usrloc_user.sgml

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

<chapter>
	<chapterinfo>
	<revhistory>
		<revision>
		<revnumber>$Revision: 1.6 $</revnumber>
		<date>$Date: 2006/05/19 11:58:11 $</date>
		</revision>
	</revhistory>
	</chapterinfo>
	<title>User's Guide</title>
	
	<section>
	<title>Overview</title>
	<para>
		User location module. The module keeps a user location table and 
		provides access to the table to other modules. The module exports no 
		functions that could be used directly from scripts.
	</para>
		<section id="contact-matching-algs">
		<title>Contact matching</title>
		<para>
		How the contacts are matched (dor same AOR - Address of Record) is an 
		important aspect of the usrloc modules, especialy in the context of NAT
		traversal - this raise mre problems since contacts from different 
		phones of same users may overlap (if behind NATs with same
		configuration) or the re-register contact of same phone may be
		seen as a new one (due different binding via NAT).
		</para>
		<para>
		The SIP RFC 3261 publishes a matching algorithm based only on the 
		contact string with callid and cseq number extra checking (if callid
		is the same, it must have a higher cseq number, otherwise invalid).
		But as argumented above, this is not enough in NAT traversal context, 
		so the &ser; implementation of contact machting offers more algorithms:
		</para>
		<itemizedlist>
			<listitem>
			<para>
				<emphasis>contact based only</emphasis> - it strict RFC 3261
				compiancy - the contact is matched as string and extra checked
				via callid and cseg (if callid is the same, it must have a 
				higher cseq number, otherwise invalid).
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis>contact nad callid based</emphasis> - it an extension
				of the first case - the contact and callid must matched as 
				string; the cseg must be higher than the previous one - so be
				careful how you deal with REGISTER retransmissions in this 
				case.
			</para>
			</listitem>
		</itemizedlist>
		<para>
		How to control/select the contact maching algorithm, please see the
		module parameter matching_mode at <xref linkend="matching-mode">.
		</para>
		</section>
	</section>

	<section>
	<title>Dependencies</title>
	<section>
		<title>&ser; Modules</title>
		<para>
		The following modules must be loaded before this module:
			<itemizedlist>
			<listitem>
			<para>
				<emphasis>Optionally a database module</emphasis>.
			</para>
			</listitem>
			</itemizedlist>
		</para>
	</section>
	<section>
		<title>External Libraries or Applications</title>
		<para>
		The following libraries or applications must be installed before 
		running &ser; with this module loaded:
			<itemizedlist>
			<listitem>
			<para>
				<emphasis>None</emphasis>.
			</para>
			</listitem>
			</itemizedlist>
		</para>
	</section>
	</section>
	<section>
	<title>Exported Parameters</title>
	<section>
		<title><varname>user_column</varname> (string)</title>
		<para>
		Name of column containing usernames.
		</para>
		<para>
		<emphasis>
			Default value is <quote>username</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>user_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "user_column", "username")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>domain_column</varname> (string)</title>
		<para>
		Name of column containing domains.
		</para>
		<para>
		<emphasis>
			Default value is <quote>domain</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>user_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "domain_column", "domain")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>contact_column</varname> (string)</title>
		<para>
		Name of column containing contacts.
		</para>
		<para>
		<emphasis>
			Default value is <quote>contact</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>contact_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "contact_column", "contact")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>expires_column</varname> (string)</title>
		<para>
		Name of column containing expires value.
		</para>
		<para>
		<emphasis>
			Default value is <quote>expires</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>expires_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "expires_column", "expires")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>q_column</varname> (string)</title>
		<para>
		Name of column containing q values.
		</para>
		<para>
		<emphasis>
			Default value is <quote>q</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>q_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "q_column", "q")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>callid_column</varname> (string)</title>
		<para>
		Name of column containing callid values.
		</para>
		<para>
		<emphasis>
			Default value is <quote>callid</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>callid_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "callid_column", "callid")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>cseq_column</varname> (string)</title>
		<para>
		Name of column containing cseq numbers.
		</para>
		<para>
		<emphasis>
			Default value is <quote>cseq</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>cseq_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "cseq_column", "cseq")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>methods_column</varname> (string)</title>
		<para>
		Name of column containing supported methods.
		</para>
		<para>
		<emphasis>
			Default value is <quote>methods</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>methods_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "methods_column", "methods")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>flags_column</varname> (string)</title>
		<para>
		Name of column to save the internal flags of the record.
		</para>
		<para>
		<emphasis>
			Default value is <quote>flags</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>flags_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "flags_column", "flags")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>user_agent_column</varname> (string)</title>
		<para>
		Name of column containing user-agent values.
		</para>
		<para>
		<emphasis>
			Default value is <quote>user_agent</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>user_agent_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "user_agent_column", "user_agent")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>received_column</varname> (string)</title>
		<para>
		Name of column containing the source IP, port, and protocol from the REGISTER
		message.
		</para>
		<para>
		<emphasis>
			Default value is <quote>received</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>received_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "received_column", "received")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>socket_column</varname> (string)</title>
		<para>
		Name of column containing the received socket information (IP:port)
		for the REGISTER message.
		</para>
		<para>
		<emphasis>
			Default value is <quote>socket</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>socket_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "socket_column", "socket")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>use_domain</varname> (integer)</title>
		<para>
		If the domain part of the user should be also saved and used for
		identifing the user (along with the username part). Useful in 
		multi domain scenarios. Non 0 value means true.
		</para>
		<para>
		<emphasis>
			Default value is <quote>0 (false)</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>use_domain</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "use_domain", 1)
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>desc_time_order</varname> (integer)</title>
		<para>
		If the user location records should be kept timestamp ordered.
		Non 0 value means true.
		</para>
		<para>
		<emphasis>
			Default value is <quote>0 (false)</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>desc_time_order</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "desc_time_order", 1)
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>timer_interval</varname> (integer)</title>
		<para>
		Number of seconds between two timer runs. The module uses timer to 
		delete expired contacts, synchronize with database and other tasks, 
		that need to be run periodically.
		</para>
		<para>
		<emphasis>
			Default value is 60.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>timer_interval</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "timer_interval", 120)
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>db_url</varname> (string)</title>
		<para>
		&url; of the database that should be used.
		</para>
		<para>
		<emphasis>
			Default value is 
			<quote>mysql://openser:openserrw@localhost/openser</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>db_url</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "db_url", "mysql://username:password@localhost/openser")
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>db_mode</varname> (integer)</title>
		<para>
		The usrloc module can utilize database for persistent contact storage.
		If you use database, your contacts will survive machine restarts or 
		SW crashes. The disadvantage is that accessing database can be very 
		time consuming. Therefore, usrloc module implements four database 
		accessing modes:
		</para>
		<itemizedlist>
		<listitem>
			<para>
			0 - This disables database completely. Only memory will be used. 
			Contacts will not survive restart. Use this value if you need a 
			really fast usrloc and contact persistence is not necessary or 
			is provided by other means.
			</para>
		</listitem>
		<listitem>
			<para>
			1 - Write-Through scheme. All changes to usrloc are immediately 
			reflected in database too. This is very slow, but very reliable. 
			Use this scheme if speed is not your priority but need to make 
			sure that no registered contacts will be lost during crash or 
			reboot.
			</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 contacts to 
			database.  Use this scheme if you encounter high-load peaks 
			and want them to process as fast as possible. The mode will 
			not help at all if the load is high all the time.  Also, latency 
			of this mode is much lower than latency of mode 1, but slightly 
			higher than latency of mode 0.
			</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 contacts from database - cleans after clients that didn't
			un-register or re-register. 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.
			For example NAT pinging is a killer since during each ping cycle
			all nated contact are loaded from the DB; The lack of memory 
			caching also disable the location watcher registration (in will
			not work with PA module) and disable the statistics exports.
			</para>
		</listitem>
		</itemizedlist>
		<warning>
		<para>
			In case of crash or restart contacts that are in memory only and 
			haven't been flushed yet will get lost. If you want minimize the 
			risk, use shorter timer interval.
		</para>
		</warning>
		<para>
		<emphasis>
			Default value is 0.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>db_mode</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "db_mode", 2)
...
</programlisting>
		</example>
	</section>

	<section id="matching-mode">
		<title><varname>matching_mode</varname> (integer)</title>
		<para>
		What contact matching algorithm to be used. Refer to section 
		<xref linkend="contact-matching-algs"> for the description of the 
		algorithms.
		</para>
		<para>
		The parameter may take the following values:
		</para>
		<itemizedlist>
			<listitem>
				<para><emphasis>0</emphasis> - CONTACT ONLY based matching
				algorithm.
				</para>
			</listitem>
			<listitem>
				<para><emphasis>1</emphasis> - CONTACT and CALLID based 
				matching algorithm.
				</para>
			</listitem>
		</itemizedlist>
		<para>
		<emphasis>
			Default value is <emphasis>0 (CONTACT_ONLY)</emphasis>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>matching_mode</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "matching_mode", 1)
...
</programlisting>
		</example>
	</section>

	<section>
		<title><varname>cseq_delay</varname> (integer)</title>
		<para>
		Delay (in seconds) for accepting as retransmissions register requests
		with same Call-ID and Cseq. The delay is calculated starting from the 
		receiving time of the first register with that Call-ID and Cseq.
		</para>
		<para>
		Retransmissions within this delay interval will be accepted and replied
		as the original request, but no update will be done in location. If the
		delay is exceeded, error is reported.
		</para>
		<para>
		A value of 0 disable the retransmission detection.
		</para>
		<para>
		<emphasis>
			Default value is <quote>20 seconds</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>cseq_delay</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "cseq_delay", 5)
...
</programlisting>
		</example>
	</section>

	</section>

	<section>
	<title>Exported Functions</title>
	<para>
		There are no exported functions that could be used in scripts.
	</para>
	</section>
</chapter>

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