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presence:module-exports [2011/09/07 16:25]
92.112.156.8 		presence:module-exports [2012/03/22 13:38] (current)
80.250.1.245 removed spam
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 +====== Presence Module - Parameters and Functions ======
 +
 +
 +===== Exported Functions =====
 +
 +  * **handle_publish()**
 +  * **handle_subscribe()**
 +
 +
 +
 +==== handle_publish() ====
 +
 +  * function which handles PUBLISH requests. It stores and updates presence information in database and calls functions to send NOTIFY messages when changes in presence information occur;
 +  * it does not take any parameter.
 +   
 +__ Actions:  __ 
 +
 +     - verifies if the PUBLISH message is correct: 
 +                - check its structure;
 +                - if it has a SIP-if-Match header, checks is there is a previous storage for the same presentity;
 +                - if not present checks if a body is present
 +     - if the conditions are not complied with it sends an adequate error message
 +     - if a correct message:
 +                - sends a 200Ok message with 2 extra header fields : Expires and SIP-if-Match 
 +                - if a new PUBLISH without a Sip-if-Match header field 
 +                             - it generates one
 +                             - inserts a new row in database
 +                             - calls a function which sends Notify with presence to all the watchers which have subscribed to the presentity
 +                - if the PUBLISH message is inside a dialog
 +                             - updates the expires value
 +                             - if body present
 +                                       - updates body (replace with the new one) 
 +                                       - calls a function which sends Notify with presence to all watchers  
 +                                      
 +
 +
 +
 +
 +
 +==== handle_subscribe() ====
 +
 + 
 +  * function which handles SUBSCRIBE requests. It stores or updates information in database and calls functions to send Notify messages when a Subscribe which initiate a dialog is received
 +  * it does not take any parameter.
 +
 +__Actions__
 +       -verifies if the SUBSCRIBE message is correct: 
 +                - check its structure;
 +                - if inside a dialog checks is a record of that dialog is present
 +       -if the conditions are not complied with it sends an adequate error message
 +       -if a correct message 
 +                - sends 200OK for SUBSCRIBE messages for event "presence.winfo" and 202OK for Subscribe for "presence"; they both contain a Expires header field
 +                - if a new SUBSCRIBE: 
 +                           -it inserts a new row in database
 +                           -if SUBSCRIBE for "presence": 
 +                                  -calls a function to send Notify with presence.winfo to the presentity with a partial state informing only about the subscription status of the new watcher
 +                                  -calls a function to send Notify with the presence information of the person he  has subscribed to
 +                                  
 +                          -if SUBSCRIBE for "presence.winfo"
 +                                   -calls a function to send Notify with presence.winfo to the subscriber with full state informing only about all the watchers
 +                - if a Subscribe inside a dialog
 +                          -if the Expires header field value is 0 
 +                                    -deletes the registration from the database
 +                                    -if event is "presence" calls a function which sends Notify with presence.winfo to the presentity with full state
 +                          -if update, it updates the stored expires value
 +
 +
 +=====  Exported parameters =====
 +
 +
 +* [b]db_url[/b] : database url
 +* [b]clean_period[/b] : time period for cleaning expired PUBLISH or SUBSCRIBE messages from database
 +* [b]to_tag_pref[/b] : prefix used when generating to_tag when sending replies for SUBSCRIBE requests
 +* [b]totag_avpid[/b]: the id of the avp variable used for storing to_tag value;
 +* [b]lock_set_size[/b] : the size of the lock used for synchronizing updating information from database
 +* [b]expires_offset[/b] : the value that should be substracted from the expires value when sending a 200OK for a publish to force the client cu send an update before the old publish expires
 +* [b]force_active[/b] : this parameter is used for permissions when handling Subscribe messages. If set to 1, subscription state is considered active and the presentity is not queried for permissions. Otherwise,the xcap_table is queried and the state is extracted from there. If no record exists, the subscriptions remains in pending state and the watcher receives Notify messages with no body. ( If not using an xcap server, you should set this parameter to 1).
 +* [b]max_expires[/b] : reduce validity of PUBLISH/SUBSCRIBE to this value if the Expires in request is greater.
 +* [b]server_address[/b]: presence server address to be included in Contact header field for Subscribe and Publish replies and in Notify messages.
 +
 +===== Presence-Related Stuff =====
 +
 +{{indexmenu>presence|js}}
  

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