SIPREC                                           Ram Mohan. Ravindranath
Internet-Draft                                       Cisco Systems, Inc.
Intended status: Standards Track                Parthasarathi. Ravindran
Expires: May 3, 2012                                      Sonus Networks
                                                           Paul. Kyzivat
                                                            Unaffiliated
                                                        October 31, 2011


          Session Initiation Protocol (SIP) Recording Metadata
                     draft-ietf-siprec-metadata-05

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) and the Recording metadata
   format.

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 May 3, 2012.

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



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   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
   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 . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   4.  Metadata Model . . . . . . . . . . . . . . . . . . . . . . . .  5
   5.  Recording Metadata Format  . . . . . . . . . . . . . . . . . .  6
     5.1.  XML data format  . . . . . . . . . . . . . . . . . . . . .  6
       5.1.1.  Namespace  . . . . . . . . . . . . . . . . . . . . . .  7
       5.1.2.  recording  . . . . . . . . . . . . . . . . . . . . . .  7
   6.  Recording Metadata classes . . . . . . . . . . . . . . . . . .  7
     6.1.  Recording Session  . . . . . . . . . . . . . . . . . . . .  7
       6.1.1.  Attributes . . . . . . . . . . . . . . . . . . . . . .  8
       6.1.2.  Linkages . . . . . . . . . . . . . . . . . . . . . . .  8
       6.1.3.  XML element  . . . . . . . . . . . . . . . . . . . . .  8
     6.2.  Communication Session Group  . . . . . . . . . . . . . . .  9
       6.2.1.  Attributes . . . . . . . . . . . . . . . . . . . . . .  9
       6.2.2.  Linkages . . . . . . . . . . . . . . . . . . . . . . .  9
       6.2.3.  XML element  . . . . . . . . . . . . . . . . . . . . . 10
     6.3.  Communication Session  . . . . . . . . . . . . . . . . . . 10
       6.3.1.  Attributes . . . . . . . . . . . . . . . . . . . . . . 11
       6.3.2.  Linkages . . . . . . . . . . . . . . . . . . . . . . . 11
       6.3.3.  XML element  . . . . . . . . . . . . . . . . . . . . . 12
     6.4.  Participant  . . . . . . . . . . . . . . . . . . . . . . . 12
       6.4.1.  Attributes . . . . . . . . . . . . . . . . . . . . . . 13
       6.4.2.  Linkages . . . . . . . . . . . . . . . . . . . . . . . 13
       6.4.3.  XML element  . . . . . . . . . . . . . . . . . . . . . 13
     6.5.  ParticipantCSAssociation . . . . . . . . . . . . . . . . . 14
       6.5.1.  Attributes . . . . . . . . . . . . . . . . . . . . . . 14
       6.5.2.  Linkages . . . . . . . . . . . . . . . . . . . . . . . 15
       6.5.3.  XML element  . . . . . . . . . . . . . . . . . . . . . 15
     6.6.  Media Stream . . . . . . . . . . . . . . . . . . . . . . . 15
       6.6.1.  Attributes . . . . . . . . . . . . . . . . . . . . . . 16
       6.6.2.  Linkages . . . . . . . . . . . . . . . . . . . . . . . 16
       6.6.3.  XML element  . . . . . . . . . . . . . . . . . . . . . 16
     6.7.  ParticipantStream Association  . . . . . . . . . . . . . . 16
       6.7.1.  Attributes . . . . . . . . . . . . . . . . . . . . . . 17
       6.7.2.  Linkages . . . . . . . . . . . . . . . . . . . . . . . 17
       6.7.3.  XML element  . . . . . . . . . . . . . . . . . . . . . 17
     6.8.  associate-time/disassociate-time . . . . . . . . . . . . . 17



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     6.9.  Unique ID format . . . . . . . . . . . . . . . . . . . . . 18
   7.  SIP Recording Metadata Example . . . . . . . . . . . . . . . . 18
     7.1.  Complete SIP Recording Metadata Example  . . . . . . . . . 18
     7.2.  Partial Update of Recording metadata XML body  . . . . . . 20
   8.  XML Schema definition for Recording metadata . . . . . . . . . 20
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 23
     9.1.  Connection Security  . . . . . . . . . . . . . . . . . . . 23
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 24
     10.1. SIP recording metadata Schema Registration . . . . . . . . 24
   11. Acknowledgement  . . . . . . . . . . . . . . . . . . . . . . . 24
   12. Appendix A: Metadata Model Object Instances  . . . . . . . . . 24
     12.1. Use case 1: Basic Call . . . . . . . . . . . . . . . . . . 24
     12.2. Use case 2: Hold/Resume  . . . . . . . . . . . . . . . . . 25
     12.3. Use case 3: Basic call with Transfer . . . . . . . . . . . 27
     12.4. Conference Use Cases . . . . . . . . . . . . . . . . . . . 28
       12.4.1. Case 1:  . . . . . . . . . . . . . . . . . . . . . . . 29
       12.4.2. Case 2:  . . . . . . . . . . . . . . . . . . . . . . . 31
       12.4.3. Case 3:  . . . . . . . . . . . . . . . . . . . . . . . 33
       12.4.4. Case 4:  . . . . . . . . . . . . . . . . . . . . . . . 34
   13. Appendix B: Metadata XML schema Instances  . . . . . . . . . . 35
     13.1. Use case 1: Basic Call . . . . . . . . . . . . . . . . . . 35
     13.2. Use case 2: Hold/resume  . . . . . . . . . . . . . . . . . 37
     13.3. Use case 3: Basic Call with transfer . . . . . . . . . . . 39
     13.4. Use Case 4: Call disconnect  . . . . . . . . . . . . . . . 43
   14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 44
     14.1. Normative References . . . . . . . . . . . . . . . . . . . 44
     14.2. Informative References . . . . . . . . . . . . . . . . . . 45
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 45























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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 and the
   Recording metadata format, the requirements for which are described
   in [RFC6341] 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.  Definitions

   Metadata Model: An abstract representation of metadata using a
   Unified Modelling Language(UML) class diagram.

   Metadata classes: Each block in the model represents a class.  A
   class is a construct that is used as a blueprint to create
   instances(called objects) of itself.  The description of each class
   also has representation of its attributes in a second compartment
   below the class name.

   Attributes: Attributes represents the attributes listed in each of
   the classes.  The attributes of a class are listed in the second
   compartment below the class name.  Each instance of class conveys
   values for these attributes which adds to the recording's Metadata.

   Linkages: Linkages represents the relationship between the classes in
   the model.  It represents the logical connections betweens classes(or
   objects) in class diagrams/ object diagrams.  The linkages used in
   the Metadata model of this document are associations.







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4.  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).




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



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               +------------------+    +----------------------+



   The Metadata model is a class diagram in Unified Modelling
   Language(UML).  The model describes the structure of a metadata in
   general by showing the classes, their attributes, and the
   relationships among the classes.  Each block in the model above
   represents a class.  The linkages between the classes represents the
   relationships which can be associations or Composition.  The metadata
   is conveyed from SRC to SRS.

   The model allows the capture of a snapshot of a recording's Metadata
   at a given instant in time.  Metadata changes to reflect changes in
   what is being recorded.  For example, if in a conference a
   participant joins SRC sends a snapshot of metadata having that
   participant information (with attributes like name/AoR pair and
   associate-time) to the SRS.

   Some of the metadata is not required to be conveyed explicitly from
   the SRC to the SRS, if it can be obtained contextually by the
   SRS(e.g., from SIP or SDP signalling).


5.  Recording Metadata Format

   This section gives an overview of Recording Metadata Format.  Some
   data from the metadata model is assumed to be made available to the
   SRS through Session Description Protocol (SDP)[RFC4566], and
   therefore this data is not represented in the XML document format
   specified in this document.  SDP attributes describes about different
   media formats like audio, video.  The other metadata attributes like
   participant details are represented in a new Recording specific XML
   document namely application/rs-metadata+xml.  The SDP label attribute
   [RFC4574] provides an identifier by which a metadata XML document can
   refer to a specific media description in the SDP sent from the SRC to
   the SRS.

   The XML document format can be used to represent either the complete
   metadata or a partial update to the metadata.  The latter includes
   only elements that have changed compared to the previously reported
   metadata.

5.1.  XML data format

   Recording Metadata document is an XML document. recording element
   MUST present in all recording metadata XML document. recording acts
   as container for all other elements in this XML document.



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   Recording object is a XML document.  It MUST have the XML declaration
   and it SHOULD contain an encoding declaration in the XML declaration,
   e.g., "<?xml version='1.0' encoding='UTF-8'?>".  If the charset
   parameter of the MIME content type declaration is present and it is
   different from the encoding declaration, the charset parameter takes
   precedence.

   Every application conforming to this specification MUST accept the
   UTF-8 character encoding to ensure the minimal interoperability.

   Syntax and semantics error in recording XML document has to be
   informed to the originator using application specific mechanism.

5.1.1.  Namespace

   The namespace URI for elements defined by this specification is a
   Uniform Resource Namespace (URN) [RFC2141], using the namespace
   identifier 'ietf' defined by [RFC2648] and extended by [RFC3688].

   The URN is as follows: urn:ietf:params:xml:ns:recording

5.1.2.  recording

   recording element MUST contain an xmlns namespace attribute with
   value as urn:ietf:params:xml:ns:recording.  One recording element
   MUST present in the all recording metadata XML document.

   dataMode element shows whether the XML document is complete document
   or partial update.  The default value is complete.


6.  Recording Metadata classes

   This section describes each class of the metadata model, and the
   attributes of each class.  This section also describes how different
   classes are linked and the XML element for each of them.

6.1.  Recording Session













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   +-------------------------------+
   | Recording Session (RS)        |
   +-------------------------------+
   |                               |
   |     Start/End Time            |
   |                               |
   |                               |
   |                               |
   +-------------------------------+
         |1..*            | 1..*
         |                |
         |0..*            | 0..*
    Communication    Communication
    Session          Session Group(CS Group)


   Each instance of a Recording Session class (namely the Recording
   Session Object) represents a SIP session created between an SRC and
   SRS for the purpose of recording a Communication Session.

6.1.1.  Attributes

   A Recording Session class has the following attributes:
   o  Start/End Time - Represents the Start/End time of a Recording
      Session object.

6.1.2.  Linkages

   Each instance of Recording Session has:

   o  Zero or more instances of Communication Session Group.  CSG may be
      zero because it is optional metadata object.  Also the allowance
      of zero instances is to accommodate persistent recording, where
      there may be none.
   o  Zero or more instances of Communication Session objects.

6.1.3.  XML element

   Recording Session object is represented by recording XML element.
   That in turn relies on the SIP/SDP session with which the XML
   document is associated to provide some of the attributes of the
   Recording Session element.

   Start and End time value are derivable from Date header(if present in
   SIP message) in RS.  In cases where Date header is not present,
   Start/End time are derivable from the time at which SRS receives the
   notification of SIP message to setup RS / disconnect RS.




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6.2.  Communication Session Group


    Recording Session (RS)
              | 1..*
              |
              | 0..*
   +-------------------------------+
   | Communication Session         |
   |     Group                     |
   +-------------------------------+
   |  Unique-ID                    |
   |  associate-time               |
   |  disassociate-time            |
   |                               |
   +-------------------------------+
              | 0..1
              |
              | 1..*
    Communication Session (CS)


   One instance of a Communication Session Group class (namely the
   Communication Session Group object) provides association or linking
   of Communication Sessions.

6.2.1.  Attributes

   A CS Group has the following attributes:
   o  Unique-ID - This Unique-ID is to group different CSs that are
      related.  SRC (or SRS) is responsible for ensuring 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.
   o  Associate-time - Associate-time for CS-Group shall be calculated
      by SRC as the time when a grouping is formed.  The rules that
      determine how a grouping of different Communication Session
      objects is done by SRC is outside the scope of SIPREC.
   o  Disassociate-time - Disassociate-time for CS-Group shall be
      calculated by SRC as the time when the grouping ends

6.2.2.  Linkages

   The linkages between Communication Session Group class and other
   classes is association.  A communication Session Group is associated
   with RS and CS in the following manner:





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   o  There is one or more Recording Session objects per Communication
      Session Group.
   o  Each Communication Session Group object has to be associated with
      one or more RS [Here each RS can be setup by the potentially
      different SRCs]
   o  There is one or more Communication Sessions per CS Group [e.g.
      Consult Transfer]

6.2.3.  XML element

   Group element is an optional element provides the information about
   the communication session group

   Each communication session group (CSG)object is represented using one
   group element.  Each group element has unique Base 64 URN UUID
   attribute which helps to uniquely identify CSG.

6.3.  Communication Session



   Recording              Communication
   Session            Session Group(CS Group)
      |1..*                  | 0..1
      |                      |
      |0..*                  | 1..*
   +-------------------------------+
   |   Communication Session (CS)  |
   |                               |
   +-------------------------------+
   |   CS Identifier               |
   |   Termination Reason          |
   |   Associate Time              |
   |   Disassociate Time           |
   +-------------------------------+
      |                      |
      | 1..*                 |1..*
      |                      |
      | 2..*                 |0..*
   Participant              Media Stream



   A Communication Session class and its object in the metadata model
   represents Communication Session and its properties needed as seen by
   SRC.





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6.3.1.  Attributes

   A communication Session class has the following attributes:

   o  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.
   o  Associate Time - This optional attribute represents the time a CS
      is associated with a RS
   o  Disassociate Time - This optional attribute represents the time a
      CS is disassociated with a RS.

   This document does not specify attributes relating to what should
   happen to a recording of a CS after it has been delivered to the SRS,
   e.g., how long to retain the recording, what access controls to
   apply.  The SRS is assumed to behave in accordance with policy.  The
   ability for the SRC to influence this policy is outside the scope of
   this document.  However if there are implementations where SRC has
   enough information, this could be sent as Extension Data attached to
   CS

6.3.2.  Linkages

   A Communication Session is linked to CS-Group, Participant, Media
   Stream and Recording Session classes using the association
   relationship.  Association between CS and Participant allows:

   o  CS to have atleast two or more participants
   o  Participant is associated with one or more CS's.  This includes
      participants who are not directly 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.  To summarize even if SRC does
      not have direct signalling relationships with all participants in
      a CS, it should nevertheless create a Participant object for each
      participant that it knows about
   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.

   Association between CS and Media Stream allows:



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   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.

   Association between CS and RS allows:

   o  Each instance of RS has Zero or more instances of Communication
      Session objects.
   o  Each CS has to be associated with one more RS [ Here each RS can
      be potentially setup by different SRCs]

6.3.3.  XML element

   Session element provides the information about the communication
   session

   Each communication session(CS) object is represented by one session
   element.  Each session element has unique Base 64 URN UUID attribute
   which helps to uniquely identify CS.

   Reason element MAY be included to represent the Termination Reason
   attribute. group-ref element MAY exist to indicate the group where
   the mentioned session belongs.

6.4.  Participant


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



   A Participant class and its objects has information about a device
   that is part of a CS and/or contributes/consumes media stream(s)



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   belonging to a CS.

6.4.1.  Attributes

   Participant has attributes like:

   o  AoR / Name pair list - This attribute is a list of Name/AoR tuple.
      An AoR MAY be SIP/SIPS/TEL URI.  Name represents Participant
      name(SIP display name) or DN number ( in case it is known).  There
      are cases where a participant can have more than one AoR [ e.g.
      P-Asserted-ID which can have both SIP and TEL URIs]

   This document does not specify other attributes relating to
   participant e.g.  Participant Role, Participant type.  An SRC which
   has information of these attributes can indicate the same as part of
   extension data to Participant from SRC to SRS.

6.4.2.  Linkages

   The participant class is linked to MS and CS class using association
   relationship.  The association 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)
   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 receives Zero or more streams -
   a Supervisor may have side conversation with Agent, while Agent
   converses with customer.

6.4.3.  XML element

   A participant element represents a Participant object.

   There MUST be atleast 2 participant for any given session. "send" or
   "recv" element in each participant is associating SDP m-lines with
   the participant. send element indicates that participant is sending
   the stream of media with the mentioned media description. recv
   element indicates that participant is receiving the stream and by



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   default all participant will receive the stream. recv element has
   relevance in case whisper call scenario wherein few of the
   participant in the session receives the stream and not others.

   Participant MUST have a NameID complex element which contains AoR as
   attribute and Name as element.  AOR element is SIP/SIPS URI FQDN or
   IP address which represents the user. name is an optional element to
   represent display name.

   Each participant element has unique ID (Base 64 URN UUID) attribute
   which helps to uniquely identify participant and session Base 64 URN
   UUID to associate participant with specific session element.  Base 64
   URN UUID of participant *MUST* used in the scope of CSG and no new
   Base 64 URN UUID has to be created for the same element (participant,
   stream) between different CS in the same CSG.  In case Base 64 URN
   UUID has to be used permanent, careful usage of Base 64 URN UUID to
   original AoR has to be decided by the implementers and it is
   implementer's choice.

6.5.  ParticipantCSAssociation



                        1..*            2..*
      Communication
       Session        ----------+---------- Participant
                                |
                                |
                                |
                      +-------------------+
                      | ParticipantCS     |
                      | Association       |
                      +-------------------+
                      | Capabilities      |
                      | Association-Time  |
                      | Disassociaton-Time|
                      +-------------------+


   A participantCS Association class and its objects has attributes of
   participant object which are attributes of association of a
   participant to a Session.

6.5.1.  Attributes

   ParticipantCS association class has the following attributes:





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   o  Associate-time - associate-time is calculated by SRC as the time
      it sees a participant is associated to CS
   o  Disassociate-time- Disassociate-time is calculated by SRC as the
      time it see a participant disassociate from a CS.  It is possible
      that a given participant can have multiple associate/disassociate
      times within given communication session.
   o  Capabilities - A participant capabilities as defined in RFC 3840
      [RFC3840] is an optional attribute that includes the capabilities
      of a participant in a CS.  Each participant shall have Zero or
      more capabilities.  A participant may use different capabilities
      depending on the role it plays at a particular instance.  IOW if a
      participants moves across different CSs ( due to transfer e.t.c)
      OR is simultaneously present in different CSs its role may be
      different and hence the capability used.

6.5.2.  Linkages

   The participantCS association class is linked to participant and CS
   classes.  There are no cardinalties for this linkage.

6.5.3.  XML element

   TBD

   NOTE: RFC 4235 encoding shall be used to represent capabilities
   attribute in XML.

6.6.  Media Stream


                                   Participant
                               | 0..*       1..*|
                       receives|                |sends
                               | 0..*       0..*|
                            +-------------------------+
                            |          Media Stream   |
                            |                         |
   Communication 1..*  0..* +-------------------------+
     Session    ------------|                         |
                            |  Media Stream Reference |
                            |  Content-type           |
                            |                         |
                            +-------------------------+



   A Media Stream class (and its objects) has the properties of media as
   seen by SRC and sent to SRS.  Different snapshots of media stream



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   object may be sent whenever there is a change in media (e.g. dir
   change like pause/resume and/or codec change and/or participant
   change.).

6.6.1.  Attributes

   A Media Stream class has the the following attributes:

   o  Media Stream Reference - In implementations this can reference to
      m-line
   o  Content - The content of an MS element will be described in terms
      of value from the RFC 4796 [RFC4796] registry.

   The metadata model should include media streams that are not being
   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

6.6.2.  Linkages

   A Media Stream is linked to participant and CS classes using the
   association relationship.  The details of association with the
   Participant are described in the Participant class section.  The
   details of association with CS is mentioned in the CS section.

6.6.3.  XML element

   stream element represents a Media Stream object.  Stream element
   indicates SDP media lines associated with the session and
   participants.

   This element indicates the SDP m-line properties like label
   attributes, media mode.  Label attribute is used to link m-line SDP
   body using label attribute in SDP m-line.  The media mode helps in
   understanding whether the media is mixed or not.

   Each stream element has unique Base 64 URN UUID attribute which helps
   to uniquely identify stream and session Base 64 URN UUID to associate
   stream with specific session element.

   The content attribute if an SRC wishes to send is conveyed in RS SDP.

6.7.  ParticipantStream Association







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   +-------------------+
   | ParticipantSteam  |
   | Association       |
   +-------------------+   +----------Participant
   | CSRC              |   |           |     |
   | Association-Time  |   |       0..*| 1..*|
   | Disassociaton-Time|---+       recv|     |sends
   | Recv              |   |       0..*| 0..*|
   | Send              |   |           |     |
   +-------------------+   |           |     |
                           +----------Media Stream



   A ParticipantStream association class and its object has attributes
   that are attributes of association of a Participant to a Stream.

6.7.1.  Attributes

   A participantStream association class has the following attributes:

   o  CSRC - The linkage between the participants to its contributing
      media stream in a mixed RS stream is provided by CSRC attribute.
      Not all SRC may have the capability to determine this and hence
      this is a optional attribute.  Having this info can allow the SRS
      to determine which participants are part(contributors) of
      particular parts of the mixed stream.  This attribute carries SSRC
      of contributing sender.
   o  Associate-Time: This attributes indicates the time a Participant
      started contributing to a Media Stream
   o  Disassociate-Time: This attribute indicates the time a Participant
      stopped contributing to a Media Stream

6.7.2.  Linkages

   The participantStream association class is linked to participant and
   Stream classes.  There are no cardinalties for this linkage.

6.7.3.  XML element

   TBD

6.8.  associate-time/disassociate-time

   associate-time/disassociate-time contains a string indicating the
   date and time of the status change of this tuple.  The value of this
   element MUST follow the IMPP datetime format [RFC3339].  Timestamps
   that contain 'T' or 'Z' MUST use the capitalized forms.  At a time,



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   any of the time tuple associate-time or disassociate-time MAY exist
   in the element namely group, session, participant and not both
   timestamp at the same time.

   As a security measure, the timestamp element SHOULD be included in
   all tuples unless the exact time of the status change cannot be
   determined.

6.9.  Unique ID format

   Unique id is generated in two steps:
   o  UUID is created using [RFC4122])
   o  UUID is encoded using base64 as defined in RFC 4648 [RFC4648]

   The above mentioned unique-id mechanism SHOULD be used for each
   metadata element.


7.  SIP Recording Metadata Example

7.1.  Complete SIP Recording Metadata Example

   The following example provides all the tuples involved in Recording
   Metadata XML body.


   <?xml version="1.0" encoding="UTF-8"?>
          <recording xmlns='urn:ietf:params:xml:ns:recording'>
                 <dataMode>complete</dataMode>
             <group id="7+OTCyoxTmqmqyA/1weDAg==">
               <associate-time>2010-12-16T23:41:07Z</associate-time>
                <!-- Standardized extension -->
               <call-center xmlns='urn:ietf:params:xml:ns:callcenter'>
                 <supervisor>sip:alice@cisco.com</supervisor>
               </call-center>
               <mydata xmlns='http://example.com/my'>
                 <structure>FOO!</structure>
                 <whatever>bar</whatever>
               </mydata>
             </group>
             <session id="hVpd7YQgRW2nD22h7q60JQ==">
               <group-ref>7+OTCyoxTmqmqyA/1weDAg==
               </group-ref>
               <associate-time>2010-12-16T23:41:07Z</associate-time>
                <!-- Standardized extension -->
               <structure>FOO!</structure>
               <whatever>bar</whatever>
             </session>



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             <participant
                id="srfBElmCRp2QB23b7Mpk0w=="
                session="hVpd7YQgRW2nD22h7q60JQ==">
                <nameID aor=sip:ram@blr.cisco.com>
                              <name xml:lang="it">RamMohan R</name>
                             </nameID>
                <send>i1Pz3to5hGk8fuXl+PbwCw==</send>
                <send>UAAMm5GRQKSCMVvLyl4rFw==</send>
                <recv>8zc6e0lYTlWIINA6GR+3ag==</recv>
                <recv>EiXGlc+4TruqqoDaNE76ag==</recv>
                <associate-time>2010-12-16T23:41:07Z</associate-time>
                <!-- Standardized extension -->
               <structure>FOO!</structure>
               <whatever>bar</whatever>
             </participant>

             <participant
                 id="zSfPoSvdSDCmU3A3TRDxAw=="
                 session="hVpd7YQgRW2nD22h7q60JQ==">
                 <nameID aor=sip:paul@box.cisco.com>
                              <name xml:lang="it">Paul Kyzivat</name>
                             </nameID>
                 <send>8zc6e0lYTlWIINA6GR+3ag==</send>
                 <send>EiXGlc+4TruqqoDaNE76ag==</send>
                 <recv>UAAMm5GRQKSCMVvLyl4rFw==</recv>
                 <recv>i1Pz3to5hGk8fuXl+PbwCw==</recv>
                 <associate-time>2010-12-16T23:41:07Z</associate-time>
                 <!-- Standardized extension -->
               <structure>FOO!</structure>
               <whatever>bar</whatever>
             </participant>

             <stream id="UAAMm5GRQKSCMVvLyl4rFw=="
                 session="hVpd7YQgRW2nD22h7q60JQ==">
                 <label>96</label>
             </stream>
             <stream id="i1Pz3to5hGk8fuXl+PbwCw=="
                 session="hVpd7YQgRW2nD22h7q60JQ==">
                 <label>97</label>
             </stream>
             <stream id="8zc6e0lYTlWIINA6GR+3ag=="
                 session="hVpd7YQgRW2nD22h7q60JQ==">
                 <label>98</label>
             </stream>
             <stream id="EiXGlc+4TruqqoDaNE76ag=="
                 session="hVpd7YQgRW2nD22h7q60JQ==">
                 <label>99</label>
             </stream>



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        </recording>


                  SIP Recording Metadata Example XML body

7.2.  Partial Update of Recording metadata XML body

   The following example provides partial update in Recording Metadata
   XML body for the above example.  The example has a snapshot that
   carries the disassociate-time for a participant from a session.


    <?xml version="1.0" encoding="UTF-8"?>
       <recording xmlns='urn:ietf:params:xml:ns:recording'>
         <dataMode>partial</dataMode>
         <participant
            id="srfBElmCRp2QB23b7Mpk0w=="
            session="hVpd7YQgRW2nD22h7q60JQ==">
            <name ID=sip:partha@blr.cisco.com>
                      <name xml:lang="it">Parathasarathi R</name>
                    </nameID>
             <disassociate-time>2010-12-16T23:41:07Z</disassociate-time>
             <structure>FOO!</structure>
             <whatever>bar</whatever>
         </participant>
       </recording>


             Partial update of SIP Recording Example XML body


8.  XML Schema definition for Recording metadata

   This section defines XML schema for Recording metadata document


<?xml version="1.0" encoding="UTF-8"?>
   <xs:schema targetNamespace="urn:ietf:params:xml:ns:recording"
    xmlns:tns="urn:ietf:params:xml:ns:recording"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    elementFormDefault="qualified"
    attributeFormDefault="unqualified">
   <!-- This import brings in the XML language attribute xml:lang-->
   <xs:import namespace="http://www.w3.org/XML/1998/namespace"/>
   <xs:element name="recording" type="recording"/>
   <xs:complexType name="recording">
       <xs:sequence>
           <xs:element name="datamode" type="dataMode"



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                minOccurs="0"/>
         <xs:element name="group" type="group"
                minOccurs="0" maxOccurs="unbounded"/>
           <xs:element name="session" type="session"
                minOccurs="0" maxOccurs="unbounded"/>
           <xs:element name="participant" type="participant"
                minOccurs="0" maxOccurs="unbounded"/>
           <xs:element name="stream" type="stream"
               minOccurs="0" maxOccurs="unbounded"/>
          <xs:any namespace='##other'
                   minOccurs='0'
                   maxOccurs='unbounded'
                   processContents='lax'/>
       </xs:sequence>
   </xs:complexType>
   <xs:complexType name="group">
       <xs:sequence>
         <xs:element name="associate-time" type="xs:dateTime"
            minOccurs="0"/>
         <xs:element name="disassociate-time" type="xs:dateTime"
            minOccurs="0"/>
        <xs:any namespace='##other'
                   minOccurs='0'
                   maxOccurs='unbounded'
                   processContents='lax'/>
       </xs:sequence>
       <xs:attribute name="id" type="xs:base64Binary"
            use="required"/>
   </xs:complexType>
   <xs:complexType name="session">
       <xs:sequence>
         <xs:element name="associate-time" type="dateTime"
                minOccurs="0"/>
         <xs:element name="disassociate-time" type="dateTime"
                minOccurs="0"/>
         <xs:element name="reason" type="xs:string"
                minOccurs="0"/>
         <xs:element name="group-ref" type="xs:base64Binary"
                minOccurs="0" maxOccurs="1"/>
           <xs:any namespace='##other'
                   minOccurs='0'
                   maxOccurs='unbounded'
                   processContents='lax'/>
       </xs:sequence>
       <xs:attribute name="id" type="xs:base64Binary"
            use="required"/>
   </xs:complexType>
   <xs:complexType name="participant">



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       <xs:sequence>
           <xs:element name="nameID" type="nameID"
             maxOccurs="1"/>
           <xs:element name="send" type="xs:base64Binary"
             minOccurs="0" maxOccurs="unbounded"/>
           <xs:element name="recv" type="xs:base64Binary"
             minOccurs="0" maxOccurs="unbounded"/>
         <xs:element name="associate-time" type="xs:dateTime"
                minOccurs="0"/>
       <xs:element name="disassociate-time" type="xs:dateTime"
                minOccurs="0"/>
        <xs:any namespace='##other'
                   minOccurs='0'
                   maxOccurs='unbounded'
                   processContents='lax'/>
       </xs:sequence>
       <xs:attribute name="id" type="xs:base64Binary"
            use="required"/>
       <xs:attribute name="session" type="xs:base64Binary"
            use="required"/>
   </xs:complexType>
   <xs:complexType name="stream">
       <xs:sequence>
         <xs:element name="label" type="xs:string"
             minOccurs="0" maxOccurs="1"/>
          <xs:element name="associate-time" type="xs:dateTime"
                minOccurs="0"/>
          <xs:element name="disassociate-time" type="xs:dateTime"
                minOccurs="0"/>
          <xs:element name="csrc" type='xs:string'
           minOccurs='0' maxOccurs='1'/>
          <xs:any namespace='##other'
                   minOccurs='0'
                   maxOccurs='unbounded'
                   processContents='lax'/>
       </xs:sequence>
       <xs:attribute name="id" type="xs:base64Binary"
            use="required"/>
       <xs:attribute name="session" type="xs:base64Binary"
            use="required"/>
   </xs:complexType>
     <xs:simpleType name="dataMode">
         <xs:restriction base="xs:string">
            <xs:enumeration value="complete"/>
                    <xs:enumeration value="partial"/>
         </xs:restriction>
   </xs:simpleType>




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   <xs:complexType name="nameID">
    <xs:sequence>
      <xs:element name="name" type ="name" minOccurs="0" maxOccurs="1"/>
    </xs:sequence>
    <xs:attribute name="aor" type="xs:anyURI" use="required"/>
  </xs:complexType>

 <xs:complexType name="name">
   <xs:simpleContent>
        <xs:extension base="xs:string">
         <xs:attribute ref="xml:lang" use="optional"/>
        </xs:extension>
       </xs:simpleContent>
  </xs:complexType>

  </xs:schema>




9.  Security Considerations

   The metadata information sent from SRC to SRS MAY reveal sensitive
   information about different participants in a session.  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 format
   defined in this document.  The following sections will discuss each
   of these aspects in more detail.

9.1.  Connection Security

   It is RECOMMENDED that a SRC authenticate SRS using the normal SIP
   authentication mechanisms, such as Digest as defined in Section 22 of
   [RFC3261].  The mechanism used for conveying the metadata information
   MUST ensure integrity and SHOULD ensure confidentially of the
   information.  In order to achieve these, an end-to-end SIP encryption
   mechanism, such as S/MIME described in [RFC3261], SHOULD be used.

   If a strong end-to-end security means (such as above) is not
   available, it is RECOMMENDED that a SRC use mutual hop-by-hop
   Transport Layer Security (TLS) authentication and encryption
   mechanisms described in "SIPS URI Scheme" and "Interdomain Requests"
   of [RFC3261].







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10.  IANA Considerations

   This specification registers a new XML namespace, and a new XML
   schema.

10.1.  SIP recording metadata Schema Registration

   URI: urn:ietf:params:xml:ns:recording

   Registrant Contact: IETF SIPREC working group, Ram mohan
   R(rmohanr@cisco.com)

   XML: the XML schema to be registered is contained in Section 6.

   Its first line is <?xml version="1.0" encoding="UTF-8"?> and its last
   line is </xs:schema>


11.  Acknowledgement

   We wish to thank John Elwell(Siemens-Enterprise), Henry Lum(Alcatel-
   Lucent), Leon Portman(Nice), De Villers, Andrew Hutton(Siemens-
   Enterprise), Deepanshu Gautam(Huawei), Charles Eckel(Cisco), Muthu
   Arul(Cisco), Michael Benenson(Cisco), Hadriel Kaplan (ACME), Brian
   Rosen(Neustar), Scott Orton(Broadsoft) for their valuable comments
   and inputs.

   We wish to thank Joe Hildebrand(Cisco), Peter Saint-Andre(Cisco) for
   the valuable XML related guidance and Martin Thompson for validating
   the XML schema and providing comments on the same.


12.  Appendix A: 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.  Also for the sake of ease not all
   attributes of each object are shown in these instance diagrams.

12.1.  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)   |
     +----------------+-----------------------+
     |  Start Time    |                       |
     +----------------+                       |
              |                               |
              |-------------------+           |
              |                   |           |
   +---------------+     +---------------+    |
   | ParticipantA  |     | ParticipantB  |    |
   |               |     |               |    |
   +---------------+     +---------------+    |
              |                  |            |
     sends    |                  |  sends     |
              |                  |            |
   +---------------+       +---------------+  |
   |Media Stream A1|       |Media Stream B1|  |
   +---------------+       +---------------+  |
   |MediaStream Ref|       |MediaStream Ref|  |
   |               |       |               |  |
   +---------------+       +---------------+  |
          |                       |           |
          +-----------------------------------+


12.2.  Use case 2: 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 can 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)        |
   +-------------------------------+
              |                   |
              |                   |
              |                   |



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              |                 +-------------------------------+
              |                 |   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| |  |              | |
   | +---------------+  |   |  +---------------+ |  |              | |
   +-|MediaStreamref |  |   |  |MediaStreamRef | |  +--------------+ |
     |               |  |   |  |               |-|-------------------|
     +---------------+  |   |  +---------------+ |                   |
                        |   |                    |                   |
           +------------+   |sends               |sends (hold)       |
           | sends          |(Resume)            |                   |
           | (hold)         +-------+             +-------+          |
           |                        |                     |          |
     +---------------+       +---------------+   +--------------+    |
     |Media Stream A2|       |Media Stream A3|   |MediaStream B2|    |
     +---------------+       +---------------+   |              |    |
     |MediaStreamref |       |MediaStreamRef |   +--------------+    |
     |               |       |               |   |Codec Params  |    |
     +---------------+       +---------------+   |              |    |
              |                     |            |              |    |
              |                     |            +--------------+    |
              |                     |                  |             |
              +------------------------------------------------------+




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12.3.  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 can 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  |             |
   |               |   | |               |             |
   +---------------+   | +---------------+             |
              |        |         |                     |
     sends    |        |         |  sends              |
              |        |         |                     |
   +---------------+   |   +---------------+           |
   |Media Stream A1|   |   |Media Stream B1|           |
   +---------------+   |   +---------------+           |
   |               |   |   |               |           |



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   |               |   |   | Media Stream  |           |
   | Media Stream  |---+---|  Ref          |           |
   | Ref           |       |               |           |
   +---------------+       +---------------+           |
                                                       |
                                                       |
                          +----------------------------|
                          |                            |
         +--------------------------------+            |
         |                                |            |
   +---------------+                +---------------+  |
   | Participant A |                | Participant C |  |
   |   (same)      |                |               |  |
   +---------------+                +---------------+  |
         |                                    |        |
         | sends (After transfer)             | sends  |
   +----------------+                +----------------+|
   | Media Stream A2|                | Media Stream C1||
   +----------------+                +----------------+|
   | Media StreamRef|                | Media StreamRef||
   |                |                |                ||
   |                |                |                ||
   +----------------+                +----------------+|
           |                                  |        |
           |                                  |        |
           |                                  |        |
           +-------------------------------------------+


12.4.  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)
   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.






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12.4.1.  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                  |  |
   +-------------------------------+  |
              |                       |
              |-----------------------+
              |
     +----------------+
     | Communication  |
     | Session (CS)   |--+----------------+-----+
     +----------------+  |                |     |
     |                |  |                |     |
     +----------------+  |                |     |
              |          |                |     |
              |          |                |     |



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              |          |                |     |
   +---------------+     |                |     |
   | ParticipantA  |     |                |     |
   |               |     |                |     |
   +---------------+     |                |     |
              |          |                |     |
     sends    |          |                |     |
              |          |                |     |
   +---------------+     |                |     |
   |Media Stream A1|     |                |     |
   +---------------+     |                |     |
   |MediaStream Ref|-----|----------------+     |
   |               |     |                |     |
   +---------------+     |                |     |
                         |                |     |
                         |                |     |
           +-------------+                |     |
           |                              |     |
           |                              |     |
   +----------------+                     |     |
   | Participant B  |                     |     |
   |  (in conf)     |                     |     |
   +----------------+                     |     |
           |                              |     |
    sends  |                              |     |
           |                              |     |
   +----------------+                     |     |
   | Media Stream B1|---------------------+     |
   +----------------+        sends              |
   | MediaStream Ref|                           |
   |                |         +-----------------+
   +----------------+         |
              |               |
              |sends          |
              |               |
        +-----------------+-------------+------------+
        |                 |             |            |
        |                 |             |            |
   +------------+  +------------+ +------------+ +-------------+
   |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
   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



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   instance diagram Participant B is a user in a conference.  The SRC
   (Participant B) subscribes to conference event package to get the
   details of other particiants.  Participant B(SRC) sends the same
   through the metadata to SRS.  In this instance diagram the Media
   Stream(mixed stream) sent from Participant B has 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).

12.4.2.  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| |
   |               |---+---|               | |
   +---------------+       +---------------+ |
                                             |
          +----------------------------------+
          |            |         |           |
          |            |         |           |
   +---------------+   | +---------------+   |
   | ParticipantD  |   | | ParticipantE  |   |
   |               |   | |               |   |
   +---------------+   | +---------------+   |
              |        |         |           |
     sends    |        |         |  sends    |
              |        |         |           |
   +---------------+   |   +---------------+ |
   |Media Stream D1|   |   |Media Stream E1| |
   +---------------+   |   +---------------+ |
   |MediaStream Ref|   |   |MediaStream Ref| |
   |               |---+---|               | |
   +---------------+       +---------------+ |
                                             |



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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 has access to the details of other
   particiants.  SRC (Participant C) sends the same through the metadata
   to SRS.  In this instance diagram the Media Stream(mixed stream) sent
   by C has media streams contributed by conference participants (A, B,
   D and E).  Participants A, B,D and E sends Media Streams A1, B1, D1
   and E1 respectively.  The media stream sent by Participant C(Focus)
   is 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) can send mixed stream or seperate streams
   to SRS

12.4.3.  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)


12.4.4.  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 sends
   "isfocus" in SIP message to SRC.  The SRC subscribe to conference
   event package on seeing this "isfocus".  SRC learns 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
   is 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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13.  Appendix B: Metadata XML schema Instances

   This section describes the metadata model XML instances for different
   use cases of SIPREC.  For the sake of simplicity the complete SIP
   messages are NOT shown here.

13.1.  Use case 1: Basic Call

   Basic call between two Participants A(Ram) and B(Partha) who are part
   of one session.  In this use case each participant sends two Media
   Streams.  Media Streams sent by each participant is received all
   other participants of that CS in this use-case.  Below is the initial
   snapshot sent by SRC that has complete metadata.  For the sake of
   completeness even snippets of SDP is shown.  For the sake of
   simplicity these use-cases assume the RS stream is unmixed.


      Content-Type: application/SDP
      ...
      m=audio 49170 RTP/AVP 0
      a=rtpmap:0 PCMU/8000
      a=label:96
      a=sendonly
      ...
      m=video 49174 RTP/AVPF 96
      a=rtpmap:96 H.264/90000
      a=label:97
      a=sendonly
      ...
      m=audio 51372 RTP/AVP 0
      a=rtpmap:0 PCMU/8000
      a=label:98
      a=sendonly
      ...
      m=video 49176 RTP/AVPF 96
      a=rtpmap:96 H.264/90000
      a=label:99
      a=sendonly
      ....
   <?xml version="1.0" encoding="UTF-8"?>
       <recording xmlns='urn:ietf:params:xml:ns:recording'>
              <dataMode>complete</dataMode>
          <group id="7+OTCyoxTmqmqyA/1weDAg==">
            <associate-time>2010-12-16T23:41:07Z</associate-time>
            <!-- Standardized extension -->
            <call-center xmlns='urn:ietf:params:xml:ns:callcenter'>
              <supervisor>sip:alice@cisco.com</supervisor>
            </call-center>



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            <mydata xmlns='http://example.com/my'>
              <structure>FOO!</structure>
              <whatever>bar</whatever>
            </mydata>
         </group>
         <session id="hVpd7YQgRW2nD22h7q60JQ==">
            <group-ref>7+OTCyoxTmqmqyA/1weDAg==
            </group-ref>
            <start-time>2010-12-16T23:41:07Z</start-time>
            <!-- Standardized extension -->
            <structure>FOO!</structure>
            <whatever>bar</whatever>
          </session>
          <participant
             id="srfBElmCRp2QB23b7Mpk0w=="
             session="hVpd7YQgRW2nD22h7q60JQ==">
            <nameID aor=sip:ram@blr.cisco.com>
             <name xml:lang="it">RamMohan R</name>
            </nameID>
           <send>i1Pz3to5hGk8fuXl+PbwCw==</send>
           <send>UAAMm5GRQKSCMVvLyl4rFw==</send>
           <recv>8zc6e0lYTlWIINA6GR+3ag==</recv>
           <recv>EiXGlc+4TruqqoDaNE76ag==</recv>
           <associate-time>2010-12-16T23:41:07Z</associate-time>
            <!-- Standardized extension -->
            <structure>FOO!</structure>
            <whatever>bar</whatever>
          </participant>

          <participant
              id="zSfPoSvdSDCmU3A3TRDxAw=="
              session="hVpd7YQgRW2nD22h7q60JQ==">
              <nameID aor=sip:partha@blr.sonus.com>
               <name xml:lang="it">Parthasarathi R</name>
            </nameID>
            <send>8zc6e0lYTlWIINA6GR+3ag==</send>
            <send>EiXGlc+4TruqqoDaNE76ag==</send>
            <recv>UAAMm5GRQKSCMVvLyl4rFw==</recv>
            <recv>i1Pz3to5hGk8fuXl+PbwCw==</recv>
            <associate-time>2010-12-16T23:41:07Z</associate-time>
            <!-- Standardized extension -->
            <structure>FOO!</structure>
            <whatever>bar</whatever>
          </participant>
          <stream id="UAAMm5GRQKSCMVvLyl4rFw=="
              session="hVpd7YQgRW2nD22h7q60JQ==">
              <label>96</label>
          </stream>



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          <stream id="i1Pz3to5hGk8fuXl+PbwCw=="
              session="hVpd7YQgRW2nD22h7q60JQ==">
              <label>97</label>
          </stream>
          <stream id="8zc6e0lYTlWIINA6GR+3ag=="
              session="zSfPoSvdSDCmU3A3TRDxAw==">
              <label>98</label>
          </stream>
          <stream id="EiXGlc+4TruqqoDaNE76ag=="
              session="zSfPoSvdSDCmU3A3TRDxAw==">
              <label>99</label>
          </stream>
     </recording>


13.2.  Use case 2: Hold/resume

   Basic call between two Participants A and B. This is the continuation
   of above use-case.  One of the participants(say A) goes on hold and
   then resumes as part of the same session.  The metadata snapshot
   looks as below

   During hold




























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      Content-Type: application/SDP
      ...
      m=audio 49170 RTP/AVP 0
      a=rtpmap:0 PCMU/8000
      a=label:96
      a=inactive
      ...
      m=video 49174 RTP/AVPF 96
      a=rtpmap:96 H.264/90000
      a=label:97
      a=inactive
      ...
      m=audio 51372 RTP/AVP 0
      a=rtpmap:0 PCMU/8000
      a=label:98
      a=sendonly
      ...
      m=video 49176 RTP/AVPF 96
      a=rtpmap:96 H.264/90000
      a=label:99
      a=sendonly
      ....

      <?xml version="1.0" encoding="UTF-8"?>
        <recording xmlns='urn:ietf:params:xml:ns:recording'>
          <dataMode>partial</dataMode>
               <participant
             id="srfBElmCRp2QB23b7Mpk0w=="
             session="hVpd7YQgRW2nD22h7q60JQ==">
             <nameID aor=sip:ram@blr.cisco.com/>
                     <recv>8zc6e0lYTlWIINA6GR+3ag==</recv>
            <recv>EiXGlc+4TruqqoDaNE76ag==</recv>
            </participant>
                    <participant
             id="srfBElmCRp2QB23b7Mpk0w=="
             session="hVpd7YQgRW2nD22h7q60JQ==">
              <nameID aor=sip:partha@blr.sonusnet.com/>
             <send>8zc6e0lYTlWIINA6GR+3ag==</send>
             <send>EiXGlc+4TruqqoDaNE76ag==</send>
          </participant>
           </recording>


   During resume

   The snapshot will look pretty much same as Use-case 1.





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13.3.  Use case 3: Basic Call with transfer

   Basic call between two Participants A and B is connected as in Use-
   case 1.  Transfer is initiated by one of the participants of by other
   entity(3PCC case).  SRC sends a snapshot of the participant changes
   to SRS.  In this instance participant A(Ram) drops out during the
   transfer and Participant C(Paul) joins the session.  There can be two
   cases here, same session continues after transfer or a new session
   (e.g.  REFER based transfer) is created

   Transfer with same session retained - (.e.g.  RE-INVITE based
   transfer).  Participant A drops out and C is added to the same
   session.  No change to session/group element.  C will be new stream
   element which maps to RS SDP using the same labels in this instance.


      Content-Type: application/SDP
      ...
      m=audio 49170 RTP/AVP 0
      a=rtpmap:0 PCMU/8000
      a=label:96
      a=sendonly
      ...
      m=video 49174 RTP/AVPF 96
      a=rtpmap:96 H.264/90000
      a=label:97
      a=sendonly
      ...
      m=audio 51372 RTP/AVP 0
      a=rtpmap:0 PCMU/8000
      a=label:98
      a=sendonly
      ...
      m=video 49176 RTP/AVPF 96
      a=rtpmap:96 H.264/90000
      a=label:99
      a=sendonly
      ....
   <?xml version="1.0" encoding="UTF-8"?>
       <recording xmlns='urn:ietf:params:xml:ns:recording'>
              <dataMode>partial</dataMode>
          <participant
              id="zSfPoSvdSDCmU3A3TRDxAw=="
              session="hVpd7YQgRW2nD22h7q60JQ==">
              <nameID aor=sip:partha@blr.sonusnet.com/>
             <send>8zc6e0lYTlWIINA6GR+3ag==</send>
             <send>EiXGlc+4TruqqoDaNE76ag==</send>
             <recv>urn:uuid:60JAJm9UTvik0Ltlih/Gzw==</recv>



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             <recv>AcR5FUd3Edi8cACQJy/3JQ==</recv>
           </participant>

          <participant
             id="Atnm1ZRnOC6Pm5MApkrDzQ=="
             session="hVpd7YQgRW2nD22h7q60JQ==">
             <nameIDaor=sip:paul@box.mit.com>
              <name xml:lang="it">Paul Kyzivat</name>
            </nameID>
            <send>60JAJm9UTvik0Ltlih/Gzw==</send>
            <send>AcR5FUd3Edi8cACQJy/3JQ==</send>
            <recv>8zc6e0lYTlWIINA6GR+3ag==</recv>
            <recv>EiXGlc+4TruqqoDaNE76ag==</recv>
             <associate-time>2010-12-16T23:41:07Z</associate-time>
            <!-- Standardized extension -->
            <structure>FOO!</structure>
            <whatever>bar</whatever>
          </participant>

          <stream id="60JAJm9UTvik0Ltlih/Gzw=="
              session="hVpd7YQgRW2nD22h7q60JQ==">
              <label>96</label>
          </stream>
          <stream id="AcR5FUd3Edi8cACQJy/3JQ=="
              session="hVpd7YQgRW2nD22h7q60JQ==">
              <label>97</label>
          </stream>
          <stream id="8zc6e0lYTlWIINA6GR+3ag=="
              session="zSfPoSvdSDCmU3A3TRDxAw==">
              <label>98</label>
          </stream>
          <stream id="EiXGlc+4TruqqoDaNE76ag=="
              session="zSfPoSvdSDCmU3A3TRDxAw==">
              <label>99</label>
          </stream>
     </recording>


   Transfer with new session - (.e.g.  REFER based transfer).  In this
   case new session is part of same grouping (done by SRC).

   SRC may send an optional snapshot indicating stop for the old
   session.








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           <?xml version="1.0" encoding="UTF-8"?>
       <recording xmlns='urn:ietf:params:xml:ns:recording'>
              <dataMode>Partial</dataMode>
          <session id="hVpd7YQgRW2nD22h7q60JQ==">
            <group-ref>7+OTCyoxTmqmqyA/1weDAg==
            </group-ref>
            <stop-time>2010-12-16T23:41:07Z</stop-time>
             <!-- Standardized extension -->
             <structure>FOO!</structure>
             <whatever>bar</whatever>
          </session>
          <participant
             id="srfBElmCRp2QB23b7Mpk0w=="
             session="hVpd7YQgRW2nD22h7q60JQ==">
                     <nameID aor=sip:ram@blr.cisco.com/>
           <disassociate-time>2010-12-16T23:41:07Z</disassociate-time>
           </participant>

          <participant
              id="zSfPoSvdSDCmU3A3TRDxAw=="
             session="hVpd7YQgRW2nD22h7q60JQ==">
              <nameID aor=sip:partha@blr.sonus.com/>
             <disasociate-time>2010-12-16T23:41:07Z</disassociate-time>
           </participant>

     </recording>


   SRC sends a snapshot to indicate the participant change and new
   session information after transfer.  In this example the same RS is
   used.


     Content-Type: application/SDP
      ...
      m=audio 49170 RTP/AVP 0
      a=rtpmap:0 PCMU/8000
      a=label:96
      a=sendonly
      ...
      m=video 49174 RTP/AVPF 96
      a=rtpmap:96 H.264/90000
      a=label:97
      a=sendonly
      ...
      m=audio 51372 RTP/AVP 0
      a=rtpmap:0 PCMU/8000
      a=label:98



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      a=sendonly
      ...
      m=video 49176 RTP/AVPF 96
      a=rtpmap:96 H.264/90000
      a=label:99
      a=sendonly
      ....
   <?xml version="1.0" encoding="UTF-8"?>
       <recording xmlns='urn:ietf:params:xml:ns:recording'>
              <dataMode>partial</dataMode>
          <session id="bfLZ+NTFEeCNxQTuRyQBmw==">
            <group-ref>7+OTCyoxTmqmqyA/1weDAg==
            </group-ref>
            <start-time>2010-12-16T23:41:07Z</start-time>
              <!-- Standardized extension -->
             <structure>FOO!</structure>
             <whatever>bar</whatever>
          </session>
          <participant
              id="zSfPoSvdSDCmU3A3TRDxAw=="
              session="bfLZ+NTFEeCNxQTuRyQBmw==">
              <nameID aor=sip:partha@blr.sonus.com/>
            <send>8zc6e0lYTlWIINA6GR+3ag==</send>
            <send>EiXGlc+4TruqqoDaNE76ag==</send>
            <recv>60JAJm9UTvik0Ltlih/Gzw==</recv>
            <recv>AcR5FUd3Edi8cACQJy/3JQ==</recv>
            <associate-time>2010-12-16T23:32:03Z</associate-time>
             <!-- Standardized extension -->
             <structure>FOO!</structure>
             <whatever>bar</whatever>
           </participant>

          <participant
             id="Atnm1ZRnOC6Pm5MApkrDzQ=="
             session="bfLZ+NTFEeCNxQTuRyQBmw==">
             <nameID aor=sip:paul@box.mit.com/>
           <send>60JAJm9UTvik0Ltlih/Gzw==</send>
           <send>AcR5FUd3Edi8cACQJy/3JQ==</send>
           <recv>8zc6e0lYTlWIINA6GR+3ag==</recv>
           <recv>EiXGlc+4TruqqoDaNE76ag==</recv>
           <associate-time>2010-12-16T23:41:07Z</associate-time>
             <!-- Standardized extension -->
             <structure>FOO!</structure>
             <whatever>bar</whatever>
          </participant>

          <stream id="60JAJm9UTvik0Ltlih/Gzw=="
              session="bfLZ+NTFEeCNxQTuRyQBmw==">



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              <label>96</label>
          </stream>
          <stream id="AcR5FUd3Edi8cACQJy/3JQ=="
              session="bfLZ+NTFEeCNxQTuRyQBmw==">
              <label>97</label>
          </stream>
          <stream id="8zc6e0lYTlWIINA6GR+3ag=="
              session="bfLZ+NTFEeCNxQTuRyQBmw==">
              <label>98</label>
          </stream>
          <stream id="EiXGlc+4TruqqoDaNE76ag=="
              session="bfLZ+NTFEeCNxQTuRyQBmw==">
              <label>99</label>
          </stream>
     </recording>


13.4.  Use Case 4: Call disconnect

   This example shows a snapshot of metadata sent by an SRC at CS
   disconnect where the participants of CS are Ram and Partha



   <?xml version="1.0" encoding="UTF-8"?>
       <recording xmlns='urn:ietf:params:xml:ns:recording'>
              <dataMode>Partial</dataMode>
          <session id="hVpd7YQgRW2nD22h7q60JQ==">
            <group-ref>7+OTCyoxTmqmqyA/1weDAg==
            </group-ref>
            <stop-time>2010-12-16T23:41:07Z</stop-time>
             <!-- Standardized extension -->
             <structure>FOO!</structure>
             <whatever>bar</whatever>
          </session>
          <participant
             id="srfBElmCRp2QB23b7Mpk0w=="
             session="hVpd7YQgRW2nD22h7q60JQ==">
                     <nameID aor=sip:ram@blr.cisco.com/>
             <disassociate-time>2010-12-16T23:41:07Z</disassociate-time>
           </participant>

          <participant
              id="zSfPoSvdSDCmU3A3TRDxAw=="
             session="hVpd7YQgRW2nD22h7q60JQ==">
              <nameID aor=sip:partha@blr.sonus.com/>
             <disasociate-time>2010-12-16T23:41:07Z</disassociate-time>
           </participant>



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      </recording>




14.  References

14.1.  Normative References

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

   [RFC2141]  Moats, R., "URN Syntax", RFC 2141, May 1997.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              June 2002.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

   [RFC3339]  Klyne, G., Ed. and C. Newman, "Date and Time on the
              Internet: Timestamps", RFC 3339, July 2002.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, July 2006.

   [RFC4574]  Levin, O. and G. Camarillo, "The Session Description
              Protocol (SDP) Label Attribute", RFC 4574, August 2006.

   [RFC4796]  Hautakorpi, J. and G. Camarillo, "The Session Description
              Protocol (SDP) Content Attribute", RFC 4796,
              February 2007.

   [RFC3840]  Rosenberg, J., Schulzrinne, H., and P. Kyzivat,
              "Indicating User Agent Capabilities in the Session
              Initiation Protocol (SIP)", RFC 3840, August 2004.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              July 2005.

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, October 2006.






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14.2.  Informative References

   [RFC6341]  Rehor, K., Portman, L., Hutton, A., and R. Jain, "Use
              Cases and Requirements for SIP-Based Media Recording
              (SIPREC)", RFC 6341, August 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-03
              (work in progress), October 2011.

   [RFC2648]  Moats, R., "A URN Namespace for IETF Documents", RFC 2648,
              August 1999.


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
   Sonus Networks
   Prestige Shantiniketan - Business Precinct
   Whitefield Road
   Bangalore, Karnataka  560066
   India

   Email: pravindran@sonusnet.com


   Paul Kyzivat
   Unaffiliated
   Boxborough, MA
   USA

   Email: pkyzivat@alum.mit.edu






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