Presence Module

Anca-Maria Vamanu

Voice Sistem SRL

Juha Heinanen

TutPro Inc.

Edited by

Anca-Maria Vamanu

Edited by

Juha Heinanen


Table of Contents

1. Admin Guide
1. Overview
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
3. Parameters
3.1. db_url(str)
3.2. presentity_table(str)
3.3. active_watchers_table(str)
3.4. watchers_table(str)
3.5. clean_period (int)
3.6. cseq_offset (int)
3.7. db_update_period (int)
3.8. waitn_time (int)
3.9. notifier_poll_rate (int)
3.10. notifier_processes (int)
3.11. force_delete (int)
3.12. startup_mode (int)
3.13. to_tag_pref (str)
3.14. expires_offset (int)
3.15. max_expires (int)
3.16. min_expires (int)
3.17. min_expires_action (int)
3.18. server_address (str)
3.19. subs_db_mode (int)
3.20. publ_cache (int)
3.21. subs_htable_size (int)
3.22. pres_htable_size (int)
3.23. send_fast_notify (int)
3.24. enable_sphere_check (int)
3.25. timeout_rm_subs (int)
3.26. fetch_rows (integer)
3.27. db_table_lock_type (integer)
3.28. local_log_level (int)
3.29. local_log_facility (int)
3.30. subs_remove_match (int)
3.31. xavp_cfg (str)
3.32. retrieve_order (int)
3.33. retrieve_order_by (str)
3.34. sip_uri_match (int)
3.35. enable_dmq (integer)
4. Functions
4.1. handle_publish([sender_uri])
4.2. handle_subscribe([watcher_uri])
4.3. pres_auth_status(watcher_uri, presentity_uri)
4.4. pres_has_subscribers(presentity_uri, event)
4.5. pres_refresh_watchers(uri, event, type[, file_uri, filename])
4.6. pres_update_watchers(uri, event)
5. RPC Commands
5.1. presence.cleanup
5.2. presence.refreshWatchers
6. Exported Variables
6.1. $subs(attr)
6.2. $notify_reply(attr)
7. Events
7.1. present:notify-reply
8. Installation
2. Developer Guide
1. bind_presence(presence_api_t* api)
2. add_event
3. get_rules_doc
4. get_auth_status
5. apply_auth_nbody
6. agg_nbody
7. free_body
8. aux_body_processing
9. aux_free_body
10. evs_publ_handl
11. evs_subs_handl
12. contains_event
13. get_event_list
14. update_watchers_status
15. get_sphere
16. get_presentity
17. free_presentity

List of Examples

1.1. Set db_url parameter
1.2. Set presentity_table parameter
1.3. Set active_watchers_table parameter
1.4. Set watchers_table parameter
1.5. Set clean_period parameter
1.6. Set cseq_offset parameter
1.7. Set db_update_period parameter
1.8. Set waitn_time parameter
1.9. Set notifier_poll_rate parameter
1.10. Set notifier_processes parameter
1.11. Set force_delete parameter
1.12. Set startup_mode parameter
1.13. Set to_tag_pref parameter
1.14. Set expires_offset parameter
1.15. Set max_expires parameter
1.16. Set min_expires parameter
1.17. Set min_expires parameter
1.18. Set server_address parameter
1.19. Set subs_db_mode parameter
1.20. Set publ_cache parameter
1.21. Set subs_htable_size parameter
1.22. Set pres_htable_size parameter
1.23. Set send_fast_notify parameter
1.24. Set enable_sphere_check parameter
1.25. Set timeout_rm_subs parameter
1.26. Set fetch_rows parameter
1.27. Set db_table_lock_type parameter
1.28. Set local_log_level parameter
1.29. Set local_log_facility parameter
1.30. Set subs_remove_match parameter
1.31. Set xavp_cfg parameter
1.32. Set retrieve_order parameter
1.33. Set retrieve_order_by parameter
1.34. Set sip_uri_match parameter
1.35. Set enable_dmq parameter
1.36. handle_publish usage
1.37. handle_subscribe usage
1.38. pres_auth_status usage
1.39. pres_has_subscribers usage
1.40. pres_refresh_watchers usage
1.41. pres_update_watchers usage
1.42. $subs(name) usage
1.43. $notify_reply(name) usage
1.44. $notify_reply(name) usage
2.1. presence_api_t structure

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. db_url(str)
3.2. presentity_table(str)
3.3. active_watchers_table(str)
3.4. watchers_table(str)
3.5. clean_period (int)
3.6. cseq_offset (int)
3.7. db_update_period (int)
3.8. waitn_time (int)
3.9. notifier_poll_rate (int)
3.10. notifier_processes (int)
3.11. force_delete (int)
3.12. startup_mode (int)
3.13. to_tag_pref (str)
3.14. expires_offset (int)
3.15. max_expires (int)
3.16. min_expires (int)
3.17. min_expires_action (int)
3.18. server_address (str)
3.19. subs_db_mode (int)
3.20. publ_cache (int)
3.21. subs_htable_size (int)
3.22. pres_htable_size (int)
3.23. send_fast_notify (int)
3.24. enable_sphere_check (int)
3.25. timeout_rm_subs (int)
3.26. fetch_rows (integer)
3.27. db_table_lock_type (integer)
3.28. local_log_level (int)
3.29. local_log_facility (int)
3.30. subs_remove_match (int)
3.31. xavp_cfg (str)
3.32. retrieve_order (int)
3.33. retrieve_order_by (str)
3.34. sip_uri_match (int)
3.35. enable_dmq (integer)
4. Functions
4.1. handle_publish([sender_uri])
4.2. handle_subscribe([watcher_uri])
4.3. pres_auth_status(watcher_uri, presentity_uri)
4.4. pres_has_subscribers(presentity_uri, event)
4.5. pres_refresh_watchers(uri, event, type[, file_uri, filename])
4.6. pres_update_watchers(uri, event)
5. RPC Commands
5.1. presence.cleanup
5.2. presence.refreshWatchers
6. Exported Variables
6.1. $subs(attr)
6.2. $notify_reply(attr)
7. Events
7.1. present:notify-reply
8. Installation

1. Overview

The Presence module implements the core functionality of SIP event notification. It handles PUBLISH and SUBSCRIBE messages and generates NOTIFY messages in a general, event independent way. It is extensible and allows registering events to it from other Kamailio modules. Supported SIP event packages are presence, presence.winfo, dialog;sla from the presence_xml module and message-summary from the presence_mwi module.

The module can use database and memory storage (to improve performance). For subscriptions it supports the 4 storage modes: Memory Only, Write Back, Write Through and DB Only. For publishes, it stores the state documents in database only(because of the large size) and it can store a publish cache in memory to avoid unnecessary database queries. Read the subs_db_mode and publ_cache parameter sections to decide which is the best storage configuration for you.

The module implements several API functions, that can be used by other modules. In fact, it can be used only as a resource module, or "library". This mode of operation is enabled if the db_url parameter is not set to any value.

The Kamailio Presence module implements the specifications in: RFC3265, RFC3856, RFC3857, RFC3858.

2. Dependencies

2.1. Kamailio Modules

The following modules must be loaded before this module:

  • a database module.

  • sl.

  • tm.

  • dmq (only if replication is enabled).

2.2. External Libraries or Applications

  • libxml.

3. Parameters

3.1. db_url(str)

The database url.

If set, the module is a fully operational presence server. Otherwise, it is used as a 'library', for its exported functions.

Default value is NULL.

Example 1.1. Set db_url parameter

...
modparam("presence", "db_url",
	"mysql://kamailio:kamailiorw@localhost/kamailio")
...

3.2. presentity_table(str)

The name of the db table where PUBLISH presence information is stored.

Default value is presentity.

Example 1.2. Set presentity_table parameter

...
modparam("presence", "presentity_table", "presentity")
...

3.3. active_watchers_table(str)

The name of the db table where active subscription information is stored.

Default value is active_watchers.

Example 1.3. Set active_watchers_table parameter

...
modparam("presence", "active_watchers_table", "active_watchers")
...

3.4. watchers_table(str)

The name of the db table where subscription states are stored.

Default value is watchers.

Example 1.4. Set watchers_table parameter

...
modparam("presence", "watchers_table", "watchers")
...

3.5. clean_period (int)

The period in seconds between checks if there are expired messages stored in database.

Default value is 100. A zero or negative value disables this activity.

Example 1.5. Set clean_period parameter

...
modparam("presence", "clean_period", 100)
...

3.6. cseq_offset (int)

The allowed offset between server and client cseq.

Default value is 0.

Example 1.6. Set cseq_offset parameter

                ...
                modparam("presence", "cseq_offset", 1)
                ...

3.7. db_update_period (int)

The period at which to synchronize cached subscriber info with the database.

Default value is 100. A zero or negative value disables synchronization.

Example 1.7. Set db_update_period parameter

...
modparam("presence", "db_update_period", 100)
...

3.8. waitn_time (int)

The maximum time period that NOTIFY requests will be buffered for. The server will attempt to send NOTIFY requests within many seconds of a change occurring.

Note: this parameter is only used when notifier_processes is greater than 0. When notifier_processes is less than or equal to 0 NOTIFY requests are sent immediately.

Default value is 5.

Example 1.8. Set waitn_time parameter

...
modparam("presence", "waitn_time", 10)
...

3.9. notifier_poll_rate (int)

The number of times per second that the notifier processes should check for work. Approximately 1/(waitn_time * notifier_poll_rate * notifier_processes) of the pending updates will be sent each time a notifier process runs.

Separate notifier processes are only run when subs_db_mode is 3 (DB only mode).

Default value is 10.

Example 1.9. Set notifier_poll_rate parameter

...
modparam("presence", "notifier_poll_rate", 20)
...

3.10. notifier_processes (int)

The number of notifier processes that should be started.

Separate notifier processes are only run when subs_db_mode is 3 (DB only mode).

Note: setting this parameter to 0 when subs_db_mode is 3 keeps the old behaviour (sending NOTIFY requests immediately). This (old) behaviour is disabled by default in DB only mode because under load, when lots of NOTIFY requests can be sent on a dialog at the same time, there are race conditions which result in CSeq re-use.

Default value is 1.

Example 1.10. Set notifier_processes parameter

...
modparam("presence", "notifier_processes", 2)
...

3.11. force_delete (int)

Enabling this parameter will delete expired presentity records without updating watchers.

Set this parameter to 1 to enable.

Default value is 0.

Example 1.11. Set force_delete parameter

...
modparam("presence", "force_delete", 1)
...

3.12. startup_mode (int)

Setting this parameter to 0 will provide startup related backward compatibility for some modules. Setting to 0 fixes presentity requests with low expires (e.g. time() + 1)

Set this parameter to 0 to enable backward compatibility.

Default value is 1.

Example 1.12. Set startup_mode parameter

...
modparam("presence", "startup_mode", 0)
...

3.13. to_tag_pref (str)

The prefix used when generating to_tag when sending replies for SUBSCRIBE requests.

Default value is 10.

Example 1.13. Set to_tag_pref parameter

...
modparam("presence", "to_tag_pref", 'pres')
...

3.14. expires_offset (int)

The value in seconds that should be subtracted from the expires value when sending a 200OK for a publish. It is used for forcing the client to send an update before the old publish expires.

Default value is 0.

Example 1.14. Set expires_offset parameter

...
modparam("presence", "expires_offset", 10)
...

3.15. max_expires (int)

The maximum admissible expires value for PUBLISH/SUBSCRIBE message (in seconds).

Default value is 3600.

Example 1.15. Set max_expires parameter

...
modparam("presence", "max_expires", 3600)
...

3.16. min_expires (int)

The minimum admissible expires value for PUBLISH/SUBSCRIBE message (in seconds).

If > 0 then min_expires_action parameter determines the response.

Default value is 0.

Example 1.16. Set min_expires parameter

            ...
            modparam("presence", "min_expires", 1800)
            ...

3.17. min_expires_action (int)

The action to take when UA sends a expires value less then min_expires.

Possible Values

  • 1 : RFC Compliant, returns 423 Interval Too Brief

  • 2 : forces the min_expires value in the subscription

If > 0 then min_expires_action parameter determines the response.

Default value is 1.

Example 1.17. Set min_expires parameter

            ...
            modparam("presence", "min_expires", 1800)
            ...

3.18. server_address (str)

The presence server address which will become the value of Contact header filed for 200 OK replies to SUBSCRIBE and PUBLISH and in NOTIFY messages.

Example 1.18. Set server_address parameter

...
modparam("presence", "server_address", "sip:10.10.10.10:5060")
...

3.19. subs_db_mode (int)

The presence module can utilize database for persistent subscription storage. If you use database, your subscriptions will survive machine restarts or SW crashes. The disadvantage is that accessing database can be time consuming. Therefore, presence module implements four database accessing modes:

  • 0 - This disables database completely. Only memory will be used. Subscriptions will not survive restart. Use this value if you need a really fast presence module and subscription persistence is not necessary or is provided by other means.

  • 1 - Write-Through scheme. Subscriptions are updated synchronously in database and in memory(used for read operations). Use this scheme if speed is not top priority, but it's important that no subscriptions will be lost during crash or reboot or if you have an external application that reads the state of the subscriptions from database and they need to be updated synchronously.

  • 2 - Write-Back scheme. This is a combination of previous two schemes. All changes are made to memory and database synchronization is done in the timer. The timer deletes all expired contacts and flushes all modified or new subscriptions to database. Use this scheme if you encounter high-load peaks and want them to process as fast as possible. Latency of this mode is much lower than latency of mode 1, but slightly higher than latency of mode 0. To control the interval at which data is flushed to database, set the db_update_period parameter.

  • 3 - DB-Only scheme. No memory cache is kept, all operations being directly performed with the database. The timer deletes all expired subscriptions from database. The mode is useful if you configure more servers sharing the same DB without any replication at SIP level. The mode may be slower due the high number of DB operation.

Default value is 2 (Write-Back scheme).

Example 1.19. Set subs_db_mode parameter

...
modparam("presence", "subs_db_mode", 1)
...

3.20. publ_cache (int)

To improve performance, the presence module holds by default a publish cache that says if a certain publication exists in database. This is only a list of URI + event, so it does not use much memory. The cache is used when a Subscription is received to check if there is any published state in database. This way unnecessary queries in presentity table are avoided.

Setting this parameter to 0 will disable the usage of the publish cache. This is desirable when you have more servers sharing the same database or there are other external entities inserting data into the presentity table.

Default value is 1.

Example 1.20. Set publ_cache parameter

...
modparam("presence", "publ_cache", 0)
...

3.21. subs_htable_size (int)

The size of the in-memory hash table to store subscription dialogs. This parameter will be used as the power of 2 when computing table size.

Default value is 9 (512).

Example 1.21. Set subs_htable_size parameter

...
modparam("presence", "subs_htable_size", 11)
...

3.22. pres_htable_size (int)

The size of the in-memory hash table to store publish records. This parameter will be used as the power of 2 when computing table size.

Default value is 9 (512).

Example 1.22. Set pres_htable_size parameter

...
modparam("presence", "pres_htable_size", 11)
...

3.23. send_fast_notify (int)

This parameter enables or disables the sending of an initial empty NOTIFY after a SUBSCRIBE/reSUBSCRIBE. This caused problems for MWI application, because some CPEs (like Samsung) fail to understand an empty NOTIFY to an message-summary event. This parameter is enabled by default, thus adhering to the standard.

Default value is 1 .

Example 1.23. Set send_fast_notify parameter

...
modparam("presence", "send_fast_notify", 0)
...

3.24. enable_sphere_check (int)

This parameter is a flag that should be set if permission rules include sphere checking. The sphere information is expected to be present in the RPID body published by the presentity. The flag is introduced as this check requires extra processing that should be avoided if this feature is not supported by the clients.

Default value is 0 .

Example 1.24. Set enable_sphere_check parameter

...
modparam("presence", "enable_sphere_check", 1)
...

3.25. timeout_rm_subs (int)

This parameter is a flag that should be set if subscriptions should be removed from the active_watchers when a NOTIFY times out. RFC3265 section 3.2.2 defines this behaviour as a SHOULD, so by default it is on. Disabling this will keep subscriptions active on unreliable networks.

Default value is 1.

Example 1.25. Set timeout_rm_subs parameter

...
modparam("presence", "timeout_rm_subs", 0)
...

3.26. fetch_rows (integer)

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

Default value is 500.

Example 1.26. Set fetch_rows parameter

...
modparam("presence", "fetch_rows", 1000)
...

3.27. db_table_lock_type (integer)

Enable (=1) or disable (=0) the Locks for table during an transaction. Locking only the "current" table causes problems with a MySQL-Databases in "DB-Only" mode.

In order to use the Presence-Module in "DB_ONLY"-mode with a MySQL-Backend, set this parameter to "0", otherwise the MySQL-Operations will fail. The Presence-Module will generate a "500 Server error" due to the failed MySQL-queries.

Default value is 1 (Write Lock for the Tables).

Example 1.27. Set db_table_lock_type parameter

...
modparam("presence", "db_table_lock_type", 0)
...

3.28. local_log_level (int)

Control log level for some debug messages inside the module.

Default value is 2 (L_INFO).

Example 1.28. Set local_log_level parameter

...
modparam("presence", "local_log_level", 3)
...

3.29. local_log_facility (int)

Control syslog facility for some debug messages inside the module.

Default value is taken from the core log_facility configuration parameter.

Example 1.29. Set local_log_facility parameter

...
modparam("presence", "local_log_facility", "LOG_LOCAL3")
...

3.30. subs_remove_match (int)

Control how to match the subscriptions to remove from memory. If set to 0, then the match is done on To-Tag (local generated), if set to 1, then the match is done on all dialog attributes (Call-Id, From-Tag, To-Tag).

Default value is 0.

Example 1.30. Set subs_remove_match parameter

...
modparam("presence", "subs_remove_match", 1)
...

3.31. xavp_cfg (str)

The name of the xavp to be used to specify attributes for internal processing of presence module.

Inner attributes inside xavp can be:

  • priority - integer value to set the priority of the presence document (higher value, higher priority). It can set the order of the aggregated presence documents sent by NOTIFY (first the document with higher priority). If xavp_cfg parameter is set but this attribute is not in the avp, the priority of the presence document is based on timestamp, so newer documents have higher priority.

  • delete_subscription - integer value to give extra control of deleting the subscription after processing of event_route[presence:notify-reply]. If value = 1, it deletes the subscription. If xavp_cfg parameter is set but this attribute is not in the avp, the subscription is not deleted. this does not apply for codes 404, 481 and 408 (when timeout_rm_subs = 1) where subscription is deleted.

Default value is empty (not set).

Example 1.31. Set xavp_cfg parameter

...
modparam("presence", "xavp_cfg", "pres")
...
if(is_method("PUBLISH")) {
    $xavp(pres=>priority) = 100;
}
...

3.32. retrieve_order (int)

If set to 0, presentity records are retrieve by received_time order. If set to 1, presentity records are retrieve by the value of retrieve_order_by parameter.

Default value is 0.

Example 1.32. Set retrieve_order parameter

...
modparam("presence", "retrieve_order", 1)
...

3.33. retrieve_order_by (str)

Used to set the order-by of the db query for fetching the presence records when retrieve_order is set to 1.

Default value is priority.

Example 1.33. Set retrieve_order_by parameter

...
modparam("presence", "retrieve_order_by", "priority, received_time")
...

3.34. sip_uri_match (int)

The mode used when comparing uris.

Possible Values

  • 0 : case sensitive

  • 1 : case insensitive

Default value is 0.

Example 1.34. Set sip_uri_match parameter

            ...
            modparam("presence", "sip_uri_match", 1)
            ...

3.35. enable_dmq (integer)

If set to 1, will enable DMQ replication of presentities between nodes. Use this instead of a shared DB to share state across a cluster and update local watchers in realtime (subs_db_mode < 3) or on next notifier run (subs_db_mode = 3).

If this parameter is enabled, the DMQ module must be loaded first - otherwise, startup will fail.

Default value is 0.

Example 1.35. Set enable_dmq parameter

			...
			modparam("presence", "enable_dmq", 1)
			...

4. Functions

4.1.  handle_publish([sender_uri])

Handles PUBLISH requests by storing and updating published information in memory cache and database, then calls functions to send NOTIFY messages when changes in the published information occur. It takes one argument -> sender_uri. The parameter was added for enabling BLA implementation. If present, notification of a change in published state is not sent to the respective uri even though a subscription exists. It should be taken from the Sender header. It was left at the decision of the administrator whether or not to transmit the content of this header as parameter for handle_publish, to prevent security problems.

This function can be used from REQUEST_ROUTE.

Return code:

  • 1 - if success.

  • -1 - if error.

The module sends an appropriate stateless reply in all cases.

Example 1.36. handle_publish usage

...
	if(is_method("PUBLISH"))
	{
		if($hdr(Sender)!= NULL)
			handle_publish("$hdr(Sender)");
		else
			handle_publish();
		t_release();
	}
...

4.2.  handle_subscribe([watcher_uri])

The function which handles SUBSCRIBE requests. It stores or updates information in memory and database and calls functions to send NOTIFY messages when a SUBSCRIBE which initiate a dialog is received.

By default this function uses the From: URI from the SUBSCRIBE request as the Watcher URI. The optional watcher_uri parameter can be used to specify a different Watcher URI, possibly taken from a SIP header like P-Asserted-Identity:.

This function can be used from REQUEST_ROUTE.

Return code:

  • 1 - if success.

  • -1 - if error.

The module sends an appropriate stateless reply in all cases.

Example 1.37. handle_subscribe usage

...
if(method=="SUBSCRIBE")
    handle_subscribe();
...

4.3.  pres_auth_status(watcher_uri, presentity_uri)

The function checks if watcher URI is authorized to subscribe event 'presence' of presentity URI. Both watcher_uri and presentity_uri can be static strings or contain pseudo variables.

The function returns ACTIVE_STATUS, if subscription is allowed, and PENDING_STATUS, TERMINATED_STATUS, or WAITING_STATUS otherwise. See presence/subscribe.h for the corresponding integer codes. In case of error, function returns -1.

This function can be used from REQUEST_ROUTE.

Example 1.38. pres_auth_status usage

...
if (method=="MESSAGE") {
    pres_auth_status("$fu", $ru");
    if ($retcode == 1) {
        t_relay();
    } else {
        send_reply("403", "Forbidden");
    }
}
...

4.4.  pres_has_subscribers(presentity_uri, event)

Allows to check if presentity has any subscribers of event.

This function can be used from ANY_ROUTE.

Example 1.39. pres_has_subscribers usage

            ...
            if(pres_has_subscribers($var(uri), "message-summary"))
            do something...;
            ...

4.5.  pres_refresh_watchers(uri, event, type[, file_uri, filename])

The function can be used in configuration to trigger notifies to watchers if a change in watchers authorization or in published state occurred (i.e., updates of xcap documents).

Parameters:

  • uri - the uri of the user who made the change and whose watchers should be informed.

  • event - the event package.

  • type - it distinguishes between the three different types of events that can trigger the refresh, depending on its value:

    • 0 - a change in watchers authentication.

    • 1 - a statical update in published state through direct update in db table.

    • 2 - a statical update in published state by modifying the pidf manipulation document.

  • file_uri - the uri of the pidf-manipulation file on the XCAP server (only used for type 2).

  • filename - the name of the pidf-manipulation file on the XCAP server (only used for type 2).

This function can be used from ANY_ROUTE.

Example 1.40. pres_refresh_watchers usage

...
pres_refresh_watchers("sip:test@kamailio.org", "presence", 1);
...

4.6.  pres_update_watchers(uri, event)

The function can be used in configuration to triger updates to watchers status if a change in watchers authorization state occurred (i.e., updates of xcap documents change state from pending to active).

Parameters:

  • uri - the uri of the user who made the change and whose watchers should be informed. Can be PV.

  • event - the event package (e.g., presence).

This function can be used from ANY_ROUTE.

Example 1.41. pres_update_watchers usage

...
pres_update_watchers("sip:test@kamailio.org", "presence");
...

5. RPC Commands

5.1. presence.cleanup

Manually triggers the cleanup functions for the active_watchers, presentity, and watchers tables. Useful if you have set clean_period and/or db_update_period to zero or less.

Name: presence.cleanup

Parameters: none

RPC Command Format:

...
kamcmd presence.cleanup
...

5.2. presence.refreshWatchers

Triggers sending Notify messages to watchers if a change in watchers authorization or in published state occurred.

Name: presence.refreshWatchers

Parameters:

  • uri - the uri of the user who made the change and whose watchers should be informed

  • event - the event package.

  • type - it distinguishes between the three different types of events that can trigger the refresh, depending on its value:

    • 0 - a change in watchers authentication.

    • 1 - a statical update in published state through direct update in db table.

    • 2 - a statical update in published state by modifying the pidf manipulation document.

  • file_uri - the uri of the pidf-manipulation file on the XCAP server (only used for type 2).

  • filename - the name of the pidf-manipulation file on the XCAP server (only used for type 2).

RPC Command Format:

...
kamcmd presence.refreshWatchers sip:test@kamailio.org presence 1
...

6. Exported Variables

6.1. $subs(attr)

Access the attributes of handled subscription. It must be used after a successful call of handle_subscription() or in the following events.

  • tm:local-request - before notify is sent

  • present:notify-reply - after notify is sent

The attr can be:

  • uri - subscription presentity uri

  • pres_uri - alias for presentity uri

  • to_user

  • to_domain

  • from_user

  • from_domain

  • watcher_username

  • watcher_domain

  • event

  • event_id

  • to_tag

  • from_tag

  • callid

  • remote_cseq

  • local_cseq

  • contact

  • local_contact

  • record_route

  • expires

  • status

  • reason

  • version

  • flags

  • user_agent

Example 1.42. $subs(name) usage

...
if(handle_subscription())
{
  xlog("presentity=$subs(uri)\n");
}
...

6.2. $notify_reply(attr)

Access the reply message received when notifying subscriber. It must be used in the following events.

  • present:notify-reply - after notify is sent

The attr can be any pseudo var that accesses attributes of msg

Example 1.43. $notify_reply(name) usage

...
event_route[presence:notify-reply]
{
  xlog("received message = $notify_reply($mb)\n");
}
...

7. Events

7.1. present:notify-reply

Fired after notify reply is received or timeout.

Example 1.44. $notify_reply(name) usage

...
event_route[presence:notify-reply]
{
  xlog("received message = $notify_reply($mb)\n");
}
...

8. Installation

The module requires 3 tables in the Kamailio database: "presentity", "active_watchers" and "watchers". The SQL syntax to create them can be found in presence-create.sql script in the database directories in the kamailio/scripts folder. You can also find the complete database documentation on the project webpage, https://www.kamailio.org/docs/db-tables/kamailio-db-devel.html.

Chapter 2. Developer Guide

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

1.  bind_presence(presence_api_t* api)

This function binds the presence modules and fills the structure with one exported function -> add_event, which when called adds a new event to be handled by presence.

Example 2.1. presence_api_t structure

...
typedef struct presence_api {
	add_event_t add_event;
	contains_event_t contains_event;
	search_event_t search_event;
	get_event_list_t get_event_list;
	
	update_watchers_t update_watchers_status;
	
	/* subs hash table handling functions */
	new_shtable_t new_shtable;
	destroy_shtable_t destroy_shtable;
	insert_shtable_t insert_shtable;
	search_shtable_t search_shtable;
	delete_shtable_t delete_shtable;
	update_shtable_t update_shtable;
	/* function to duplicate a subs structure*/
	mem_copy_subs_t  mem_copy_subs;
	/* function used for update in database*/
	update_db_subs_t update_db_subs_timer;
	/* function to extract dialog information from a
	SUBSCRIBE message */
	extract_sdialog_info_t extract_sdialog_info;
	/* function to request sphere definition for a presentity */
	pres_get_sphere_t get_sphere;

}presence_api_t;
...

2.  add_event

Field type:

...
typedef int (*add_event_t)(pres_ev_t* event);
...

This function receives as a parameter a structure with event specific information and adds it to presence event list.

The structure received as a parameter:

...
typedef struct pres_ev
{
	str name;
	event_t* evp;
	str content_type;
	int default_expires;
	int type;
	int etag_not_new;
	/*
	 *  0 - the standard mechanism (allocating new etag
			for each Publish)
	 *  1 - allocating an etag only
			for an initial Publish 
	*/
	int req_auth;
	get_rules_doc_t* get_rules_doc;
	apply_auth_t*  apply_auth_nbody;
	is_allowed_t*  get_auth_status;
	
	/* an agg_body_t function should be registered
	 * if the event permits having multiple published
	 * states and requires an aggregation of the information
	 * otherwise, this field should be NULL and the last
	 * published state is taken when constructing Notify msg
	 */
	agg_nbody_t* agg_nbody;
	publ_handling_t  * evs_publ_handl;
	subs_handling_t  * evs_subs_handl;
	free_body_t* free_body;
    /* sometimes it is necessary that a module make changes for a body for each
     * active watcher (e.g. setting the "version" parameter in an XML document.
     * If a module registers the aux_body_processing callback, it gets called for
     * each watcher. It either gets the body received by the PUBLISH, or the body
     * generated by the agg_nbody function.
     * The module can deceide if it makes a copy of the original body, which is then
     * manipulated, or if it works directly in the original body. If the module makes a
     * copy of the original body, it also has to register the aux_free_body() to
     * free this "per watcher" body.
     */
    aux_body_processing_t* aux_body_processing;
    free_body_t* aux_free_body;
	struct pres_ev* wipeer;			
	struct pres_ev* next;
	
}pres_ev_t;
...

3.  get_rules_doc

Filed type:

...
typedef int (get_rules_doc_t)(str* user, str* domain, str** rules_doc);
...

This function returns the authorization rules document that will be used in obtaining the status of the subscription and processing the notified body. A reference to the document should be put in the auth_rules_doc of the subs_t structure given as a parameter to the functions described bellow.

4.  get_auth_status

This filed is a function to be called for a subscription request to return the state for that subscription according to authorization rules. In the auth_rules_doc field of the subs_t structure received as a parameter should contain the rules document of the presentity in case, if it exists.

It is called only if the req_auth field is not 0.

Filed type:

...
typedef int (is_allowed_t)(struct subscription* subs);
...

5.  apply_auth_nbody

This parameter should be a function to be called for an event that requires authorization, when constructing final body. The authorization document is taken from the auth_rules_doc field of the subs_t structure given as a parameter. It is called only if the req_auth field is not 0.

Filed type:

...
typedef int (apply_auth_t)(str* , struct subscription*, str** );
...

6.  agg_nbody

If present, this field marks that the events requires aggregation of states. This function receives a body array and should return the final body. If not present, it is considered that the event does not require aggregation and the most recent published information is used when constructing Notifies.

Filed type:

...
typedef str* (agg_nbody_t)(str* pres_user, str* pres_domain, 
str** body_array, int n, int off_index);
..

7.  free_body

This field must be field in if subsequent processing is performed on the info from database before being inserted in Notify message body(if agg_nbody or apply_auth_nbody fields are filled in). It should match the allocation function used when processing the body.

Filed type:

...
typedef void(free_body_t)(char* body);
..

8.  aux_body_processing

This field must be set if the module needs to manipulate the NOTIFY body for each watcher. E.g. if the XML body includes a 'version' parameter which will be increased for each NOTIFY, on a "per watcher" basis. The module can either allocate a new buffer for the new body an return it (aux_free_body function must be set too) or it manipulates the original body directly and returns NULL.

Filed type:

...
typedef str* (aux_body_processing_t)(struct subscription *subs, str* body);
..

9.  aux_free_body

This field must be set if the module registers the aux_body_processing function and allocates memory for the new modified body. Then, this function will be used to free the pointer returned by the aux_body_processing function. If the module does use the aux_body_processing, but does not allocate new memory, but manipulates directly the original body buffer, then the aux_body_processing must return NULL and this field should not be set.

Filed type:

...
typedef void(free_body_t)(char* body);
..

10.  evs_publ_handl

This function is called when handling Publish requests. Most contain body correctness check.

...
typedef int (publ_handling_t)(struct sip_msg*);
..

11.  evs_subs_handl

It is not compulsory. Should contain event specific handling for Subscription requests.

Filed type:

...
typedef int (subs_handling_t)(struct sip_msg*);
..

12.  contains_event

Field type:

..
typedef pres_ev_t* (*contains_event_t)(str* name,
event_t* parsed_event);
...

The function parses the event name received as a parameter and searches the result in the list. It returns the found event or NULL, if not found. If the second argument is an allocated event_t* structure it fills it with the result of the parsing.

13.  get_event_list

Field type:

...
typedef int (*get_event_list_t) (str** ev_list);
...

This function returns a string representation of the events registered in presence module.( used for Allowed-Events header).

14.  update_watchers_status

Field type:

...
typedef int (*update_watchers_t)(str pres_uri, pres_ev_t* ev,
str* rules_doc);
...

This function is an external command that can be used to announce a change in authorization rules for a presentity. It updates the stored status and sends a Notify to the watchers whose status has changes. (used by presence_xml module when notified through an RPC command of a change in an xcap document).

15.  get_sphere

Field type:

...
typedef char* (*pres_get_sphere_t)(str* pres_uri);
...

This function searches for a sphere definition in the published information if this has type RPID. If not found returns NULL. (the return value is allocated in private memory and should be freed)

16.  get_presentity

Field type:

...
typedef str* (*pres_get_presentity_t)(str pres_uri, pres_ev_t *ev, str *etag, str *contact);
...

This function returns a pointer to a str containing an XML document with all of the matching presentities. If no matching presentities are found the function returns NULL.

The etag and contact parameters are optional and may be set to NULL. Once you are finished with the presentity document you must call free_presentity to free the allocated memory.

17.  free_presentity

Field type:

...
typedef void (*pres_free_presentity_t)(str *presentity, pres_ev_t *ev);
...

This function frees memory allocated by a call to get_presentity. The ev parameter MUST point to the same pres_ev_t data-structure that was used in the call to get_presentity.