Streaming Media Supplement sa2150 and sa2250

Chapter 7 Configuring Media-IXT for RealNetworks

Media-IXT configuration variables

There are no configuration variable that apply exclusively to RealNetworks streaming.

Configuring Media-IXT for streaming over HTTP

Streaming over HTTP is normally only a last-resort streaming strategy, chosen by a browser as a fallback after

its preferred strategies fail. Rarely, streaming over HTTP is chosen by a network designer as the primary

streaming strategy for a deployment.

Streaming servers mark streams served through HTTP as non-cacheable, so Media-IXT, being a cache, can not

provide any bandwidth savings or service improvements for such service.

Streaming over HTTP works by making one persistent connection from the origin server to Media-IXT, and

another from Media-IXT to the client. Media-IXT terminates HTTP connections after a configurable period of

time whose default value is too brief for streaming over HTTP to work properly.

If your deployment relies on streaming over HTTP, you must tune Media-IXT’s HTTP timeout values so that

Media-IXT does not terminate streaming HTTP transactions before the play is complete.

Here are the relevant variables as they appear in the records.config file:

CONFIG proxy.config.http.transaction_no_activity_timeout_in INT 120

CONFIG proxy.config.http.transaction_no_activity_timeout_out INT 120

CONFIG proxy.config.http.transaction_active_timeout_in INT 7200

CONFIG proxy.config.http.transaction_active_timeout_out INT 7200

Note their default values, which are in seconds: 120 seconds equals two minutes; 7200 seconds equals two

hours.

These variables are documented in the HP Cache Server Appliance Administrator Guide, although streaming

over HTTP is not.

To configure Media-IXT for streaming over HTTP:

1. Decide which clip you plan to stream over HTTP has the longest duration. Add some extra time to that

duration and convert the total to seconds. We will call this value X.

2. Edit records.config such that all four timeout variables have the value X instead of the default values.

So, if X is 14520 for example (where your longest clip is four hours, or 14400 seconds, plus a margin of two

minutes), you have:

CONFIG proxy.config.http.transaction_no_activity_timeout_in INT 14520

CONFIG proxy.config.http.transaction_no_activity_timeout_out INT 14520

CONFIG proxy.config.http.transaction_active_timeout_in INT 14520

CONFIG proxy.config.http.transaction_active_timeout_out INT 14520

3. Force Media-IXT to re-read its configuration files. From Media-IXT’s

bin

directory, run the command:

./traffic_line -x

NOTE This procedure affects all streaming formats: RealNetworks, WMT, and QuickTime.

NOTE Elsewhere in this manual, we say to restart Media-IXT after editing configuration

variables. That rule is valid for configuration variables associated with streaming

protocols. HTTP is not normally a streaming protocol, though, and after editing HTTP

configuration variables, the command

traffic_line -x

is sufficient.