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

<chapter>
	<title>&develguide;</title>
	<section>
		<title>Available Functions</title>
		<section>
			<title>
				<function moreinfo="none">erl_load_api(erl_api)</function>
			</title>
			<para>
				Function to be called directly from other modules to load the API.
				On success return 0, on error 1.
			</para>
			<para>Meaning of the parameters is as follows:</para>
			<itemizedlist mark="none">
				<listitem>
					<para><emphasis>erl_api_t* erl_api</emphasis> - API bindings structure.</para>
				</listitem>
			</itemizedlist>
		</section>
		<section>
			<title>
				<function moreinfo="none">rpc(reply,module,function,args)</function>
			</title>
			<para>
				This function supports calling Erlang functions on remote nodes. On success function returns 0.
			</para>
			<para>Meaning of parameters is as follows:</para>
			<itemizedlist mark="none">
				<listitem>
					<para><emphasis>ei_x_buff* reply</emphasis> - dynamic ei buffer where RPC reply returns.</para>
				</listitem>
				<listitem>
					<para><emphasis>str *module</emphasis> - string containing module name.</para>
				</listitem>
				<listitem>
					<para><emphasis>str *function</emphasis> - string containing function name.</para>
				</listitem>
				<listitem>
					<para><emphasis>ei_x_buff *args</emphasis> - dynamic ei buffer with encoded arguments.</para>
				</listitem>
			</itemizedlist>
		</section>
		<section>
			<title>
				<function moreinfo="none">reg_send(server,msg)</function>
			</title>
			<para>
				This function sends an Erlang term to a registered process. On success return 0.
			</para>
			<para>Meaning of parameters is as follows:</para>
			<itemizedlist mark="none">
				<listitem>
					<para><emphasis>str *server</emphasis> - string containing
					registered name of the intended recipient process on remote node.</para>
				</listitem>
				<listitem>
					<para><emphasis>ei_x_buff *msg</emphasis> - dynamic ei buffer
					with encoded erlang term. The msg must be encoded with version byte.</para>
				</listitem>
			</itemizedlist>
		</section>
		<section>
			<title>
				<function moreinfo="none">send(pid,msg)</function>
			</title>
			<para>
				This function sends an Erlang term to a process. On success return 0.
			</para>
			<para>Meaning of parameters is as follows:</para>
			<itemizedlist mark="none">
				<listitem>
					<para><emphasis>erlang_pid *pid</emphasis> - pid of the intended
					recipient process on remote node.</para>
				</listitem>
				<listitem>
					<para><emphasis>ei_x_buff *msg</emphasis> - dynamic ei buffer
					with encoded erlang term. The msg must be encoded with version byte.</para>
				</listitem>
			</itemizedlist>
		</section>
		<section>
			<title>
				<function moreinfo="none">reply(msg)</function>
			</title>
			<para>
				Function to send reply on processed message.
			</para>
			<para>Meaning of parameters is as follows:</para>
			<itemizedlist mark="none">
				<listitem>
					<para><emphasis>ei_x_buff *msg</emphasis> - dynamic ei buffer
					with encoded erlang term.</para>
				</listitem>
			</itemizedlist>
		</section>
		<section>
			<title>
				<function moreinfo="none">xavp2xbuff(xbuff,xavp)</function>
			</title>
			<para>
				Function encodes XAVP variable into ei dynamic buffer. How to create XAVP variable
				see source code.
			</para>
			<para>Meaning of parameters is as follows:</para>
			<itemizedlist mark="none">
				<listitem>
					<para><emphasis>ei_x_buff *xbuff</emphasis> - dynamic ei buffer
					where XAVP variable will be encoded.</para>
				</listitem>
				<listitem>
					<para><emphasis>sr_xavp_t *xavp</emphasis> - XAVP variable to be encoded.</para>
				</listitem>
			</itemizedlist>
		</section>
		<section>
			<title>
				<function moreinfo="none">xbuff2xavp(xavp,xbuff)</function>
			</title>
			<para>
				Function decodes ei dynamic buffer into XAVP variable.
			</para>
			<para>Meaning of parameters is as follows:</para>
			<itemizedlist mark="none">
				<listitem>
					<para><emphasis>sr_xavp_t **xavp</emphasis> - XAVP variable where ei buffer will be decoded.</para>
				</listitem>
				<listitem>
					<para><emphasis>ei_x_buff *xbuff</emphasis> - dynamic ei buffer.</para>
				</listitem>
			</itemizedlist>
		</section>
		<example>
				<title>Example of using API</title>
				<programlisting format="linespecific" language="C">
<![CDATA[

/* note: new without version byte */
ei_x_new(&ei_req);

/* ei_x_buff <- XAVP */
if (erl_api.xavp2xbuff(&ei_req,xreq)) {
	LM_ERR("failed to encode\n");
	ei_x_free(&ei_req);
	return -1;
}

memset((void*)&ei_rep,0,sizeof(ei_x_buff));

erl_api.rpc(&ei_rep,&module,&function,&ei_req);
...

/* must be XAVP */
xrepl->val.type = SR_XTYPE_XAVP;

/* XAVP <- ei_x_buff */
if (erl_api.xbuff2xavp(&xrepl->val.v.xavp,&ei_rep)){
	LM_ERR("failed to decode\n");
	ei_x_free(&ei_req);
	ei_x_free(&ei_rep);
	return -1;
}

]]>
				</programlisting>
			</example>
	</section>
</chapter>
