<?xml version="1.0" encoding='ISO-8859-1'?>
<!DOCTYPE book 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>

	<title>&adminguide;</title>

	<section>
	<title>Overview</title>
	<para>
		This module provides a connector to interact with REDIS NoSQL Database
		from configuration file. You can read more about REDIS at
		http://redis.io.
	</para>
	<para>
		It can connect to many REDIS servers and store the results in different
		containers.
	</para>
	</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>
		<para>
		The following libraries or applications must be installed before running
		&kamailio; with this module loaded:
			<itemizedlist>
			<listitem>
			<para>
				<emphasis>hiredis</emphasis> - available at
				https://github.com/antirez/hiredis .
			</para>
			</listitem>
			</itemizedlist>
		</para>
	</section>
	</section>
	<section>
	<title>Parameters</title>
	<section id="ndb_redis.p.server">
		<title><varname>server</varname> (str)</title>
		<para>
			Specify the details to connect to REDIS server. It takes a list of attribute=value
			separated by semicolon, the attributes can be name, unix, addr, port, db and pass. Name
			is a generic identifier to be used with module functions. unix is the path to the unix
			domain socket provided by redis server. addr and port are the IP address and the port to
			connect to REDIS server. pass is the server password. unix and (addr, port) are mutually
			exclusive.  If both appear in same server settings unix domain socket is configured.  db
			is the DB number to use (defaults to 0 if not specified).
		</para>
		<para>
			You can set this parameter many times, in case you want to connect to
			many REDIS servers, just give different attributes and use the specific
			server name when querying the REDIS instance.
		</para>
		<para>
		<emphasis>
			Default value is NULL.
		</emphasis>
		</para>
		<example>
			<title>Set <varname>server</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("ndb_redis", "server", "name=srvN;addr=127.0.0.1;port=6379;db=1")
modparam("ndb_redis", "server", "name=srvX;addr=127.0.0.2;port=6379;db=4;pass=mypassword")

# Unix domain socket
modparam("ndb_redis", "server", "name=srvY;unix=/tmp/redis.sock;db=3")

# sentinel (for a redis slave)
modparam("ndb_redis", "server", "name=srvZ;sentinel_group=group_name;sentinel_master=0;sentinel=1.2.3.4:26379;sentinel=1.2.3.5:26379")

# sentinel (for a redis master)
modparam("ndb_redis", "server", "name=srvZ;sentinel_group=group_name;sentinel_master=1;sentinel=1.2.3.4:26379;sentinel=1.2.3.5:26379")

...
</programlisting>
		</example>
	</section>
	<section id="ndb_redis.p.init_without_redis">
		<title><varname>init_without_redis</varname> (integer)</title>
		<para>
			If set to 1, the module will correctly initialize even if redis is not available at start up.
		</para>
		<para>
		<emphasis>
			Default value is <quote>0</quote>.
		</emphasis>
		</para>
		<example>
			<title>Set <varname>init_without_redis</varname> parameter</title>
			<programlisting format="linespecific">
...
modparam("ndb_redis", "init_without_redis", 1)
...
			</programlisting>
		</example>
	</section>
	<section id="ndb_redis.p.connect_timeout">
		<title><varname>connect_timeout</varname> (int)</title>
		<para>
			The timeout when connecting to the redis server
		</para>
		<para>
		<emphasis>
			Default value is 1000 ms.
		</emphasis>
		</para>
		<example>
			<title>Set <varname>connect_timeout</varname> parameter</title>
			<programlisting format="linespecific">
...
modparam("ndb_redis", "connect_timeout", 500)
...
			</programlisting>
		</example>
	</section>
	<section id="ndb_redis.p.cmd_timeout">
		<title><varname>cmd_timeout</varname> (int)</title>
		<para>
			The timeout for each query to the redis server. If the redis server does
			not reply within the timeout value, the command will fail and kamailio will
			continue executing the cfg file.
		</para>
		<para>
		<emphasis>
			Default value is 1000 ms.
		</emphasis>
		</para>
		<example>
			<title>Set <varname>cmd_timeout</varname> parameter</title>
			<programlisting format="linespecific">
...
modparam("ndb_redis", "cmd_timeout", 500)
...
			</programlisting>
		</example>
	</section>
	<section id="ndb_redis.p.cluster">
		<title><varname>cluster</varname> (integer)</title>
		<para>
			If set to 1, the module will connect to servers indicated in the "MOVED" reply.
		</para>
		<para>
			The module needs to know all existing REDIS-Nodes at startup.
			The nodes are searched by the name "ip:port", e.g. if REDIS
			replies with "MOVED 127.0.0.1:4711", ndb_redis needs to know
			the databases "127.0.0.1:4711".
		</para>
		<para>
		<emphasis>
			Default value is <quote>0</quote> (disabled).
		</emphasis>
		</para>
		<example>
			<title>Set <varname>cluster</varname> parameter</title>
			<programlisting format="linespecific">
...
modparam("ndb_redis", "server", "name=127.0.0.1:26001;addr=127.0.0.1;port=26001")
modparam("ndb_redis", "server", "name=127.0.0.1:26004;addr=127.0.0.1;port=26004")
modparam("ndb_redis", "server", "name=127.0.0.1:26008;addr=127.0.0.1;port=26008")
...
modparam("ndb_redis", "cluster", 1)
...
			</programlisting>
		</example>
	</section>
	<section id="ndb_redis.p.allowed_timeouts">
		<title><varname>allowed_timeouts</varname> (integer)</title>
		<para>
			If this is set to a non-negative value, it sets the number
			of consecutive REDIS commands that can fail before temporarily
			disabling the REDIS server. This is similar to rtpengine_disable_tout
			parameter from the rtpengine module.
		</para>
		<para>
			When communicating with a REDIS server, if redis_cmd or redis_execute
			will fail for more than <quote>allowed_timeouts</quote> consecutive
			times, the server will be temporary disabled for a number of seconds 
			configured by the <quote>disable_time</quote> parameter.
		</para>
		<para>
			Disabling a server means that further redis_cmd and redis_execute commands
			will not do anything and return a negative value <quote>-2</quote>. 
			Messages are also logged when disabling and re-enabling a server.
		</para>
		<para>
			The number of consecutive fails are counted by each Kamailio process, 
			so when disabling a server this is done just for that process, not globally.
		</para>
		<para>
		<emphasis>
			Default value is <quote>-1</quote> (disabled).
		</emphasis>
		</para>
		<example>
			<title>Set <varname>allowed_timeouts</varname> parameter</title>
			<programlisting format="linespecific">
...
modparam("ndb_redis", "allowed_timeouts", 3)
...
			</programlisting>
		</example>
	</section>
	<section id="ndb_redis.p.disable_time">
		<title><varname>disable_time</varname> (integer)</title>
		<para>
			If allowed_timeouts is set to a non negative value this determines the
			number of seconds the REDIS server will be disabled
		</para>
		<para>
		<emphasis>
			Default value is <quote>0</quote>.
		</emphasis>
		</para>
		<example>
			<title>Set <varname>disable_time</varname> parameter</title>
			<programlisting format="linespecific">
...
modparam("ndb_redis", "allowed_timeouts", 0)
modparam("ndb_redis", "disable_time", 30)
...
			</programlisting>
		</example>
	</section>
	<section id="ndb_redis.p.flush_on_reconnect">
		<title><varname>flush_on_reconnect</varname> (integer)</title>
		<para>
			If this is set to a non zero value, a "FLUSHALL" command is
			issued after reconnecting to a REDIS server, to clear the
			entire database.
		</para>
		<para>
			When a command to a REDIS server fails, a reconnection
			to that server is made, so with this parameter each failed
			command will result in a flush of the database.
		</para>
		<para>
			This is useful in scenarios when a REDIS server does not respond
			to commands, but the commands might have been issued, and the
			responses lost. If this leaves the data in the db in an uncertain
			state, a flush might fix any issues that may occur.
		</para>
		<para>
		<emphasis>
			Default value is <quote>0</quote> (disabled).
		</emphasis>
		</para>
		<example>
			<title>Set <varname>flush_on_reconnect</varname> parameter</title>
			<programlisting format="linespecific">
...
modparam("ndb_redis", "flush_on_reconnect", 1)
...
			</programlisting>
		</example>
	</section>
	<section id="ndb_redis.p.allow_dynamic_nodes">
		<title><varname>allow_dynamic_nodes</varname> (integer)</title>
		<para>
			If set to 1, the module will connect to servers indicated in the "MOVED" reply,
			even if they are not specified at startup.
		</para>
		<para>
			When <quote>cluster</quote> is enabled the module supports redirections ("MOVED") replies.
			Set <quote>allow_dynamic_nodes</quote> to 1 to avoid listing all the nodes at startup.
			You can only list one node, e.g. by using a DNS name for the cluster instead of an IP address.
			The module will add dynamically the new nodes as the MOVED replies are received.
			Only works if <quote>cluster</quote> is set to 1.
		</para>
		<para>
		<emphasis>
			Default value is <quote>0</quote> (disabled).
		</emphasis>
		</para>
		<example>
			<title>Set <varname>allow_dynamic_nodes</varname> parameter</title>
			<programlisting format="linespecific">
...
modparam("ndb_redis", "server", "name=redis_cluster;addr=127.0.0.1;port=26008")
...
modparam("ndb_redis", "cluster", 1)
modparam("ndb_redis", "allow_dynamic_nodes", 1)
...
			</programlisting>
		</example>
	</section>
	</section>

	<section>
	<title>Functions</title>
	<section id="ndb_redis.f.redis_cmd">
		<title>
		<function moreinfo="none">redis_cmd(srvname, command, ..., replyid)</function>
		</title>
		<para>
			Send a command to REDIS server identified by srvname. The reply will
			be stored in a local container identified by replyid. All the
			parameters can be strings with pseudo-variables that are evaluated
			at runtime.
		</para>
		<para>
			Minimum required arguments are srvname, command and replyid. Command argument
			can be separated into several ones using %s token. (See examples)
			Total number of arguments cannot exceed six.
		</para>
		<para>
			The reply can be accessed via pseudo-variable $redis(key). The key
			can be: type - type of the reply (as in hiredis.h); value - the value
			returned by REDIS server; info - in case of error from REDIS, it will
			contain an info message.
		</para>
		<para>
			If reply type is an array (as in hiredis.h), there are other keys
			available:
			<itemizedlist>
			<listitem>
				<para>
				size - returns number of elements in the array.
				</para>
			</listitem>
			<listitem>
				<para>
				type[n] - returns the type of the nth element in the array. type
				- returns array type.
				</para>
			</listitem>
			<listitem>
				<para>
				value[n] - returns value of the nth element. value - returns null
				for an array. You need to get each element by index.
				</para>
			</listitem>
			</itemizedlist>
		</para>
		<para>
			In case one of the members of the array is also an array (for example calling SMEMBERS
			in a MULTI/EXEC transaction), the members of the array can be accessed by adding any of
			the above keys, after a value[n] key. The first value[n] references the element in the
			first array, while the next key references an element of the referenced array.
		</para>
		<para>
			The result type can be compared with $redisd(key) variable to test
			its value. The key can be: rpl_str, rpl_arr, rpl_int, rpl_err, rpl_sts, rpl_nil.
		</para>
		<example>
		<title><function>redis_cmd</function> usage</title>
		<programlisting format="linespecific">
...
if(redis_cmd("srvN", "INCR cnt", "r")) {
    # success - the incremented value is in $redis(r=>value)
    xlog("===== $redis(r=>type) * $redis(r=>value)\n");
}

# set a value
redis_cmd("srvN", "SET foo bar", "r");

redis_cmd("srvN", "SET ruri $ru", "r");

# get a value
redis_cmd("srvN", "GET foo", "r");

# same command separated into two arguments:
redis_cmd("srvN", "GET %s", "foo", "r");

# if we have a key with spaces within it:
redis_cmd("srvN", "GET %s", "foo bar", "r");

# several values substitution:
redis_cmd("srvN", "HMGET %s %s %s", "key1", "field1", "field2", "r");


# array example
if(redis_cmd("srvN", "HMGET foo_key field1 field3", "r")) {
    xlog("array size: $redis(r=>size)\n");
    xlog("first values: $redis(r=>value[0]) , $redis(r=>value[1])\n");
}


# array as element of an array example
redis_cmd("srvN", "MULTI", "r1");
redis_cmd("srvN", "SMEMBERS foo", "r2");
if (redis_cmd("srvN", "EXEC", "r")) {
    xlog("array size: $redis(r=>value[0]=>size)\n");
    xlog("first member of the set:$redis(r=>value[0]=>value[0])\n");
    xlog("type of the second member of the set:$redis(r=>value[0]=>type[1])\n");
}
...
</programlisting>
		</example>
	</section>
	<section id="ndb_redis.f.redis_pipe_cmd">
		<title>
		<function moreinfo="none">redis_pipe_cmd(srvname, command, ..., replyid)</function>
		</title>
		<para>
			Add a command to be sent to REDIS server identified by srvname.
			All the commands will be stored in a buffer until a call to
			redis_execute is made. When calling redis_execute the stored commands
			are sent using the pipelining functionality of redis. The replies
			will be stored in local containers identified by the replyid of each
			added command. All the parameters can be strings with pseudo-variables
			that are evaluated at runtime.
		</para>
		<para>
			This command is similar in syntax with redis_cmd, the only difference
			is that it does not send the command but instead appends it to a buffer.
		</para>
		<para>
			See examples from redis_execute.
		</para>
		<para>
			Note: Pipelining feature is incompatible with the clustering feature.
			If cluster parameter is set to 1, this function will log an error and do nothing.
		</para>
	</section>
	<section id="ndb_redis.f.redis_execute">
	<title>
		<function moreinfo="none">redis_execute(srvname)</function>
	</title>
	<para>
		Sends commands to REDIS server identified by srvname. Commands are added
		with redis_pipe_cmd function, and will be stored for an existing REDIS server.
		When this function is called all the commands will be sent in a single message
		to the REDIS server.

	</para>
	<para>
		When using redis_cmd together with redis_pipe_cmd it is recommended that a call to
		redis_execute is made before calling redis_cmd in case there are pipelined commands,
		otherwise when calling redis_cmd, if pipelined messages exist, a call to redis_execute
		is made automatically and a warning message is logged.
	</para>
	<para>
		Note: Pipelining feature is incompatible with the clustering feature.
		If cluster parameter is set to 1, this function will log an error and do nothing.
	</para>
	<example>
		<title><function>redis_execute</function> usage</title>
		<programlisting format="linespecific">
...
After several redis command calls:
	redis_pipe_cmd("srvA", "SET foo bar", "r1");

	redis_pipe_cmd("srvB", "SET ruri $ru", "r2");

	redis_pipe_cmd("srvB", "GET foo", "r3");

Send the data and retrieve the results:
	redis_execute("srvA"); //send command to srvA and wait for reply. Store the reply in r1

	redis_execute("srvB"); //send command to srvA and wait for reply. Store the replies in r2 (for SET ruri $ru) and r3 (for GET foo)

Using both redis_cmd and redis_pipe_cmd:
	redis_pipe_cmd("srvA", "SET foo bar", "r1");

	redis_pipe_cmd("srvA", "SET ruri $ru", "r2");

	redis_execute("srvA"); //send commands to srvA and wait for reply. Store replies in r1 and r2

	redis_cmd("srvA", "GET foo", "r3"); //send command, wait for reply and store it in r3


	redis_pipe_cmd("srvA", "SET foo bar", "r1");

	redis_pipe_cmd("srvA", "SET ruri $ru", "r2");

	redis_cmd("srvA", "GET foo", "r3"); //first call redis execute (replies are stored in r1 and r2), log warning and execute redis_cmd

	redis_execute("srvA"); //this does nothing as there are no more pipelined commands. The call is not necessary
...
		</programlisting>
	</example>
	</section>
	<section id="ndb_redis.f.redis_free">
	<title>
		<function moreinfo="none">redis_free(replyid)</function>
	</title>
	<para>
		Frees data in a previous reply from memory.
		After this function call, accessing to a freed replyid returns null value.
	</para>
	<para>
		It is not necessary to free a reply to use it again in a new redis_cmd
		function. When ndb_redis module closes, all pending replies are freed
		automatically.
	</para>
	<example>
		<title><function>redis_free</function> usage</title>
		<programlisting format="linespecific">
...
After a redis command call:
	redis_cmd("srvN", "INCR cnt", "r");

free reply data:
	redis_free("r");
...
		</programlisting>
	</example>
	</section>
	</section>
</chapter>

