EVAPI Module

Daniel-Constantin Mierla

Edited by

Daniel-Constantin Mierla


Table of Contents

1. Admin Guide
1. Overview
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
3. Parameters
3.1. workers (int)
3.2. bind_addr (str)
3.3. netstring_format (int)
3.4. event_callback (str)
4. Functions
4.1. evapi_relay(evdata)
4.2. evapi_async_relay(evdata)
4.3. evapi_multicast(evdata, etag)
4.4. evapi_async_multicast(evdata, etag)
4.5. evapi_unicast(evdata, etag)
4.6. evapi_async_unicast(evdata, etag)
4.7. evapi_close()
4.8. evapi_set_tag(tname)
5. Event routes
5.1. evapi:connection-new
5.2. evapi:connection-closed
5.3. evapi:message-received
6. Exported pseudo-variables

List of Examples

1.1. Set workers parameter
1.2. Set bind_addr parameter
1.3. Set netstring_format parameter
1.4. Set event_callback parameter
1.5. evapi_relay usage
1.6. TCP message
1.7. evapi_async_relay usage
1.8. evapi_multicast usage
1.9. evapi_async_multicast usage
1.10. evapi_unicast usage
1.11. evapi_async_unicast usage
1.12. evapi_close usage
1.13. evapi_set_tag usage

Chapter 1. Admin Guide

1. Overview

The EVAPI module can be used to create an event message flow from Kamailio to any application that can connect to a TCP socket. The remote application can also issue messages received by Kamailio.

There is no protocol definition, it is all up to the author of the routing script. Events can be generated for any event in Kamailio. For 3rd party transaction control, a transaction can be automatically suspended when sending the event, to be resumed at a later point, maybe triggered by an incoming message on the event socket.

2. Dependencies

2.1. Kamailio Modules

The following modules must be loaded before this module:

  • tm - (optional) needed only by evapi_async_relay()

2.2. External Libraries or Applications

The following libraries or applications must be installed before running Kamailio with this module loaded:

3. Parameters

3.1. workers (int)

Number of worker processes to be started to handle incoming messages from remote applications.

Default value is 1.

Example 1.1. Set workers parameter

...
modparam("evapi", "workers", 2)
...

3.2. bind_addr (str)

Local IP and port to listen on for incoming TCP connections.

Default value is "127.0.0.1:8448".

Example 1.2. Set bind_addr parameter

...
modparam("evapi", "bind_addr", "1.2.3.4:8228")
...

3.3. netstring_format (int)

Control if messages on the socket (to and from clients) are encapsulated in netstring format.

Default value is 1 (netstring format).

Example 1.3. Set netstring_format parameter

...
modparam("evapi", "netstring_format", 0)
...

3.4. event_callback (str)

The name of the function in the kemi configuration file (embedded scripting language such as Lua, Python, ...) to be executed instead of event_route[...] blocks.

The function receives a string parameter with the name of the event, the values are: 'evapi:connection-new', 'evapi:connection-closed', 'evapi:message-received'.

Default value is 'empty' (no function is executed for events).

Example 1.4. Set event_callback parameter

...
modparam("evapi", "event_callback", "ksr_evapi_event")
...
-- event callback function implemented in Lua
function ksr_evapi_event(evname)
	KSR.info("===== evapi module triggered event: " .. evname .. "\n");
	return 1;
end
...

4. Functions

4.1.  evapi_relay(evdata)

Relay the event data given as parameter to connected applications.

The format on the network is netstring with evdata payload if netstring_format parameter is set to 1 or bare evdata if netstring_format parameter is set to 0.

The function is passing the task to evapi dispatcher process, therefore the SIP worker process is not blocked. Also, it doesn't wait for any response, therefore the processing of the configuration continues very fast when executing evapi_relay().

This function can be used from ANY_ROUTE.

Example 1.5. evapi_relay usage

...
evapi_relay("{ \"event\": \"test\",\n \"data\": { \"fU\": \"$fU\" }\n}");
...

The above exaple will send the following message over tcp:

Example 1.6. TCP message

...
47:{
 "event": "test",
 "data": { "fU": "test" }
},
...

4.2.  evapi_async_relay(evdata)

Relay the event data given as parameter to connected applications. Before evaluating the parameter, the request processing is suspended using tm module (using the t_suspend()/t_continue() framework). The routing of the SIP request can be continued once event_route[evapi:message-received] is triggered. After evapi_async_relay() returns true, no relaying should happen in request_route(), it should be followed by exit;.

The format on the network is netstring with evdata payload if netstring_format parameter is set to 1 or bare evdata if netstring_format parameter is set to 0.

This function can be used from REQUEST_ROUTE.

Example 1.7. evapi_async_relay usage

...
evapi_async_relay("{ \"event\": \"suspend\",\n \"data\":"
        " { \"index\": \"$T(id_index)\", \"label\": \"$T(id_label)\" }\n}");
...

4.3.  evapi_multicast(evdata, etag)

Relay the event data given as parameter to connections that match the tag provided by etag value. The etag can be a variable. For more see evapi_relay() and evapi_set_tag().

Example 1.8. evapi_multicast usage

...
evapi_multicast("{ \"event\": \"test\",\n \"data\": { \"fU\": \"$fU\" }\n}", "tagx");
...

4.4.  evapi_async_multicast(evdata, etag)

Async relay the event data given as parameter to connections that match the tag provided by etag value. The etag can be a variable. For more see evapi_async_relay() and evapi_set_tag().

Example 1.9. evapi_async_multicast usage

...
evapi_async_multicast("{ \"event\": \"suspend\",\n \"data\":"
    " { \"index\": \"$T(id_index)\", \"label\": \"$T(id_label)\" }\n}", "tagx");
...

4.5.  evapi_unicast(evdata, etag)

Relay the event data given as parameter to the first connection that match the tag provided by etag value. The etag can be a variable. For more see evapi_relay() and evapi_set_tag().

Example 1.10. evapi_unicast usage

...
evapi_unicast("{ \"event\": \"test\",\n \"data\": { \"fU\": \"$fU\" }\n}", "tagx");
...

4.6.  evapi_async_unicast(evdata, etag)

Async relay the event data given as parameter to the first connection that match the tag provided by etag value. The etag can be a variable. For more see evapi_async_relay() and evapi_set_tag().

Example 1.11. evapi_async_unicast usage

...
evapi_async_unicast("{ \"event\": \"suspend\",\n \"data\":"
    " { \"index\": \"$T(id_index)\", \"label\": \"$T(id_label)\" }\n}", "tagx");
...

4.7.  evapi_close()

Close evapi current client connection.

This function can be used from ANY_ROUTE.

Example 1.12. evapi_close usage

...
event_route[evapi:connection-new] {
  if($evapi(srcaddr)!="127.0.0.1") {
    evapi_close();
    exit;
  }
}
...

4.8.  evapi_set_tag(tname)

Set tag name for current client connection. The parameters has to be a string up to 64 characters. It can also be a variable holding such string.

This function can be used from ANY_ROUTE.

Example 1.13. evapi_set_tag usage

...
event_route[evapi:connection-new] {
  if($evapi(srcaddr)=="127.0.0.1") {
    evapi_set_tag("local");
    exit;
  }
}
...

5. Event routes

5.1.  evapi:connection-new

If defined, the module calls event_route[evapi:connection-new] when a new client is connected.

...
event_route[evapi:connection-new] {
    xlog("new connection from $evapi(srcaddr):$evapi(srcport)\n");
}
...

5.2.  evapi:connection-closed

If defined, the module calls event_route[evapi:connection-closed] when a client connection is closed.

...
event_route[evapi:connection-closed] {
    xlog("connection closed by $evapi(srcaddr):$evapi(srcport)\n");
}
...

5.3.  evapi:message-received

If defined, the module calls event_route[evapi:message-received] when a message is received from a client.

...
event_route[evapi:message-received] {
    xlog("received [$evapi(msg)] from $evapi(srcaddr):$evapi(srcport)\n");
}
...

6. Exported pseudo-variables

  • $evapi(srcaddr) - source ip

  • $evapi(srcport) - source port

  • $evapi(msg) - received event message

  • $evapi(conidx) - internal connection index

Exported pseudo-variables are documented at https://www.kamailio.org/wiki/.