
QOS Module

Ovidiu Sas

   SOMA Networks, Inc.

Edited by

Ovidiu Sas

   Copyright © 2008 SOMA Networks, Inc.
   Revision History
   Revision $Revision: 4594 $ $Date: 2008-08-06 06:08:33 -0400
   (Wed, 06 Aug 2008) $
     _________________________________________________________

   Table of Contents

   1. Admin Guide

        1.1. Overview
        1.2. How it works
        1.3. Dependencies

              1.3.1. Kamailio Modules
              1.3.2. External Libraries or Applications

        1.4. Exported Parameters

              1.4.1. qos_flag (integer)

        1.5. Exported Functions
        1.6. Exported Statistics
        1.7. Exported MI Functions
        1.8. Exported pseudo-variables
        1.9. Installation and Running

   2. Developer Guide

        2.1. Available Functions

              2.1.1. register_qoscb (qos, type, cb, param) 

   List of Examples

   1.1. Set qos_flag parameter

Chapter 1. Admin Guide

1.1. Overview

   The qos module provides a way to keep track of per dialog SDP
   session(s).

1.2. How it works

   The qos module uses the dialog module to be notified of any
   new or updated dialogs. It will then look for and extract the
   SDP session (if present) from SIP requests and replies and
   keep track of it for the entire life of a dialog.

   All of this happens with a properly configured dialog and qos
   module and setting the dialog flag and the qos flag at the
   time any INVITE sip message is seen. There is no config script
   function call required to set the SDP session tracking
   mechanism. See the dialog module users guide for more
   information.

   A dialog can have one or more SDP sessions active in one of
   the following states:
     * pending - only one end point of the SDP session is known.
     * negotiated - both end points of the SDP session are known.

   An SDP session can be established in one of the following
   scenarios:
     * INVITE/200ok - typical "INVITE" and "200 OK" SDP exchange.
     * 200ok/ACK - "200 OK" and "ACK" SDP exchange (for calls
       starting with an empty INVITE).
     * 183/PRACK - early media via "183 Session Progress" and
       "PRACK" (see rfc3959 for more information) - not
       implemented yet.

1.3. Dependencies

1.3.1. Kamailio Modules

   The following modules must be loaded before this module:
     * dialog - dialog module and its decencies (tm).

1.3.2. External Libraries or Applications

   The following libraries or applications must be installed
   before running Kamailio with this module loaded:
     * None.

1.4. Exported Parameters

1.4.1. qos_flag (integer)

   Keeping with Kamailio, the module will not do anything to any
   message unless instructed to do so via the config script. You
   must set the qos_flag value in the setflag() call of the
   INVITE you want the qos module to process. But before you can
   do that, you need to tell the qos module which flag value you
   are assigning to qos.

   In most cases when ever you set the dialog flag you will want
   to set the qos flag. If the dialog flag is not set and the qos
   flag is set, it will not have any effect.

   This parameter must be set of the module will not load.

   Default value is "Not set!". 

   Example 1.1. Set qos_flag parameter
...
modparam("dialog", "dlg_flag", 5)
modparam("qos", "qos_flag", 7)
...
route {
  ...
  if (method=="INVITE") {
    setflag(5); # set the dialog flag
    setflag(7); # Set the qos flag
  }
  ...
}

1.5. Exported Functions

   There are no exported functions that could be used in scripts.

1.6. Exported Statistics

   There are no exported statistics for the qos module.

1.7. Exported MI Functions

   There are no exported MI functions for the qos module. Check
   the dialog MI functions for a way to inspect the internals of
   a dialog.

1.8. Exported pseudo-variables

   There are no exported pseudo-variables for the qos module.

1.9. Installation and Running

   Just load the module and remember to set the flag.

Chapter 2. Developer Guide

2.1. Available Functions

2.1.1.  register_qoscb (qos, type, cb, param)

   Register a new callback to the qos.

   Meaning of the parameters is as follows:
     * struct qos_ctx_st* qos - qos to register callback to. If
       maybe NULL only for QOSCB_CREATED callback type, which is
       not a per qos type.
     * int type - types of callbacks; more types may be register
       for the same callback function; only QOSCB_CREATED must be
       register alone. Possible types:
          + QOSCB_CREATED - called when a new qos context is
            created - it's a global type (not associated to any
            qos).
          + QOSCB_ADD_SDP - called when a new SDP was added to
            the qos context - it's a per qos type.
          + QOSCB_UPDATE_SDP - called when an existing SDP is
            updated - it's a per qos type.
          + QOSCB_REMOVE_SDP - called when an existing SDP is
            removed - it's a per qos type.
          + QOSCB_TERMINATED - called when the qos is terminated.
     * qos_cb cb - callback function to be called. Prototype is:
       "void (qos_cb) (struct qos_ctx_st *qos, int type, struct
       qos_cb_params *params); "
     * void *param - parameter to be passed to the callback
       function.
