SIPREC                                           Ram Mohan. Ravindranath
Internet-Draft                                  Parthasarathi. Ravindran
Intended status: Standards Track                           Paul. Kyzivat
Expires: October 15, 2011                            Cisco Systems, Inc.
                                                          April 13, 2011


          Session Initiation Protocol (SIP) Recording Metadata
                   draft-ietf-siprec-metadata-00

Abstract

   Session recording is a critical requirement in many communications
   environments such as call centers and financial trading.  In some of
   these environments, all calls must be recorded for regulatory,
   compliance, and consumer protection reasons.  Recording of a session
   is typically performed by sending a copy of a media stream to a
   recording device.  This document describes the metadata model as
   viewed by Session Recording Server(SRS).

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 15, 2011.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Metadata Model . . . . . . . . . . . . . . . . . . . . . . . .  3
   4.  Recording Metadata elements  . . . . . . . . . . . . . . . . .  5
     4.1.  Recording Session  . . . . . . . . . . . . . . . . . . . .  5
       4.1.1.  Attributes . . . . . . . . . . . . . . . . . . . . . .  5
       4.1.2.  Associations . . . . . . . . . . . . . . . . . . . . .  6
     4.2.  Communication Session Group  . . . . . . . . . . . . . . .  6
       4.2.1.  Attributes . . . . . . . . . . . . . . . . . . . . . .  6
       4.2.2.  Associations . . . . . . . . . . . . . . . . . . . . .  6
     4.3.  Communication Session  . . . . . . . . . . . . . . . . . .  7
       4.3.1.  Attributes . . . . . . . . . . . . . . . . . . . . . .  7
       4.3.2.  Associations . . . . . . . . . . . . . . . . . . . . .  8
     4.4.  Participant  . . . . . . . . . . . . . . . . . . . . . . .  8
       4.4.1.  Attributes . . . . . . . . . . . . . . . . . . . . . .  9
       4.4.2.  Associations . . . . . . . . . . . . . . . . . . . . .  9
     4.5.  Media Stream . . . . . . . . . . . . . . . . . . . . . . . 10
       4.5.1.  Attributes . . . . . . . . . . . . . . . . . . . . . . 10
       4.5.2.  Associations . . . . . . . . . . . . . . . . . . . . . 11
     4.6.  Extension Data . . . . . . . . . . . . . . . . . . . . . . 11
   5.  Metadata Model Object Instances  . . . . . . . . . . . . . . . 11
     5.1.  Use case 1: Basic Call . . . . . . . . . . . . . . . . . . 11
     5.2.  Use case 2: Basic Call with hold/resume  . . . . . . . . . 12
     5.3.  Use case 3: Basic call with Transfer . . . . . . . . . . . 14
     5.4.  Conference Use Cases . . . . . . . . . . . . . . . . . . . 15
       5.4.1.  Case 1:  . . . . . . . . . . . . . . . . . . . . . . . 16
       5.4.2.  Case 2:  . . . . . . . . . . . . . . . . . . . . . . . 18
       5.4.3.  Case 3:  . . . . . . . . . . . . . . . . . . . . . . . 20
       5.4.4.  Case 4:  . . . . . . . . . . . . . . . . . . . . . . . 21
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 22
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 22
   8.  Acknowledgement  . . . . . . . . . . . . . . . . . . . . . . . 22
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 22
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 22
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22








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1.  Introduction

   Session recording is a critical requirement in many communications
   environments such as call centers and financial trading.  In some of
   these environments, all calls must be recorded for regulatory,
   compliance, and consumer protection reasons.  Recording of a session
   is typically performed by sending a copy of a media stream to a
   recording device.  This document focuses on the Recording metadata
   which describes the communication session.  The document describes a
   metadata model as viewed by Session Recording Server, the
   requirements for which are described in [I-D.ietf-siprec-req] and the
   architecture for which is described in
   [I-D.ietf-siprec-architecture].


2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].  This
   document only uses these key words when referencing normative
   statements in existing RFCs."


3.  Metadata Model

   Metadata is the information that describes recorded media and the CS
   to which they relate.  Below diagram shows a model for Metadata as
   viewed by Session Recording Server (SRS).






















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  +-------------------------------+       1
  | Recording Session (RS)        |---------------+
  +-------------------------------+               |
             | 1..*                               |
             |                                    |
             | 0..*                               |
  +-------------------------------+               |
  |   Communication Session (CS)  |       1       |
  |      Group                    |---------------|
  +-------------------------------+               |
             | 1                                  |
             |                                    |
             | 1..*                               |
  +-------------------------------+               |
  |   Communication Session (CS)  |       1       |
  |                               |---------------|
  +-------------------------------+               |       +------------+
        | 0..*                 |1..*              |       |            |
        |                      |                  |  0..* |Extension   |
        | 2..*                 |0..*              |-------| Data       |
  +-------------+ receives +----------------+     |       |            |
  | Participant |----------|  Media Streams |     |       +------------+
  |             |0..*  0..*|                |     |
  |             |          |                |     |
  |             |          |                |     |
  |             |  sends   |                |     |
  |             |----------|                |     |
  |             |1.*   0..*|                |     |
  +-------------+          +----------------+     |
         |                         |              |
         |1                        |1             |
         |                         |              |
         +----------------------------------------+




   The mechanism MUST provide a means to convey every attribute
   mentioned in the metadata model.  Session Recording Client (SRC) MAY
   initiate the Recording Session.  It should be noted that the
   Recording Session is a completely independent from the Communication
   Session that is being recorded at both the SIP dialog level and at
   the session level.  The metadata MUST be conveyed from SRC to SRS.
   The metadata MAY be conveyed within the Recording Session Dialog.

   Note that the metadata model captures changes that occur over the
   duration of the recording session.  For example, if the call is
   transferred from one participant to another, then the SRC SHALL



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   convey a change of participant and the properties of the new media
   stream to the SRS.

   Some of the data in the model may not be conveyed explicitly from the
   SRC to the SRS, if it can be obtained contextually by the SRS.  For
   instance, the timing of changes may not explicitly conveyed from the
   SRC to the SRC, because the mechanism (yet to be defined) which
   conveys the metadata may implicitly provide the timing.  (E.g. the
   time a change occurred by be assumed to be the same as the time when
   notification of the change is received by the SRS.)


4.  Recording Metadata elements

   This section describes each element of the metadata model, and the
   attributes of each element.  This section also describes how
   different elements are associated.

4.1.  Recording Session


   +-------------------------------+
   | Recording Session (RS)        |
   +-------------------------------+
   |  Recording Requestor(SRC or   |            +-----------------+
   |                     SRS)      |    1  0..* |                 |
   |                               |------------|Extension Data   |
   |  Recording Type (Selective    |            |                 |
   |  Persistant)                  |            +-----------------+
   +-------------------------------+
              | 1..*
              |
              | 0..*
    Communication Session Group(CS Group)


   A Recording Session element represents one instance of a Recording
   Session.

4.1.1.  Attributes

   A Recording Session element MAY have attributes like:
   o  Recording requestor(which could be SRS or SRC).
   o  Recording type - This attribute indicates whether the recording
      session is selective or persistent.






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4.1.2.  Associations

   One instance of Recording Session SHALL have:

   o  Zero or more instances of Communication Session Group.The
      allowance of zero instances is to accommodate persistent
      recording, where there may be none.
   o  Each CS Group MUST be associated with one or more Recording
      Sessions [ setup by the same SRC.]

4.2.  Communication Session Group


    Recording Session (RS)
              | 1..*
              |
              | 0..*
   +-------------------------------+
   | Communication Session         |
   |     Group                     |
   +-------------------------------+
   |  Unique-ID                    |           +----------------+
   |                               |   1  0..* |                |
   |                               |-----------|Extension Data  |
   |                               |           |                |
   +-------------------------------+           +----------------+
              | 1
              |
              | 1..*
    Communication Session (CS)


   A Communication Session Group provides association or linking of
   Communication Sessions.

4.2.1.  Attributes

   A CS Group MUST have a Unique-ID attribute.  This Unique-ID is to
   group different CSs that are related.  SRC (or MAY be SRS) MUST
   ensure the uniqueness of Unique-ID in case multiple SRC interacts
   with the same SRS.  The mechanism by which SRC groups the CS is
   outside the scope of SIPREC.

4.2.2.  Associations

   A communication Session Group SHALL be associated with RS and CS in
   the following manner:




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   o  There can be one or more Recording Session elements per
      Communication Session Group.
   o  Each Communication Session Group MUST be associated with one or
      more RS [ setup by the same SRC]
   o  There MAY be one or more Communication Sessions per CS Group [e.g.
      Consult Transfer]
   o  Each CS MUST be associated to one CS-Group

4.3.  Communication Session



           Communication Session Group(CS Group)
              | 1
              |
              | 1..*
   +-------------------------------+               +-----------------+
   |   Communication Session (CS)  |       1  0..* |                 |
   |                               |---------------|Extension Data   |
   +-------------------------------+               |                 |
   |   CS Identifier               |               +-----------------+
   |   Call Termination Reason     |
   |   Start Time                  |
   |   End Time                    |
   +-------------------------------+
      |                      |
      | 0..*                 |1..*
      |                      |
      | 2..*                 |0..*
   Participant              Media Stream



   A Communication Session block/element in the metadata model
   represents Communication Session and its properties needed as seen by
   SRC.

4.3.1.  Attributes

   A communication Session block SHALL have the following attributes:

   o  Call Termination Reason - This represents the reason why a CS was
      terminated.  The communication session MAY contain a Call
      Termination Reason.  This MAY be derived from SIP Reason header of
      CS.
   o  CS Identifier - This attribute is used to uniquely identify a CS.





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   o  Start Time - This attribute represents CS start time
   o  End Time - This attribute represents CS end time

   Attributes like Retention (represent the value/duration for which
   Media streams of the CS needs to be retained), Force Deletion, Access
   Information e.t.c that are primarily related to policy will not be
   passed in metadata from SRC to SRS.  However if there are
   implementations where SRC has enough information, this could be sent
   as Extension Data attached to CS

4.3.2.  Associations

   A Communication Session SHALL be associated to CS-Group,Participant
   and Media Stream.  Cardinalities between CS and Participant allows:

   o  CS to have atleast two or more participants
   o  Participant may be associated with zero or more CS's (It is
      possible, though unlikely, that there are participants who are not
      part of any CS).  An example of such a case is participants in a
      premixed media stream.  The SRC may have knowledge of such
      Participants, yet not have any signaling relationship with them.
      This might arise if one participant in CS is a conf focus.
      Another use case is if one UA in CS works in 3pcc mode to acquire
      an MoH media stream, this might be reflected as unique source for
      media stream without having a reported signaling relationship to
      it.
   o  The model also allows participants in CS that are not participants
      in the media.  An example is the identity of a 3pcc controller
      that has initiated a CS to two or more participants of the CS.
      Another example is the identity of a conference focus.  Of course
      a focus is probably in the media, but since it may only be there
      as a mixer, it may not report itself as a participant in any of
      the media streams.

   Cardinalities between CS and Media Stream allows:

   o  A CS to have zero or more Streams
   o  A stream can be associated with 1 or more CS.  An example is
      multicast MoH stream which might be associated with many CSs.
      Also if we were to consider a B2BUA to have a separate CS on each
      "side" then they might share a stream.(Though more likely this
      would be treated as a single CS.)

4.4.  Participant







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    Communication Session (CS)
              | 0..*
              |
              | 2..*
   +-------------------------------+
   |          Participant          |
   |                               |
   +-------------------------------+
   |  AoR list                     |            +-----------------+
   |  Name                         |    1  0..* |                 |
   |  Participant Type             |------------|Extension Data   |
   |                               |            |                 |
   +-------------------------------+            +-----------------+
           | 0..*       1..*|
   receives|                |sends
           | 0..*       0..*|
             Media Stream



   A Participant block has information about a device that is part of a
   CS and/or contributes/consumes media stream(s) belonging to a CS.

4.4.1.  Attributes

   Participant has attributes like:

   o  AoR list - Has list of AoRs.  An AoR MAY be SIP/SIPS/TEL URI.
      There MAY be cases where a participant can have more than one AoR
      [ e.g.  P-Asserted-ID which can have both SIP and TEL URIs]
   o  Name - This attribute represents Participant name(SIP display
      name) or DN number ( in case it is known)
   o  Participant Type - This attribute can have values as "internal" or
      "external" or "don't know" (in cases where it is not possible to
      determine).

   Other attributes [ like Participant Role ] MAY be carried as part of
   extension data to Participant from SRC to SRS.

4.4.2.  Associations

   Cardinalities between participant and Media Stream allows:

   o  Participant to receives zero or more media streams
   o  Participant to send zero or more media streams.  (Same participant
      provides multiple streams e.g. audio and video)





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   o  Media stream to be received by zero or more participants.  Its
      possible, though perhaps unlikely, that a stream is generated but
      sent only to the SRC and SRS, not to any participant.  E.g.  In
      conferencing where all participants are on hold and the SRC is
      collocated with the focus.  Also a media stream may be received by
      multiple participants (e.g.  Whisper calls, side conversations).
   o  Media stream to be sent by one or more participants (pre-mixed
      streams).

   Example of a case where a participant may receive Zero or more
   streams - a Supervisor may have side conversation with Agent, while
   Agent converses with customer.

4.5.  Media Stream


                              Participant
                            | 0..*       1..*|
                    receives|                |sends
                            | 0..*       0..*|
                         +-------------------------+
                         |          Media Stream   |
                         |                         |
Communication 1..*  0..* +-------------------------+
  Session    ------------|  Start Time             |        +----------+
                         |  End Time               |1  0..* |          |
                         |  Codec params           |--------|Extension |
                         |  Media Stream Reference |        | Data     |
                         +-------------------------+        +----------+


   A Media Stream block shall have properties of media as seen by SRC
   and sent to SRS.  Different instances of Media Stream block would be
   created whenever there is a change in media (e.g. dir change like
   pause/resume and/or codec change and/or participant change.).

4.5.1.  Attributes

   A Media Stream block SHALL have the following attributes:

   o  Start Time - Represents Media Start time at SRC.
   o  End Time - Represents Media End time at SRC.  This is an optional
      attribute and MAY be included after a stream ends
   o  Codec params - represents codec parameters of the CS media
   o  Media Stream Reference - In implementations this can reference to
      m-line

   The metadata model should include media streams that are not being



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   delivered to the SRS.  Examples include cases where SRC offered
   certain media types but SRS chooses to accept only a subset of them
   OR an SRC may not even offer a certain media type due it its
   restrictions to record

4.5.2.  Associations

   A Media Stream SHALL be associated with Participant and CS.  The
   details of association with the Participant are described in the
   Participant block section.  The details of association with CS is
   mentioned in the CS section.

4.6.  Extension Data

   A recording metadata object contains additional data not specified as
   part of siprec.  This is intended to accommodate future standards
   track extensions, as well as vendor and user specific extensions.
   The mechanism MUST provide a means of unambiguously distinguishing
   such extension data.


5.  Metadata Model Object Instances

   This section describes the metadata model object instances for
   different use cases of SIPREC.  For the sake of simplicity as the
   media streams sent by each of the participants is received by every
   other participant in these use cases, it is NOT shown in the object
   instance diagrams below.

5.1.  Use case 1: Basic Call

   Basic call between two Participants A and B. In this use case each
   participant sends one Media Stream.  For the sake of simplicity
   "receives" lines are not shown in this instance diagram.  Media
   Streams sent by each participant is received all other participants
   of that CS.















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   +-------------------------------+
   | Recording Session (RS)        |
   +-------------------------------+
              |
              |
              |
   +-------------------------------+
   |   Communication Session (CS)  |
   |      Group(CSG)               |
   +-------------------------------+
   |   Unique-id1                  |
   +-------------------------------+
              |
              |
              |
     +----------------+
     | Communication  |
     | Session (CS)   |
     +----------------+
     |                |
     +----------------+
              |
              |-------------------+
              |        |          |
   +---------------+   | +---------------+
   | ParticipantA  |   | | ParticipantB  |
   |               |   | |               |
   +---------------+   | +---------------+
              |        |         |
     sends    |        |         |  sends
              |        |         |
   +---------------+   |   +---------------+
   |Media Stream A1|   |   |Media Stream B1|
   +---------------+   |   +---------------+
   |MediaStream Ref|   |   |MediaStream Ref|
   |codec  params  |---+---|codec params   |
   +---------------+       +---------------+



5.2.  Use case 2: Basic Call with hold/resume

   Basic call between two Participants A and B and with Participant A or
   B doing a Hold/Resume.  In this use case each participant sends one
   Media Stream.  After Hold/Resume the properties of Media MAY change.
   For the sake of simplicity "receives" lines are not shown in this
   instance diagram.  Media Streams sent by each participant is received
   all other participants of that CS.



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   +-------------------------------+
   | Recording Session (RS)        |
   +-------------------------------+
              |
              |
              |
   +-------------------------------+
   |   Communication Session (CS)  |
   |      Group(CSG)               |
   +-------------------------------+
   |   Unique-id1                  |
   +-------------------------------+
              |
              |
              |
     +----------------+
     | Communication  |
   +-| Session (CS)   |----------------------------------------------+
   | +----------------+                                              |
   | |                |                                              |
   | +----------------+                                              |
   |            |                                                    |
   |            |-------------------+                                |
   |            |                   |                                |
   | +---------------+     +---------------+                         |
   | | ParticipantA  |     | ParticipantB  |-----------+             |
   | |               |--+  |               |           |             |
   | +---------------+  |  +---------------+           |sends(After  |
   |       |       |    |       |         |            |     Resume) |
   |       |       |    |       |         |         +--------------+ |
   | sends |       |     +--+   |  sends  |         |MediaStream B3| |
   |       |       -----+   |   |          +-----+  +--------------+ |
   | +---------------+  |   |  +---------------+ |  |MediaStreamRef|-|
   | |Media Stream A1|  |   |  |Media Stream B1| |  |Codec Params  | |
   | +---------------+  |   |  +---------------+ |  |              | |
   +-|MediaStreamref |  |   |  |MediaStreamRef | |  +--------------+ |
     |codec params   |  |   |  |codec params   |-|-------------------|
     +---------------+  |   |  +---------------+ |                   |
                        |   |                    |                   |
           +------------+   |sends               |sends (hold)       |
           | sends          |(Resume)            |                   |
           | (hold)         +-------+             +-------+          |
           |                        |                     |          |
     +---------------+       +---------------+   +--------------+    |
     |Media Stream A2|       |Media Stream A3|   |MediaStream B2|    |
     +---------------+       +---------------+   |              |    |
     |MediaStreamref |       |MediaStreamRef |   +--------------+    |
     |codec params   |       |codec params   |   |Codec Params  |    |



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     +---------------+       +---------------+   |MediaStreamRef|    |
              |                     |            |              |    |
              |                     |            +--------------+    |
              |                     |                  |             |
              +------------------------------------------------------+


   NOTE: Need discssions on how to represent Hold/Resume from SRC to SRS
   and Pause/Resume from SRS to SRC.

5.3.  Use case 3: Basic call with Transfer

   Basic call between two Participants A and B and with Participant A
   transfer(consult transfer) to Participant C. In this use case each
   participant sends one Media Stream.  After transfer the properties of
   Participant A Media MAY change.  For the sake of simplicity
   "receives" lines are not shown in this instance diagram.  Media
   Streams sent by each participant is received all other participants
   of that CS.


   +-------------------------------+
   | Recording Session (RS)        |
   +-------------------------------+
              |
              |
              |
   +-------------------------------+
   |   Communication Session (CS)  |
   |      Group(CSG)               |
   +-------------------------------+
   |   Unique-id1                  |
   +-------------------------------+
              |
              |-----------------
              |                 |
   +----------------+     +----------------+
   | Communication  |     | Communication  |
   | Session (CS)1  |     | Session (CS)2  |
   +----------------+     +----------------+-----------+
   |                |     |                |           |
   +----------------+     +----------------+           |
              |                                        |
              |-------------------+                    |
              |        |          |                    |
   +---------------+   | +---------------+             |
   | ParticipantA  |   | | ParticipantB  |             |
   |               |   | |               |             |



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   +---------------+   | +---------------+             |
              |        |         |                     |
     sends    |        |         |  sends              |
              |        |         |                     |
   +---------------+   |   +---------------+           |
   |Media Stream A1|   |   |Media Stream B1|           |
   +---------------+   |   +---------------+           |
   |               |   |   |               |           |
   |codec params   |   |   | Media Stream  |           |
   | Media Stream  |---+---|  Ref          |           |
   | Ref           |       |codec params   |           |
   +---------------+       +---------------+           |
                                                       |
                                                       |
                          +----------------------------|
                          |                            |
         +--------------------------------+            |
         |                                |            |
   +---------------+                +---------------+  |
   | Participant A |                | Participant C |  |
   |   (same)      |                |               |  |
   +---------------+                +---------------+  |
         |                                    |        |
         | sends (After transfer)             | sends  |
   +----------------+                +----------------+|
   | Media Stream A2|                | Media Stream C1||
   +----------------+                +----------------+|
   | Media StreamRef|                | Media StreamRef||
   | Codec params   |                | Codecparams    ||
   |                |                |                ||
   +----------------+                +----------------+|
           |                                  |        |
           |                                  |        |
           |                                  |        |
           +-------------------------------------------+


5.4.  Conference Use Cases

   Depending on who act as SRC and the information that an SRC has there
   can be several ways to model conference use cases.  This section has
   instance diagrams for the following cases:

   o  A CS where one of the participant (which is also SRC) is a user in
      a conference
   o  A CS where one of the participant is focus ( which is also SRC)





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   o  A CS where one of the participant is user and the SRC is a
      different entity like B2BUA
   o  A CS where one of the participant is focus and the SRC is a
      different entity like B2BUA

   NOTE: There MAY be other ways to model the same use cases depending
   on what information the SRC has.

5.4.1.  Case 1:

   This is the usecase where there is a CS with one of the participant
   (who is also SRC) as a user in a conference.  For the sake of
   simplicity the receive lines for each of the participant is not
   shown.


+---------------------------------------------------+
|      Communication Session                        |
| +-------------+              +--------------+     |
| |             |              |              |     |
| |Participant B|              | Participant A|     |
| |  (User in   |--------------|              |     |
| |  conf/SRC)  |              |              |     |
| +-------------+              +--------------+     |
|   |  |  |  |                                      |
+---------------------------------------------------+
    |  |  |  |
    |  |  |  |
    D   E  F  G (Participants of Conference)


Instance Diagram:

+-------------------------------+
| Recording Session (RS)        |
+-------------------------------+
           |
           |
           |
+-------------------------------+
|   Communication Session (CS)  |
|      Group(CSG)               |
+-------------------------------+
|   Unique-id1                  |
+-------------------------------+
           |
           |
           |



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  +----------------+
  | Communication  |
  | Session (CS)   |--+
  +----------------+  |
  |                |  |
  +----------------+  |
           |          |
           |          |
           |          |
+---------------+     |
| ParticipantA  |     |
|               |     |
+---------------+     |
           |          |
  sends    |          |
           |          |
+---------------+     |
|Media Stream A1|     |
+---------------+     |
|MediaStream Ref|     |
|codec  params  |     |
+---------------+     |
                      |
                      |
        +-------------+
        |          |
        |          |
+----------------+ |
| Participant B  | |
|  (in conf)     | |
+----------------+ |
        |          |
 sends  |  +-------+
        |  |
+----------------+
| Media Stream B1|
+----------------+        sends ( not sure if sends is right word)
| MediaStream Ref|-----+-----------+-------------+---------+
| Codec Params   |     |           |             |         |
+----------------+     |           |             |         |
           +------------+  +------------+ +------------+ +-------------+
           |participantD|  |ParticipantE| |ParticipantF| |Participant G|
           +------------+  +------------+ +------------+ +-------------+



   In this example we have two participants A and B who are part of a
   Communication Session(CS).  One of the participants B is part of a



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   conference and also acts as SRC.There can be two cases here.  B can
   be a participant of the conference or B can be a focus.  In this
   instance diagram Participant B is a user in a conference.  The SRC
   (Participant B) SHALL subscribe to conference event package to get
   the details of other particiants.  Participant B(SRC) SHALL send the
   same through the metadata to SRS.  In this instance diagram the Media
   Stream(mixed stream) sent from Participant B SHALL have media streams
   contributed by conference participants (D,E,F and G).  For the sake
   of simplicity the "receives" line is not shown here.  In this example
   the media stream sent by each participant(A or B) of CS is received
   by all other participant(A or B).

5.4.2.  Case 2:

   This is the usecase where there is a CS where one of the participant
   is focus ( which is also SRC).



   +---------------------------------------------------+
   |      Communication Session                        |
   | +--------------+              +--------------+    |
   | |              |--------------|              |    |
   | |Participant C |              | Participant A|    |
   | |  (Focus in   |------+       |              |    |
   | | conf and SRC)|---+  |       +--------------+    |
   | +--------------+   |  |                           |
   |   |                |  +---------+                 |
   |   |                |            |                 |
   | +--------------+   |         +---------------+    |
   | | Participant B|   +---+     | Participant D |    |
   | |              |       |     |               |    |
   | +--------------+       |     +---------------+    |
   |                        |                          |
   |                   +--------------+                |
   |                   |Participant E |                |
   |                   |              |                |
   |                   +--------------+                |
   |                                                   |
   +---------------------------------------------------+

   Instance Diagram:

   +-------------------------------+
   | Recording Session (RS)        |
   +-------------------------------+
              |
              |



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              |
   +-------------------------------+
   |   Communication Session (CS)  |
   |      Group(CSG)               |
   +-------------------------------+
   |   Unique-id1                  |
   +-------------------------------+
              |
              |
              |
     +----------------+
     | Communication  |
     | Session (CS)   |----------------------+
     +----------------+                      |
     |                |                      |
     +----------------+                      |
              |                              |
              |-------------------+          |
              |        |          |          |
   +---------------+   | +---------------+   |
   | ParticipantA  |   | | ParticipantB  |   |
   |               |   | |               |   |
   +---------------+   | +---------------+   |
              |        |         |           |
     sends    |        |         |  sends    |
              |        |         |           |
   +---------------+   |   +---------------+ |
   |Media Stream A1|   |   |Media Stream B1| |
   +---------------+   |   +---------------+ |
   |MediaStream Ref|   |   |MediaStream Ref| |
   |codec  params  |---+---|codec params   | |
   +---------------+       +---------------+ |
                                             |
          +----------------------------------+
          |            |         |           |
          |            |         |           |
   +---------------+   | +---------------+   |
   | ParticipantD  |   | | ParticipantE  |   |
   |               |   | |               |   |
   +---------------+   | +---------------+   |
              |        |         |           |
     sends    |        |         |  sends    |
              |        |         |           |
   +---------------+   |   +---------------+ |
   |Media Stream D1|   |   |Media Stream E1| |
   +---------------+   |   +---------------+ |
   |MediaStream Ref|   |   |MediaStream Ref| |
   |codec  params  |---+---|codec params   | |



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   +---------------+       +---------------+ |
                                             |
                                             |
                                  +----------+
                +-----------------|
                |                 |
                |                 |
               +----------------+ |
               | Participant C  | |
               |  (focus +src)  | |
               +----------------+ |
                       |          |
                Sends  |  +-------+
                       |  |
   "sends" OR          |  |
   contributed +----------------+
    by         | Media Stream C1|
   Participants+----------------+  "receives" by participants A,B,D,E
   A,B,D,E     | MediaStream Ref|------------------------------------
   ------------| Codec Params   |
               +----------------+



   In this example we have two participants A and B who are part of a
   Communication Session(CS).  One of the participants (C) is focus of a
   conference and also acts as SRC.  The SRC (Participant C) being the
   Focus of the conference SHALL have access to the details of other
   particiants.  SRC (Participant C) SHALL send the same through the
   metadata to SRS.  In this instance diagram the Media Stream(mixed
   stream) sent by C SHALL have media streams contributed by conference
   participants (A, B, D and E).  Participants A, B,D and E SHALL send
   Media Streams A1, B1, D1 and E1 respectively.  The media stream sent
   by Participant C(Focus) shall be received by all other participants
   of CS.  For the sake of simplicity the "receives" line is not shown
   linked to all other participants.

   NOTE: SRC ( Participant C) MAY send mixed stream or seperate streams
   to SRS

5.4.3.  Case 3:

   A CS where one of the participant is user and the SRC is a different
   entity like B2BUA.  In this case the SRC MAY not know that one of the
   user is part of conference.  Hence the instance diagram will not have
   information about the conference participants.





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   +---------------------------------------------------+
   |      Communication Session                        |
   | +-------------+  +------+    +--------------+     |
   | |             |  | (SRC)|    |              |     |
   | |Participant B|--|B2BUA |----| Participant A|     |
   | |  (User in   |  +------+    |              |     |
   | |  conf)      |              |              |     |
   | +-------------+              +--------------+     |
   |   |  |  |  |                                      |
   +---------------------------------------------------+
       |  |  |  |
       |  |  |  |
       D   E  F  G (Participants of Conference)


5.4.4.  Case 4:

   A CS where one of the participant is focus and the SRC is a different
   entity like B2BUA.  In this case the participant which is focus MAY
   send "isfocus" in SIP message to SRC.  The SRC MAY subscribe to
   conference event package on seeing this "isfocus".  SRC SHALL learn
   the details of other participants of conference from the conference
   package and send the same in metadata to SRS.  The instance diagram
   for this use case SHALL be same as Case 1.


              +--------------------------------+
              |   Conference Event Package     |
              |                                |
              +--------------------------------+
                         |
                         | subscribes
                         |
   +---------------------|-----------------------------+
   |      Communication  |Session                      |
   | +-------------+  +------+    +--------------+     |
   | |             |  | (SRC)|    |              |     |
   | |Participant B|--|B2BUA |----| Participant A|     |
   | |  (FOCUS in  |  +------+    |              |     |
   | |  conf)      |              |              |     |
   | +-------------+              +--------------+     |
   |   |  |  |  |                                      |
   +---------------------------------------------------+
       |  |  |  |
       |  |  |  |
       D   E  F  G (Participants of Conference)





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6.  Security Considerations

   The metadata information sent from SRC to SRS MAY reveal sensitive
   Information about different participants of CS.  For this reason, it
   is RECOMMENDED that a SRC use a strong means for authentication and
   metadata information protection and that it apply comprehensive
   authorization rules when using the metadata model defined in this
   document.  The security considerations for this SHALL be defined in
   the solution document.


7.  IANA Considerations

   Not Applicable


8.  Acknowledgement

   We wish to thank John Elwell, Henry Lum, Leon Portman, De Villers,
   Andrew Hutton, Deepanshu Gautam, Charles Eckel for their valuable
   comments.


9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

9.2.  Informative References

   [I-D.ietf-siprec-req]
              Rehor, K., Portman, L., Hutton, A., and R. Jain, "Use
              Cases and Requirements for SIP-based Media Recording
              (SIPREC)", draft-ietf-siprec-req-09 (work in progress),
              March 2011.

   [I-D.ietf-siprec-architecture]
              Hutton, A., Portman, L., Jain, R., and K. Rehor, "An
              Architecture for Media Recording using the Session
              Initiation Protocol", draft-ietf-siprec-architecture-01
              (work in progress), October 2010.








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Authors' Addresses

   Ram Mohan Ravindranath
   Cisco Systems, Inc.
   Cessna Business Park,
   Kadabeesanahalli Village, Varthur Hobli,
   Sarjapur-Marathahalli Outer Ring Road
   Bangalore, Karnataka  560103
   India

   Email: rmohanr@cisco.com


   Parthasarathi Ravindran
   Cisco Systems, Inc.
   Cessna Business Park,
   Kadabeesanahalli Village, Varthur Hobli,
   Sarjapur-Marathahalli Outer Ring Road
   Bangalore, Karnataka  560103
   India

   Email: partr@cisco.com


   Paul Kyzivat
   Cisco Systems, Inc.
   1414 Massachusetts Avenue
   Boxborough, MA  01719
   USA

   Email: pkyzivat@cisco.com




















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