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

<chapter>
	<chapterinfo>
	<revhistory>
		<revision>
			<revnumber>$Revision: 1.6 $</revnumber>
			<date>$Date: 2004/08/24 08:58:26 $</date>
		</revision>
	</revhistory>
	</chapterinfo>
	<title>User's Guide</title>


	<section>
		<title>Overview</title>
		<para>cpl-c modules implements a CPL (Call Processing Language) 
		interpreter. Support for uploading/downloading/removing scripts via 
		SIP REGISTER method is present.
		</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>TM (Transaction) module- used for proxying/forking 
				requests
				</emphasis>
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis>SL (StateLess) module - used for sending stateless 
				reply when responding to REGISTER request or for sending back 
				error responses
				</emphasis>
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis>USRLOC (User Location) module - used for implementing
				lookup("registration") tag (adding into location set of the
				users' contact)
				</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>libxml2 and libxml2-devel - on some SO, these to 
					packages are merged into libxml2. This library contains an 
					engine for XML parsing, DTD validation and
					DOM manipulation.
					</emphasis>
				</para>
				</listitem>
				</itemizedlist>
			</para>
		</section>
	</section>


	<section>
		<title>Exported Parameters</title>
		<section>
			<title><varname>cpl_db</varname> (string)</title>
			<para>
				A SQL URL have to be given to the module for knowing where the 
				database containing the table with CPL scripts is locates. If 
				required a user name and password can be specified for allowing 
				the module to connect to the database server.
			</para>
			<para>
				<emphasis>
					This parameter is MANDATORY!
				</emphasis>
			</para>
			<example>
				<title>Set <varname>cpl_db</varname> parameter</title>
				<programlisting format="linespecific">
...
modparam("cpl_c","cpl_db","mysql://user:passwd@host/database")
...
				</programlisting>
			</example>
		</section>
		<section>
			<title><varname>cpl_table</varname> (string)</title>
			<para>
				Indicates the name of the table that store the CPL scripts. 
				This table must be locate into the database specified by 
				"cpl_db" parameter. For more about the format of the CPL table 
				please see modules/cpl-c/init.mysql.
			</para>
			<para>
				<emphasis>
					This parameter is MANDATORY!
				</emphasis>
			</para>
			<example>
				<title>Set <varname>cpl_table</varname> parameter</title>
				<programlisting format="linespecific">
...
modparam("cpl_c","cpl_table","cpltable")
...
				</programlisting>
			</example>
		</section>
		<section>
			<title><varname>cpl_dtd_file</varname> (string)</title>
			<para>
				Points to the DTD file describing the CPL grammar. The file 
				name may include also the path to the file. This path can be 
				absolute or relative (be careful the the path will be relative 
				to the starting directory of SER).
			</para>
			<para>
				<emphasis>
					This parameter is MANDATORY!
				</emphasis>
			</para>
			<example>
				<title>Set <varname>cpl_dtd_file</varname> parameter</title>
				<programlisting format="linespecific">
...
modparam("cpl_c","cpl_dtd_file","/etc/ser/cpl-06.dtd")
...
				</programlisting>
			</example>
		</section>
		<section>
			<title><varname>log_dir</varname> (string)</title>
			<para>
				Points to a directory where should be created all the log file 
				generated by the LOG CPL node. A log file per user will be 
				created (on demand) having the name username.log.
			</para>
			<para>
				<emphasis>
					If this parameter is absent, the logging will be disabled 
					without generating error on execution.
				</emphasis>
			</para>
			<example>
				<title>Set <varname>log_dir</varname> parameter</title>
				<programlisting format="linespecific">
...
modparam("cpl_c","log_dir","/var/log/ser/cpl")
...
				</programlisting>
			</example>
		</section>
		<section>
			<title><varname>proxy_recurse</varname> (int)</title>
			<para>
				Tells for how many time is allow to have recurse for PROXY CPL 
				node If it has value 2, when doing proxy, only twice the proxy 
				action will be re-triggered by  a redirect response; the third 
				time, the proxy execution will end by going on REDIRECTION 
				branch. The recurse feature can be disable by setting this 
				parameter to 0 
			</para>
			<para>
				<emphasis>
					Default value of this parameter is 0.
				</emphasis>
			</para>
			<example>
				<title>Set <varname>proxy_recurse</varname> parameter</title>
				<programlisting format="linespecific">
...
modparam("cpl_c","proxy_recurse",2)
...
				</programlisting>
			</example>
		</section>
		<section>
			<title><varname>proxy_route</varname> (int)</title>
			<para>
				Before doing proxy (forward), a script route can be executed.
				All modifications made by that route will be reflected only for
				the current branch.
			</para>
			<para>
				<emphasis>
					Default value of this parameter is 0 (none).
				</emphasis>
			</para>
			<example>
				<title>Set <varname>proxy_route</varname> parameter</title>
				<programlisting format="linespecific">
...
modparam("cpl_c","proxy_route",1)
...
				</programlisting>
			</example>
		</section>
		<section>
			<title><varname>nat_flag</varname> (int)</title>
			<para>
				Sets the flag used for marking calls via NAT. Used by lookup
				tag when retrieving a contact behind a NAT (this flag will be 
				set).
			</para>
			<para>
				<emphasis>
					Default value of this parameter is 6.
				</emphasis>
			</para>
			<example>
				<title>Set <varname>nat_flag</varname> parameter</title>
				<programlisting format="linespecific">
...
modparam("cpl_c","nat_flag",4)
...
				</programlisting>
			</example>
		</section>
		<section>
			<title><varname>lookup_domain</varname> (int)</title>
			<para>
				Tells if the lookup tag should use or not the domain part when
				doing user_location search. Set it to a non zero value to force
				also domain matching.
			</para>
			<para>
				<emphasis>
					Default value of this parameter is 0.
				</emphasis>
			</para>
			<example>
				<title>Set <varname>lookup_domain</varname> parameter</title>
				<programlisting format="linespecific">
...
modparam("cpl_c","lookup_domain",1)
...
				</programlisting>
			</example>
		</section>
	</section>


	<section>
		<title>Exported Functions</title>
		<section>
			<title>
				<function moreinfo="none">cpl_run_script(type,mode)</function>
			</title>
			<para>
				Starts the execution of the CPL script. The user name is 
				fetched from new_uri or requested uri or from To header -in 
				this order- (for incoming execution) or from FROM header (for 
				outgoing execution).
				Regarding the stateful/stateless message processing, the
				function  is very flexible, being able to run in different 
				modes (see below the"mode" parameter).
				Normally this function will end script execution.  There is no 
				guaranty that the CPL script interpretation ended when ser 
				script ended also (for the same INVITE ;-)) - this can happen 
				when the CPL script does a PROXY and the script interpretation 
				pause after proxying and it will be resume when some reply is
				received (this can happen in a different process of SER). 
				If the function returns to script, the SIP server should 
				continue with the normal behavior as if no script existed.
				When some error is returned, the function itself haven't sent 
				any SIP error reply (this can be done from script).
			</para>
			<para>Meaning of the parameters is as follows:</para>
			<itemizedlist>
			<listitem>
				<para><emphasis>type</emphasis> - which part of the script 
				should be run; set it to "incoming" for having the incoming 
				part of script executed (when an INVITE is received) or to 
				"outgoing" for running the outgoing part of script (when a 
				user is generating an INVITE - call).
				</para>
			</listitem>
			<listitem>
				<para><emphasis>mode</emphasis> - sets the interpreter mode as
				stateless/stateful behavior. The following modes are accepted:
				</para>
				<itemizedlist>
				<listitem>
					<para>
					<emphasis>IS_STATELESS<emphasis> - the current INVITE has 
					no transaction created yet. All replies (redirection or 
					deny) will be done is a stateless way. The execution will 
					switch to stateful only when proxy is done. So, if the 
					function returns, will be in stateless mode.
					</para>
				</listitem>
				<listitem>
					<para>
					<emphasis>IS_STATEFUL<emphasis> - the current INVITE has 
					already a transaction associated. All signaling operations
					(replies or proxy) will be done in stateful way.So, if
					the function returns, will be in stateful mode.
					</para>
				</listitem>
				<listitem>
					<para>
					<emphasis>FORCE_STATEFUL<emphasis> - the current INVITE 
					has no transaction created yet. All signaling operations
					will be done is a stateful way (on signaling, the
					transaction will be created from within the interpreter).
					So, if the function returns, will be in stateless mode.
					</para>
				</listitem>
				</itemizedlist>
				<para>
				<emphasis>HINT</emphasis>: is_stateful is vary 
				difficult to manage from the routing script (script processing
				can continue in stateful mode); is_stateless is the fastest and
				less resources consumer (transaction is created only if
				proxying is done), but there is minimal protection against
				retransmissions (since replies are send stateless);
				force_stateful is a good compromise - all signaling is done
				stateful (retransmission protection) and in the same time, if
				returning to script, it will be in stateless mode (easy to
				continue the routing script execution)
				</para>
			</listitem>
			</itemizedlist>
			<example>
				<title><function>cpl_run_script</function> usage</title>
				<programlisting format="linespecific">
...
cpl_run_script("incoming","force_stateful");
...
				</programlisting>
			</example>
		</section>
		<section>
			<title>
				<function moreinfo="none">cpl_process_register()</function>
			</title>
			<para>
				This function MUST be called only for REGISTER requests. It 
				checks if the current REGISTER request is related or not with 
				CPL script upload/download/ remove. If it is, all the needed 
				operation will be done. For checking if the REGISTER is CPL 
				related, the function looks fist to "Content-Type" header. If 
				it exists and has a the mime type set to "application/cpl+xml" 
				means this is a CPL script upload/remove operation. The 
				distinction between to case is made by looking at 
				"Content-Disposition" header; id its value is 
				"script;action=store", means it's an upload; if it's 
				"script;action=remove", means it's a remove operation; other 
				values are considered to be errors. If no "Content-Type" 
				header is present, the function looks to "Accept" header and 
				if it contains the "*" or "application/cpl-xml" the request 
				it will be consider one for downloading CPL scripts.
				The functions returns to script only if the the REGISTER is 
				not related to CPL. In other case, the function will send by 
				itself the necessary replies (stateless - using sl), including 
				for errors.
			</para>
		</section>
	</section>


	<section>
		<title>Installation & Running</title>
		<para>Notes about installation and running.</para>
	</section>
</chapter>

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