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))
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters

              3.1. force_single_dialog (int)

        4. Functions

   List of Examples

   1.1. Set parameter

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. force_single_dialog (int)

   4. Functions

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.

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:
     * presence.

2.2. External Libraries or Applications

   None.

3. Parameters

   3.1. force_single_dialog (int)

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)
...

4. Functions

   None to be used in configuration file.
