Presence User Agent Module

Anca-Maria Vamanu

   Voice Sistem SRL

Edited by

Anca-Maria Vamanu

   Copyright © 2006 Voice Sistem SRL
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters

              3.1. hash_size (int)
              3.2. db_url (str)
              3.3. db_table (str)
              3.4. min_expires (int)
              3.5. default_expires (int)
              3.6. update_period (int)
              3.7. outbound_proxy (str)
              3.8. dlginfo_increase_version (int)
              3.9. reginfo_increase_version (int)
              3.10. db_mode (int)
              3.11. check_remote_contact (int)
              3.12. fetch_rows (integer)

        4. Functions

              4.1. pua_update_contact()

        5. MI Commands

              5.1. pua_cleanup

        6. Installation

   2. Developer Guide

        1. bind_pua(pua_api_t* api)
        2. send_publish
        3. send_subscribe
        4. is_dialog
        5. register_puacb
        6. add_event

   List of Examples

   1.1. Set hash_size parameter
   1.2. Set db_url parameter
   1.3. Set db_table parameter
   1.4. Set min_expires parameter
   1.5. Set default_expires parameter
   1.6. Set update_period parameter
   1.7. Set outbound_proxy parameter
   1.8. Set dlginfo_increase_version parameter
   1.9. Set reginfo_increase_version parameter
   1.10. Set db_mode parameter
   1.11. Set check_remote_contact parameter
   1.12. Set fetch_rows parameter
   1.13. pua_update_contact usage
   2.1. pua_api structure
   2.2. pua_is_dialog usage example
   2.3. register_puacb usage example
   2.4. add_event usage example

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Dependencies

        2.1. Kamailio Modules
        2.2. External Libraries or Applications

   3. Parameters

        3.1. hash_size (int)
        3.2. db_url (str)
        3.3. db_table (str)
        3.4. min_expires (int)
        3.5. default_expires (int)
        3.6. update_period (int)
        3.7. outbound_proxy (str)
        3.8. dlginfo_increase_version (int)
        3.9. reginfo_increase_version (int)
        3.10. db_mode (int)
        3.11. check_remote_contact (int)
        3.12. fetch_rows (integer)

   4. Functions

        4.1. pua_update_contact()

   5. MI Commands

        5.1. pua_cleanup

   6. Installation

1. Overview

   This module offer the functionality of a presence user agent client,
   sending SUBSCRIBE and PUBLISH SIP messages. It's a core part of
   Kamailio's SIP presence package, implementing SIMPLE and various shared
   line appearance implementations.

   It can be used with the following modules: pua_mi, pua_usrloc, pua_bla,
   pua_dialoginfo, pua_reginfo and pua_xmpp. The pua_mi module offer the
   possibility to publish any kind of information or subscribing to a
   resource through the manager interface. The pua_usrloc module calls a
   function exported by pua modules to publish elementary presence
   information, such as basic status "open" or "closed", for clients that
   do not implement client-to-server presence. Through pua_bla , BRIDGED
   LINE APPEARANCE features are added to Kamailio The pua_xmpp module
   represents a gateway between SIP and XMPP, so that jabber and SIP
   clients can exchange presence information. The pua_reginfo modules
   presents registration information from the usrloc module using the
   reginfo event package.

   The module supports 2 modes of operation. In the first a cache is used
   to store the presentity list and writes to database on timer to be able
   to recover upon restart. The presence is kept in-memory during
   run-time. The second is a database only mode where the presentity list
   is stored purely in a database, allowing both scalability and
   resilience.

2. Dependencies

   2.1. Kamailio Modules
   2.2. External Libraries or Applications

2.1. Kamailio Modules

   The following modules must be loaded before this module:
     * a database modules.
     * tm.

2.2. External Libraries or Applications

   The following libraries or applications must be installed before
   running Kamailio with this module loaded:
     * libxml.

3. Parameters

   3.1. hash_size (int)
   3.2. db_url (str)
   3.3. db_table (str)
   3.4. min_expires (int)
   3.5. default_expires (int)
   3.6. update_period (int)
   3.7. outbound_proxy (str)
   3.8. dlginfo_increase_version (int)
   3.9. reginfo_increase_version (int)
   3.10. db_mode (int)
   3.11. check_remote_contact (int)
   3.12. fetch_rows (integer)

3.1. hash_size (int)

   The size of the hash table used for storing SUBSCRIBE and PUBLISH
   information. This parameter will be used as the power of 2 when
   computing table size.

   Default value is "9".

   Example 1.1. Set hash_size parameter
...
modparam("pua", "hash_size", 11)
...

3.2. db_url (str)

   Database url.

   Default value is ">mysql://openser:openserrw@localhost/openser".

   Example 1.2. Set db_url parameter
...
modparam("pua", "db_url" "dbdriver://username:password@dbhost/dbname")
...

3.3. db_table (str)

   The name of the database table.

   Default value is "pua".

   Example 1.3. Set db_table parameter
...
modparam("pua", "db_table", "pua")
...

3.4. min_expires (int)

   The inferior expires limit for both Publish and Subscribe.

   Default value is "0".

   Example 1.4. Set min_expires parameter
...
modparam("pua", "min_expires", 0)
...

3.5. default_expires (int)

   The default expires value used in case this information is not
   provisioned.

   Default value is "3600".

   Example 1.5. Set default_expires parameter
...
modparam("pua", "default_expires", 3600)
...

3.6. update_period (int)

   The interval at which the information in database and hash table should
   be updated. In the case of the hash table updating means deleting
   expired messages. Setting a value less than or equal to zero, disables
   updates.

   Default value is "100".

   Example 1.6. Set update_period parameter
...
modparam("pua", "update_period", 100)
...

3.7. outbound_proxy (str)

   SIP URI of outbound proxy to be used when sending PUBLISH requests.

   By default, no outbound proxy has been defined.

   Example 1.7. Set outbound_proxy parameter
...
modparam("pua", "outbound_proxy", "sip:outbound.example.com")
...

3.8. dlginfo_increase_version (int)

   When sending PUBLISH messages for Event: dialog, the body contains an
   XML document according to RFC 4235. This XML document contains a
   version attribute to easily detect changes in the dialog state. By
   setting this parameter, the pua module parses the XML document and sets
   the version attribute to the proper value. If the receiver of the
   PUBLISH does not care about the version parameter (e.g. like Kamailio
   presence_dialoginfo module) it makes no sense to waste CPU resources
   for parsing the XML body and the parameter should be set to 0.

   Default value is "0".

   Example 1.8. Set dlginfo_increase_version parameter
...
modparam("pua", "dlginfo_increase_version", 1)
...

3.9. reginfo_increase_version (int)

   When sending PUBLISH messages for Event: reg, the body contains an XML
   document according to RFC 4235(?). This XML document contains a version
   attribute to easily detect changes in the registration state. By
   setting this parameter, the pua module parses the XML document and sets
   the version attribute to the proper value. If the receiver of the
   PUBLISH does not care about the version parameter (e.g. like Kamailio
   presence_reginfo module) it makes no sense to waste CPU resources for
   parsing the XML body and the parameter should be set to 0.

   Default value is "0".

   Example 1.9. Set reginfo_increase_version parameter
...
modparam("pua", "reginfo_increase_version", 1)
...

3.10. db_mode (int)

   The module supports 2 modes of operation, high speed memory based
   storage (mode 0), and database only (mode 2) where all data is stored
   in a database, allowing scalability at the expense of speed. Mode 1 is
   reserved.

   Default value is "0".

   Example 1.10. Set db_mode parameter
...
modparam("pua", "db_mode", 0)
...

3.11. check_remote_contact (int)

   When sending a SUBSCRIBE check that the remote contact matches the one
   in the stored dialog or not. If the remote contact is checked and does
   not match the one in the stored dialog then the dialog is not matched.
   Checking the remote contact can cause problems when using modules like
   RLS and should not be required in order to properly match the dialog
   anyway. Set this parameter to 0 to disable checking of remote contact
   for SUBSCRIBE dialog matching.

   Default value is "1".

   Example 1.11. Set check_remote_contact parameter
...
modparam("pua", "check_remote_contact", 0)
...

3.12. fetch_rows (integer)

   Number of rows to be loaded in one step from database.

   Default value is 500.

   Example 1.12. Set fetch_rows parameter
...
modparam("pua", "fetch_rows", 1000)
...

4. Functions

   4.1. pua_update_contact()

4.1. pua_update_contact()

   The remote target can be updated by the Contact of a subsequent in
   dialog request. In the PUA watcher case (sending a SUBSCRIBE messages),
   this means that the remote target for the following Subscribe messages
   can be updated at any time by the contact of a Notify message. If this
   function is called on request route on receiving a Notify message, it
   will try to update the stored remote target.

   This function can be used from REQUEST_ROUTE.

   Return code:
     * 1 - if success.
     * -1 - if error.

   Example 1.13. pua_update_contact usage
...
if(method=="NOTIFY")
    pua_update_contact();
...

5. MI Commands

   5.1. pua_cleanup

5.1. pua_cleanup

   Manually triggers the cleanup functions for the pua table. Useful if
   you have set update_period to zero or less.

   Name: pua_cleanup

   Parameters: none

   MI FIFO Command Format:
                :pua_cleanup:fifo_reply
                _empty_line_

6. Installation

   The module requires one table in the Kamailio database: pua. The SQL
   syntax to create it can be found in presence_xml-create.sql script in
   the database directories in the kamailio/scripts folder. You can also
   find the complete database documentation on the project webpage,
   http://www.kamailio.org/docs/db-tables/kamailio-db-devel.html.

Chapter 2. Developer Guide

   Table of Contents

   1. bind_pua(pua_api_t* api)
   2. send_publish
   3. send_subscribe
   4. is_dialog
   5. register_puacb
   6. add_event

   The module provides the following functions that can be used by other
   Kamailio modules.

1. bind_pua(pua_api_t* api)

   This function binds the pua modules and fills the structure with the
   two exported functions.

   Example 2.1. pua_api structure
...
typedef struct pua_api {
        send_subscribe_t send_subscribe;
        send_publish_t send_publish;
        query_dialog_t is_dialog;
        register_puacb_t register_puacb;
        add_pua_event_t add_event;
} pua_api_t;
...

2. send_publish

   Field type:
...
typedef int (*send_publish_t)(publ_info_t* publ);
...

   This function receives as a parameter a structure with Publish required
   information and sends a Publish message.

   The structure received as a parameter:
...
typedef struct publ_info

  str id;             /*  (optional )a value unique for one combination
                          of pres_uri and flag */
  str* pres_uri;      /*  the presentity uri */
  str* body;          /*  the body of the Publish message;
                          can be NULL in case of an update expires*/
  int  expires;       /*  the expires value that will be used in
                          Publish Expires header*/
  int flag;           /*  it can be : INSERT_TYPE or UPDATE_TYPE
                          if missing it will be established according
                          to the result of the search in hash table*/
  int source_flag;    /*  flag identifying the resource ;
                          supported values: UL_PUBLISH, MI_PUBLISH,
                          BLA_PUBLISH, XMPP_PUBLISH*/
  int event;          /*  the event flag;
                          supported values: PRESENCE_EVENT, BLA_EVENT,
                          MWI_EVENT */
  str content_type;   /*  the content_type of the body if present
                          (optional if the same as the default value
                          for that event)*/
  str* etag;          /*  (optional) the value of the etag the request
                          should match */
  str* extra_headers  /*  (optional) extra_headers that should be added
                          to Publish msg*/
}publ_info_t;
...

3. send_subscribe

   Field type:
...
typedef int (*send_subscribe_t)(subs_info_t* subs);
...

   This function receives as a parameter a structure with Subscribe
   required information and sends a Subscribe message.

   The structure received as a parameter:
...
typedef struct subs_info

  str id;              /*  an id value unique for one combination
                           of pres_uri and flag */
  str* pres_uri;       /*  the presentity uri */
  str* watcher_uri;    /*  the watcher uri */
  str* contact;        /*  the uri that will be used in
                           Contact header*/
  str* remote_target;  /*  the uri that will be used as R-URI
                           for the Subscribe message(not compulsory;
                           if not set the value of the pres_uri field
                           is used) */
  str* outbound_proxy; /*  the outbound_proxy to use when sending the
                           Subscribe request*/
  int event;           /*  the event flag; supported value:
                           PRESENCE_EVENT, BLA_EVENT, PWINFO_EVENT*/
  int expires;         /*  the expires value that will be used in
                           Subscribe Expires header */
  int flag;            /*  it can be : INSERT_TYPE or UPDATE_TYPE
                           not compulsory */
  int source_flag;     /*  flag identifying the resource ;
                           supported values:  MI_SUBSCRIBE,
                           BLA_SUBSCRIBE, XMPP_SUBSCRIBE,
                           XMPP_INITIAL_SUBS */
}subs_info_t;
...

4. is_dialog

   Field type:
...
typedef int  (*query_dialog_t)(ua_pres_t* presentity);
...

   This function checks is the parameter corresponds to a stored Subscribe
   initiated dialog.

   Example 2.2. pua_is_dialog usage example
...
        if(pua_is_dialog(dialog) < 0)
        {
                LM_ERR("querying dialog\n");
                goto error;
        }
...

5. register_puacb

   Field type:
...
typedef int (*register_puacb_t)(int types, pua_cb f, void* param );
...

   This function registers a callback to be called on receiving the reply
   message for a sent Publish or Subscribe request. The type parameter
   should be set the same as the source_flag for that request. The
   function registered as callback for pua should be of type pua_cb ,
   which is: typedef void (pua_cb)(ua_pres_t* hentity, struct msg_start *
   fl); The parameters are the dialog structure for that request and the
   first line of the reply message.

   Example 2.3. register_puacb usage example
...
        if(pua.register_puacb(XMPP_SUBSCRIBE, Sipreply2Xmpp, NULL) & 0)
        {
                LM_ERR("Could not register callback\n");
                return -1;
        }
...

   The callback function type:
...
typedef int (pua_cb)(ua_pres_t* hentity, struct sip_msg*);
...

6. add_event

   Field type:
...
typedef int (*add_pua_event_t)(int ev_flag, char* name,
   char* content_type,evs_process_body_t* process_body);

- ev_flag     : an event flag defined as a macro in pua module
- name        : the event name to be used in Event request headers
- content_type: the default content_type for Publish body for
                that event (NULL if winfo event)
- process_body: function that processes the received body before
                using it to construct the PUBLISH request
                (NULL if winfo event)
...

   This function allows registering new events to the pua module. Now
   there are 4 events supported by the pua module: presence,
   presence;winfo, message-summary, dialog;sla, application/reginfo+xml.
   These events are registered from within the pua module.

   Filed type for process_body:
...
typedef int (evs_process_body_t)(struct publ_info* publ,
  str** final_body, int ver, str* tuple);
- publ      : the structure received as a parameter in send_publish
              function ( initial body found in publ->body)
- final_body: the pointer where the result(final_body) should be stored
- ver       : a counter for the sent Publish requests
              (used for winfo events)
- tuple     : a unique identifier for the resource;
              if an initial Publish it should be returned as a result
              and it will be stored  for that record, otherwise it will
              be given as a parameter;
...

   Example 2.4. add_event usage example
...
        if(pua.add_event((PRESENCE_EVENT, "presence", "application/pidf+xml",
                                pres_process_body) & 0)
        {
                LM_ERR("Could not register new event\n");
                return -1;
        }
...
