gflags.sgml

用来作为linux中SIP SERVER,完成VOIP网络电话中服务器的功能

<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook V4.2//EN">

<book>
    <bookinfo>
	<title>gflags Module</title>
	<authorgroup>
	    <author>
		<firstname>Jiri</firstname>
		<surname>Kuthan</surname>
		<email>[e-mail]</email>
	    </author>
	</authorgroup>
	<copyright>
	    <year>2004</year>
	    <holder>FhG FOKUS</holder>
	</copyright>
	<revhistory>
	    <revision>
		<revnumber>$Revision: 1.1.2.1 $</revnumber>
		<date>$Date: 2005/06/22 23:16:52 $</date>
	    </revision>
	</revhistory>
    </bookinfo>
    <toc></toc>
    
    <chapter>
	<title>User's Guide</title>
	
	<section>
	    <title>Overview</title>
	    <para>
		The module implements global flags. The difference between the
		global flags and flags that can be used in the configuration
		file or AVPs is that they the scope of the global flags is not
		limited to the SIP message or transaction being
		processed. Global flags are always available, their contents is
		not forgotten when a SIP transaction gets destroyed in SER.
	    </para>
	    <para>
		Global flags can be accessed from the configuration script, for example:
	    </para>
	    <programlisting>
if (is_gflag("1")) {
    t_relay_to_udp("10.0.0.1", "5060");
} else {
    t_relay_to_udp("10.0.0.2", "5060");
};
</programlisting>
	    <para>
		The value of the global flags can be manipulated by external
		tools such as the web interface of SER or cmd line
		administration tools. One particular application of global
		flags could be runtime configuration changes without the need
		to restart SER.
	    </para>
	</section>
	<section>
	<title>Dependencies</title>
	    <para>
		None.
	    </para>
	</section>
	<section>
	    <title>Exported Parameters</title>
	    
	    <section>
		<title><varname>initial</varname> (integer)</title>
		<para>
		    The initial value of global flags. Each bit in the integer
		    represents one flag.
		</para>
		<para>
		    Default value is 0.
		</para>
	    </section>
	</section>
	
	<section>
	    <title>Exported Functions</title>

	    <section>
		<title><function moreinfo="none">set_gflag(flag_num)</function></title>
		<para>
		    Set the flag identified by flag_num to 1. The range of
		    flag_num is 0 to 31.
		</para>
		<example>
		    <title><function moreinfo="none">set_gflag</function> usage</title>
		    <programlisting format="linespecific">
...
set_gflag("2");
...
</programlisting>
		</example>
	    </section>

	    <section>
		<title><function moreinfo="none">reset_gflag(flag_num)</function></title>
		<para>
		    Set the flag identified by flag_num to 0. The range of
		    flag_num is 0 to 31.
		</para>
		<example>
		    <title><function moreinfo="none">reset_gflag</function> usage</title>
		    <programlisting format="linespecific">
...
reset_gflag("2");
...
</programlisting>
		</example>
	    </section>

	    <section>
		<title><function moreinfo="none">is_gflag(flag_num)</function></title>
		<para>
		    Returns 1 when flag identified by flag_num is set, 0
		    otherwise. The range of flag_num parameter is 0 to 31.
		</para>
	    </section>

	</section>
	<section>
	    <title>FIFO Interface</title>
	    <para>
		The state of the global flags can be read and modified over the
		FIFO interface of SER. This module implements the following
		FIFO interface functions:
	    </para>
	    <itemizedlist>
		<listitem>
		    <para>
		    <emphasis>set_gflag</emphasis> - Set the value of a flag to 1. The
		    function accepts one parameter which is the number of the
		    flag to be set.
		    </para>
		</listitem>
		<listitem>
		    <para>
		    <emphasis>reset_gflag</emphasis> - Reset the value of a flag to
		    0. The function accepts one parameter which is the number
		    of the flag to be reset.
		    </para>
		</listitem>
		<listitem>
		    <para>
		    <emphasis>is_gflag</emphasis> - Return the status of a flag. The
		    FIFO function would return TRUE if the flag is set and
		    FALSE if it is not set. The only parameter of this function
		    is the number of the flag.
		    </para>
		</listitem>
	    </itemizedlist>
	</section>
    </chapter>
</book>

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