presence_dialoginfo Module

Juha Heinanen

   <jh@tutpro.com>
   Klaus
   Darilion
   <klaus.darilion@mailinglists@pernau.at>

Edited by

Juha Heinanen

   <jh@tutpro.com>

Edited by

Klaus Darilion

   <klaus.darilion@mailinglists@pernau.at>

   Copyright © 2007 Juha Heinanen

   Copyright © 2008 Klaus Darilion, IPCom (Module implementation
   was partly sponsored by Silver Server (www.sil.at))
   Revision History
   Revision $Revision: 1 $ $Date: 2007-04-30 14:05:57 +0200 (Mon,
                           30 Jan 2007) $
     __________________________________________________________

   Table of Contents

   1. Admin Guide

        1.1. Overview
        1.2. Dependencies

              1.2.1. Kamailio Modules
              1.2.2. External Libraries or Applications

        1.3. Exported Parameters

              1.3.1. force_single_dialog (int)

        1.4. Exported Functions

   List of Examples

   1.1. Set parameter

Chapter 1. Admin Guide

1.1. Overview

   The module enables the handling of "Event: dialog" (as defined
   in RFC 4235) inside of the presence module. This can be used
   distribute the dialog-info status to the subscribed watchers.

   The module does not currently implement any authorization
   rules. It assumes that publish requests are only issued by an
   authorized application and subscribe requests only by
   authorized users. Authorization can thus be easily done in
   Kamailio configuration file before calling handle_publish() and
   handle_subscribe() functions.

   Note: This module only activates the processing of the "dialog"
   in the presence module. To send dialog-info to watchers you
   also need a source which PUBLISH the dialog info to the
   presence module. For example you can use the pua_dialoginfo
   module or any external component. This approach allows to have
   the presence server and the dialog-info aware publisher (e.g.
   the main proxy) on different Kamailio instances.

   This module by default does body aggregation. That means, if
   the presence module received PUBLISH from multiple presentities
   (e.g. if the entity has multiple dialogs the pua_dialoginfo
   will send multiple PUBLISH), the module will parse all the
   received (and still valid, depending on the Expires header in
   the PUBLISH request) XML documents and generate a single XML
   document with multiple "dialog" elements. This is perfectly
   valid, but unfortunately not supported by all SIP phones, e.g.
   Linksys SPA962 crashes when it receives dialog-info with
   multiple dialog elements. In this case use the ..... module
   parameter.

   To get better understanding how all the module works together
   please take a look at the follwing figure:


    Main Proxy and Presence Server on the same Instance

   caller        proxy &      callee         watcher
alice@example   presence   bob@example   watcher@example
                 server
     |             |            |               |
     |             |<-------SUBSCRIBE bob-------|
     |             |--------200 OK------------->|
     |             |--------NOTIFY------------->|
     |             |<-------200 OK--------------|
     |             |            |               |
     |--INV bob--->|            |               |
     |             |--INV bob-->|               |
     |             |<-100-------|               |
     |             |            |               |
     |             |<-180 ring--|               |
     |<--180 ring--|            |               |
     |             |--          |               |
     |             |   \        |               |
     |             | PUBLISH bob|               |
     |             |   /        |               |
     |             |<-          |               |
     |             |            |               |
     |             |--          |               |
     |             |   \        |               |
     |             | 200 ok     |               |
     |             |   /        |               |
     |             |<-          |               |
     |             |--------NOTIFY------------->|
     |             |<-------200 OK--------------|
     |             |            |               |


     * The watcher subscribes the "Event: dialog" of Bob.
     * Alice calls Bob.
     * Bob replies with ringing, the dialog in the dialog module
       transits to "early". The callback in pua_dialoginfo is
       executed. The pua_dialoginfo module creates the XML
       document and uses the pua module to send the PUBLISH. (pua
       module itself uses tm module to send the PUBLISH stateful)
     * PUBLISH is received and handled by presence module.
       Presence module updates the "presentity". Presence module
       checks for active watchers of the presentity. It gives all
       the XML dcouments to presence_dialoginfo module to
       aggregate them into a single XML document. Then it sends
       the NOTIFY with the aggregated XML document to all active
       watchers.

   The presence server can also be separated from the main proxy
   by using a separate Kamailio instance as shown in the following
   figure. (Either set the outbound_proxy parameter of pua module
   or make sure to route the "looped" PUBLISH requests from the
   main proxy to the presence server).


    Main Proxy and Presence Server use a separate Instance

   caller        proxy &   presence      callee         watcher
alice@example    server     server     bob@example   watcher@example
     |             |            |               |            |
     |             |<--------------------SUBSCRIBE bob-------|
     |             |-SUBSC bob->|               |            |
     |             |<-200 ok----|               |            |
     |             |---------------------200 OK------------->|
     |             |          .... NOTIFY ... 200 OK ...     |
     |             |            |               |            |
     |             |            |               |            |
     |--INV bob--->|            |               |            |
     |             |--INV bob------------------>|            |
     |             |<-100-----------------------|            |
     |             |            |               |            |
     |             |<-180 ring------------------|            |
     |<--180 ring--|            |               |            |
     |             |--PUBL bob->|               |            |
     |             |<-200 ok----|               |            |
     |             |            |--------NOTIFY------------->|
     |             |            |<-------200 OK--------------|
     |             |            |               |            |




   Known issues:
     * The "version" attribute is increased for every NOTIFY, even
       if the XML document has not changed. This is of course
       valid, but not very smart.

1.2. Dependencies

1.2.1. Kamailio Modules

   The following modules must be loaded before this module:
     * presence.

1.2.2. External Libraries or Applications

   None.

1.3. Exported Parameters

1.3.1. force_single_dialog (int)

   By default the module aggregates all available dialog info into
   a single dialog-info document containing multiple "dialog"
   elements. If the phone does not support this, you can activate
   this parameter.

   If this parameter is set, only the dialog element with the
   currently most interesting dialog state will be put into the
   dialog-info document. Thus, the dialog-info element will
   contain only a single "dialog" element. The algorithm chooses
   the state based onf the following order of priority (least
   important first): terminated, trying, proceeding, confirmed,
   early. Note: I consider the "early" state more intersting than
   confirmed as often you might want to pickup a call if the
   originall callee is already busy in a call.

   Default value is "0".

   Example 1.1. Set parameter
...
modparam("presence_dialoginfo", "force_single_dialog", 1)
...

1.4. Exported Functions

   None to be used in configuration file.
