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Documentation: Tutorials-Presence-PresenceModule

Documentation -> Tutorials -> Presence -> Presence Server -> Presence Module - Parameters and Functions

1. Exported Functions

• handle_publish()
• handle_subscribe()

1.1 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 takes one optional parameter - the URI of the sender, used by the BLA feature( event dialog;sla ).

Actions:

• verifies if the PUBLISH message is correct:
  • check its structure - calls an event specific function defined in a presence_ev module (presence_xml or presence_mwi);
  • if it has a SIP-if-Match header, checks is there is a previous record 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 a sequential one
  • updates the expires value
  • generates a new E-Tag and sends it in the Sip-Etag header of the 200OK reply
• if body present
  • updates body (replace with the new one)
  • calls a function which sends Notify with presence to all watchers

1.2 handle_subscribe()

• function which handles SUBSCRIBE requests. It stores or updates dialog information in and calls functions to send Notify messages to teh watcher and to the presentity (if a subscription for event presence.winfo exists for the presentity and the event)
• it does not take any parameter.

Actions

• checks if the SUBSCRIBE message is correct:
  • check its structure;
  • if inside a dialog tries to match the dialogs with the records stored
• if the conditions are not complied with it sends an adequate error message
• if a correct message sends 2XX reply
  • the reply contains an Expires header
  • for SUBSCRIBE messages for event "presence.winfo" the status of the reply is 202OK and for all the other 200OK
• if a new SUBSCRIBE, saves the dialog information in cache
• if a Subscribe inside a dialog
  • if the Expires header field value is 0
    • deletes the registration from cache and database
    • if event is a PUBLISH event - sends a Notify for winfo to the presentity with full state
  • if update
    • updates the expires value
    • sends Notifies
• if a SUBSCRIBE for a PUBLISH event( 'presence', 'dialog.sla', 'message-summary'):
  • sends Notify with presence.winfo to the presentity(if a winfo subscription from the presentity exists) with a partial state informing only about the subscription status of the new watcher
  • sends Notify with the presence information
• if a SUBSCRIBE for a winfo(watcher info) event
  • sends Notify with presence.winfo to the subscriber with full state informing about all the watchers

2. Exported Parameters

Please refer to the module's documentation for the full list of parameters and a comprehensive description.