SIPREC Ram Mohan. Ravindranath
Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track Parthasarathi. Ravindran
Expires: May 10, 2013 Nokia Siemens Networks
Paul. Kyzivat
Huawei
November 6, 2012
Session Initiation Protocol (SIP) Recording Metadata
draft-ietf-siprec-metadata-09
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 10, 2013.
Copyright Notice
Copyright (c) 2012 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
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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. CSRSAssociation . . . . . . . . . . . . . . . . . . . . . 12
6.4.1. Attributes . . . . . . . . . . . . . . . . . . . . . . 13
6.4.2. Linkages . . . . . . . . . . . . . . . . . . . . . . . 13
6.4.3. XML element . . . . . . . . . . . . . . . . . . . . . 13
6.5. Participant . . . . . . . . . . . . . . . . . . . . . . . 13
6.5.1. Attributes . . . . . . . . . . . . . . . . . . . . . . 14
6.5.2. Linkages . . . . . . . . . . . . . . . . . . . . . . . 14
6.5.3. XML element . . . . . . . . . . . . . . . . . . . . . 14
6.6. ParticipantCSAssociation . . . . . . . . . . . . . . . . . 15
6.6.1. Attributes . . . . . . . . . . . . . . . . . . . . . . 15
6.6.2. Linkages . . . . . . . . . . . . . . . . . . . . . . . 16
6.6.3. XML element . . . . . . . . . . . . . . . . . . . . . 16
6.7. Media Stream . . . . . . . . . . . . . . . . . . . . . . . 16
6.7.1. Attributes . . . . . . . . . . . . . . . . . . . . . . 17
6.7.2. Linkages . . . . . . . . . . . . . . . . . . . . . . . 17
6.7.3. XML element . . . . . . . . . . . . . . . . . . . . . 17
6.8. ParticipantStream Association . . . . . . . . . . . . . . 17
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6.8.1. Attributes . . . . . . . . . . . . . . . . . . . . . . 18
6.8.2. Linkages . . . . . . . . . . . . . . . . . . . . . . . 18
6.8.3. XML element . . . . . . . . . . . . . . . . . . . . . 18
6.9. associate-time/disassociate-time . . . . . . . . . . . . . 18
6.10. Unique ID format . . . . . . . . . . . . . . . . . . . . . 19
7. SIP Recording Metadata Example . . . . . . . . . . . . . . . . 19
7.1. Complete SIP Recording Metadata Example . . . . . . . . . 19
7.2. Partial Update of Recording metadata XML body . . . . . . 21
8. XML Schema definition for Recording metadata . . . . . . . . . 21
9. Security Considerations . . . . . . . . . . . . . . . . . . . 25
9.1. Connection Security . . . . . . . . . . . . . . . . . . . 25
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
10.1. SIP recording metadata Schema Registration . . . . . . . . 26
11. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 26
12. Appendix A: Metadata Model Object Instances . . . . . . . . . 26
12.1. Use case 1: Basic Call . . . . . . . . . . . . . . . . . . 26
12.2. Use case 2: Hold/Resume . . . . . . . . . . . . . . . . . 27
12.3. Use case 3: Basic call with Transfer . . . . . . . . . . . 29
12.4. Conference Use Cases . . . . . . . . . . . . . . . . . . . 30
12.4.1. Case 1: . . . . . . . . . . . . . . . . . . . . . . . 31
12.4.2. Case 2: . . . . . . . . . . . . . . . . . . . . . . . 33
12.4.3. Case 3: . . . . . . . . . . . . . . . . . . . . . . . 35
12.4.4. Case 4: . . . . . . . . . . . . . . . . . . . . . . . 36
13. Appendix B: Metadata XML schema Instances . . . . . . . . . . 37
13.1. Use case 1: Basic Call . . . . . . . . . . . . . . . . . . 37
13.2. Use case 2: Hold/resume . . . . . . . . . . . . . . . . . 39
13.3. Use case 3: Basic Call with transfer . . . . . . . . . . . 41
13.4. Use Case 4: Call disconnect . . . . . . . . . . . . . . . 45
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 46
14.1. Normative References . . . . . . . . . . . . . . . . . . . 46
14.2. Informative References . . . . . . . . . . . . . . . . . . 47
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 47
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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 |
| CSRS | | | Session (CS) |
| Association|--+ | Group |
| | | +-----------------+
+------------+ | | 0..1
| |
|0..* | 1..*
+-------------------------------+
| Communication Session (CS) |
| |
+-------------------------------+
| 1..* |0..1
+-----+ |
| | 0..* |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 be 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., "". 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 be 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 |
| Start-time |
| Stop-time |
+-------------------------------+
| |
| 0..* |0..1
| |
| 0..* |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
[RFC3326] of CS.
o CS Identifier - This attribute is used to uniquely identify a CS.
o Start-time - This optional attribute represents start time of CS
as seen by SRC
o Stop-time - This optional attribute represents stop time of CS as
seen by 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 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 zero or more participants
o 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 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 at most one CS. Stream in
persistent RS is not required to be associated with any CS before
CS is created and hence the zero association is allowed.
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. CSRSAssociation
1..* 0..*
Recording Communication
Session ----------+---------- Session
|
|
|
+-------------------+
| CSRSAssociation |
+-------------------+
| Association-Time |
| Disassociaton-Time|
+-------------------+
A CSRS Association class and its objects has attributes of CS object
which are attributes of association of a session to a RS.
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6.4.1. Attributes
CSRS association class has the following attributes:
o Associate-time - associate-time is calculated by SRC as the time
it sees a CS is associated to a RS
o Disassociate-time- Disassociate-time is calculated by SRC as the
time it see a CS disassociate from a RS.
It is possible that a given CS can have multiple associate/
disassociate times within given RS.
6.4.2. Linkages
CSRS association class is linked to CS and RS classes. There are no
cardinalties for this linkage.
6.4.3. XML element
sessionrecordingassoc is the XML element to represent CSRS
association object. session URN UUID is used to uniquely identify
this element and link with the specific session.
6.5. Participant
Communication Session (CS)
| 0..*
|
| 0..*
+-------------------------------+
| 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)
belonging to a CS.
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6.5.1. 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-identity header [RFC3325] 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.
6.5.2. 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.
6.5.3. XML element
A participant element represents a Participant object.
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
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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.
6.6. ParticipantCSAssociation
1..* 0..*
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.
6.6.1. Attributes
ParticipantCS association class has the following attributes:
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 [RFC3840]
which 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
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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.
o "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 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.
6.6.2. Linkages
The participantCS association class is linked to participant and CS
classes. There are no cardinalties for this linkage.
6.6.3. XML element
participantsessionassoc XML element represent participantCS
association object. participant and session id is used to uniquely
identify this element
NOTE: RFC 4235 encoding shall be used to represent capabilities
attribute in XML.
6.7. Media Stream
Participant
| 0..* 1..*|
receives| |sends
| 0..* 0..*|
+-------------------------+
| Media Stream |
| |
Communication 0..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
object may be sent whenever there is a change in media (e.g. dir
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change like pause/resume and/or codec change and/or participant
change.).
6.7.1. 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 [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
6.7.2. 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.
6.7.3. 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. Label attribute is used to link m-line SDP body using
label attribute in SDP m-line.
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.
6.8. ParticipantStream Association
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+-------------------+
| ParticipantSteam |
| Association |
+-------------------+ +----------Participant
| 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.
6.8.1. Attributes
A participantStream association class has the following attributes:
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
6.8.2. Linkages
The participantStream association class is linked to participant and
Stream classes. There are no cardinalties for this linkage.
6.8.3. XML element
ParticipantStreamAssoc XML element represents participant to stream
association object. participant element is used to uniquely identify
this element and related with stream using stream unique URN id..
6.9. 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,
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
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determined.
6.10. 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 [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.
complete2010-12-16T23:41:07Zsip:alice@atlanta.comFaXHlc+3WruaroDaNE87am==FOO!bar7+OTCyoxTmqmqyA/1weDAg==
FOO!bar2010-12-16T23:41:07Z
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Bob BFOO!bar2010-12-16T23:41:07Zi1Pz3to5hGk8fuXl+PbwCw==UAAMm5GRQKSCMVvLyl4rFw==8zc6e0lYTlWIINA6GR+3ag==EiXGlc+4TruqqoDaNE76ag==PaulFOO!bar2010-12-16T23:41:07Z8zc6e0lYTlWIINA6GR+3ag==EiXGlc+4TruqqoDaNE76ag==UAAMm5GRQKSCMVvLyl4rFw==i1Pz3to5hGk8fuXl+PbwCw==
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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.
partialBob RFOO!bar2010-12-16T23:41:07Z
Partial update of SIP Recording Example XML body
8. XML Schema definition for Recording metadata
This section defines XML schema for Recording metadata document
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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 and its last
line is
11. Acknowledgement
We wish to thank John Elwell, Henry Lum, Leon Portman, De Villers,
Andrew Hutton(Siemens-Enterprise), Deepanshu Gautam(Huawei),Charles
Eckel(Cisco), Muthu Arul Mozhi (Cisco), Michael Benenson(Cisco),
Hadriel Kaplan (ACME), Brian Rosen, Scott Orton(Broadsoft), Ofir Roth
(NICE) 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
Note: This Appendix has to be moved to callflow document after the
discussion in the mailing alias
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
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Streams sent by each participant is received all other participants
of that CS.
+-------------------------------+
| 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 |
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| | | |
+---------------+ | +---------------+ |
|Media Stream A1| | |Media Stream B1| |
+---------------+ | +---------------+ |
| | | | | |
| | | | 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
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NOTE: There MAY be other ways to model the same use cases depending
on what information the SRC has.
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
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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
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
Note: This Appendix has to be moved to callflow document after the
discussion in the mailing alias
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(Alice) and B(Bob) 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
....
complete2010-12-16T23:41:07Z
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sip:alice@cisco.comFOO!bar7+OTCyoxTmqmqyA/1weDAg==
2010-12-16T23:41:07ZFOO!barAliceFOO!bar2010-12-16T23:41:07Zi1Pz3to5hGk8fuXl+PbwCw==UAAMm5GRQKSCMVvLyl4rFw==8zc6e0lYTlWIINA6GR+3ag==EiXGlc+4TruqqoDaNE76ag==BobFOO!bar2010-12-16T23:41:07Z8zc6e0lYTlWIINA6GR+3ag==EiXGlc+4TruqqoDaNE76ag==UAAMm5GRQKSCMVvLyl4rFw==i1Pz3to5hGk8fuXl+PbwCw==
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
....
partial8zc6e0lYTlWIINA6GR+3ag==EiXGlc+4TruqqoDaNE76ag==8zc6e0lYTlWIINA6GR+3ag==EiXGlc+4TruqqoDaNE76ag==
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(Alice) 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
....
partial8zc6e0lYTlWIINA6GR+3ag==EiXGlc+4TruqqoDaNE76ag==60JAJm9UTvik0Ltlih/Gzw==AcR5FUd3Edi8cACQJy/3JQ==
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PaulFOO!bar2010-12-16T23:41:07Z60JAJm9UTvik0Ltlih/Gzw==AcR5FUd3Edi8cACQJy/3JQ==8zc6e0lYTlWIINA6GR+3ag==EiXGlc+4TruqqoDaNE76ag==
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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Partial7+OTCyoxTmqmqyA/1weDAg==
2010-12-16T23:41:07ZFOO!bar2010-12-16T23:41:07Z2010-12-16T23:41:07Z
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
a=sendonly
...
m=video 49176 RTP/AVPF 96
a=rtpmap:96 H.264/90000
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a=label:99
a=sendonly
....
partial7+OTCyoxTmqmqyA/1weDAg==
2010-12-16T23:41:07ZFOO!barFOO!bar2010-12-16T23:32:03Z8zc6e0lYTlWIINA6GR+3ag==EiXGlc+4TruqqoDaNE76ag==60JAJm9UTvik0Ltlih/Gzw==AcR5FUd3Edi8cACQJy/3JQ==FOO!bar2010-12-16T23:41:07Z60JAJm9UTvik0Ltlih/Gzw==
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AcR5FUd3Edi8cACQJy/3JQ==8zc6e0lYTlWIINA6GR+3ag==EiXGlc+4TruqqoDaNE76ag==
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 Alice and Bob
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Partial7+OTCyoxTmqmqyA/1weDAg==
2010-12-16T23:41:07ZFOO!bar2010-12-16T23:41:07Z2010-12-16T23:41:07Z
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
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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.
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-06
(work in progress), September 2012.
[RFC2648] Moats, R., "A URN Namespace for IETF Documents", RFC 2648,
August 1999.
[RFC3326] Schulzrinne, H., Oran, D., and G. Camarillo, "The Reason
Header Field for the Session Initiation Protocol (SIP)",
RFC 3326, December 2002.
[RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private
Extensions to the Session Initiation Protocol (SIP) for
Asserted Identity within Trusted Networks", RFC 3325,
November 2002.
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Authors' Addresses
Ram Mohan Ravindranath
Cisco Systems, Inc.
Cessna Business Park,
Kadabeesanahalli Village, Varthur Hobli,
Sarjapur-Marathahalli Outer Ring Road
Bangalore, Karnataka 560103
India
Email: rmohanr@cisco.com
Parthasarathi Ravindran
Nokia Siemens Networks
Bangalore, Karnataka
India
Email: partha@parthasarathi.co.in
Paul Kyzivat
Huawei
Hudson, MA
USA
Email: pkyzivat@alum.mit.edu
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