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

<chapter>
    
    <title>&develguide;</title>
	<para>
		The module exports a number of functions that allow selecting 
		and retrieving an element from an xcap server and also registering
		a callback to be called when the management command refreshXcapDoc is received
		and the document in question is retrieved.
   </para>
   <section>
      <title>
	     <function moreinfo="none">bind_xcap_api(xcap_api_t* api)</function>
     </title>
		<para>
		This function allows binding the needed functions. 
		</para>
			<example>
			<title><function>xcap_api</function> structure</title>
			<programlisting format="linespecific">
...
typedef struct xcap_api {
	
	/* xcap node selection and retrieving functions*/
	xcap_get_elem_t get_elem;
	xcap_nodeSel_init_t int_node_sel;
	xcap_nodeSel_add_step_t add_step;
	xcap_nodeSel_add_terminal_t add_terminal;
	xcap_nodeSel_free_t free_node_sel;
	xcapGetNewDoc_t getNewDoc; /* an initial request for the module 
	fo fetch this document that does not exist in xcap db table
	and handle its update*/

	/* function to register a callback to document changes*/
	register_xcapcb_t register_xcb;
}xcap_api_t;
...
			</programlisting>
			</example>
	</section>
	
	<section>
		<title>
			<function moreinfo="none">get_elem</function>
		</title>
		<para>
			Field type:
				<programlisting format="linespecific">
...
typedef char* (*xcap_get_elem_t)(char* xcap_root,
xcap_doc_sel_t* doc_sel, xcap_node_sel_t* node_sel);
...
				</programlisting>
		</para>		
		<para>
			This function sends a HTTP request and gets the specified information
			from the xcap server.
		</para>
		<para>
		The parameters signification:
		</para>
			<itemizedlist>
			<listitem>
			<para>
				<emphasis>xcap_root</emphasis>-
				the XCAP server address;
			</para>
			</listitem>
			<listitem>
			<para>
				<emphasis>doc_sel</emphasis>-
				structure with document selection info;
			</para>
			<programlisting format="linespecific">
Parameter type:
...
typedef struct xcap_doc_sel
{
	str auid; /* application defined Unique ID*/
	int type; /* the type of the path segment
				after the AUID  which must either
				be GLOBAL_TYPE (for "global") or
				USERS_TYPE (for "users") */ 
	str xid; /* the XCAP User Identifier 
				if type is USERS_TYPE */
	str filename; 
}xcap_doc_sel_t;
...
</programlisting>
</listitem>
			
<listitem>
<para>
<emphasis>node_sel</emphasis>-
structure with node selection info;
</para>
<programlisting format="linespecific">
Parameter type:
...
typedef struct xcap_node_sel
{
	step_t* steps;
	step_t* last_step;
	int size;
	ns_list_t* ns_list;
	ns_list_t* last_ns;
	int ns_no;

}xcap_node_sel_t;

typedef struct step
{
	str val;
	struct step* next;
}step_t;

typedef struct ns_list
{
	int name;
	str value;
	struct ns_list* next;
}ns_list_t;
...

</programlisting>
		<para>
		The node selector is represented like a list of steps that will
		be represented in the path string separated by '/' signs. 
		The namespaces for the nodes are stored also in a list, as an
		association of name and value, where the value is to be included
		in the respective string val field of the step.
		</para>
		<para>
		To construct the node structure the following functions in the xcap_api
		structure should be used: 'int_node_sel', 'add_step' and if needed, 
		'add_terminal'.
		</para>
		<para>
		If the intention is to retrieve the whole document this argument must
		be NULL.
		</para>
		</listitem>
		</itemizedlist>	
	
		</section>
<section>
		<title>
			<function moreinfo="none">register_xcb</function>
		</title>
		<para>
			Field type:
				<programlisting format="linespecific">
...
typedef int (*register_xcapcb_t)(int types, xcap_cb f);
...
	</programlisting>
	</para>
	<para>
	- 'types' parameter can have a combined value of PRES_RULES, RESOURCE_LIST,
	RLS_SERVICES and PIDF_MANIPULATION.
	</para>
	<para>
	-the callback function has type :
	<programlisting format="linespecific">
...
typedef int (xcap_cb)(int doc_type, str xid, char* doc);
...
	</programlisting>
	</para>
	</section>	
	</chapter>

