Table of Contents
List of Examples
Table of Contents
The module provides an NATS consumer for Kamailio. NATS is a real time distributed messaging platform, more details about it can be found at nats.io .
From a high-level perspective, the module may be used for:
Provide a real-time distributed messaging layer in Kamailio
Supported NATS operations are:
Subscribe to a Subject and Queue Group
The module creates invokes a consumer process for each defined `subject_queue_group`. The messages are visible in event routes matching the "subject" name.
The following libraries or applications must be installed
libuv
The nats url.
Usage: nats related.
Default value is nats://127.0.0.1:4222
Example 1.1.
Set
nats_url
parameter
...
modparam("nats", "nats_url", "nats://127.0.0.1:4222")
modparam("nats", "nats_url", "nats://user1:pass1127.0.1.2:4222") // with auth
modparam("nats", "nats_url", "nats://127.1.2.3:4222")
...
The number of worker threads for publishing messages.
Usage: nats related.
Default value is “2”.
The NATS Subject and Queue Group. Separated by ":"
Usage: nats related.
Default value is not set.
Example 1.3.
Set
subject_queue_group
parameter
...
modparam("nats", "subject_queue_group", "Kamailio-World:2020")
modparam("nats", "subject_queue_group", "Kamailio-World:2021") // this will create two processes for the Kamailio-World subject
modparam("nats", "subject_queue_group", "MyQueue1:2021")
modparam("nats", "subject_queue_group", "MyQueue2:2021")
...
Name of the KEMI function to be executed instead of the event route.
Default value is not set.
Example 1.4.
Set
event_callback
parameter
...
modparam("nats", "event_callback", "ksr_nats_event")
-- event callback function implemented in Lua
function ksr_nats_event(evname)
KSR.info("===== nats module received event: " .. evname ..
", data:" .. KSR.pv.gete('$natsData') .. "\n");
return 1;
end
...
Publishes the payload to subject, with an optional reply subject.
Example 1.5.
nats_publish
usage
...
$var(my_info) = "$ci=" + $ci + " $fU=" + $fU;
nats_publish("mysubject", "$var(my_info)"); # publish $var(my_info) to "mysubject"
# publish $var(my_info) to "mysubject" with a reply.topic topic, so a response
# can be published back from the other side, like the NATS Request-Reply mode.
nats_publish("mysubject", "$var(my_info)", "reply.topic");
...
The worker process issues an event-route where we can act on the received payload. The name of the event-route name must match the subject of the message.
Example 1.7. Define the event routes
...
modparam("nats", "subject_queue_group", "Kamailio-World:2021")
modparam("nats", "subject_queue_group", "MyQueue1:2021")
...
event_route[nats:Kamailio-World]
{
if ($(natsData{json.parse,Event-Package}) == "dialog") {
xlog("L_INFO", "received $(natsData{json.parse,Event-Package}) update for $(natsData{json.parse,From})");
pua_json_publish($natsData);
}
}
event_route[nats:MyQueue1]
{
xlog("L_INFO", "received $(natsData{json.parse,Event-Package}) update for $(natsData{json.parse,From})");
...
}