<?xml version="1.0" encoding='ISO-8859-1'?>
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [

<!-- Include general documentation entities -->
<!ENTITY % docentities SYSTEM "../../../../doc/docbook/entities.xml">
%docentities;

]>
<!-- Module User's Guide -->

<chapter xmlns:xi="http://www.w3.org/2001/XInclude">
	<title>&adminguide;</title>
	<section>
		<title>Overview</title>
		<para>The Kazoo is a general purpose AMQP connector (tested with rabbitmq-server). It
			exposes publish/consume capabilities into Kamailio.</para>
		<para>From a high-level, the purpose of the module might be for things like: <itemizedlist>
				<listitem>
					<para>Integrate to an AMQP application to make real-time routing decisions
						(instead of using, say, a SQL database)</para>
				</listitem>
				<listitem>
					<para>Provide a real-time integration into your program, instead of your
						database, so you can overlay additional logic in your preferred language
						while also utilizing a message bus</para>
				</listitem>
				<listitem>
					<para>Utilize messaging to have a distributed messaging layer, such that
						machines processing requests/responses/events can go up/down or share the
						workload and your Kamailio node will still be happy</para>
				</listitem>
			</itemizedlist>
		</para>


		<para>supported operations are: <itemizedlist>
				<listitem>
					<para>publish json payloads to rabbitmq</para>
				</listitem>
				<listitem>
					<para>publish json payloads to rabbitmq and wait for correlated response
						message</para>
				</listitem>
				<listitem>
					<para>subscribe to an exchange with a routing key</para>
				</listitem>
			</itemizedlist>
		</para>
		<para>The Kazoo module also has support to publish updates to presence module thru the
			kazoo_pua_publish function</para>

	</section>
	<section>
		<title>How it works</title>
		<para>The module works with a main forked process that does the communication with rabbitmq
			for issuing publishes, waiting for replies and consuming messages. When it consumes a
			message it defers the process to a worker process so that it doesn't block this main
			process.</para>
		<section>
			<title>event routes</title>
			<para>The worker process issues an event-route where we can act on the received
				payload. The name of the event-route is composed by values extracted from the
				payload.</para>
			<para>Kazoo module will try to execute the event route from most significant to less
				significant. define the event route like
				event_route[kazoo:consumer-event[-payload_key_value[-payload_subkey_value]]]</para>
			<para>we can set the key/subkey pair on a subscription base. check the payload on
				subscribe.</para>
			<example>
				<title>define the event route</title>
				<programlisting format="linespecific">
...
modparam("kazoo", "amqp_consumer_event_key", "Event-Category")
modparam("kazoo", "amqp_consumer_event_subkey", "Event-Name")
...

event_route[kazoo:consumer-event-presence-update]
{
# presence is the value extracted from Event-Category field in json payload
# update is the value extracted from Event-Name field in json payload
xlog("L_INFO", "received $(kzE{kz.json,Event-Package}) update for $(kzE{kz.json,From})");
...
}

event_route[kazoo:consumer-event-presence]
{
# presence is the value extracted from Event-Category field in json payload
xlog("L_INFO", "received $(kzE{kz.json,Event-Package}) update for $(kzE{kz.json,From})");
...
}

event_route[kazoo:consumer-event-event-category-event-name]
{
# event-category is the name of the amqp_consumer_event_key parameter
# event-name is the name of the amqp_consumer_event_subkey parameter
# this event route is executed if we can't find the previous
...
}

event_route[kazoo:consumer-event-event-category]
{
# event-category is the name of the amqp_consumer_event_key parameter
# this event route is executed if we can't find the previous
...
}

event_route[kazoo:consumer-event]
{
# this event route is executed if we can't find the previous
}

</programlisting>
			</example>
		</section>
		<section>
			<title>acknowledge messages</title>
			<para>Consumed messages have the option of being acknowledge in two ways: <itemizedlist>
					<listitem>
						<para>immediately when received</para>
					</listitem>
					<listitem>
						<para>after processing by the worker</para>
					</listitem>
				</itemizedlist>
			</para>

		</section>
	</section>

	<section>
		<title>Dependencies</title>
		<section>
			<title>&kamailio; Modules</title>
			<para>The following modules must be loaded before this module: <itemizedlist>
					<listitem>
						<para>
							<emphasis>none</emphasis>.</para>
					</listitem>
				</itemizedlist>
			</para>
		</section>
		<section>
			<title>External Libraries or Applications</title>
			<itemizedlist>
				<listitem>
					<para>
						<emphasis>librabbitmq</emphasis>.</para>
				</listitem>
				<listitem>
					<para>
						<emphasis>libjson</emphasis>.</para>
				</listitem>
				<listitem>
					<para>
						<emphasis>libuuid</emphasis>.</para>
				</listitem>
			</itemizedlist>

		</section>
	</section>


	<section>
		<title>Parameters</title>
		<section>
			<title>amqp related</title>
			<section>
				<title><varname>node_hostname</varname>(str)</title>
				<para>The name of this host to register in rabbitmq.</para>
				<para>
					<emphasis>Default value is NULL. you must set this parameter value for the
						module to work</emphasis>
				</para>
				<example>
					<title>Set <varname>node_hostname</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "node_hostname", "sipproxy.mydomain.com")
...
</programlisting>
				</example>
			</section>
			<section>
				<title><varname>amqp_consumer_processes</varname>(int)</title>
				<para>The number of worker processes to handle messages consumption.</para>
				<para>
					<emphasis>Default value is 4.</emphasis>
				</para>
				<example>
					<title>Set <varname>amqp_consumer_processes</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_consumer_processes", 10)
...
</programlisting>
				</example>
			</section>

			<section>
				<title><varname>amqp_consumer_event_key</varname>(str)</title>
				<para>The default name of the field in json payload to compose the event name 1st
					part</para>
				<para>
					<emphasis>Default value is <quote>Event-Category</quote>.</emphasis>
				</para>
				<example>
					<title>Set <varname>amqp_consumer_event_key</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_consumer_event_key", "My-JSON-Field-Name")
...
</programlisting>
				</example>
			</section>

			<section>
				<title><varname>amqp_consumer_event_subkey</varname>(str)</title>
				<para>The default name of the field in json payload to compose the event name 2nd
					part</para>
				<para>
					<emphasis>Default value is <quote>Event-Name</quote>.</emphasis>
				</para>
				<example>
					<title>Set <varname>amqp_consumer_event_subkey</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_consumer_event_subkey", "My-JSON-SubField-Name")
...
</programlisting>
				</example>
			</section>

			<section>
				<title><varname>amqp_max_channels</varname>(str)</title>
				<para>The number of pre allocated channels for the connection.</para>
				<para>
					<emphasis>Default value is 50.</emphasis>
				</para>
				<example>
					<title>Set <varname>amqp_max_channels</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_max_channels", 100)
...
</programlisting>
				</example>
			</section>

			<section>
				<title><varname>amqp_connection</varname>(str)</title>
				<para>The connection url to rabbitmq. can be set multiple times for failover.</para>
				<example>
					<title>Set <varname>amqp_connection</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_connection", "amqp://guest:guest@localhost:5672")
modparam("kazoo", "amqp_connection", "kazoo://guest:guest@otherhost:5672")
...
</programlisting>
				</example>
			</section>

			<section>
				<title><varname>event_callback</varname>(str)</title>
				<para>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.</para>
				<para>The function receives a string parameter with the name of the event, the
					values can be: 'kazoo:mod-init', 'kazoo:consumer-event'.</para>

				<example>
					<title>Set <varname>event_callback</varname> parameter</title>
					<programlisting format="linespecific">
    ...
    modparam("kazoo", "event_callback", "ksr_kazoo_event")
    ...
    </programlisting>
				</example>
			</section>






		</section>

		<section>
			<title>execution control</title>
			<para>execution control of main loop can be controlled by changing the parameter values
				in this section.</para>
			<para>The main loop has 3 sub-loops were it listen for actions to execute with a
				timeout. These group of parameters allow to set the maximum number of times the
				sub-loop is executed if it doesn't timeout.</para>
			<para>On busy systems, we may have a condition where a sub-loop never times out because
				it always has data to process. The purpose of these parameters is to set a maximum
				number of times it executes before it handles control to the next sub-loop.</para>
			<programlisting format="linespecific">
...
while(true) // main  loop
while(ACK or timeout)  // acknowledge from worker process
while(SEND or timeout) // anything to send ?
while(CONSUME or timeout) // any data on consumed exchanges ?
...
</programlisting>

			<section>
				<title><varname>amqp_consumer_loop_count</varname>(int)</title>
				<para>The consumer loop count.</para>
				<para>
					<emphasis>Default value is 10.</emphasis>
				</para>
				<example>
					<title>Set <varname>amqp_consumer_loop_count</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_consumer_loop_count", 3)
...
</programlisting>
				</example>
			</section>

			<section>
				<title><varname>amqp_internal_loop_count</varname>(int)</title>
				<para>The internal listen for commands loop count.</para>
				<para>
					<emphasis>Default value is 5.</emphasis>
				</para>
				<example>
					<title>Set <varname>amqp_internal_loop_count</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_internal_loop_count", 1)
...
</programlisting>
				</example>
			</section>

			<section>
				<title><varname>amqp_consumer_ack_loop_count</varname>(int)</title>
				<para>The work ack loop count.</para>
				<para>
					<emphasis>Default value is 20.</emphasis>
				</para>
				<example>
					<title>Set <varname>amqp_consumer_ack_loop_count</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_consumer_ack_loop_count", 5)
...
</programlisting>
				</example>
			</section>
			<section>
				<title><varname>consume_messages_on_reconnect</varname>(int)</title>
				<para>This parameter indicates if the module ignores the loop counters on reconnect
					and consumes all the pending messages ready to be consumed.</para>
				<para>
					<emphasis>Default value is 1.</emphasis>
				</para>
				<example>
					<title>Set <varname>consume_messages_on_reconnect</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "consume_messages_on_reconnect", 0)
...
</programlisting>
				</example>
			</section>
			<section>
				<title><varname>single_consumer_on_reconnect</varname>(int)</title>
				<para>When the main loop receives a message from rabbitmq it will defer the
					execution to a worker in a round-robin manner. This parameter allows to use the
					same worker when kazoo reconnects to rabbitmq.</para>
				<para>
					<emphasis>Default value is 1.</emphasis>
				</para>
				<example>
					<title>Set <varname>single_consumer_on_reconnect</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "single_consumer_on_reconnect", 0)
...
</programlisting>
				</example>
			</section>


		</section>

		<section>
			<title>timers</title>
			<para>each functional parameter related to timers come with 2 reflected parameters.
				name_sec and name_micro</para>
			<section>
				<title><varname>amqp_consumer_ack_timeout</varname>(str)</title>
				<para>Timeout when checking for acknowledge from workers.</para>
				<para>
					<emphasis>Default value is 100000 micro.</emphasis>
				</para>
				<example>
					<title>Set <varname>amqp_consumer_ack_timeout</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_consumer_ack_timeout_sec", 1)
modparam("kazoo", "amqp_consumer_ack_timeout_micro", 200000)
...
</programlisting>
				</example>
			</section>

			<section>
				<title><varname>amqp_interprocess_timeout</varname>(str)</title>
				<para>Timeout when checking for commands (publish/query) for sending to rabbitmq.</para>
				<para>
					<emphasis>Default value is 100000 micro.</emphasis>
				</para>
				<example>
					<title>Set <varname>amqp_interprocess_timeout</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_interprocess_timeout_sec", 1)
modparam("kazoo", "amqp_interprocess_timeout_micro", 200000)
...
</programlisting>
				</example>
			</section>

			<section>
				<title><varname>amqp_waitframe_timeout</varname>(str)</title>
				<para>Timeout when checking for messages from rabbitmq.</para>
				<para>
					<emphasis>Default value is 100000 micro.</emphasis>
				</para>
				<example>
					<title>Set <varname>amqp_waitframe_timeout</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_waitframe_timeout_sec", 1)
modparam("kazoo", "amqp_waitframe_timeout_micro", 200000)
...
</programlisting>
				</example>
			</section>

			<section>
				<title><varname>amqp_query_timeout</varname>(str)</title>
				<para>Timeout when checking for reply messages from rabbitmq for kazoo_query
					commands.</para>
				<para>
					<emphasis>Default value is 2 sec.</emphasis>
				</para>
				<example>
					<title>Set <varname>amqp_query_timeout</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_query_timeout_sec", 1)
modparam("kazoo", "amqp_query_timeout_micro", 200000)
...
</programlisting>
				</example>
			</section>

			<section>
				<title><varname>amqp_query_timeout_avp</varname>(str)</title>
				<para>avp holding the value in seconds for Timeout when checking for reply messages
					from rabbitmq for kazoo_query commands.</para>
				<para>
					<emphasis>Default value is NULL (no value).</emphasis>
				</para>
				<example>
					<title>>Set <varname>amqp_query_timeout_avp</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "amqp_query_timeout_avp", "$var(kz_timeout)")

route[SOME_ROUTE]
{
    $var(kz_timeout) = 12;
    kazoo_query(exchange, routingkey, payload);
}

...
</programlisting>
				</example>
			</section>


		</section>

		<section>
			<title>presence related</title>
			<section>
				<title><varname>db_url</varname>(str)</title>
				<para>The database for the presentity table.</para>
				<para>If set, the kazoo_ppua_publish function will update the presentity status in
					the database.</para>
				<para>
					<emphasis>Default value is <quote>NULL</quote>.</emphasis>
				</para>
				<example>
					<title>Set <varname>db_url</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "db_url", "&defaultdb;")
...
</programlisting>
				</example>
			</section>

			<section>
				<title><varname>presentity_table</varname>(str)</title>
				<para>The name of the presentity table in the database.</para>
				<para>
					<emphasis>Default value is <quote>presentity</quote>.</emphasis>
				</para>
				<example>
					<title>Set <varname>presentity_table</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "presentity_table", "my_presentity_table")
...
</programlisting>
				</example>
			</section>

			<section id="kazoo.p.pua_mode">
				<title><varname>pua_mode</varname>(int)</title>
				<para>Control if the module has to connect to presence database tables. Set it to 0
					to not connect to database.</para>
				<para>
					<emphasis>Default value is <quote>1</quote>.</emphasis>
				</para>
				<example>
					<title>Set <varname>pua_mode</varname> parameter</title>
					<programlisting format="linespecific">
...
modparam("kazoo", "pua_mode", 0)
...
</programlisting>
				</example>
			</section>

		</section>





	</section>
	<section>
		<title>Functions</title>
		<section>
			<title>amqp related</title>

			<section>
				<title>
					<function moreinfo="none">kazoo_publish(exchange, routing_key,
						json_payload [, amqp_headers])</function>
				</title>
				<para>The function publishes a json payload to rabbitmq. The routing_key parameter
					should be encoded. Optional AMQP-Headers are specified in the format key1=value1;key2=value2</para>
				<para>This function can be used from ANY ROUTE.</para>

				<example>
					<title><function>kazoo_publish</function> usage</title>
					<programlisting format="linespecific">
...
$var(amqp_payload_request) = $_s({"Event-Category" : "directory", "Event-Name" : "reg_success", "Contact" : "$(ct{s.escape.common}{s.replace,\','}{s.replace,$$,})", "Call-ID" : "$ci", "Realm" : "$fd", "Username" : "$fU", "From-User" : "$fU", "From-Host" : "$fd", "To-User" : "$tU", "To-Host" : "$td", "User-Agent" : "$(ua{s.escape.common}{s.replace,\','}{s.replace,$$,})" });
$var(amqp_routing_key) = "registration.success." + $(fd{kz.encode}) + "." + $fU;
kazoo_publish("callmgr", $var(amqp_routing_key), $var(amqp_payload_request));
...
</programlisting>
				</example>
			</section>

			<section>
				<title>
					<function moreinfo="none">kazoo_query(exchange, routing_key, json_payload [,
						target_var] [, amqp_headers])</function>
				</title>
				<para>The function publishes a json payload to rabbitmq, waits for a correlated
					messageand puts the result in target_var. The routing_key parameter should be
					encoded. target_var is optional as the function also puts the result in
					pseudo-variable $kzR. Optional AMQP-Headers are specified in the format key1=value1;key2=value2</para>
				<para>This function can be used from ANY ROUTE.</para>

				<example>
					<title><function>kazoo_query</function> usage</title>
					<programlisting format="linespecific">
...
$var(amqp_payload_request) = "{'Event-Category' : 'call_event' , 'Event-Name' : 'query_user_channels_req', 'Realm' : '" + $fd + "', 'Username' : '" + $fU + "', 'Active-Only' : false }";
kazoo_encode("$ci", "$var(callid_encoded)");
$var(amqp_routing_key) = "call.status_req.$var(callid_encoded)";
if(kazoo_query("callevt", $var(amqp_routing_key), $var(amqp_payload_request), "$var(amqp_result)")) {
   kazoo_json("$var(amqp_result)", "Channels[0].switch_url", "$du");
   if($du != $null) {
       xlog("L_INFO", "$ci|log|user channels found redirecting call to $du");
       return;
   }
}
...
</programlisting>
				</example>
			</section>

			<section>
				<title>
					<function moreinfo="none">kazoo_subscribe(exchange, exchange_type, queue,
						routing_key)</function>
				</title>
				<para>The function subscribes to exchange/type on queue with routing_key. The
					routing_key parameter should be encoded.</para>
				<para>This function must be called from event_route[kazoo:mod-init].</para>

				<example>
					<title><function>kazoo_subscribe</function> usage</title>
					<programlisting format="linespecific">
...
event_route[kazoo:mod-init]
{
   kazoo_subscribe("dialoginfo", "direct", "BLF-QUEUE-MY_HOSTNAME", "BLF-MY_HOSTNAME");
}

event_route[kazoo:consumer-event]
{
    xlog("L_INFO","Received json payload : $kzE");
}
...
</programlisting>
				</example>
			</section>

			<section>
				<title>
					<function moreinfo="none">kazoo_subscribe(json_description)</function>
				</title>
				<para>The function takes additional parameters to the subscribe function.</para>
				<para>
					<itemizedlist>
						<title>json payload fields description</title>
						<listitem>
							<para>exchange : str, required</para>
						</listitem>
						<listitem>
							<para>type : str, required</para>
						</listitem>
						<listitem>
							<para>queue : str, required</para>
						</listitem>
						<listitem>
							<para>routing : str, required</para>
						</listitem>
						<listitem>
							<para>auto_delete : int, default 1</para>
						</listitem>
						<listitem>
							<para>durable : int, default 0</para>
						</listitem>
						<listitem>
							<para>no_ack : int, default 1</para>
						</listitem>
						<listitem>
							<para>wait_for_consumer_ack : int, default 0</para>
						</listitem>
						<listitem>
							<para>event_key : str, no default</para>
						</listitem>
						<listitem>
							<para>event_subkey : str, no default</para>
						</listitem>
					</itemizedlist>
				</para>
				<para>This function must be called from event_route[kazoo:mod-init].</para>
				<example>
					<title><function>kazoo_subscribe</function> usage</title>
					<programlisting format="linespecific">
...
event_route[kazoo:mod-init]
{
    $var(payload) = "{ 'exchange' : 'dialoginfo' , 'type' : 'direct', 'queue' : 'BLF-QUEUE-MY_HOSTNAME', 'routing' : 'BLF-MY_HOSTNAME', 'auto_delete' : 0, 'durable' : 1, 'no_ack' : 0, 'wait_for_consumer_ack' : 1 }";
    kazoo_subscribe("$var(payload)");
}

event_route[kazoo:consumer-event]
{
    xlog("L_INFO","Received json payload : $kzE");
}
...
</programlisting>
				</example>
			</section>

		</section>
		<section>
			<title>presence related</title>
			<section>
				<title>
					<function moreinfo="none">kazoo_pua_publish(json_payload)</function>
				</title>
				<para>The function build presentity state from json_payload and updates presentity
					table.</para>
				<para>This function can be used from ANY ROUTE.</para>

				<example>
					<title><function>kazoo_pua_publish</function> usage</title>
					<programlisting format="linespecific">
...
event_route[kazoo:consumer-event-presence-update]
{
    xlog("L_INFO", "received $(kzE{kz.json,Event-Package}) update for $(kzE{kz.json,From})");
    kazoo_pua_publish($kzE);
    pres_refresh_watchers("$(kzE{kz.json,From})", "$(kzE{kz.json,Event-Package})", 1);
}
...
</programlisting>
				</example>
			</section>


		</section>
		<section>
			<title>other</title>
			<section>
				<title>
					<function moreinfo="none">kazoo_encode(to_encode, target_var)</function>
				</title>
				<para>The function encodes the 1st parameter for amqp and puts the result in the
					2nd parameter.</para>
				<para>This function can be used from ANY ROUTE.</para>

				<example>
					<title><function>kazoo_encode</function> usage</title>
					<programlisting format="linespecific">
...
kazoo_encode("$ci", "$var(callid_encoded)");
$var(amqp_routing_key) = "call.status_req.$var(callid_encoded)";
...
</programlisting>
				</example>
			</section>

			<section>
				<title>
					<function moreinfo="none">kazoo_json(json_payload, field, target_var)</function>
				</title>
				<para>The function extracts the value from a json payload and puts the result in
					the 3rd parameter. It can use nested values for the query part.</para>
				<para>This function can be used from ANY ROUTE.</para>

				<example>
					<title><function>kazoo_json</function> usage</title>
					<programlisting format="linespecific">
...
kazoo_json("$var(amqp_result)", "Channels[0].switch_url", "$du");
if($du != $null) {
  xlog("L_INFO", "$ci|log|user channels found redirecting call to $du");
  return;
}
...
</programlisting>
				</example>
			</section>

		</section>
	</section>

	<section>
		<title>Exported pseudo-variables</title>
		<itemizedlist>
			<listitem>
				<para>
					<emphasis>$kzR</emphasis> Contains the payload result of kazoo_query execution.
				</para>
			</listitem>
			<listitem>
				<para>
					<emphasis>$kzE</emphasis> Contains the payload of a consumed message</para>
			</listitem>
		</itemizedlist>
	</section>

	<section>
		<title>Transformations</title>
		<para>The prefix for kazoo transformations is kz.</para>
		<itemizedlist>
			<listitem>
				<para>
					<emphasis>json</emphasis>
				</para>
				<example>
					<title><function>kz.json</function> usage</title>
					<programlisting format="linespecific">
...
#kazoo_json("$var(amqp_result)", "Channels[0].switch_url", "$du");
$du = $kzR{kz.json,Channels[0].switch_url};
if($du != $null) {
  xlog("L_INFO", "$ci|log|user channels found redirecting call to $du");
  return;
}
...
</programlisting>
				</example>

			</listitem>
			<listitem>
				<para>
					<emphasis>encode</emphasis>
				</para>
				<example>
					<title><function>kz.encode</function> usage</title>
					<programlisting format="linespecific">
...
#kazoo_encode("$ci", "$var(callid_encoded)");
#$var(amqp_routing_key) = "call.status_req.$var(callid_encoded)";
$var(amqp_routing_key) = "call.status_req." + $(ci{kz.encode})
...
</programlisting>
				</example>

			</listitem>
		</itemizedlist>
	</section>


</chapter>
