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rfc:rfc7865

Internet Engineering Task Force (IETF) R. Ravindranath Request for Comments: 7865 Cisco Systems Category: Standards Track P. Ravindran ISSN: 2070-1721 Nokia Networks

                                                            P. Kyzivat
                                                                Huawei
                                                              May 2016
        Session Initiation Protocol (SIP) Recording Metadata

Abstract

 Session recording is a critical requirement in many communications
 environments, such as call centers and financial trading
 organizations.  In some of these environments, all calls must be
 recorded for regulatory, compliance, and consumer protection reasons.
 The 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 the Session Recording Server (SRS) and
 the recording metadata format.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 7841.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc7865.

Ravindranath, et al. Standards Track [Page 1] RFC 7865 SIP Recording Metadata May 2016

Copyright Notice

 Copyright (c) 2016 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
 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. Definitions .....................................................4
 4. Metadata Model ..................................................5
 5. Recording Metadata Format from SRC to SRS .......................6
    5.1. XML Data Format ............................................7
         5.1.1. Namespace ...........................................7
         5.1.2. 'recording' Element .................................7
 6. Recording Metadata Classes ......................................7
    6.1. Recording Session ..........................................8
         6.1.1. Attributes ..........................................8
         6.1.2. Linkages ............................................9
    6.2. Communication Session Group ................................9
         6.2.1. Attributes .........................................10
         6.2.2. Linkages ...........................................10
    6.3. Communication Session .....................................11
         6.3.1. Attributes .........................................11
         6.3.2. Linkages ...........................................12
    6.4. CS-RS Association .........................................13
         6.4.1. Attributes .........................................14
         6.4.2. Linkages ...........................................14
    6.5. Participant ...............................................14
         6.5.1. Attributes .........................................15
         6.5.2. Linkages ...........................................15
    6.6. Participant-CS Association ................................16
         6.6.1. Attributes .........................................17
         6.6.2. Linkages ...........................................17
    6.7. Media Stream ..............................................18
         6.7.1. Attributes .........................................18
         6.7.2. Linkages ...........................................19

Ravindranath, et al. Standards Track [Page 2] RFC 7865 SIP Recording Metadata May 2016

    6.8. Participant-Stream Association ............................19
         6.8.1. Attributes .........................................20
         6.8.2. Linkages ...........................................20
    6.9. Syntax of XML Elements for Date and Time ..................21
    6.10. Format of Unique ID ......................................21
    6.11. Metadata Version Indicator ...............................21
 7. Recording Metadata Snapshot Request Format .....................22
 8. SIP Recording Metadata Examples ................................23
    8.1. Complete SIP Recording Metadata Example ...................23
    8.2. Partial Update of Recording Metadata XML Body .............25
 9. XML Schema Definition for Recording Metadata ...................26
 10. Security Considerations .......................................30
 11. IANA Considerations ...........................................31
    11.1. SIP Recording Metadata Schema Registration ...............31
 12. References ....................................................31
    12.1. Normative References .....................................31
    12.2. Informative References ...................................32
 Acknowledgements ..................................................34
 Authors' Addresses ................................................34

1. Introduction

 Session recording is a critical requirement in many communications
 environments, such as call centers and financial trading
 organizations.  In some of these environments, all calls must be
 recorded for regulatory, compliance, and consumer protection reasons.
 The 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
 (CS).  The document describes a metadata model as viewed by the
 Session Recording Server (SRS) and the recording metadata format, the
 requirements for which are described in [RFC6341] and the
 architecture for which is described in [RFC7245].

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.

Ravindranath, et al. Standards Track [Page 3] RFC 7865 SIP Recording Metadata May 2016

3. Definitions

 Metadata model:  A metadata model is an abstract representation of
    metadata using a Unified Modeling Language (UML) [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 a representation of its attributes in a second
    compartment below the class name.
 Attributes:  Attributes represent the elements listed in each of the
    classes.  The attributes of a class are listed in the second
    compartment below the class name.  Each instance of a class
    conveys values for the attributes of that class.  These values get
    added to the recording's metadata.
 Linkages:  Linkages represent the relationship between the classes in
    the model.  Each linkage represents a logical connection between
    classes (or objects) in class diagrams (or object diagrams).  The
    linkages used in the metadata model of this document are
    associations.
 This document also refers to the terminology defined in [RFC6341].

Ravindranath, et al. Standards Track [Page 4] RFC 7865 SIP Recording Metadata May 2016

4. Metadata Model

 Metadata is the information that describes recorded media and the CS
 to which they relate.  The diagram below shows a model for metadata
 as viewed by an SRS.
           +-------------------------------+ 1..*
           |    Recording Session (RS)     |----+
           +-------------------------------+    |
                 | 1..*          | 1..*         |
                 |               |              |
                 |               | 0..*         |
                 |        +-----------------+   |
 +------------+  |        | Communication   |   |
 | CS-RS      |  |        | Session Group   |   |
 | Association|--+        |  (CS-Group)     |   |
 |            |  |        +-----------------+   |
 +------------+  |              | 0..1          |
                 |              |               |
                 | 0..*         | 1..*          |
 +-------------------------------+              |
 |   Communication Session (CS)  |              |
 |                               |              |
 +-------------------------------+              |
       | 1..*                   | 0..1          |
 +-----+                        |               |
 |     | 0..*                   | 0..*          | 0..*
 | +-------------+ receives +----------------+  |
 | | Participant |----------|  Media Stream  |--+
 | |             |0..*  0..*|                |
 | |             |          |                |
 | |             |          |                |
 | |             |  sends   |                |
 | |             |----------|                |
 | |             |1.*   0..*|                |
 | +-------------+          +----------------+
 |        |                        |
 |        |                        |
 |        +------------------------+------------+
 |                                              |
 |                                              |
 |           +------------------+    +----------------------+
 |           |Participant-CS    |    |  Participant-Stream  |
 +-----------|  Association     |    |    Association       |
             |                  |    |                      |
             +------------------+    +----------------------+

Ravindranath, et al. Standards Track [Page 5] RFC 7865 SIP Recording Metadata May 2016

 The metadata model is a class diagram in UML.  The model describes
 the structure of 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
 represent the relationships, which can be associations or
 compositions.  The metadata is conveyed from the Session Recording
 Client (SRC) to the SRS.
 The model allows metadata describing CSs to be communicated to the
 SRS as a series of snapshots, each representing the state as seen by
 a single SRC at a particular instant in time.  Metadata changes from
 one snapshot to another reflect changes in what is being recorded.
 For example, if a participant joins a conference, then the SRC sends
 the SRS a snapshot of metadata having that participant information
 (with attributes like (Name, AoR) tuple and associate-time).  (Note:
 "AoR" means "Address-of-Record".)
 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 Session Description Protocol (SDP) signaling).
 For example, the 'label' attribute within the 'stream' XML element
 references an SDP "a=label" attribute that identifies an m-line
 within the Recording Session (RS) SDP.  The SRS would learn the media
 properties from the media line.

5. Recording Metadata Format from SRC to SRS

 This section gives an overview of the recording metadata format.
 Some data from the metadata model is assumed to be made available to
 the SRS through SDP [RFC4566], and therefore this data is not
 represented in the XML document format specified in this document.
 SDP attributes describe different media formats like audio and video.
 The other metadata attributes, such as participant details, are
 represented in a new recording-specific XML document of type
 '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.

Ravindranath, et al. Standards Track [Page 6] RFC 7865 SIP Recording Metadata May 2016

5.1. XML Data Format

 Every recording metadata XML document sent from the SRC to the SRS
 contains a 'recording' element.  The 'recording' element acts as a
 container for all other elements in this XML document.  A 'recording'
 object is an XML document.  It has the XML declaration and contains
 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 minimal interoperability.
 Syntax and semantic errors in an XML document should be reported to
 the originator, using application-specific mechanisms.

5.1.1. Namespace

 With the following URN, this document defines a new namespace URI for
 elements defined herein:
 urn:ietf:params:xml:ns:recording:1

5.1.2. 'recording' Element

 The 'recording' element MUST contain an xmlns namespace attribute
 with a value of urn:ietf:params:xml:ns:recording:1.  Exactly one
 'recording' element MUST be present in every recording metadata XML
 document.
 A 'recording' element MAY contain a 'dataMode' element indicating
 whether the XML document is a complete document or a partial update.
 If no 'dataMode' element is present, then 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.

Ravindranath, et al. Standards Track [Page 7] RFC 7865 SIP Recording Metadata May 2016

6.1. Recording Session

 +-------------------------------+
 | Recording Session (RS)        |
 +-------------------------------+
 |                               | 1..*     0..*
 |     start-time                |-------------- Media Stream
 |     end-time                  |
 |                               |
 |                               |
 +-------------------------------+
       | 1..*           | 1..*
       |                |
       | 0..*           | 0..*
  Communication    Communication
  Session (CS)     Session Group (CS-Group)
 Each instance of an RS class, namely the RS object, represents a SIP
 session created between an SRC and SRS for the purpose of recording
 a CS.
 The RS object is represented in the XML schema using the 'recording'
 element, which in turn relies on the SIP/SDP session with which the
 XML document is associated to provide the attributes of the RS
 element.

6.1.1. Attributes

 An RS class has the following attributes:
 o  start-time - Represents the start time of an RS object.
 o  end-time - Represents the end time of an RS object.
 'start-time' and 'end-time' attribute values are derivable from the
 Date header (if present in the SIP message) in the RS.  In cases
 where the Date header is not present, 'start-time' is derivable from
 the time at which the SRS receives the notification of the SIP
 message to set up the RS, and 'end-time' is derivable from the time
 at which the SRS receives a disconnect on the RS SIP dialog.

Ravindranath, et al. Standards Track [Page 8] RFC 7865 SIP Recording Metadata May 2016

6.1.2. Linkages

 Each instance of an RS has:
 o  Zero or more instances of CS-Groups.
 o  Zero or more instances of CS objects.
 o  Zero or more instances of MediaStream objects.
 Zero instances of CSs and CS-Groups in a 'recording' element are
 allowed to accommodate persistent recording scenarios.  A persistent
 RS is a SIP dialog that is set up between the SRC and the SRS, even
 before any CS is set up.  The metadata sent from the SRC to the SRS
 when the persistent RS SIP dialog is set up may not have any CS (and
 the related CS-Group) elements in the XML, as there may not be a
 session that is associated to the RS yet.  For example, a phone
 acting as an SRC can set up an RS with the SRS, possibly even before
 the phone is part of a CS.  Once the phone joins a CS, the same RS
 would be used to convey the CS metadata.

6.2. Communication Session Group

  Recording Session (RS)
            | 1..*
            |
            | 0..*
 +-------------------------------+
 | Communication Session         |
 |   Group (CS-Group)            |
 +-------------------------------+
 |  group_id                     |
 |  associate-time               |
 |  disassociate-time            |
 |                               |
 +-------------------------------+
            | 0..1
            |
            | 1..*
  Communication Session (CS)
 One instance of a CS-Group class, namely the CS-Group object,
 provides association or grouping of all related CSs.  For example, in
 a contact center flow, a call can get transferred to multiple agents.
 Each of these can trigger the setup of a new CS.  In cases where the
 SRC knows the related CSs, it can group them using the CS-Group
 element.  The CS-Group object is represented in the XML schema using
 the 'group' element.

Ravindranath, et al. Standards Track [Page 9] RFC 7865 SIP Recording Metadata May 2016

6.2.1. Attributes

 A CS-Group has the following attributes:
 o  group_id - This attribute groups different CSs that are related.
    The SRC (or the SRS) is responsible for ensuring the uniqueness of
    'group_id' in cases where multiple SRCs interact with the same
    SRS.  The mechanism by which the SRC groups the CS is outside the
    scope of this document.
 o  associate-time - This is the time when a grouping is formed.  The
    rules that determine how a grouping of different CS objects is
    done by the SRC are outside the scope of this document.
 o  disassociate-time - 'disassociate-time' for the CS-Group is
    calculated by the SRC as the time when the grouping ends.

6.2.2. Linkages

 The linkages between a CS-Group class and other classes are
 associations.  A CS-Group is associated with the RS and CS in the
 following manner:
 o  There are one or more RS objects per CS-Group.
 o  Each CS-Group object has to be associated with one or more RSs.
    Here, each RS can be set up by the potentially different SRCs.
 o  There are one or more CSs per CS-Group (for example, in cases
    where the call is transferred).  A CS cannot be associated with
    more than one CS-Group.

Ravindranath, et al. Standards Track [Page 10] RFC 7865 SIP Recording Metadata May 2016

6.3. Communication Session

 Recording               Communication
 Session (RS)       Session Group (CS-Group)
    | 1..*                 | 0..1
    |                      |
    | 0..*                 | 1..*
 +-------------------------------+
 |   Communication Session (CS)  |
 +-------------------------------+
 |   session_id                  |
 |   sipSessionID                |
 |   reason                      |
 |   group-ref                   |
 |   start-time                  |
 |   stop-time                   |
 +-------------------------------+
    |                      |
    | 0..*                 | 0..1
    |                      |
    | 0..*                 | 0..*
 Participant              Media Stream
 A CS class and its object in the metadata model represent the CS and
 its properties as seen by the SRC.  The CS object is represented in
 the XML schema using the 'session' element.

6.3.1. Attributes

 A CS class has the following attributes:
 o  session_id - This attribute is used to uniquely identify an
    instance of a CS object, namely the 'session' XML element within
    the metadata XML document.  'session_id' is generated using the
    rules mentioned in Section 6.10.
 o  reason - This represents the reason why a CS was terminated.  The
    value for this attribute is derived from the SIP Reason header
    [RFC3326] of the CS.  There MAY be multiple instances of the
    'reason' XML element inside a 'session' element.  The 'reason' XML
    element has 'protocol' as an attribute, which indicates the
    protocol from which the reason string is derived.  The default
    value for the 'protocol' attribute is "SIP".  The 'reason' element
    can be derived from a SIP Reason header in the CS.

Ravindranath, et al. Standards Track [Page 11] RFC 7865 SIP Recording Metadata May 2016

 o  sipSessionID - This attribute carries a SIP Session-ID as defined
    in [SessionID].  Each CS object can have zero or more
    'sipSessionID' elements.  More than one 'sipSessionID' attribute
    may be present in a CS.  For example, if three participants -- A,
    B, and C -- are in a conference that has a focus acting as an SRC,
    the metadata sent from the SRC to the SRS will likely have three
    'sipSessionID' elements that correspond to the SIP dialogs that
    the focus has with each of the three participants.
 o  group-ref - A 'group-ref' attribute MAY be present to indicate the
    group (identified by 'group_id') to which the enclosing session
    belongs.
 o  start-time - This optional attribute represents the start time of
    the CS as seen by the SRC.
 o  stop-time - This optional attribute represents the stop time of
    the CS as seen by the SRC.
 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 its local
 policy.  The ability of the SRC to influence this policy is outside
 the scope of this document.  However, if there are implementations
 where the SRC desires to specify its own policy preferences, this
 information could be sent as extension data attached to the CS.

6.3.2. Linkages

 A CS is linked to the CS-Group, participant, MediaStream (MS), and
 RS classes by using the association relationship.  The association
 between the CS and the participant allows the following:
 o  A CS will have zero or more participants.
 o  A participant is associated with zero or more CSs.  This includes
    participants who are not directly part of any CS.  An example of
    such a case is participants in a pre-mixed media stream.  The SRC
    may have knowledge of such participants but not have any signaling
    relationship with them.  This might arise if one participant in a
    CS is a conference focus.  To summarize, even if the SRC does not
    have direct signaling relationships with all participants in a CS,
    it should nevertheless create a participant object for each
    participant that it knows about.

Ravindranath, et al. Standards Track [Page 12] RFC 7865 SIP Recording Metadata May 2016

 o  The model also allows participants in a CS that are not
    participants in the media.  An example is the identity of a Third
    Party Call Control (3pcc) that has initiated a CS to two or more
    participants in 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.
 The association between the CS and the media stream allows the
 following:
 o  A CS will have zero or more streams.
 o  A stream can be associated with at most one CS.  A stream in a
    persistent RS is not required to be associated with any CS before
    the CS is created, and hence the zero association is allowed.
 The association between the CS and the RS allows the following:
 o  Each instance of an RS has zero or more instances of CS objects.
 o  Each CS has to be associated with one or more RSs.  Each RS can be
    potentially set up by different SRCs.

6.4. CS-RS Association

                      1..*             0..*
            Recording                       Communication
              Session ----------+---------- Session
                                |
                                |
                                |
                    +-----------------------+
                    | CS-RS Association     |
                    |                       |
                    +-----------------------+
                    | associate-time        |
                    | disassociate-time     |
                    | session_id            |
                    +-----------------------+
 The CS-RS Association class describes the association of a CS to an
 RS for a period of time.  A single CS may be associated with
 different RSs (perhaps by different SRCs) and may be associated and
 dissociated several times.
 The CS-RS Association class is represented in XML using the
 'sessionrecordingassoc' XML element.

Ravindranath, et al. Standards Track [Page 13] RFC 7865 SIP Recording Metadata May 2016

6.4.1. Attributes

 The CS-RS Association class has the following attributes:
 o  associate-time - associate-time is calculated by the SRC as the
    time it sees a CS associated to an RS.
 o  disassociate-time - disassociate-time is calculated by the SRC as
    the time it sees a CS disassociate from an RS.
 o  session_id - Each instance of this class MUST have a 'session_id'
    attribute that identifies the CS to which this association
    belongs.

6.4.2. Linkages

 The CS-RS Association class is linked to the CS and RS classes.

6.5. Participant

  Communication Session (CS)
            | 0..*
            |
            | 0..*
 +-------------------------------+
 |          Participant          |
 +-------------------------------+
 |  nameID                       |
 |  participant_id               |
 |                               |
 +-------------------------------+
         | 0..*       1..* |
 receives|                 |sends
         | 0..*       0..* |
            Media Stream
 A participant class and its objects have information about a device
 that is part of a CS and/or contributes/consumes media stream(s)
 belonging to a CS.
 The participant object is represented in the XML schema using the
 'participant' element.

Ravindranath, et al. Standards Track [Page 14] RFC 7865 SIP Recording Metadata May 2016

6.5.1. Attributes

 A participant class has two attributes:
 o  nameID - This attribute is a list of (Name, AoR) tuples.  An AoR
    (Section 6 of [RFC3261]) can be either a SIP/SIPS/tel URI ("SIPS"
    means "SIP Secure"; the tel URI is discussed in [RFC3966]), a
    Fully Qualified Domain Name (FQDN), or an IP address.  For
    example, the AoR may be drawn from the From header field or the
    P-Asserted-Identity header [RFC3325] field.  The SRC's local
    policy is used to decide where to draw the AoR from.  The Name
    parameter represents the participant name (SIP display name) or
    dialed number (when known).  Multiple tuples are allowed for cases
    where a participant has more than one AoR.  For example, a
    P-Asserted-Identity header can have both SIP and tel URIs.
 o  participant_id - This attribute is used to identify the
    'participant' XML element within the XML document.  It is
    generated using the rules mentioned in Section 6.10.  This
    attribute MUST be used for all references to a participant within
    a CS-Group, and MAY be used to reference the same participant more
    globally.
 This document does not specify other attributes relating to
 participants (e.g., participant role, participant type).  An SRC that
 has information regarding these attributes can provide this
 information as part of extension data to the 'participant' XML
 element from the SRC to the SRS.

6.5.2. Linkages

 The participant class is linked to the MS and CS classes by using an
 association relationship.  The association between the participant
 and the MS allows the following:
 o  A participant will receive zero or more media streams.
 o  A participant will send zero or more media streams.  (The same
    participant provides multiple streams, e.g., audio and video.)

Ravindranath, et al. Standards Track [Page 15] RFC 7865 SIP Recording Metadata May 2016

 o  A media stream will be received by zero or more participants.  It
    is possible, though perhaps unlikely, that a stream is generated
    but sent only to the SRC and SRS, not to any participant -- for
    example, 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  A media stream will be sent by one or more participants (pre-mixed
    streams).
 An example of a case where a participant receives zero or more
 streams is where a supervisor may have a side conversation with an
 agent while the agent converses with a customer.

6.6. Participant-CS Association

                       1..*             0..*
       Communication
             Session -----------+----------- Participant
                                |
                                |
                                |
                  +---------------------------+
                  | Participant-CS Association|
                  |                           |
                  |                           |
                  +---------------------------+
                  | associate-time            |
                  | disassociate-time         |
                  | param                     |
                  | participant_id            |
                  | session_id                |
                  +---------------------------+
 The Participant-CS Association class describes the association of a
 participant to a CS for a period of time.  A participant may be
 associated to and dissociated from a CS several times (for example,
 connecting to a conference, then disconnecting, then connecting
 again).
 The Participant-CS Association object is represented in the XML
 schema using the 'participantsessionassoc' element.

Ravindranath, et al. Standards Track [Page 16] RFC 7865 SIP Recording Metadata May 2016

6.6.1. Attributes

 The Participant-CS Association class has the following attributes:
 o  associate-time - associate-time is calculated by the SRC as the
    time it sees a participant associated to a CS.
 o  disassociate-time - disassociate-time is calculated by the SRC as
    the time it sees a participant disassociate from a CS.  It is
    possible that a given participant can have multiple associate
    times / disassociate times within a given communication session.
 o  param - The capabilities here are those that are indicated in the
    Contact header as defined in Section 9 of [RFC3840].  For example,
    in a CS (which can be a conference), you can have participants who
    are playing the role of "focus".  These participants do not
    contribute to media in the CS; however, they switch the media
    received from one participant to every other participant in the
    CS.  Indicating the capabilities of the participants (here,
    "focus") would be useful for the recorder to learn about these
    kinds of participants.  The capabilities are represented using the
    'param' XML element in the metadata.  The 'param' XML element
    encoding defined in [RFC4235] is used to represent the capability
    attributes in metadata.  Each participant may have zero or more
    capabilities.  A participant may use different capabilities,
    depending on the role it plays at a particular instance -- for
    example, if a participant moves across different CSs (e.g., due to
    transfer) or is simultaneously present in different CSs with
    different roles.
 o  participant_id - This attribute identifies the participant to
    which this association belongs.
 o  session_id - This attribute identifies the session to which this
    association belongs.

6.6.2. Linkages

 The Participant-CS Association class is linked to the participant and
 CS classes.

Ravindranath, et al. Standards Track [Page 17] RFC 7865 SIP Recording Metadata May 2016

6.7. Media Stream

                                    Participant
                                | 0..*       1..* |
                        receives|                 |sends
                                | 0..*       0..* |
                            +-------------------------+
                            |        Media Stream     |
                 0..1  0..* +-------------------------+
  Communication ------------|                         |
        Session             |  label                  |
                            |  content-type           |
                            |  stream_id              |
                            |  session_id             |
                            +-------------------------+
                                    0..* |
                                         |
                                         |
                                    1..* |
                                   Recording Session
 A MS class (and its objects) has the properties of media as seen by
 the SRC and sent to the SRS.  Different snapshots of MS objects may
 be sent whenever there is a change in media (e.g., a direction
 change, like pause/resume, codec change, and/or participant change).
 The MS object is represented in the XML schema using the 'stream'
 element.

6.7.1. Attributes

 A MS class has the following attributes:
 o  label - The 'label' attribute within the 'stream' XML element
    references an SDP "a=label" attribute that identifies an m-line
    within the RS SDP.  That m-line carries the media stream from the
    SRC to the SRS.
 o  content-type - The content of a MS element will be described in
    terms of the "a=content" attribute defined in Section 5 of
    [RFC4796].  If the SRC wishes to convey the content-type to the
    SRS, it does so by including an "a=content" attribute with the
    m-line in the RS SDP.

Ravindranath, et al. Standards Track [Page 18] RFC 7865 SIP Recording Metadata May 2016

 o  stream_id - Each 'stream' element has a unique 'stream_id'
    attribute that helps to uniquely identify the stream.  This
    identifier is generated using the rules mentioned in Section 6.10.
 o  session_id - This attribute associates the stream with a specific
    'session' element.
 The metadata model can include media streams that are not being
 delivered to the SRS.  For example, an SRC offers audio and video
 towards an SRS that accepts only audio in response.  The metadata
 snapshots sent from the SRC to the SRS can continue to indicate the
 changes to the video stream as well.

6.7.2. Linkages

 A MS class is linked to the participant and CS classes by using the
 association relationship.  Details regarding associations with the
 participant are described in Section 6.5.  Details regarding
 associations with the CS are mentioned in Section 6.3.

6.8. Participant-Stream Association

 +-------------------------+
 | Participant-Stream      |
 | Association             |
 +-------------------------+   +-----------Participant
 | associate-time          |   |       0..* | 1..* |
 | disassociate-time       |---+    receives|      |sends
 | send                    |   |       0..* | 0..* |
 | recv                    |   |            |      |
 | participant_id          |   |            |      |
 +-------------------------+   |            |      |
                               +-----------Media Stream
 A Participant-Stream Association class describes the association of a
 participant to a MS for a period of time, as a sender or as a
 receiver, or both.
 This class is represented in XML using the 'participantstreamassoc'
 element.

Ravindranath, et al. Standards Track [Page 19] RFC 7865 SIP Recording Metadata May 2016

6.8.1. Attributes

 A Participant-Stream Association class has the following attributes:
 o  associate-time - This attribute indicates the time a participant
    started contributing to a MS.
 o  disassociate-time - This attribute indicates the time a
    participant stopped contributing to a MS.
 o  send - This attribute indicates whether a participant is
    contributing to a stream or not.  This attribute has a value that
    points to a stream represented by its unique_id.  The presence of
    this attribute indicates that a participant is contributing to a
    stream.  If a participant stops contributing to a stream due to
    changes in a CS, a snapshot MUST be sent from the SRC to the SRS
    with no 'send' element for that stream.
 o  recv - This attribute indicates whether a participant is receiving
    a media stream or not.  This attribute has a value that points to
    a stream represented by its unique_id.  The presence of this
    attribute indicates that a participant is receiving a stream.  If
    the participant stops receiving a stream due to changes in a CS
    (like hold), a snapshot MUST be sent from the SRC to the SRS with
    no 'recv' element for that stream.
 o  participant_id - This attribute points to the participant with
    which a 'stream' element is associated.
 The 'participantstreamassoc' XML element is used to represent a
 participant association with a stream.  The 'send' and 'recv' XML
 elements MUST be used to indicate whether a participant is
 contributing to a stream or receiving a stream.  There MAY be
 multiple instances of the 'send' and 'recv' XML elements inside a
 'participantstreamassoc' element.  If a metadata snapshot is sent
 with a 'participantstreamassoc' element that does not have any 'send'
 and 'recv' elements, it means that the participant is neither
 contributing to any streams nor receiving any streams.

6.8.2. Linkages

 The Participant-Stream Association class is linked to the participant
 and MS classes.

Ravindranath, et al. Standards Track [Page 20] RFC 7865 SIP Recording Metadata May 2016

6.9. Syntax of XML Elements for Date and Time

 The XML elements 'associate-time', 'disassociate-time', 'start-time',
 and 'stop-time' contain strings representing the date and time.  The
 value of these elements MUST follow the Instant Messaging and
 Presence Protocol (IMPP) date-time format [RFC3339].  Timestamps that
 contain "T" or "Z" MUST use the capitalized forms.
 As a security measure, the 'timestamp' element MUST be included in
 all tuples, unless the exact time of the status change cannot be
 determined.

6.10. Format of Unique ID

 A unique_id is generated in two steps:
 o  The Universally Unique Identifier (UUID) is created using any of
    the procedures mentioned in Sections 4.3, 4.4, and 4.5 of
    [RFC4122].  The algorithm MUST ensure that it does not use any
    potentially personally identifying information to generate the
    UUIDs.  If implementations are using a Name-Based UUID as defined
    in Section 4.3 of [RFC4122], a namespace ID generated using the
    guidance in Section 4.2 or 4.5 of [RFC4122] might be a good
    choice.
 o  The UUID is encoded using base64 as defined in [RFC4648].
 The above-mentioned unique_id mechanism SHOULD be used for each
 metadata element.  Multiple SRCs can refer to the same element/UUID
 (how each SRC learns the UUID here is beyond the scope of this
 document).  If two SRCs use the same UUID, they MUST retain the
 UUID/element mapping.  If the SRS detects that a UUID is mapped to
 more than one element at any point in time, it MUST treat this as an
 error.  For example, the SRS may choose to reject or ignore the
 portions of metadata where it detects that the same UUID is mapped to
 an element that is different than the expected element (the SRS
 learns the mapped UUID when it sees an element for the first time in
 a metadata instance).

6.11. Metadata Version Indicator

 The Metadata version is defined to help the SRC and SRS know the
 version of metadata XML schema used.  SRCs and SRSs that support this
 specification MUST use version 1 in the namespace
 (urn:ietf:params:xml:ns:recording:1) in all the XML documents.
 Implementations may not interoperate if the version implemented by
 the sender is not known by the receiver.  No negotiation of versions
 is provided.  The version number has no significance, although

Ravindranath, et al. Standards Track [Page 21] RFC 7865 SIP Recording Metadata May 2016

 documents that update or obsolete this document (possibly including
 drafts of such documents) should include a higher version number if
 the metadata XML schema changes.

7. Recording Metadata Snapshot Request Format

 The SRS can explicitly request a metadata snapshot from the SRC.  To
 request a metadata snapshot, the SRS MUST send a SIP request message
 with an XML document having the namespace
 urn:ietf:params:xml:ns:recording:1.  The XML document has the
 following elements:
 o  A 'requestsnapshot' XML element MUST be present as the top-level
    element in the XML document.
 o  A 'requestreason' XML element that indicates the reason (as a
    string) for requesting the snapshot MAY be present as a child XML
    element of 'requestsnapshot'.
 The example below shows a metadata snapshot request from the SRS.
 <?xml version="1.0" encoding="UTF-8"?>
   <requestsnapshot xmlns='urn:ietf:params:xml:ns:recording:1'>
   <requestreason xml:lang="it">SRS internal error</requestreason>
 </requestsnapshot>
           Example Metadata Snapshot Request from SRS to SRC

Ravindranath, et al. Standards Track [Page 22] RFC 7865 SIP Recording Metadata May 2016

8. SIP Recording Metadata Examples

8.1. Complete SIP Recording Metadata Example

 The following example provides all the tuples involved in the
 recording metadata XML body.
 <?xml version="1.0" encoding="UTF-8"?>
   <recording xmlns='urn:ietf:params:xml:ns:recording:1'>
   <datamode>complete</datamode>
   <group 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@atlanta.com</supervisor>
     </call-center>
     <mydata xmlns='http://example.com/my'>
           <structure>FOO!</structure>
           <whatever>bar</whatever>
     </mydata>
   </group>
   <session session_id="hVpd7YQgRW2nD22h7q60JQ==">
         <sipSessionID>ab30317f1a784dc48ff824d0d3715d86;
         remote=47755a9de7794ba387653f2099600ef2</sipSessionID>
         <group-ref>7+OTCyoxTmqmqyA/1weDAg==</group-ref>
         <!-- Standardized extension -->
     <mydata xmlns='http://example.com/my'>
           <structure>FOO!</structure>
            <whatever>bar</whatever>
         </mydata>
   </session>
   <participant participant_id="srfBElmCRp2QB23b7Mpk0w==">
         <nameID aor="sip:bob@biloxi.com">
            <name xml:lang="it">Bob</name>
         </nameID>
         <!-- Standardized extension -->
         <mydata xmlns='http://example.com/my'>
                 <structure>FOO!</structure>
                 <whatever>bar</whatever>
         </mydata>
   </participant>

Ravindranath, et al. Standards Track [Page 23] RFC 7865 SIP Recording Metadata May 2016

   <participant participant_id="zSfPoSvdSDCmU3A3TRDxAw==">
         <nameID aor="sip:Paul@biloxi.com">
           <name xml:lang="it">Paul</name>
         </nameID>
         <!-- Standardized extension -->
         <mydata xmlns='http://example.com/my'>
            <structure>FOO!</structure>
            <whatever>bar</whatever>
         </mydata>
   </participant>
   <stream stream_id="UAAMm5GRQKSCMVvLyl4rFw=="
           session_id="hVpd7YQgRW2nD22h7q60JQ==">
         <label>96</label>
   </stream>
   <stream stream_id="i1Pz3to5hGk8fuXl+PbwCw=="
            session_id="hVpd7YQgRW2nD22h7q60JQ==">
          <label>97</label>
   </stream>
   <stream stream_id="8zc6e0lYTlWIINA6GR+3ag=="
            session_id="hVpd7YQgRW2nD22h7q60JQ==">
         <label>98</label>
   </stream>
   <stream stream_id="EiXGlc+4TruqqoDaNE76ag=="
            session_id="hVpd7YQgRW2nD22h7q60JQ==">
         <label>99</label>
   </stream>
   <sessionrecordingassoc session_id="hVpd7YQgRW2nD22h7q60JQ==">
                 <associate-time>2010-12-16T23:41:07Z</associate-time>
   </sessionrecordingassoc>
   <participantsessionassoc
        participant_id="srfBElmCRp2QB23b7Mpk0w=="
        session_id="hVpd7YQgRW2nD22h7q60JQ==">
         <associate-time>2010-12-16T23:41:07Z</associate-time>
   </participantsessionassoc>
   <participantsessionassoc
        participant_id="zSfPoSvdSDCmU3A3TRDxAw=="
        session_id="hVpd7YQgRW2nD22h7q60JQ==">
            <associate-time>2010-12-16T23:41:07Z</associate-time>
   </participantsessionassoc>

Ravindranath, et al. Standards Track [Page 24] RFC 7865 SIP Recording Metadata May 2016

   <participantstreamassoc
        participant_id="srfBElmCRp2QB23b7Mpk0w==">
            <send>i1Pz3to5hGk8fuXl+PbwCw==</send>
            <send>UAAMm5GRQKSCMVvLyl4rFw==</send>
            <recv>8zc6e0lYTlWIINA6GR+3ag==</recv>
            <recv>EiXGlc+4TruqqoDaNE76ag==</recv>
   </participantstreamassoc>
   <participantstreamassoc
        participant_id="zSfPoSvdSDCmU3A3TRDxAw==">
            <send>8zc6e0lYTlWIINA6GR+3ag==</send>
            <send>EiXGlc+4TruqqoDaNE76ag==</send>
            <recv>UAAMm5GRQKSCMVvLyl4rFw==</recv>
            <recv>i1Pz3to5hGk8fuXl+PbwCw==</recv>
   </participantstreamassoc>
 </recording>
               Example Metadata Snapshot from SRC to SRS

8.2. Partial Update of Recording Metadata XML Body

 The following example provides a partial update in the 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:1'>
     <datamode>partial</datamode>
       <participant
         participant_id="srfBElmCRp2QB23b7Mpk0w==">
         <nameID aor="sip:bob@biloxi.com">
                   <name xml:lang="it">Bob</name>
             </nameID>
       </participant>
       <participantsessionassoc
          participant_id="srfBElmCRp2QB23b7Mpk0w=="
          session_id="hVpd7YQgRW2nD22h7q60JQ==">
         <disassociate-time>2010-12-16T23:41:07Z</disassociate-time>
       </participantsessionassoc>
   </recording>
           Partial Update of SIP Recording Example XML Body

Ravindranath, et al. Standards Track [Page 25] RFC 7865 SIP Recording Metadata May 2016

9. XML Schema Definition for Recording Metadata

 This section defines the XML schema for the recording metadata
 document.

<?xml version="1.0" encoding="UTF-8"?>

 <xs:schema targetNamespace="urn:ietf:params:xml:ns:recording:1"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:tns="urn:ietf:params:xml:ns:recording:1"
    elementFormDefault="qualified"
    attributeFormDefault="unqualified">
  <!-- This import brings in the XML language attribute xml:lang -->
  <xs:import namespace="http://www.w3.org/XML/1998/namespace"
               schemaLocation="https://www.w3.org/2001/xml.xsd"/>
  <xs:element name="recording" type="tns:recording"/>
  <xs:complexType name="recording">
      <xs:sequence>
          <xs:element name="datamode" type="tns:dataMode"
                minOccurs="0"/>
          <xs:element name="group" type="tns:group"
                minOccurs="0" maxOccurs="unbounded"/>
          <xs:element name="session" type="tns:session"
                minOccurs="0" maxOccurs="unbounded"/>
          <xs:element name="participant" type="tns:participant"
                minOccurs="0" maxOccurs="unbounded"/>
          <xs:element name="stream" type="tns:stream"
                minOccurs="0" maxOccurs="unbounded"/>
          <xs:element name="sessionrecordingassoc"
                type="tns:sessionrecordingassoc"
                minOccurs="0" maxOccurs="unbounded"/>
          <xs:element name="participantsessionassoc"
                type="tns:participantsessionassoc"
                minOccurs="0" maxOccurs="unbounded"/>
          <xs:element name="participantstreamassoc"
                type="tns:participantstreamassoc"
                minOccurs="0" maxOccurs="unbounded"/>
          <xs:any namespace='##other'
                   minOccurs='0'
                   maxOccurs='unbounded'
                   processContents='lax'/>
       </xs:sequence>
  </xs:complexType>

Ravindranath, et al. Standards Track [Page 26] RFC 7865 SIP Recording Metadata May 2016

  <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="group_id" type="xs:base64Binary"
            use="required"/>
  </xs:complexType>
  <xs:complexType name="session">
      <xs:sequence>
         <xs:element name="sipSessionID" type="xs:string"
                minOccurs="0" maxOccurs="unbounded"/>
         <xs:element name="reason" type="tns:reason"
                minOccurs="0" maxOccurs="unbounded"/>
         <xs:element name="group-ref" type="xs:base64Binary"
                minOccurs="0" maxOccurs="1"/>
         <xs:element name="start-time" type="xs:dateTime"
                minOccurs="0" maxOccurs="1"/>
         <xs:element name="stop-time" type="xs:dateTime"
                minOccurs="0" maxOccurs="1"/>
            <xs:any namespace='##other'
                   minOccurs='0'
                   maxOccurs='unbounded'
                   processContents='lax'/>
      </xs:sequence>
      <xs:attribute name="session_id" type="xs:base64Binary"
            use="required"/>
  </xs:complexType>
  <xs:complexType name="sessionrecordingassoc">
      <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="session_id" type="xs:base64Binary"
            use="required"/>
  </xs:complexType>

Ravindranath, et al. Standards Track [Page 27] RFC 7865 SIP Recording Metadata May 2016

  <xs:complexType name="participant">
      <xs:sequence>
           <xs:element name="nameID" type="tns:nameID"
                   maxOccurs='unbounded'/>
      <xs:any namespace='##other'
                   minOccurs='0'
                   maxOccurs='unbounded'
                   processContents='lax'/>
      </xs:sequence>
      <xs:attribute name="participant_id" type="xs:base64Binary"
            use="required"/>
  </xs:complexType>
  <xs:complexType name="participantsessionassoc">
      <xs:sequence>
      <xs:element name="associate-time" type="xs:dateTime"
                minOccurs="0"/>
      <xs:element name="disassociate-time" type="xs:dateTime"
                minOccurs="0"/>
      <xs:element name="param" minOccurs="0" maxOccurs="unbounded">
          <xs:complexType>
              <xs:attribute name="pname" type="xs:string"
                use="required"/>
              <xs:attribute name="pval" type="xs:string"
                use="required"/>
          </xs:complexType>
      </xs:element>
      <xs:any namespace='##other'
              minOccurs='0'
              maxOccurs='unbounded'
              processContents='lax'/>
      </xs:sequence>
      <xs:attribute name="participant_id" type="xs:base64Binary"
            use="required"/>
      <xs:attribute name="session_id" type="xs:base64Binary"
            use="required"/>
  </xs:complexType>

Ravindranath, et al. Standards Track [Page 28] RFC 7865 SIP Recording Metadata May 2016

  <xs:complexType name="participantstreamassoc">
      <xs:sequence>
          <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="participant_id" 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:any namespace='##other'
                   minOccurs='0'
                   maxOccurs='unbounded'
                   processContents='lax'/>
      </xs:sequence>
      <xs:attribute name="stream_id" type="xs:base64Binary"
            use="required"/>
      <xs:attribute name="session_id" type="xs:base64Binary"/>
  </xs:complexType>
  <xs:simpleType name="dataMode">
      <xs:restriction base="xs:string">
          <xs:enumeration value="complete"/>
              <xs:enumeration value="partial"/>
      </xs:restriction>
  </xs:simpleType>
  <xs:complexType name="nameID">
    <xs:sequence>
      <xs:element name="name" type ="tns:name" minOccurs="0"
                          maxOccurs="1"/>
    </xs:sequence>
    <xs:attribute name="aor" type="xs:anyURI" use="required"/>
  </xs:complexType>

Ravindranath, et al. Standards Track [Page 29] RFC 7865 SIP Recording Metadata May 2016

 <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:complexType name="reason">
    <xs:simpleContent>
     <xs:extension base="xs:string">
        <xs:attribute type="xs:short" name="cause" use="required"/>
        <xs:attribute type="xs:string" name="protocol" default="SIP"/>
     </xs:extension>
    </xs:simpleContent>
 </xs:complexType>
 <xs:element name="requestsnapshot" type="tns:requestsnapshot"/>
  <xs:complexType name="requestsnapshot">
     <xs:sequence>
        <xs:element name="requestreason" type="tns:name"
          minOccurs="0"/>
        <xs:any namespace='##other'
          minOccurs='0'
          maxOccurs='unbounded'
          processContents='lax'/>
     </xs:sequence>
  </xs:complexType>

</xs:schema>

10. Security Considerations

 This document describes an extensive set of metadata that may be
 recorded by the SRS.  Most of the metadata could be considered
 private data.  The procedures mentioned in the Security
 Considerations section of [RFC7866] MUST be followed by the SRC and
 the SRS for mutual authentication and to protect the content of the
 metadata in the RS.
 An SRC MAY, by policy, choose to limit the parts of the metadata sent
 to the SRS for recording.  Also, the policy of the SRS might not
 require recording all the metadata it receives.  For the sake of data
 minimization, the SRS MUST NOT record additional metadata that is not
 explicitly required by local policy.  Metadata in storage needs to be
 provided with a level of security that is comparable to that of the
 recording session.

Ravindranath, et al. Standards Track [Page 30] RFC 7865 SIP Recording Metadata May 2016

11. IANA Considerations

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

11.1. SIP Recording Metadata Schema Registration

 URI: urn:ietf:params:xml:ns:recording:1
 Registrant Contact:  IETF SIPREC working group, Ram Mohan R
    (rmohanr@cisco.com)
 XML: The registered XML schema is contained in Section 9.
 Its first line is <?xml version="1.0" encoding="UTF-8"?>, and its
 last line is </xs:schema>.

12. References

12.1. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119,
            DOI 10.17487/RFC2119, March 1997,
            <http://www.rfc-editor.org/info/rfc2119>.
 [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
            A., Peterson, J., Sparks, R., Handley, M., and E.
            Schooler, "SIP: Session Initiation Protocol", RFC 3261,
            DOI 10.17487/RFC3261, June 2002,
            <http://www.rfc-editor.org/info/rfc3261>.
 [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
            Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
            <http://www.rfc-editor.org/info/rfc3339>.
 [RFC3840]  Rosenberg, J., Schulzrinne, H., and P. Kyzivat,
            "Indicating User Agent Capabilities in the Session
            Initiation Protocol (SIP)", RFC 3840,
            DOI 10.17487/RFC3840, August 2004,
            <http://www.rfc-editor.org/info/rfc3840>.
 [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
            Unique IDentifier (UUID) URN Namespace", RFC 4122,
            DOI 10.17487/RFC4122, July 2005,
            <http://www.rfc-editor.org/info/rfc4122>.

Ravindranath, et al. Standards Track [Page 31] RFC 7865 SIP Recording Metadata May 2016

 [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
            Description Protocol", RFC 4566, DOI 10.17487/RFC4566,
            July 2006, <http://www.rfc-editor.org/info/rfc4566>.
 [RFC4574]  Levin, O. and G. Camarillo, "The Session Description
            Protocol (SDP) Label Attribute", RFC 4574,
            DOI 10.17487/RFC4574, August 2006,
            <http://www.rfc-editor.org/info/rfc4574>.
 [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
            Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
            <http://www.rfc-editor.org/info/rfc4648>.
 [RFC4796]  Hautakorpi, J. and G. Camarillo, "The Session Description
            Protocol (SDP) Content Attribute", RFC 4796,
            DOI 10.17487/RFC4796, February 2007,
            <http://www.rfc-editor.org/info/rfc4796>.
 [RFC7866]  Portman, L., Lum, H., Ed., Eckel, C., Johnston, A., and A.
            Hutton, "Session Recording Protocol", RFC 7866,
            DOI 10.17487/RFC7866, May 2016,
            <http://www.rfc-editor.org/info/rfc7866>.

12.2. Informative References

 [RFC3325]  Jennings, C., Peterson, J., and M. Watson, "Private
            Extensions to the Session Initiation Protocol (SIP) for
            Asserted Identity within Trusted Networks", RFC 3325,
            DOI 10.17487/RFC3325, November 2002,
            <http://www.rfc-editor.org/info/rfc3325>.
 [RFC3326]  Schulzrinne, H., Oran, D., and G. Camarillo, "The Reason
            Header Field for the Session Initiation Protocol (SIP)",
            RFC 3326, DOI 10.17487/RFC3326, December 2002,
            <http://www.rfc-editor.org/info/rfc3326>.
 [RFC3966]  Schulzrinne, H., "The tel URI for Telephone Numbers",
            RFC 3966, DOI 10.17487/RFC3966, December 2004,
            <http://www.rfc-editor.org/info/rfc3966>.
 [RFC4235]  Rosenberg, J., Schulzrinne, H., and R. Mahy, Ed., "An
            INVITE-Initiated Dialog Event Package for the Session
            Initiation Protocol (SIP)", RFC 4235,
            DOI 10.17487/RFC4235, November 2005,
            <http://www.rfc-editor.org/info/rfc4235>.

Ravindranath, et al. Standards Track [Page 32] RFC 7865 SIP Recording Metadata May 2016

 [RFC6341]  Rehor, K., Ed., Portman, L., Ed., Hutton, A., and R. Jain,
            "Use Cases and Requirements for SIP-Based Media Recording
            (SIPREC)", RFC 6341, DOI 10.17487/RFC6341, August 2011,
            <http://www.rfc-editor.org/info/rfc6341>.
 [RFC7245]  Hutton, A., Ed., Portman, L., Ed., Jain, R., and K. Rehor,
            "An Architecture for Media Recording Using the Session
            Initiation Protocol", RFC 7245, DOI 10.17487/RFC7245,
            May 2014, <http://www.rfc-editor.org/info/rfc7245>.
 [SessionID]
            Jones, P., Salgueiro, G., Pearce, C., and P. Giralt,
            "End-to-End Session Identification in IP-Based Multimedia
            Communication Networks", Work in Progress,
            draft-ietf-insipid-session-id-22, April 2016.
 [UML]      Object Management Group, "OMG Unified Modeling Language
            (UML)", 2011, <http://www.omg.org/spec/UML/2.4/>.

Ravindranath, et al. Standards Track [Page 33] RFC 7865 SIP Recording Metadata May 2016

Acknowledgements

 Thanks to John Elwell, Henry Lum, Leon Portman, De Villiers de Wet,
 Andrew Hutton, Deepanshu Gautam, Charles Eckel, Muthu Arul Mozhi
 Perumal, Michael Benenson, Hadriel Kaplan, Brian Rosen, Scott Orton,
 Ofir Roth, Mary Barnes, Ken Rehor, Gonzalo Salgueiro, Yaron Pdut,
 Alissa Cooper, Stephen Farrell, and Ben Campbell for their valuable
 comments and inputs.
 Thanks to Joe Hildebrand, Peter Saint-Andre, and Matt Miller for
 helping in writing the XML schema, and to Martin Thomson for
 validating the XML schema and providing comments on the same.

Authors' Addresses

 Ram Mohan Ravindranath
 Cisco Systems
 Cessna Business Park
 Bangalore, Karnataka
 India
 Email: rmohanr@cisco.com
 Parthasarathi Ravindran
 Nokia Networks
 Bangalore, Karnataka
 India
 Email: partha@parthasarathi.co.in
 Paul Kyzivat
 Huawei
 Hudson, MA
 United States
 Email: pkyzivat@alum.mit.edu

Ravindranath, et al. Standards Track [Page 34]

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