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

<chapter>
	<title>&adminguide;</title>
	
	<section>
	<title>Overview</title>
	<para> The Presence module implements the core functionality of SIP event notification.
	It handles PUBLISH and SUBSCRIBE messages and generates
	NOTIFY messages in a general, event independent way. It is extensible and allows registering 
	events to it from other &kamailio; modules.
	Supported SIP event packages are presence, presence.winfo, dialog;sla from the presence_xml
	module and message-summary from the presence_mwi module.
	</para>
	<para>
	The module can use database and memory storage (to improve performance).
	For subscriptions it supports the 4 storage modes: Memory Only, Write Back,
	Write Through and DB Only. For publishes, it stores the state documents in
	database only(because of the large size) and it can store a publish cache in
	memory to avoid unnecessairy database queries. Read the 
	<emphasis>subs_db_mode</emphasis> and <emphasis>publ_cache</emphasis> parameter
	sections to decide which is the best storage configuration for you.
	</para>
	<para>The module implements several API functions, that can be used by other
	modules. In fact, it can be used only as a resource module, or "library".
	This mode of operation is enabled if the db_url parameter is not set to any value.
	</para>
	<para>
	The &kamailio; Presence module implements the specifications in: RFC3265, RFC3856, RFC3857, 
	RFC3858.
	</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>a database module</emphasis>.
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis>sl</emphasis>.
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis>tm</emphasis>.
			</para>
			</listitem>
			</itemizedlist>
		</para>
	</section>

	<section>
		<title>External Libraries or Applications</title>
		<itemizedlist>
			<listitem>
			<para>
				<emphasis>libxml</emphasis>.
			</para>
			</listitem>
		</itemizedlist>

		</section>
	</section>
	
	<section>
	<title>Parameters</title>
	<section id="presence.p.db_url">
		<title><varname>db_url</varname>(str)</title>
		<para>
		The database url.
		</para>
		<para>If set, the module is a fully operational
		presence server. Otherwise, it is used as a 'library', for 
		its exported functions.
		</para>
		<para>
		<emphasis>Default value is <quote>NULL</quote>.</emphasis>
		</para>
		<example>
		<title>Set <varname>db_url</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "db_url", 
	"&defaultdb;")
...
</programlisting>
		</example>
	</section>
	<section id="presence.p.presentity_table">
		<title><varname>presentity_table</varname>(str)</title>
		<para>
		The name of the db table where PUBLISH presence information is stored.
		</para>
		<para>
		<emphasis>	Default value is <quote>presentity</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>presentity_table</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "presentity_table", "presentity")
...
</programlisting>
		</example>
	</section>
	<section id="presence.p.active_watchers_table">
		<title><varname>active_watchers_table</varname>(str)</title>
		<para>
		The name of the db table where active subscription information is stored. 
		</para>
		<para>
		<emphasis>	Default value is <quote>active_watchers</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>active_watchers_table</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "active_watchers_table", "active_watchers")
...
</programlisting>
		</example>
	</section>
	<section id="presence.p.watchers_table">
		<title><varname>watchers_table</varname>(str)</title>
		<para>
		The name of the db table where subscription states are stored.
		</para>
		<para>
		<emphasis>	Default value is <quote>watchers</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>watchers_table</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "watchers_table", "watchers")
...
</programlisting>
		</example>
	</section>
	<section id="presence.p.clean_period">
		<title><varname>clean_period</varname> (int)</title>
		<para>
		The period in seconds between checks if there are expired messages stored in database.
		</para>
		<para>
		<emphasis>Default value is <quote>100</quote>. A zero or negative value disables this activity.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>clean_period</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "clean_period", 100)
...
</programlisting>
		</example>
	</section>
	<section id="presence.p.db_update_period">
		<title><varname>db_update_period</varname> (int)</title>
		<para>
		The period at which to synchronize cached subscriber info with the
		database.
		</para>
		<para>
		<emphasis>Default value is <quote>100</quote>. A zero or negative value disables synchronization.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>db_update_period</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "db_update_period", 100)
...
</programlisting>
		</example>
	</section>

	<section id="presence.p.waitn_time">
		<title><varname>waitn_time</varname> (int)</title>
		<para>
		The maximum time period that NOTIFY requests will
		be buffered for.  The server will attempt to send
		NOTIFY requests within many seconds of a change occurring.
		</para>
		<para>
		Note: this parameter is only used when notifier_processes is
		greater than 0. When notifier_processes is less than or equal
		to 0 NOTIFY requests are sent immediately.
		</para>
		<para>
		<emphasis>Default value is <quote>5</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>waitn_time</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "waitn_time", 10)
...
</programlisting>
		</example>
	</section>

	<section id="presence.p.notifier_poll_rate">
		<title><varname>notifier_poll_rate</varname> (int)</title>
		<para>
		The number of times per second that the notifier processes
		should check for work.  Approximately
		1/(waitn_time * notifier_poll_rate * notifier_processes) of the
		pending updates will be sent each time a notifier process runs.
		</para>
		<para>
		Separate notifier processes are only run when subs_db_mode is 3
		(DB only mode).
		</para>
		<para>
		<emphasis>Default value is <quote>10</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>notifier_poll_rate</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "notifier_poll_rate", 20)
...
</programlisting>
		</example>
	</section>

	<section id="presence.p.notifier_processes">
		<title><varname>notifier_processes</varname> (int)</title>
		<para>
		The number of notifier processes that should be started.
		</para>
		<para>
		Separate notifier processes are only run when subs_db_mode is
		3 (DB only mode).
		</para>
		<para>
		Note: setting this parameter to 0 when subs_db_mode is 3
		keeps the old behaviour (sending NOTIFY requests immediately).
		This (old) behaviour is disabled by default in DB only mode
		because under load, when lots of NOTIFY requests can be sent
		on a dialog at the same time, there are race conditions which
		result in CSeq re-use.
		</para>
		<para>
		<emphasis>Default value is <quote>1</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>notifier_processes</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "notifier_processes", 2)
...
</programlisting>
		</example>
	</section>

	<section id="presence.p.to_tag_pref">
		<title><varname>to_tag_pref</varname> (str)</title>
		<para>
		The prefix used when generating to_tag when sending replies for
		SUBSCRIBE requests.
		</para>
		<para>
		<emphasis>Default value is <quote>10</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>to_tag_pref</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "to_tag_pref", 'pres')
...
	</programlisting>
		</example>
	</section>

	<section id="presence.p.expires_offset">
		<title><varname>expires_offset</varname> (int)</title>
		<para>
		The value in seconds that should be subtracted from the expires value when
		sending a 200OK for a publish. It is used for forcing the client
		to send an update before the old publish expires.
		</para>
		<para>
		<emphasis>Default value is <quote>0</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>expires_offset</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "expires_offset", 10)
...
</programlisting>
		</example>

</section>
       <section id="presence.p.max_expires">
               <title><varname>max_expires</varname> (int)</title>
               <para>
               The maximum admissible expires value for PUBLISH/SUBSCRIBE
               message (in seconds).
               </para>
               <para>
               <emphasis>Default value is <quote>3600</quote>.
               </emphasis>
               </para>
               <example>
               <title>Set <varname>max_expires</varname> parameter</title>
               <programlisting format="linespecific">
...
modparam("presence", "max_expires", 3600)
...
</programlisting>
	</example>
</section>

<section id="presence.p.min_expires">
    <title><varname>min_expires</varname> (int)</title>
    <para>
        The minimum admissible expires value for PUBLISH/SUBSCRIBE
        message (in seconds).
    </para>
    <para>
        If &gt; 0 then min_expires_action parameter determines the response.
    </para>
    <para>
        <emphasis>Default value is <quote>0</quote>.
        </emphasis>
    </para>
    <example>
        <title>Set <varname>min_expires</varname> parameter</title>
        <programlisting format="linespecific">
            ...
            modparam("presence", "min_expires", 1800)
            ...
        </programlisting>
    </example>
</section>

<section id="presence.p.min_expires_action">
    <title><varname>min_expires_action</varname> (int)</title>
    <para>
        The action to take when UA sends a expires value less then min_expires.
    </para>
    <para>
        <itemizedlist>
            <title>Possible Values</title>
            <listitem>
                <para> 1 : RFC Compliant, returns <quote>423 Interval Too Brief</quote></para>
            </listitem>
            <listitem>
                <para> 2 : forces the min_expires value in the subscription</para>
            </listitem>
        </itemizedlist>
    </para>
    <para>
        If &gt; 0 then min_expires_action parameter determines the response.
    </para>
    <para>
        <emphasis>Default value is <quote>1</quote>.</emphasis>
    </para>
    <example>
        <title>Set <varname>min_expires</varname> parameter</title>
        <programlisting format="linespecific">
            ...
            modparam("presence", "min_expires", 1800)
            ...
        </programlisting>
    </example>
</section>

<section id="presence.p.server_address">
		<title><varname>server_address</varname> (str)</title>
		<para>
		The presence server address which will become the value of Contact header filed 
		for 200 OK replies to SUBSCRIBE and PUBLISH and in NOTIFY messages.
		</para>
		<example>
		<title>Set <varname>server_address</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "server_address", "sip:10.10.10.10:5060")
...
</programlisting>
		</example>
	</section>

<section id="presence.p.subs_db_mode">
		<title><varname>subs_db_mode</varname> (int)</title>
		<para>
		The presence module can utilize database for persistent subscription storage.
		If you use database, your subscriptions will survive machine restarts or
		SW crashes. The disadvantage is that accessing database can be time consuming.
		Therefore, presence module implements four database accessing modes:
		</para>
		<itemizedlist>
		<listitem>
			<para>
			0 - This disables database completely. Only memory will be used.
			Subscriptions will not survive restart. Use this value if you need a
			really fast presence module and subscription persistence is not necessary or
			is provided by other means.
			</para>
		</listitem>
		<listitem>
			<para>
			1 - Write-Through scheme. Subscriptions are updated synchronously
			in database and in memory(used for read operations). Use this
			scheme if speed is not top priority, but it's important that no
			subscriptions will be lost during crash or reboot or if you have
			an external application that reads the state of the subscriptions
			from database and they need to be updated synchronously.
			</para>
		</listitem>
		<listitem>
			<para>
			2 - Write-Back scheme. This is a combination of previous two
			schemes. All changes are made to memory and database
			synchronization is done in the timer. The timer deletes all
			expired contacts and flushes all modified or new subscriptions to
			database. Use this scheme if you encounter high-load peaks
			and want them to process as fast as possible. Latency of this
			mode is much lower than latency of mode 1, but slightly higher
			than latency of mode 0. To control the interval at which data is
			flushed to database, set the <emphasis>db_update_period</emphasis>
			parameter.
			</para>
		</listitem>
		<listitem>
			<para>
			3 - DB-Only scheme. No memory cache is kept, all operations being
			directly performed with the database. The timer deletes all expired
			subscriptions from database. The mode is useful if you configure
			more servers sharing the same DB without any replication at SIP
			level. The mode may be slower due the high number of DB operation.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		<emphasis>Default value is 2 (Write-Back scheme).</emphasis>
		</para>

		<example>
		<title>Set <varname>subs_db_mode</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "subs_db_mode", 1)
...
</programlisting>
		</example>
	</section>

	<section id="presence.p.publ_cache">
		<title><varname>publ_cache</varname> (int)</title>
		<para>
		To improve performance, the presence module holds by default a
		publish cache that says if a certain publication exists in database.
		This is only a list of URI + event, so it does not use much memory.
		The cache is used when a Subscription is received to check if there
		is any published state in database. This way unnecessary queries in
		presentity table are avoided.
		</para>
		<para>
		Setting this parameter to 0 will disable the usage of the publish
		cache. This is desirable when you have more servers sharing the same
		database or there are other external entities inserting data into the
		presentity table.
		</para>
		<para>
		<emphasis>Default value is <quote>1</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>publ_cache</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "publ_cache", 0)
...
	</programlisting>
		</example>
	</section>

	<section id="presence.p.subs_htable_size">
		<title><varname>subs_htable_size</varname> (int)</title>
		<para>
		The size of the in-memory hash table to store subscription dialogs.
		This parameter will be used as the power of 2 when computing table size.
		</para>
		<para>
		<emphasis>Default value is <quote>9 (512)</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>subs_htable_size</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "subs_htable_size", 11)
...
	</programlisting>
		</example>
	</section>

	<section id="presence.p.pres_htable_size">
		<title><varname>pres_htable_size</varname> (int)</title>
		<para>
        	The size of the in-memory hash table to store publish records.
        	This parameter will be used as the power of 2 when computing table size.
		</para>
		<para>
		<emphasis>Default value is <quote>9 (512)</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>pres_htable_size</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "pres_htable_size", 11)
...
	</programlisting>
		</example>
	</section>
	<section id="presence.p.send_fast_notify">
		<title><varname>send_fast_notify</varname> (int)</title>
		<para>
		This parameter enables or disables the sending of an initial empty NOTIFY after a SUBSCRIBE/reSUBSCRIBE. 
		This caused problems for MWI application, because some CPEs (like Samsung) fail to understand an empty
		NOTIFY to an message-summary event. This parameter is enabled by default, thus addering to the standard.
		</para>
		<para>
		<emphasis>Default value is <quote>1 </quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>send_fast_notify</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "send_fast_notify", 0)
...
	</programlisting>
		</example>
	</section>

	<section id="presence.p.enable_sphere_check">
		<title><varname>enable_sphere_check</varname> (int)</title>
		<para>
		This parameter is a flag that should be set if permission rules include
		sphere checking.
		The sphere information is expected to be present in the RPID body
		published by the presentity. The flag is introduced as this check requires
		extra processing that should be avoided if this feature is not supported
		by the clients.
		</para>
		<para>
		<emphasis>Default value is <quote>0 </quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>enable_sphere_check</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "enable_sphere_check", 1)
...
	</programlisting>
		</example>
	</section>

	<section id="presence.p.timeout_rm_subs">
		<title><varname>timeout_rm_subs</varname> (int)</title>
		<para>
		This parameter is a flag that should be set if subscriptions should be
		removed from the active_watchers when a NOTIFY times out. RFC3265
		section 3.2.2 defines this behaviour as a SHOULD, so by default it is
		on. Disabling this will keep subscriptions active on unreliable
		networks.
		</para>
		<para>
		<emphasis>Default value is <quote>1</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>timeout_rm_subs</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "timeout_rm_subs", 0)
...
	</programlisting>
		</example>
	</section>
	<section id="presence.p.fetch_rows">
	    <title><varname>fetch_rows</varname> (integer)</title>
	    <para>
		Number of rows to be loaded in one step from database.
	    </para>
	    <para>
		<emphasis>
		    Default value is 500.
		</emphasis>
	    </para>
	    <example>
		<title>Set <varname>fetch_rows</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "fetch_rows", 1000)
...
</programlisting>
	    </example>
	</section>
	<section id="presence.p.db_table_lock_type">
	    <title><varname>db_table_lock_type</varname> (integer)</title>
	    <para>
		Enable (=1) or disable (=0) the Locks for table during an
		transaction. Locking only the "current" table causes problems
		with a MySQL-Databases in "DB-Only" mode.
	    </para>
	    <para>
		In order to use the Presence-Module in "DB_ONLY"-mode with a 
		MySQL-Backend, set this parameter to "0", otherwise the 
		MySQL-Operations will fail. The Presence-Module will generate
		a "500 Server error" due to the failed MySQL-queries.
	    </para>
	    <para>
		<emphasis>
		    Default value is 1 (Write Lock for the Tables).
		</emphasis>
	    </para>
	    <example>
		<title>Set <varname>db_table_lock_type</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "db_table_lock_type", 0)
...
</programlisting>
	    </example>
	</section>
	<section id="presence.p.local_log_level">
	    <title><varname>local_log_level</varname> (int)</title>
	    <para>
		Control log level for some debug messages inside the module.
	    </para>
	    <para>
		<emphasis>
		    Default value is 2 (L_INFO).
		</emphasis>
	    </para>
	    <example>
		<title>Set <varname>local_log_level</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "local_log_level", 3)
...
</programlisting>
	    </example>
	</section>
	<section id="presence.p.subs_remove_match">
	    <title><varname>subs_remove_match</varname> (int)</title>
	    <para>
		Control how to match the subscriptions to remove from memory.
		If set to 0, then the match is done on To-Tag (local generated),
		if set to 1, then the match is done on all dialog attributes
		(Call-Id, From-Tag, To-Tag).
	    </para>
	    <para>
		<emphasis>
		    Default value is 0.
		</emphasis>
	    </para>
	    <example>
		<title>Set <varname>subs_remove_match</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "subs_remove_match", 1)
...
</programlisting>
	    </example>
	</section>
	<section id="presence.p.xavp_cfg">
    <title><varname>xavp_cfg</varname> (str)</title>
    <para>
		The name of the xavp to be used to specify attributes for internal
		processing of presence module.
    </para>
    <para>
		Inner attributes inside xavp can be:
    </para>
    <itemizedlist>
        <listitem>
			<para><emphasis>priority</emphasis> - integer value to set the
			priority of the presence document (higher value, higher priority).
			It can set the order of the aggregated presence documents sent by
			NOTIFY (first the document with higher priority). If xavp_cfg
			parameter is set but this attribute is not in the avp,
			the priority of the presence document is based on timestamp,
			so newer documents have higher priority.</para>
        </listitem>
     </itemizedlist>
    <para>
        Default value is <emphasis>empty</emphasis> (not set).
    </para>
    <example>
        <title>Set <varname>xavp_cfg</varname> parameter</title>
        <programlisting format="linespecific">
...
modparam("presence", "xavp_cfg", "pres")
...
if(is_method("PUBLISH")) {
    $xavp(pres=>priority) = 100;
}
...
</programlisting>
    </example>
	</section>

	<section id="presence.p.retrieve_order">
	    <title><varname>retrieve_order</varname> (int)</title>
	    <para>
		If set to 0, presentity records are retrieve by received_time order.
		if set to 1, presentity records are retrieve by priority order.
	    </para>
	    <para>
		<emphasis>
		    Default value is 0.
		</emphasis>
	    </para>
	    <example>
		<title>Set <varname>retrieve_order</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("presence", "retrieve_order", 1)
...
</programlisting>
	    </example>
	</section>

<section id="presence.p.sip_uri_match">
    <title><varname>sip_uri_match</varname> (int)</title>
    <para>
        The mode used when comparing uris.
    </para>
    <para>
        <itemizedlist>
            <title>Possible Values</title>
            <listitem>
                <para> 0 : case sensitive</para>
            </listitem>
            <listitem>
                <para> 1 : case insensitive</para>
            </listitem>
        </itemizedlist>
    </para>
    <para>
        <emphasis>Default value is <quote>0</quote>.</emphasis>
    </para>
    <example>
        <title>Set <varname>sip_uri_match</varname> parameter</title>
        <programlisting format="linespecific">
            ...
            modparam("presence", "sip_uri_match", 1)
            ...
        </programlisting>
    </example>
</section>

</section>

<section>
	<title>Functions</title>
	<section id="presence.f.handle_publish">
		<title>
		<function moreinfo="none">handle_publish([sender_uri])</function>
		</title>
		<para>
		Handles PUBLISH requests by storing and updating 
		published information in memory cache and database, then calls functions to send 
		NOTIFY messages when changes in the published information occur.
		It takes one argument -> sender_uri. The parameter was added 
		for enabling BLA implementation. If present, notification of
		a change in published state is not sent to the respective uri
		even though a subscription exists.
		It should be taken from the Sender header. It was left at the
		decision of the administrator whether or not to transmit the 
		content of this header as parameter for handle_publish, to 
		prevent security problems.  
		</para>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<para>
		<emphasis>Return code:</emphasis>
		<itemizedlist>
			<listitem>
			<para>
				<emphasis> 1 - if success</emphasis>.
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis> -1 - if error</emphasis>.
			</para>
			</listitem>
		</itemizedlist>
		</para>
		<para>
			The module sends an appropriate stateless reply
			in all cases.
		</para>

		<example>
		<title><function>handle_publish</function> usage</title>
		<programlisting format="linespecific">
...
	if(is_method("PUBLISH"))
	{
		if($hdr(Sender)!= NULL)
			handle_publish("$hdr(Sender)");
		else
			handle_publish();
		t_release();
	} 
...
</programlisting>
		</example>
	</section>

	<section id="presence.f.handle_subscribe">
		<title>
		<function moreinfo="none">handle_subscribe([watcher_uri])</function>
		</title>
		<para>
		The function which handles SUBSCRIBE requests. It stores or 
		updates information in memory and database and calls functions to send NOTIFY 
		messages when a SUBSCRIBE which initiate a dialog is received.
		</para>
		<para>
		By default this function uses the From: URI from the SUBSCRIBE
		request as the Watcher URI.  The optional watcher_uri parameter
		can be used to specify a different Watcher URI, possibly taken
		from a SIP header like P-Asserted-Identity:.
		</para>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<para>
		<emphasis>Return code:</emphasis>
		<itemizedlist>
			<listitem>
			<para>
				<emphasis> 1 - if success</emphasis>.
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis> -1 - if error</emphasis>.
			</para>
			</listitem>
		</itemizedlist>
		</para>
		<para>
			The module sends an appropriate stateless reply
			in all cases.
		</para>

		<example>
		<title><function>handle_subscribe</function> usage</title>
		<programlisting format="linespecific">
...
if(method=="SUBSCRIBE")
    handle_subscribe();
...
</programlisting>
		</example>
	</section>

	<section id="presence.f.pres_auth_status">
		<title>
		<function moreinfo="none">pres_auth_status(watcher_uri, presentity_uri)</function>
		</title>
		<para>
		The function checks if watcher is authorized to subscribe
		event 'presence' of presentity.  Both watcher_uri and
		presentity_uri are pseudo variables.  Function returns
		ACTIVE_STATUS, if subscription is allowed and
		PENDING_STATUS, TERMINATED_STATUS, or WAITING_STATUS
		otherwise.  See presence/subscribe.h for the
		corresponding integer codes.  In case of error, function
		returns -1.
		</para>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>

		<example>
		<title><function>pres_auth_status</function> usage</title>
		<programlisting format="linespecific">
...
if (method=="MESSAGE") {
    pres_auth_status("$fu", $ru");
    if ($retcode == 1) {
        t_relay();
    } else {
        send_reply("403", "Forbidden");
    }
}
...
</programlisting>
		</example>
	</section>

	<section id="presence.f.pres_refresh_watchers">
		<title>
		<function moreinfo="none">pres_refresh_watchers(uri, event, type[, file_uri, filename])</function>
		</title>
		<para>
			The function can be used in configuration to triger notifies to watchers
			if a change in watchers authorization or in published state occurred
			(i.e., updates of xcap documents).
		</para>
		<para>Parameters:</para>
		<itemizedlist>
			<listitem>
				<para>uri - the uri of the user who made the change
				and whose watchers should be informed.</para>
			</listitem>
			<listitem>
				<para>event - the event package.</para>
			</listitem>
			<listitem>
				<para>type - it distinguishes between the three different types of events
						that can trigger the refresh, depending on its value:
						<itemizedlist>
							<listitem>
								<para>0 - a change in watchers authentication.</para>
							</listitem>
							<listitem>
								<para>1 - a statical update in published state through direct
								update in db table.
								</para>
							</listitem>
							<listitem>
								<para>2 - a statical update in published state by modifying
								the pidf manipulation document.
								</para>
							</listitem>
						</itemizedlist>
				</para>
			</listitem>
			<listitem>
				<para>file_uri - the uri of the pidf-manipulation file on
				the XCAP server (only used for type 2).</para>
			</listitem>
			<listitem>
				<para>filename - the name of the pidf-manipulation file on
				the XCAP server (only used for type 2).</para>
			</listitem>
        	</itemizedlist>
		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title><function>pres_refresh_watchers</function> usage</title>
		<programlisting format="linespecific">
...
pres_refresh_watchers("sip:test@kamailio.org", "presence", 1);
...
</programlisting>
		</example>
	</section>

	<section id="presence.f.pres_update_whatchers">
		<title>
		<function moreinfo="none">pres_update_watchers(uri, event)</function>
		</title>
		<para>
			The function can be used in configuration to triger updates to watchers
			status if a change in watchers authorization state occurred
			(i.e., updates of xcap documents change state from pending to active).
		</para>
		<para>Parameters:</para>
		<itemizedlist>
			<listitem>
				<para>uri - the uri of the user who made the change
				and whose watchers should be informed. Can be PV.</para>
			</listitem>
			<listitem>
				<para>event - the event package (e.g., presence).</para>
			</listitem>
        </itemizedlist>
		<para>
		This function can be used from ANY_ROUTE.
		</para>
		<example>
		<title><function>pres_update_watchers</function> usage</title>
		<programlisting format="linespecific">
...
pres_update_watchers("sip:test@kamailio.org", "presence");
...
</programlisting>
		</example>
	</section>
</section>

<section>
	<title>MI Commands</title>
	<section>
		<title>
		<function moreinfo="none">refreshWatchers</function>
		</title>
		<para>
		Triggers sending Notify messages to watchers if a change in watchers
		authorization or in published state occurred.
		</para>
		<para>
		Name: <emphasis>refreshWatchers</emphasis>
		</para>
		<para>Parameters:</para>
		<itemizedlist>
			<listitem>
				<para>uri - the uri of the user who made the change
				and whose watchers should be informed</para>
			</listitem>
			<listitem>
				<para>event - the event package.</para>
			</listitem>
			<listitem>
				<para>type - it distinguishes between the three different types of events
						that can trigger the refresh, depending on its value:
						<itemizedlist>
							<listitem>
								<para>0 - a change in watchers authentication.</para>
							</listitem>
							<listitem>
								<para>1 - a statical update in published state through direct
								update in db table.
								</para>
							</listitem>
							<listitem>
								<para>2 - a statical update in published state by modifying
								the pidf manipulation document.
								</para>
							</listitem>
						</itemizedlist>
				</para>
			</listitem>
			<listitem>
				<para>file_uri - the uri of the pidf-manipulation file on
				the XCAP server (only used for type 2).</para>
			</listitem>
			<listitem>
				<para>filename - the name of the pidf-manipulation file on
				the XCAP server (only used for type 2).</para>
			</listitem>
        	</itemizedlist>
        <para>
		MI FIFO Command Format:
		</para>
        <programlisting  format="linespecific">
		:refreshWatchers:fifo_reply
		sip:test@kamailio.org
		presence
		1
		_empty_line_
		</programlisting>
	</section>

	<section>
	  <title>
		<function moreinfo="none">cleanup</function>
	  </title>
	  <para>
		Manually triggers the cleanup functions for the active_watchers, presentity,
		and watchers tables. Useful if you have set <varname>clean_period</varname>
		and/or <varname>db_update_period</varname> to zero or less.
	  </para>
	  <para>
		Name: <emphasis>cleanup</emphasis>
	  </para>
	  <para>Parameters: <emphasis>none</emphasis></para>

	  <para>
		MI FIFO Command Format:
	  </para>
	  <programlisting  format="linespecific">
		:cleanup:fifo_reply
		_empty_line_
	  </programlisting>
	</section>
</section>

<section>
	<title>RPC Commands</title>
	<section>
	  <title>
		<function moreinfo="none">presence.cleanup</function>
	  </title>
	  <para>
		Manually triggers the cleanup functions for the active_watchers, presentity,
		and watchers tables. Useful if you have set <varname>clean_period</varname>
		and/or <varname>db_update_period</varname> to zero or less.
	  </para>
	  <para>
		Name: <emphasis>presence.cleanup</emphasis>
	  </para>
	  <para>Parameters: <emphasis>none</emphasis></para>

	</section>
</section>

<section>
	<title>Pseudo Variables</title>
		
		<section>
			<title><varname>$subs(attr)</varname></title>
			<para>
				Access the attributes of handled subscription. 
				It must be used after a successful call of
				<quote>handle_subscription()</quote> or in the following events.
			<itemizedlist>
				<listitem>
				<para><emphasis>tm:local-request</emphasis> - before notify is sent
				</para>
				</listitem>
				<listitem>
				<para><emphasis>present:notify-reply</emphasis> - after notify is sent
				</para>
				</listitem>
			</itemizedlist>	  
			</para>
			<para>
			The <quote>attr</quote> can be:
			</para>
			<itemizedlist>
				<listitem>
				<para><emphasis>uri</emphasis> - subscription presentity uri
				</para>
				</listitem>	  
				<listitem>
				<para><emphasis>pres_uri</emphasis> - alias for presentity uri
				</para>
				</listitem>	  
				<listitem>
				<para><emphasis>to_user</emphasis>
				</para>
				</listitem>	  
				<listitem>
				<para><emphasis>to_domain</emphasis>
				</para>
				</listitem>	  
				<listitem>
				<para><emphasis>from_user</emphasis>
				</para>
				</listitem>	  
				<listitem>
				<para><emphasis>from_domain</emphasis>
				</para>
				</listitem>	  
				<listitem>
				<para><emphasis>watcher_username</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>watcher_domain</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>event</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>event_id</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>to_tag</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>from_tag</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>callid</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>remote_cseq</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>local_cseq</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>contact</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>local_contact</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>record_route</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>expires</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>status</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>reason</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>version</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>flags</emphasis>
				</para>
				</listitem>
				<listitem>
				<para><emphasis>user_agent</emphasis>
				</para>
				</listitem>
			</itemizedlist>

			<example>
			<title><function moreinfo="none">$subs(name)</function> usage</title>
<programlisting format="linespecific">
...
if(handle_subscription())
{
  xlog("presentity=$subs(uri)\n");
}
...
				 </programlisting>
			</example>
		</section>
		
		<section>
			<title><varname>$notify_reply(attr)</varname></title>
			<para>
				Access the reply message received when notifying subscriber. 
				It must be used in the following events.
			<itemizedlist>
				<listitem>
				<para><emphasis>present:notify-reply</emphasis> - after notify is sent
				</para>
				</listitem>
			</itemizedlist>	  
			</para>
			<para>
			The <quote>attr</quote> can be any pseudo var that accesses attributes of msg
			</para>

			<example>
			<title><function moreinfo="none">$notify_reply(name)</function> usage</title>
<programlisting format="linespecific">
...
event_route[presence:notify-reply]
{
  xlog("received message = $notify_reply($mb)\n");
}
...
				 </programlisting>
			</example>
		</section>
</section>

<section>
	<title>Events</title>
		<section>
			<title><varname>present:notify-reply</varname></title>
			<para>
				Fired after notify reply is received or timeout.
			</para>

			<example>
			<title><function moreinfo="none">$notify_reply(name)</function> usage</title>
<programlisting format="linespecific">
...
event_route[presence:notify-reply]
{
  xlog("received message = $notify_reply($mb)\n");
}
...
				 </programlisting>
			</example>
		</section>
</section>

<section>
	<title>Installation</title>
	<para>
	The module requires 3 tables in the &kamailio; database: "presentity",
	"active_watchers" and "watchers". The SQL 
	syntax to create them can be found in presence-create.sql     
	script in the database directories in the kamailio/scripts folder.
	You can also find the complete database documentation on the
	project webpage, &kamailiodbdocslink;.
	</para>
</section>

</chapter>

