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

<chapter>
    <chapterinfo>
	<revhistory>
	    <revision>
		<revnumber>$Revision: 1.1.8.1 $</revnumber>
		<date>$Date: 2004/07/21 10:34:46 $</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>
    <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>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>method_column</varname> (string)</title>
	    <para>
		Name of column containing supported methods.
	    </para>
	    <para>
		<emphasis>
		    Default value is <quote>method</quote>.
		</emphasis>
	    </para>
	    <example>
		<title>Set <varname>method_column</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "method_column", "method")
...
</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>db_url</varname> (string)</title>
	    <para>
		&url; of the database that should be used.
	    </para>
	    <para>
		<emphasis>
		    Default value is <quote>sql://ser:heslo@localhost/ser</quote>.
		</emphasis>
	    </para>
	    <example>
		<title>Set <varname>db_url</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("usrloc", "db_url", "sql://username:password@localhost/ser")
...
</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_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 three 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 necessarry 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>
	    </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>
    <section>
	<title>Exported Functions</title>
	<para>
	    There are no exported functions that could be used in scripts.
	</para>
    </section>
</chapter>

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