Mod event socket
mod_event_socket is a TCP based interface to control FreeSWITCH. The default values are to bind to 127.0.0.1 port 8021 and the default password is ClueCon. See the Configuration section below for a note on when to use 0.0.0.0 instead of 127.0.0.1.
The module operates in two modes, inbound and outbound.
Inbound mode means you run your applications (in whatever languages) as clients and connect to the FreeSWITCH server to invoke commands and control FreeSWITCH.
******************************************** * | * * FreeSWITCH™ | mod_event_socket * * | 127.0.0.1:8021 * * | * ******************************************** /\ /\ / \ ****************** ****************** * Client A * * Client B * * 127.0.0.1:9988 * * 127.0.0.1:9999 * ****************** ******************
In inbound mode, your application (Client A, Client B: Python, Perl, etc) connects to the FreeSWITCH™ server on the given port and sends commands, as shown in the above diagram. The rest of this document is biased toward this inbound mode, though there is a lot of overlap with outbound mode. Using inbound socket connections you can check status, make outbound calls, etc.
Outbound mode means you make a daemon (with whatever language) and then have FS connect to it. You add an extension to the dialplan and put <action application="socket" data="ip:port sync full"/> and create a script that runs on that ip:port and answer, playback and everything else you need on the script.
In outbound mode, also known as the "socket application" (or socket client), FreeSWITCH™ makes outbound connections to another process (similar to Asterisk's FAGI model). Using outbound connections you can have FreeSWITCH™ call your own application(s) when particular events occur. See Event Socket Outbound for more details regarding things specific to outbound mode.
First enable the mod_event_socket module in modules.conf.xml (in a default configuration this is located in /usr/local/freeswitch/conf/autoload_configs/modules.conf.xml)
By default the module is enabled but restricted to localhost by the settings specified below.
The module settings can be changed in the event_socket.conf.xml file (in a default configuration this is located in /usr/local/freeswitch/conf/autoload_configs/event_socket.conf.xml):
<configuration name="event_socket.conf" description="Socket Client"> <settings> <param name="listen-ip" value="127.0.0.1"/> <param name="listen-port" value="8021"/> <param name="password" value="ClueCon"/> </settings> </configuration>
The default settings allow socket connections only from the local host. To allow connections from any host on the network, use 0.0.0.0 instead of the default 127.0.0.1:
<configuration name="event_socket.conf" description="Socket Client"> <settings> <!-- Allow socket connections from any host --> <param name="listen-ip" value="0.0.0.0"/> <param name="listen-port" value="8021"/> <param name="password" value="ClueCon"/> </settings> </configuration>
<param name="apply-inbound-acl" value="<acl_list|cidr>"/>
<param name="apply-inbound-acl" value="10.20.0.0/16"/>
Note that multiple apply-inbound-acl params will not work.
The idea is that you would write your own client, but here are some examples.
Liverpie (language independent IVR proxy) is a free little piece of software, written in Ruby, that talks to FreeSWITCH on one side, and to any web application on the other, regardless of language, platform etc. It translates FreeSWITCH mod_socket dialogue into HTTP talk (embedding various parameters in HTTP headers), so you can write your own http-speaking finite state machine and hook it to FreeSWITCH via Liverpie. Note also that Liverpie expects the response in YAML so you can save yourself the pain of providing XML if you are comfortable with Liverpie doing the translation.
Find Liverpie here: www.liverpie.com
telnet to port 8021 and enter "auth ClueCon" as password to authenticate. From here you can send any of the commands listed in this document. Note that you need to provide a double empty line after the command so it processed.
There is a Perl client in scripts/socket called fs.pl.
With the module up and loaded:
cd scripts/socket perl fs.pl <optional log level>
You can enter a few api commands like "show" or "status".
Python Client Library
In the scripts/python/freepy directory, there is a python client library based on the Twisted asynchronous socket library. An example is included.
There's also an alternative twisted protocol class for FreeSWITCH's event socket. It currently supports inbound and outbound methods, and examples are included.
PySWITCH is one more library for Python and Twisted programmers. It has extensive support for FreeSWITCH API, bgapi and Dialplan Tools.
Website based PHP example PHP Event Socket
Java Client Libraries
Java_ESL describes several options for using Java to communicate with the ESL.
- Node.js esl module (available using npm) offers both a client and a server implementation. The code is on github with documentation. Examples: Voicemail with CouchDB storage and CNAM injection (short example showing how to set a variable using an async web query).
.NET Client library
 AgbaraVOIP .NET Client
The following section aims at documenting all commands that can be sent. This section is work in progress.
Send an api command (blocking mode)
api <command> <arg>
Api commands are documented in the mod_commands section.
api originate email@example.com 1000 # connect sip:firstname.lastname@example.org to extension 1000 api sleep 5000
Send an api command (non-blocking mode) this will let you execute a job in the background and the result will be sent as an event with an indicated uuid to match the reply to the command)
bgapi <command> <arg>
The same API commands available as with the api command, however the server returns immediately and is available for processing more commands.
Example return value:
Content-Type: command/reply Reply-Text: +OK Job-UUID: c7709e9c-1517-11dc-842a-d3a3942d3d63
When the command is done executing, freeswitch fires an event with the result and you can compare that to the Job-UUID to see what the result was. In order to receive this event, you will need to subscribe to BACKGROUND_JOB events.
Enable or disable events by class or all (plain or xml or json output format)
event plain <list of events to log or all for all>
The event command are used to subscribe on events from FreeSWITCH. You may specify any number events on the same line, they should be separated with space.
The events are listed in the Event List page.
event plain ALL event plain CHANNEL_CREATE CHANNEL_DESTROY CUSTOM conference::maintenance sofia::register sofia::expire event xml ALL event json CHANNEL_ANSWER
Subsequent calls to 'event' won't override the previous event sets. Supposing, you've first registered for DTMF
event plain DTMF
then you may want to register for CHANNEL_ANSWER also, it is enough to give
event plain CHANNEL_ANSWER
and you will continue to receive DTMF along with CHANNEL_ANSWER, later one doesn't override the previous.
Special Case - 'myevents'
The 'myevents' subscription allows your inbound socket connection to behave like an outbound socket connect. It will "lock on" to the events for a particular uuid and will ignore all other events, closing the socket when the channel goes away or closing the channel when the socket disconnects and all applications have finished executing.
Once the socket connection has locked on to the events for this particular uuid it will NEVER see any events that are not related to the channel, even if subsequent event commands are sent. If you need to monitor a specific channel/uuid and you need watch for other events as well then it is best to use a filter.
You can also set the event format (plain, xml or json):
myevents plain <uuid> myevents json <uuid> myevents xml <uuid>
The default format is plain.
The divert_events switch is available to allow events that an embedded script would expect to get in the inputcallback to be diverted to the event socket.
divert_events on divert_events off
An inputcallback can be registered in an embedded script using setInputCallback(). Setting divert_events to "on" can be used for chat messages like gtalk channel, ASR events and others.
Specify event types to listen for. Note, this is not a filter out but rather a "filter in," that is, when a filter is applied only the filtered values are received. Multiple filters on a socket connection are allowed.
filter <EventHeader> <ValueToFilter>
The following example will subscribe to all events and then create two filters, one to listen for HEARTBEATS and one to listen for CHANNEL_EXECUTE events.
events plain all Content-Type: command/reply Reply-Text: +OK event listener enabled plain filter Event-Name CHANNEL_EXECUTE Content-Type: command/reply Reply-Text: +OK filter added. [filter]=[Event-Name CHANNEL_EXECUTE] filter Event-Name HEARTBEAT Content-Type: command/reply Reply-Text: +OK filter added. [Event-Name]=[HEARTBEAT]
Now only HEARTBEAT and CHANNEL_EXECUTE events will be received. You can filter on any of the event headers. To filter for a specific channel you will need to use the uuid:
filter Unique-ID d29a070f-40ff-43d8-8b9d-d369b2389dfe
This method is an alternative to the myevents event type. If you need only the events for a specific channel then use myevents, otherwise use a combination of filters to narrow down the events you wish to receive on the socket.
Specify the events which you want to revoke the filter. filter delete can be used when some filters are applied wrongly or when there is no use of the filter.
filter delete <EventHeader> <ValueToFilter>
filter delete Event-Name HEARTBEAT
Now, you will no longer receive HEARTBEAT events. You can delete any filter that is applied by this way.
filter delete Unique-ID d29a070f-40ff-43d8-8b9d-d369b2389dfe
This is to delete the filter which is applied for the given unique-id. After this, you won't receive any events for this unique-id.
filter delete Unique-ID
This deletes all the filters which are applied based on the unique-id.
Send an event into the event system (multi line input for headers)
The event generated by sendevent has the correct event type in the internal event structure, so nodes which have subscribed to this event type will get the event, but unfortunately the "Event-Name" header field is always "COMMAND". In fact, the received event is simply a clone of the original COMMAND event for "sendevent" itself.
NOTE: This apparently is a bug that is being addressed. As a work-around, you can send sendevent without specifying an event type, and include a Event-Name header with the desired event name. For example:
sendevent SOME_NAME Event-Name: CUSTOM Event-Subclass: albs::Section-Alarm Section: 33 Alarm-Type: PIR State: ACTIVE
For MWI you make the FreeSWITCH event SWITCH_EVENT_MESSAGE_WAITING with headers:
MWI-Messages-Waiting (yes/no) MWI-Message-Account <any sip url you want> MWI-Voice-Message x/y (a/b) read/unread (urgent read/urgent unread)
To have Snom phones reread their settings from the settings server you can use:
sendevent NOTIFY profile: internal event-string: check-sync;reboot=false user: 1000 host: 192.168.10.4 content-type: application/simple-message-summary
Example of sendevent with a message body, the length of the body is specified by content-length:
sendevent NOTIFY profile: internal content-type: application/simple-message-summary event-string: check-sync user: 1005 host: 192.168.10.4 content-length: 2 OK
Another example with a notify:
sendevent NOTIFY profile: internal content-type: application/simple-message-summary event-string: check-sync user: 1005 host: 22.214.171.124 content-length: 2 OK
Results in a packet like this:
NOTIFY sip:email@example.com SIP/2.0 Via: SIP/2.0/UDP 126.96.36.199;rport;branch=z9hG4bKpH2DtBDcDtg0N Max-Forwards: 70 From: <sip:firstname.lastname@example.org>;tag=Dy3c6Q1y15v5S To: <sip:email@example.com> Call-ID: 129d1446-0063-122c-15aa-001a923f6a0f CSeq: 104766492 NOTIFY Contact: <sip:firstname.lastname@example.org:5060> User-Agent: FreeSWITCH-mod_sofia/1.0.trunk-9578:9586 Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, PRACK, MESSAGE, SUBSCRIBE, NOTIFY, REFER, UPDATE, REGISTER, INFO, PUBLISH Supported: 100rel, timer, precondition, path, replaces Event: check-sync Allow-Events: talk, presence, dialog, call-info, sla, include-session-description, presence.winfo, message-summary Subscription-State: terminated;timeout Content-Type: application/simple-message-summary Content-Length: 2 OK
Example of send event with a MESSAGE and a message body, the length of the body is specified by content-length:
sendevent SEND_MESSAGE profile: internal content-length: 2 content-type: text/plain user: 1005 host: 188.8.131.52 OK
Results in a packet like this:
MESSAGE sip:email@example.com SIP/2.0 Via: SIP/2.0/UDP 184.108.40.206;rport;branch=z9hG4bK0apcKrtycp64p Max-Forwards: 70 From: <sip:firstname.lastname@example.org>;tag=4c0Dp49yUNmXH To: <sip:email@example.com> Call-ID: 29916da5-0062-122c-15aa-001a923f6a0f CSeq: 104766296 MESSAGE Contact: <sip:firstname.lastname@example.org:5060> User-Agent: FreeSWITCH-mod_sofia/1.0.trunk-9578:9586 Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, PRACK, MESSAGE, SUBSCRIBE, NOTIFY, REFER, UPDATE, REGISTER, INFO, PUBLISH Supported: 100rel, timer, precondition, path, replaces Content-Type: text/plain Content-Length: 2 OK
To display a text message on a Snom 370 or Snom 820 the message must be of type "text/plain".
Authentication: Some phones require authentication for NOTIFY requests. FS can respond to a digest challenge if reverse authentication credentials are supplied for the user. See: XML_User_Directory_Guide#reverse_authentication
I've not found any documentation of any additional event headers, hopefully someone else with add that information. The events themselves can be found here: Event List
Send a message to the call of given uuid (call-command execute or hangup), see examples below.
Send message are used to send messages that controls the behavior of FreeSWITCH. You need to provide a uid (the unique id for each call/session).
originate a call directly to park by making an ext the ext part of the originate command &park()
IMPORTANT! All SendMsg commands must be followed by 2 returns.
Since messaging format is similar to RFC2882. If you are using any libraries that following line wrapping recommendation of RFC 2822 make sure that you disable line wrapping as FreeSWITCH will ignore wrapped line.
SendMsg <uuid> call-command: execute execute-app-name: playback execute-app-arg: /tmp/test.wav
The first command is Call-Command, it can do one of the following subcommands:
Execute are used to execute applications, check the Dialplan XML section for more information about all commands.
The format should be:
SendMsg <uuid> call-command: execute execute-app-name: <one of the applications> execute-app-arg: <application data> loops: <number of times to invoke the command, default: 1>
This alternate format can be used for app args that are truncated by the module's 2048 octet limit:
SendMsg <uuid> call-command: execute execute-app-name: <one of the applications> loops: <number of times to invoke the command, default: 1> content-type: text/plain content-length: <content length> <application data>
Hangup the call.
SendMsg <uuid> call-command: hangup hangup-cause: <one of the causes listed below>
Unicast is used to hook up spandsp for in and outbound faxing over a socket.
Additional information from Brian:
that is a nice way someone writing a script/app that uses the socket interface can get at the media it's good because then spandsp isn't living inside of FreeSWITCH it can run on a box sitting next to it scales better
SendMsg <uuid> call-command: unicast local-ip: <default is 127.0.0.1> local-port: <default is 8025> remote-ip: <default is 127.0.0.1> remote-port: <default is 8026> transport: <either "tcp" or "udp", without the quotes> and optionally flags: native - don't transcode audio to/from L16
SendMsg <uuid> call-command: nomedia nomedia-uuid: <noinfo>
Close the socket connection.
Enable log output. Levels same as the console.conf values
Disable log output previously enabled by the log command
nixevent <event types | ALL | CUSTOM custom event sub-class>
Command to allow 'events all' followed by 'nixevent <some_event>' to do all but 1 type scenario.
Disable all events that were previously enabled with event.
Sample Event Socket Applications
- Email2callback - Email to callback application with Python and freepy.