Mod http cache
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mod_http_cache (HTTP GET files with caching)
mod_http_cache allows one to make a HTTP GET request to cache a document. The primary use case is to download and cache audio files from a web server.
mod_http_cache will only respect the max-age cache-control directive to determine when a cached file becomes stale.
mod_httapi is also available which offers HTTP file caching via a file interface.
Installing
To use mod_http_cache:
Tell FreeSWITCH to compile in this module by editing modules.conf in /usr/src/freeswitch/trunk and adding:
applications/mod_http_cache
Now go recompile FreeSWITCH.
make make install
Tell FreeSWITCH to actually use the module when running by adding the module to modules.conf.xml in /usr/local/freeswitch/conf/autoload_configs:
<load module="mod_http_cache"/>
For HTTPS support, grab the latest CA certs from http://curl.haxx.se/ca/cacert.pem and install in /usr/local/freeswitch/conf. An older copy is also available in freeswitch/src/mod/applications/mod_http_cache/conf/cacert.pem.
Configuration
The conf/autoload_configs/http_cache.conf.xml file contains the configuration.
<configuration name="http_cache.conf" description="HTTP GET cache">
<settings>
<!-- maximum size of cache -->
<param name="max-urls" value="10000"/>
<!-- location of cached files -->
<param name="location" value="$${base_dir}/http_cache"/>
<!-- if not specified by cache-control max-age directive, this value will be used
to expire cached files -->
<param name="default-max-age" value="86400"/>
<!-- size of the prefetch thread pool -->
<param name="prefetch-thread-count" value="8"/>
<!-- size of the prefetch request queue -->
<param name="prefetch-queue-size" value="100"/>
<!-- absolute path to CA bundle file -->
<param name="ssl-cacert" value="$${base_dir}/conf/cacert.pem"/>
<!-- verify certificates -->
<param name="ssl-verifypeer" value="true"/>
<!-- verify host name matches certificate -->
<param name="ssl-verifyhost" value="true"/>
</settings>
</configuration>
API
http_prefetch
Download a URL to the cache in a background thread. Does not wait for the download to finish.
http_prefetch http://myserver.yo/media/hello_world.wav
http_get
Download a document to the cache. Returns the name of the cached file suitable for use by FreeSWITCH APPs or "-ERR" on error.
http_get http://myserver.yo/media/hello_world.wav
http_tryget
Same as http_get except if the document is missing from the cache or stale, "-ERR download" is returned. i.e. this API call checks the cache only. "-ERR" is returned on all other errors.
http_tryget http://myserver.yo/media/hello_world.wav
http_put
PUT a file. This can be used to PUT a file like a session recording to a webserver.
http_put http://user:password@myserver.yo/recordings/1df4a12708bcea.wav /tmp/1df4a12708bcea.wav
http_clear_cache
Empty the cache.
http_clear_cache
Examples
Play a .wav file hosted by a webserver
While this example below will work, it is probably best to download all the .wav files needed by a call in a background thread early in the call using http_prefetch. Subsequent calls to http_get will then just grab the cached file. That way, delays in downloading will be less likely to cause pauses in playback.
Dialplan XML
<action application="playback" data="${http_get(http://myserver.yo/media/hello_world.wav)}"/>
Play a .wav file hosted by a webserver to a single conference member
This example uses the "expand" API call to resolve the channel variables and to execute http_get. This would be executed by an external process controlling the call over ESL or the raw event socket.
expand uuid:12345 conference my_awesome_conference_123 play ${http_get(http://myserver.yo/media/hello_world.wav)} ${conference_member_id}
