com to back.door.com, the origin server
according to its rules in remap.config;
3. Media-IXT applies cache.config to the request after remap.config has been applied; the rule
matches the destination host in the request, which is back.door.com;
4. Media-IXT, following the rule, does not cache content hosted on back.door.com.