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mod_http_cache allows one to make an HTTP GET request to cache a document and HTTP PUT to store 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. Use http_remove_cache <url> to force an update if you know the source file on the server is newer than the cached file.

mod_http_cache offers the http_cache:// read and write file interfaces. See these examples for usage.

mod_http_cache offers the http:// and https:// read and write file interfaces if the "enable-file-formats" param is set to true. DO NOT LOAD mod_httapi IF YOU USE THIS PARAM.

mod_http_cache supports GET/PUT to Amazon S3 private buckets and (on FreeSWITCH later than 1.6) Microsoft's Azure Blob Service. See configuration below.

mod_httapi is also available which offers an HTTP read/write file interface.

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To use mod_http_cache:

Tell FreeSWITCH to compile in this module by editing modules.conf in /usr/src/freeswitch/trunk and adding:


Now go recompile FreeSWITCH.

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 and install in /usr/local/freeswitch/conf. An older copy is also available in freeswitch/src/mod/applications/mod_http_cache/conf/cacert.pem.


The conf/autoload_configs/http_cache.conf.xml file contains the configuration.


<configuration name="http_cache.conf" description="HTTP GET cache">
<!-- set to true if you want to enable http:// and https:// formats. Do not use if mod_httapi is also loaded -->
<param name="enable-file-formats" value="false"/>
<!-- 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"/>

<!-- amazon s3 security credentials -->
<profile name="s3">
<!-- 20 character key identifier -->
<!-- 40 character secret -->
<!-- optional list of domains that this profile will automatically be applied to -->
<!-- if you wish to apply the s3 credentials to a domain not listed here, then use
{profile=s3}http://foo.s3... -->
<domain name=""/>
<!-- Azure Blob Service security credentials -->
<profile name="azure">
<!-- key identifier, can override with AZURE_STORAGE_ACCESS_KEY environment variable -->
<!-- optional list of domains that this profile will automatically be applied to -->
<!-- if you wish to apply the Azure credentials to a domain not listed here, then use
{profile=azure}http://account.blob... -->
<domain name=""/>



Download a URL to the cache in a background thread. Does not wait for the download to finish.



Download a document to the cache. Returns the name of the cached file suitable for use by FreeSWITCH APPs or "-ERR" on error:



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:



PUT a file. This can be used to PUT a file like a session recording to a webserver:

http_put /tmp/1df4a12708bcea.wav


Invalidate a cached file, typically when the source file has been updated. This will force the updated file to be downloaded into the cache.



Empty the cache:




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.



<action application="playback" data="http_cache://"/>



<action application="playback" data=""/>


Force download of source file, for example if the file on the server has been updated and the cached file is now invalid.


<action application="playback" data="{refresh=true}"/>


How to record a .wav file to a webserver

mod_http_cache can record using the http/https/http_cache file formats. The file is PUT when the recording is completed and the file is closed.



<action application="record" data="http_cache://${uuid}.wav"/>



<action application="record" data="${uuid}.wav"/>