Network Working Group T. Melanchuk
Internet-Draft Rain Willow Communications
Intended status: Standards Track S. McGlashan
Expires: May 7, 2009 Hewlett-Packard
C. Boulton
Avaya
November 3, 2008
A Mixer Control Package for the Media Control Channel Framework
draft-ietf-mediactrl-mixer-control-package-02
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Abstract
This document defines a Mixer Control Package for the Media Control
Channel Framework. This Control Package aims to fulfill Conferencing
requirements using the SIP Control Framework.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 5
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Control Package Definition . . . . . . . . . . . . . . . . . . 8
4.1. Control Package Name . . . . . . . . . . . . . . . . . . . 8
4.2. Framework Message Usage . . . . . . . . . . . . . . . . . 8
4.3. Common XML Support . . . . . . . . . . . . . . . . . . . . 9
4.4. CONTROL Message Body . . . . . . . . . . . . . . . . . . . 9
4.5. REPORT Message Body . . . . . . . . . . . . . . . . . . . 9
4.6. Audit . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Element Definitions . . . . . . . . . . . . . . . . . . . . . 11
5.1. <mscmixer> . . . . . . . . . . . . . . . . . . . . . . . . 11
5.2. Mixer Elements . . . . . . . . . . . . . . . . . . . . . . 12
5.2.1. Conference Elements . . . . . . . . . . . . . . . . . 13
5.2.1.1. <createconference> . . . . . . . . . . . . . . . . 13
5.2.1.2. <modifyconference> . . . . . . . . . . . . . . . . 16
5.2.1.3. <destroyconference> . . . . . . . . . . . . . . . 17
5.2.1.4. Conference Configuration . . . . . . . . . . . . . 17
5.2.1.4.1. <audio-mixing> . . . . . . . . . . . . . . . . 18
5.2.1.4.2. <video-layouts> . . . . . . . . . . . . . . . 18
5.2.1.4.2.1. <video-layout> . . . . . . . . . . . . . . 19
5.2.1.4.3. <video-switch> . . . . . . . . . . . . . . . . 24
5.2.1.4.3.1. Priority assignment . . . . . . . . . . . 26
5.2.1.4.4. <subscribe> . . . . . . . . . . . . . . . . . 27
5.2.1.4.4.1. <active-talkers-sub> . . . . . . . . . . . 27
5.2.2. Joining Elements . . . . . . . . . . . . . . . . . . . 27
5.2.2.1. Joining Model . . . . . . . . . . . . . . . . . . 27
5.2.2.2. <join> . . . . . . . . . . . . . . . . . . . . . . 29
5.2.2.3. <modifyjoin> . . . . . . . . . . . . . . . . . . . 31
5.2.2.4. <unjoin> . . . . . . . . . . . . . . . . . . . . . 32
5.2.2.5. <stream> . . . . . . . . . . . . . . . . . . . . . 33
5.2.2.5.1. <volume> . . . . . . . . . . . . . . . . . . . 34
5.2.2.5.2. <clamp> . . . . . . . . . . . . . . . . . . . 34
5.2.2.5.3. <region> . . . . . . . . . . . . . . . . . . . 35
5.2.2.5.4. <priority> . . . . . . . . . . . . . . . . . . 35
5.2.3. <response> . . . . . . . . . . . . . . . . . . . . . . 35
5.2.4. <event> . . . . . . . . . . . . . . . . . . . . . . . 36
5.2.4.1. <active-talkers-notify> . . . . . . . . . . . . . 36
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5.2.4.1.1. <active-talker> . . . . . . . . . . . . . . . 36
5.2.4.2. <unjoin-notify> . . . . . . . . . . . . . . . . . 37
5.2.4.3. <conferenceexit> . . . . . . . . . . . . . . . . . 37
5.3. Audit Elements . . . . . . . . . . . . . . . . . . . . . . 38
5.3.1. <audit> . . . . . . . . . . . . . . . . . . . . . . . 39
5.3.2. <auditresponse> . . . . . . . . . . . . . . . . . . . 40
5.3.2.1. <capabilities> . . . . . . . . . . . . . . . . . . 41
5.3.2.2. <mixers> . . . . . . . . . . . . . . . . . . . . . 42
5.3.2.2.1. <conferenceaudit> . . . . . . . . . . . . . . 42
5.3.2.2.1.1. <participants> . . . . . . . . . . . . . . 43
5.3.2.2.1.1.1. <participant> . . . . . . . . . . . . 44
5.3.2.2.2. <joinaudit> . . . . . . . . . . . . . . . . . 44
5.4. <codecs> . . . . . . . . . . . . . . . . . . . . . . . . . 44
5.4.1. <codec> . . . . . . . . . . . . . . . . . . . . . . . 45
5.5. <params> . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.5.1. <param> . . . . . . . . . . . . . . . . . . . . . . . 46
5.6. Response Status Codes . . . . . . . . . . . . . . . . . . 46
5.7. Type Definitions . . . . . . . . . . . . . . . . . . . . . 51
6. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 53
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
7.1. AS-MS Framework Interaction Examples . . . . . . . . . . . 71
7.1.1. Creating a conference mixer and joining a
participant . . . . . . . . . . . . . . . . . . . . . 71
7.1.2. Receiving active talker notifications . . . . . . . . 72
7.1.3. Conference termination . . . . . . . . . . . . . . . . 72
7.2. Mixing Examples . . . . . . . . . . . . . . . . . . . . . 72
7.2.1. Audio conferencing . . . . . . . . . . . . . . . . . . 73
7.2.2. Bridging connections . . . . . . . . . . . . . . . . . 75
7.2.3. Video conferencing . . . . . . . . . . . . . . . . . . 76
8. Security Considerations . . . . . . . . . . . . . . . . . . . 78
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 79
9.1. Control Package Registration . . . . . . . . . . . . . . . 79
9.2. URN Sub-Namespace Registration . . . . . . . . . . . . . . 79
9.3. MIME Registration . . . . . . . . . . . . . . . . . . . . 79
10. Change Summary . . . . . . . . . . . . . . . . . . . . . . . . 80
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 84
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 85
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 86
13.1. Normative References . . . . . . . . . . . . . . . . . . . 86
13.2. Informative References . . . . . . . . . . . . . . . . . . 86
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 88
Intellectual Property and Copyright Statements . . . . . . . . . . 89
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1. Introduction
This document defines a Media Control Channel Framework Package for
conference mixers and connection mixers. The package defines mixer
management elements for creating, modifying and deleting conference
mixers, elements for joining, modifying and unjoining media streams
between connections and conferences (including mixers between
connections), as well as associated responses and notifications. The
package also defines elements for auditing package capabilities and
mixers.
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2. Conventions and Terminology
In this document, BCP 14/RFC 2119 [RFC2119] defines the key words
"MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
"SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL". In addition, BCP 15 indicates requirement levels for
compliant implementations.
The following additional terms are defined for use in this document:
Application server: A SIP [RFC3261] application server (AS) is a
control client that hosts and executes services such as
interactive media and conferencing in an operator's network. An
AS controls the media server (MS), influencing and impacting the
SIP sessions terminating on a media server, which the AS may have
established for example using SIP third party call control.
Media Server: A media server (MS) processes media streams on behalf
of an AS by offering functionality such as interactive media,
conferencing, and transcoding to the end user. Interactive media
functionality is realized by way of dialogs, which are identified
by a URI and initiated by the application server.
MS Conference: A MS Conference provides the media related mixing
resources and services for conferences. In this document, A MS
Conference is often referred to simply as a conference.
MS Connection: A Media Server connection represents the termination
on a media server of one or more RTP [RFC3550] sessions that are
associated to a single SIP dialog. A media server receives media
from the output(s) of a connection and it transmits media on the
input(s) of a connection.
Media Stream: A media stream on a media server represents a media
flow between either a connection and a conference, between two
connections, or between two conferences. Streams may be audio or
video and may be bi-directional or uni-directional.
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3. Overview
The SIP Control Framework [I-D.ietf-mediactrl-sip-control-framework]
provides a generic approach for establishment and reporting
capabilities of remotely initiated commands. The Framework utilizes
many functions provided by the Session Initiation Protocol [RFC3261]
(SIP) for the rendezvous and establishment of a reliable channel for
control interactions. The Control Framework also introduces the
concept of a Control Package. A Control Package is an explicit usage
of the Control Framework for a particular interaction set. This
specification defines a package for media conference mixers and media
connection mixers.
This package defines mixer management elements for creating,
modifying and deleting conference mixers, elements for joining,
modifying and unjoining media streams between connections and
conferences (including mixers between connections), as well as
associated responses and notifications. The package also defines
elements for auditing package capabilities and mixers.
This package has been designed to satisfy the IETF MediaCtrl
requirements ([RFC5167]). The package provides the major
conferencing functionality of SIP Media Server languages such as
MSCML ([RFC5022]) and MSML ([MSML]). A key differentiator is that
this package provides such functionality using the Media Control
Channel Framework.
Out of scope for this mixer package are more advanced functions
including personalized video mixes for conference participants,
support for floor control protocols, as well as support for video
overlays and text insertion. Such functionality may be addressed by
extensions to this package (through addition of foreign elements or
attributes from another namespace) or use of other control packages
which could build upon this package.
The functionality of this package is defined by messages, containing
XML [XML] elements, transported using the Media Control Channel
Framework. The XML elements can be divided into two types: mixer
management elements; and elements for auditing package capabilities
as well as mixers managed by the package.
The document is organized as follows. Section 4 describes how this
control package fulfills the requirements for a Media Control Channel
Framework control package. Section 5 describes the syntax and
semantics of defined elements, including mixer management
(Section 5.2) and audit elements (Section 5.3). Section 6 describes
an XML schema for these elements and provides extensibility by
allowing attributes and elements from other namespaces. Section 7
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provides examples of package usage.
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4. Control Package Definition
This section fulfills the mandatory requirement for information that
MUST be specified during the definition of a Control Framework
Package, as detailed in Section 8 of
[I-D.ietf-mediactrl-sip-control-framework].
4.1. Control Package Name
The Control Framework requires a Control Package definition to
specify and register a unique name. The name and version of this
Control Package is "msc-mixer/1.0" (Media Server Control - Mixer -
version 1.0). Its IANA registration is specified in Section 9.1.
Since this is the initial ("1.0") version of the control package,
there are no backwards compatibility issues to address.
4.2. Framework Message Usage
The Control Framework requires a Control Package to explicitly detail
the control messages that can be used as well as provide an
indication of directionality between entities. This will include
which role type is allowed to initiate a request type.
This package specifies CONTROL and response messages in terms of XML
elements defined in Section 5, where the message bodies have the MIME
media type defined in Section 9.3. These elements describe requests,
response and notifications and all are contained within a root
<mscmixer> element (Section 5.1).
In this package, the MS operates as a Control Server in receiving
requests from, and sending responses to, the AS (operating as Control
Client). Mixer management requests and responses are defined in
Section 5.2. Audit requests and responses are defined in
Section 5.3. Mixer management and audit responses are carried in a
framework 200 response or REPORT message bodies. This package's
response codes are defined in Section 5.6.
Note that package responses are different from framework response
codes. Framework error response codes (see Section 8 of
[I-D.ietf-mediactrl-sip-control-framework]) are used when the request
or event notification is invalid; for example, a request is invalid
XML (400), or not understood (500).
The MS also operates as a Control Client in sending event
notification to the AS (Control Server). Event notifications
(Section 5.2.4) are carried in CONTROL message bodies. The AS MUST
respond with a Control Framework 200 response.
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4.3. Common XML Support
The Control Framework requires a Control Package definition to
specify if the attributes for media dialog or conference references
are required.
This package requires that the XML Schema in Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework] MUST be supported for
media dialogs and conferences.
The package uses "connectionid" and "conferenceid" attributes for
various element definitions (Section 5). The XML schema (Section 6)
imports the definitions of these attributes from the framework
schema.
4.4. CONTROL Message Body
The Control Framework requires a Control Package to define the
control body that can be contained within a CONTROL command request
and to indicate the location of detailed syntax definitions and
semantics for the appropriate body types.
When operating as Control Server, the MS receives CONTROL messages
with the MIME media type defined in Section 9.3 and a body containing
a <mscmixer> element (Section 5.1) with either a mixer management or
audit request child element.
The following mixer management request elements are carried in
CONTROL message bodies to MS: <createconference> (Section 5.2.1.1),
<modifyconference> (Section 5.2.1.2), <destroyconference>
(Section 5.2.1.3), <join> (Section 5.2.2.2), <modifyjoin>
(Section 5.2.2.3) and <unjoin> (Section 5.2.2.4) elements.
The <audit> request element (Section 5.3.1) is also carried in
CONTROL message bodies.
When operating as Control Client, the MS sends CONTROL messages with
the MIME media type defined in Section 9.3 and a body containing a
<mscmixer> element (Section 5.1) with a notification <event> child
element (Section 5.2.4).
4.5. REPORT Message Body
The Control Framework requires a control package definition to define
the REPORT body that can be contained within a REPORT command
request, or that no report package body is required. This section
should indicate the location of detailed syntax definitions and
semantics for the appropriate body types.
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When operating as Control Server, the MS sends REPORT bodies with the
MIME media type defined in Section 9.3 and a <mscmixer> element with
a response child element. The response element for mixer management
requests is a <response> element (Section 5.2.3). The response
element for an audit request is a <auditresponse> element
(Section 5.3.2).
4.6. Audit
The Control Framework encourages Control Packages to specify whether
auditing is available, how it is triggered as well as the query/
response formats.
This Control Packages supports auditing of package capabilities and
mixers on the MS. An audit request is carried in a CONTROL message
and an audit response in a REPORT message (or a 200 response to the
CONTROL if it can execute the audit in time).
The syntax and semantics of audit request and response elements is
defined in Section 5.3.
4.7. Examples
The Control Framework recommends Control Packages to provide a range
of message flows that represent common flows using the package and
this framework document.
This Control Package provides examples of such message flows in
Section 7.
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5. Element Definitions
This section defines the XML elements for this package. The elements
are defined in the XML namespace specified in Section 9.2.
The root element is <mscmixer> (Section 5.1). All other XML elements
(requests, responses and notification elements) are contained within
it. Child elements describe mixer management (Section 5.2) and audit
(Section 5.3) functionality. Response status codes are defined in
Section 5.6 and type definitions in Section 5.7.
Implementation of this control package MUST adhere to the syntax and
semantics of XML elements defined in this section and the schema
(Section 6). The XML schema supports extensibility by allowing
attributes and elements from other namespaces. Implementations MAY
support attributes and elements from other (foreign) namespaces. If
an MS implementation receives a <mscmixer> element containing
attributes or elements from another namespace which it does not
support, the MS MUST send a 428 response (Section 5.6).
Extensible attributes and elements are not described in this section.
In all other cases where there is a difference in constraints between
the XML schema and the textual description of elements in this
section, the textual definition takes priority.
Usage examples are provided in Section 7.
5.1. <mscmixer>
The <mscmixer> element has the following attributes (in addition to
standard XML namespace attributes such as xmlns):
version: a string specifying the mscmixer package version. The
value is fixed as '1.0' for this version of the package. The
attribute is mandatory.
The <mscmixer> element has the following defined child elements, only
one of which can occur:
1. mixer management elements defined in Section 5.2:
<createconference> create and configure a new conference mixer.
See Section 5.2.1.1
<modifyconference> modify the configuration of an existing
conference mixer. See Section 5.2.1.2
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<destroyconference> destroy an existing conference mixer. See
Section 5.2.1.3
<join> create and configure media streams between connections
and/or conferences (for example, add a participant to a
conference). See Section 5.2.2.2
<modifyjoin> modify the configuration of joined media streams.
See Section 5.2.2.3
<unjoin> delete a media stream (for example, remove a
participant from a conference). See Section 5.2.2.4
<response> response to a mixer request. See Section 5.2.3
<event> mixer or subscription notification. See Section 5.2.4
2. audit elements defined in Section 5.3:
<audit> audit package capabilities and managed mixers. See
Section 5.3.1
<auditresponse> response to an audit request. See Section 5.3.2
For example, a request to the MS to create a conference mixer:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<createconference/>
</mscmixer>
and a response from the MS that the conference was successfully
created:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<response status="200" conferenceid="conference1"/>
</mscmixer>
5.2. Mixer Elements
This section defines the mixer management XML elements for this
control package. These elements are divided into requests, responses
and notifications.
Request elements are sent to the MS to request a specific mixer
operation to be executed. The following request elements are
defined:
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<createconference> create and configure a new a conference mixer.
See Section 5.2.1.1
<modifyconference> modify the configuration of an existing
conference mixer. See Section 5.2.1.2
<destroyconference> destroy an existing conference mixer. See
Section 5.2.1.3
<join> create and configure media streams between connections and/or
conferences (for example, add a participant to a conference). See
Section 5.2.2.2
<modifyjoin> modify the configuration of joined media streams. See
Section 5.2.2.3
<unjoin> delete a media stream (for example, remove a participant
from a conference). See Section 5.2.2.4
Responses from the MS describe the status of the requested operation.
Responses are specified in a <response> element (Section 5.2.3) which
includes a mandatory attribute describing the status in terms of a
numeric code. Response status codes are defined in Section 5.6. The
MS MUST respond to a request message with a response message. If the
MS is not able to process the request and carry out the mixer
operation, the request has failed and the MS MUST indicate the class
of failure using an appropriate 4xx response code. Unless an error
response code is mandated for a specific class of error within this
section, implementations follow Section 5.6 in determining the
appropriate status code for the response.
Notifications are sent from the MS to provide updates on the status
of a mixer operation or subscription. Notifications are specified in
an <event> element (Section 5.2.4).
5.2.1. Conference Elements
5.2.1.1. <createconference>
The <createconference> element is sent to the MS to request creation
of a new conference (multiparty) mixer.
The <createconference> element has the following attributes:
conferenceid: string indicating a unique name for the new
conference. If this attribute is not specified, the MS MUST
create a unique name for the conference. The value is used in
subsequent references to the conference (e.g. as conferenceid in a
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<response>). The attribute is optional. There is no default
value.
reserved-talkers: indicates the requested number of guaranteed
speaker slots to be reserved for the conference. A valid value is
a non-negative integer (see Section 5.7.2). The attribute is
optional. The default value is 0.
reserved-listeners: indicates the requested number of guaranteed
listener slots to be reserved for the conference. A valid value
is a non-negative integer (see Section 5.7.2). The attribute is
optional. The default value is 0.
The <createconference> element has the following sequence of child
elements:
<codecs>: an element to configure the codecs supported by the
conference (see Section 5.4). The element is optional.
<audio-mixing>: an element to configure the audio mixing
characteristics of a conference (see Section 5.2.1.4.1). The
element is optional.
<video-layouts>: an element to configure the video layouts of a
conference (see Section 5.2.1.4.2). The element is optional.
<video-switch>: an element to configure the video switch policy for
the layout of a conference (see Section 5.2.1.4.3). The element
is optional.
<subscribe>: an element to request subscription to conference
events. (see Section 5.2.1.4.4). The element is optional.
If the conferenceid attribute specifies the name of a conference
which already exists, the MS MUST report an error (405) and MUST NOT
create the conference.
If the MS is unable to configure the conference according to
specified reserved-talkers or reserved-listeners attributes, the MS
MUST report an error (420) and MUST NOT create the conference.
If the MS is unable to configure the conference according to a
specified <audio-mixing> element, the MS MUST report an error (421)
and MUST NOT create the conference.
If the MS is unable to configure the conference for any specified
conference event specified in the <subscribe> element, the MS MUST
report an error (422) and MUST NOT create the conference.
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If the MS is unable to configure the conference according to a
specified <video-layouts> element, the MS MUST report an error (423)
and MUST NOT create the conference.
If the MS is unable to configure the conference according to a
specified <video-switch> element, the MS MUST report an error (424)
and MUST NOT create the conference.
If the MS is unable to configure the conference according to a
specified <codecs> element, the MS MUST report an error (425) and
MUST NOT create the conference.
When a MS has finished processing a <createconference> request, it
MUST reply with an appropriate <response> element (Section 5.2.3).
For example, a request to create an audio video conference mixer with
specified codecs, video layout, video switch and subscription:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<createconference conferenceid="conference1"
reserved-talkers="1" reserved-listeners="10">
<codecs>
<codec>
<subtype>H264</subtype>
</codec>
<codec>
<subtype>PCMA</subtype>
</codec>
</codecs>
<audio-mixing type="nbest"/>
<video-layouts>
<video-layout min-participants="1">single-view</video-layout>
<video-layout min-participants="2">dual-view</video-layout>
<video-layout min-participants="3">quad-view</video-layout>
</video-layouts>
<video-switch type="vas" interval="5"/>
<subscribe>
<active-talkers-sub interval="4"/>
</subscribe>
</createconference>
</mscmixer>
and a response from the MS if the conference was successfully
created:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<response status="200" conferenceid="conference1"/>
</mscmixer>
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alternatively, a response if MS could not create the conference due
to a lack of support for the H264 codec:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<response status="425" conferenceid="conference1"
reason="H264 codec not supported"/>
</mscmixer>
5.2.1.2. <modifyconference>
The <modifyconference> element is sent to the MS to request
modification of an existing conference.
The <modifyconference> element has the following attributes:
conferenceid: string indicating the name of the conference to
modify. This attribute is mandatory.
The <modifyconference> element has the following sequence of child
elements (1 or more):
<codecs>: an element to configure the codecs supported by the
conference (see Section 5.4). Existing participants are
unaffected by any policy change. The element is optional.
<audio-mixing>: an element to configure the audio mixing
characteristics of a conference (see Section 5.2.1.4.1). The
element is optional.
<video-layouts>: an element to configure the video layouts of a
conference (see Section 5.2.1.4.2). The element is optional.
<video-switch>: an element to configure the video switch policy for
the layout of a conference (see Section 5.2.1.4.3). The element
is optional.
<subscribe>: an element to request subscription to conference
events. (see Section 5.2.1.4.4). The element is optional.
If the conferenceid attribute specifies the name of a conference
which does not exist, the MS MUST report an error (406).
If the MS is unable to configure the conference according to a
specified <audio-mixing> element, the MS MUST report an error (421)
and MUST NOT modify the conference in any way.
If the MS is unable to configure the conference for any specified
conference event specified in the <subscribe> element, the MS MUST
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report an error (422) and MUST NOT modify the conference in anyway.
If the MS is unable to configure the conference according to a
specified <video-layouts> element, the MS MUST report an error (423)
and MUST NOT modify the conference in any way.
If the MS is unable to configure the conference according to a
specified <video-switch> element, the MS MUST report an error (424)
and MUST NOT modify the conference in any way.
If the MS is unable to configure the conference according to a
specified <codecs> element, the MS MUST report an error (425) and
MUST NOT modify the conference.
When a MS has finished processing a <modifyconference> request, it
MUST reply with an appropriate <response> element (Section 5.2.3).
5.2.1.3. <destroyconference>
The <destroyconference> element is sent to the MS to request
destruction of an existing conference.
The <destroyconference> element has the following attributes:
conferenceid: string indicating the name of the conference to
destroy. This attribute is mandatory.
The <destroyconference> element does not specify any child elements.
If the conferenceid attribute specifies the name of a conference
which does not exist, the MS MUST report an error (406).
When a MS has finished processing a <destroyconference> request, it
MUST reply with an appropriate <response> element (Section 5.2.3).
Successfully destroying the conference (status code 200) will result
in all connection or conference participants being removed from the
conference mixer, <unjoin-notify> notification events
(Section 5.2.4.2) being sent for each conference participant and a
<conferenceexit> notification event (Section 5.2.4.3) indicating that
conference has exited. A <response> with any other status code
indicates that the conference mixer still exists and participants are
still joined to the mixer.
5.2.1.4. Conference Configuration
The elements in this section are used to establish and modify the
configuration of conferences.
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5.2.1.4.1. <audio-mixing>
The <audio-mixing> element defines the configuration of the
conference audio mix. It has no child elements and has the following
attributes:
type: is a string indicating the audio stream mixing policy.
Defined values are: "nbest" (where the N best participant signals
are mixed) and "controller" (where the contributing participant(s)
is/are selected by the controlling AS via an external floor
control protocol). The default value is "nbest". The attribute
is optional.
5.2.1.4.2. <video-layouts>
The <video-layouts> element describe the video presentation layout
configuration for participants providing a video input stream to the
conference. This element allows multiple video layouts to be
specified so that the MS automatically changes layout depending on
the number of video-enabled participants.
The <video-layouts> element has no attributes.
The <video-layouts> element has the following sequence of child
elements (1 or more):
<video-layout>: element describing a video layout
(Section 5.2.1.4.2.1).
If the MS does not support video conferencing at all, or does not
support multiple video layouts, or does not support a specific video
layout, the MS MUST report an 408 error in the response to the
request element containing the <video-layouts> element.
An MS MAY support more than one <video-layout> element, although only
one layout can be active at a time. A <video-layout> is active if
the number of participants in the conference is equal to or greater
than the value of its "min-participants" attribute, but less than the
value of the "min-participants" attribute for any other <video-
layout> element. An MS MUST report an error if more than one <video-
layout> has the same value for the "min-participants" attribute.
When the number of regions within the active layout is greater than
the number of participants in the conference, the display of
unassigned regions is implementation-specific.
The assignment of participant video streams to regions within the
layout is according to the video switch policy specified by the
<video-switch> element (Section 5.2.1.4.3).
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For example, a fragment describing a single layout:
<video-layouts>
<video-layout>single-view</video-layout>
</video-layouts>
And a fragment describing a sequence of layouts:
<video-layouts>
<video-layout min-participants="1">single-view</video-layout>
<video-layout min-participants="2">dual-view</video-layout>
<video-layout min-participants="3">quad-view</video-layout>
<video-layout min-participants="5">multiple-3x3</video-layout>
</video-layouts>
When the conference has one participant providing a video input
stream to the conference, then the single-view format is used. When
the conference has two such participants, the dual-view layout is
used. When the conference has three or four participants, the quad-
view layout is used. When the conference has five or more
participants, the multiple-3x3 layout is used.
5.2.1.4.2.1. <video-layout>
The <video-layout> element describes a video layout containing one or
more regions in which participant video input streams are displayed.
The <video-layout> element has the following attributes:
min-participants: the minimum number of conference participants
needed to allow this layout to be active. A valid value is a
positive integer (see Section 5.7.3). The attribute is optional.
The default value is 1.
The <video-layout> element has a content model specifying the name of
the video layout.
It is RECOMMENDED that an MS support the predefined video layouts
defined in the XCON conference information data model
([I-D.ietf-xcon-common-data-model]). The MS MAY support other video
layouts. It is RECOMMENDED that non-XCON layouts are prefixed with a
label; for example, <video-layout>mylayout:single-view<video-layout>.
Each video layout has associated with it one or more regions. The
XCON layouts have associated the following named regions:
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single-view layout with one stream in a single region as shown in
Figure 1.
+-----------+
| |
| |
| 1 |
| |
| |
+-----------+
Figure 1: single-view video layout
dual-view layout presenting two streams side-by-side in two regions
as shown in Figure 2. The MS MUST NOT alter the aspect ratio of
each stream to fit the region and hence the MS MAY have to blank
part of each region.
+-----------+-----------+
| | |
| | |
| 1 | 2 |
| | |
| | |
+-----------+-----------+
Figure 2: dual-view video layout
dual-view-crop layout presenting two streams side-by-side in two
regions as shown in Figure 3. The MS MUST alter the aspect ratio
of each stream to fit its region so that no blanking is required.
+-----------+-----------+
| | |
| | |
| 1 | 2 |
| | |
| | |
+-----------+-----------+
Figure 3: dual-view-crop video layout
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dual-view-2x1 layout presenting two streams one above the other in
two regions as shown in Figure 4. The MS MUST NOT alter the
aspect ratio of each stream to fit its region and hence the MS MAY
have to blank part of each region.
+-----------+
| |
| |
| 1 |
| |
| |
+-----------+
| |
| |
| 2 |
| |
| |
+-----------+
Figure 4: dual-view-2x1 video layout
dual-view-2x1-crop layout presenting two streams one above the other
in two regions as shown in Figure 5. The MS MUST alter the aspect
ratio of each stream to fit its region so that no blanking is
required.
+-----------+
| |
| |
| 1 |
| |
| |
+-----------+
| |
| |
| 2 |
| |
| |
+-----------+
Figure 5: dual-view-2x1-crop video layout
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quad-view layout presenting four equal-sized regions in a 2x2 layout
as shown in Figure 6. Typically the aspect ratio of the streams
is preserved, so blanking is required.
+-----------+-----------+
| | |
| | |
| 1 | 2 |
| | |
| | |
+-----------+-----------+
| | |
| | |
| 3 | 4 |
| | |
| | |
+-----------+-----------+
Figure 6: quad-view video layout
multiple-3x3 layout presenting nine equal-sized regions in a 3x3
layout as shown in Figure 7. Typically the aspect ratio of the
streams is preserved, so blanking is required.
+-----------+-----------+-----------+
| | | |
| | | |
| 1 | 2 | 3 |
| | | |
| | | |
+-----------+-----------+-----------+
| | | |
| | | |
| 4 | 5 | 6 |
| | | |
| | | |
+-----------+-----------+-----------+
| | | |
| | | |
| 7 | 8 | 9 |
| | | |
| | | |
+-----------+-----------+-----------+
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Figure 7: multiple-3x3 video layout
multiple-4x4 layout presenting sixteen equal-sized regions in a 4x4
layout as shown in Figure 8. Typically the aspect ratio of the
streams is preserved, so blanking is required.
+-----------+-----------+-----------+-----------+
| | | | |
| | | | |
| 1 | 2 | 3 | 4 |
| | | | |
| | | | |
+-----------+-----------+-----------+-----------+
| | | | |
| | | | |
| 5 | 6 | 7 | 8 |
| | | | |
| | | | |
+-----------+-----------+-----------+-----------+
| | | | |
| | | | |
| 9 | 10 | 11 | 12 |
| | | | |
| | | | |
+-----------+-----------+-----------+-----------+
| | | | |
| | | | |
| 13 | 14 | 15 | 16 |
| | | | |
| | | | |
+-----------+-----------+-----------+-----------+
Figure 8: multiple-4x4 video layout
multiple-5x1 layout presents a 5x1 layout as shown in Figure 9 where
one region will occupy 4/9 of the mixed video stream while the
others will each occupy 1/9 of the stream. Typically the aspect
ratio of the streams is preserved, so blanking is required.
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+-----------------------+-----------+
| | |
| | |
| | 2 |
| | |
| | |
| 1 +-----------+
| | |
| | |
| | 3 |
| | |
| | |
+-----------+-----------+-----------+
| | | |
| | | |
| 4 | 5 | 6 |
| | | |
| | | |
+-----------+-----------+-----------+
Figure 9: multiple-5x1 video layout
5.2.1.4.3. <video-switch>
The <video-switch> element describe the configuration of the
conference policy for how participant's input video streams are
assigned to regions within the active video layout.
The <video-switch> element has the following attributes:
type: a string indicating the video switching policy of the
conference. Defined values are:
vas (Voice Activated Switching) enables automatic display of the
most active speaker participant also providing a video input
stream to the conference. Participants who do not provide an
audio stream are not considered for automatic display. If a
participant provides more than one audio stream, then the
policy for inclusion of such a participant in the VAS is
implementation-specific; an MS could select one stream, sum
audio streams or ignore the participant for VAS consideration.
If there is only one region in the layout, then the most active
speaker is displayed there. If more than one region is
available, then the most active speaker is displayed in the
largest region, if any, and then in the first region from the
top-left corner of the layout. The MS assigns the remaining
regions based on the priority mechanism described in
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Section 5.2.1.4.3.1.
controller enables manual control over video switching. The
controller AS determines how the regions are assigned based on
an external floor control policy. The MS receives <join>,
<modifyjoin> and <join> commands with a <stream> element
(Section 5.2.2.5) indicating the region where the stream is
displayed. If no explicit region is specified, the MS assigns
the region based on the priority mechanism described in
Section 5.2.1.4.3.1.
An MS MAY support other video switching policies. It is
RECOMMENDED that other policy names are prefixed with a label;
e.g. "mypolicies:policy1". The attribute is optional. The
default value is 'vas'.
interval: specifies the period between video switches as a number of
seconds. In the case of 'vas' policy, a speaker needs to be the
most active speaker for the interval before the switch takes
place. A valid value is a non-negative integer (see
Section 5.7.2). A value of 0 indicates that switching is applied
immediately. The attribute is optional. The default value is 3
(seconds).
activespeakermix: indicates whether or not the active speaker
participant receives a video stream without themselves displayed
in the case of the 'vas' switching policy. If enabled, the MS
needs to generate two video streams for each conference mix: one
for the active speaker participant without themselves displayed -
details of this video layout are implementation-specific; and one
for other participants as described in the 'vas' switch policy
above. A valid value is a boolean (see Section 5.7.1). A value
of true indicates that a separate video mix is generated for the
active speaker without themselves being displayed. A value of
false indicates that all participants receive the same video mix.
The attribute is optional. The default value is false. If the
type attribute is not set to 'vas', the MS MUST ignore this
attribute.
If the MS does not support the specified video switching policy or
other configuration parameters (including separate active speaker
video mixes), then MS MUST report a 409 error (Section 5.6) in the
response to the request element containing the <video-switch>
element.
If the MS receives a <join> or <modifyjoin> request containing a a
<stream> element (Section 5.2.2.5) specifying a region and the
conference video switching policy is set to 'vas', then the MS MUST
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ignore the region (i.e. conference switching policy takes
precedence).
If the MS receives a <join> or <modifyjoin> request containing a
<stream> element (Section 5.2.2.5) specifying a region which is not
defined for the currently active video layout, the MS MUST NOT report
an error. Even though the participant is not currently visible, the
MS MUST display the participant if the layout changes to one which
defines the specified region.
The <video-switch> element has no child elements.
For example, a fragment specifying a 'vas' video switching policy
with an interval of 2s
<video-switch type="vas" interval="2"/>
For example, a fragment specifying a 'controller' video switching
policy where video switching takes place immediately:
<video-switch type="controller" interval="0"/>
5.2.1.4.3.1. Priority assignment
In cases where the video switching policy does not explicitly
determine the region to which a participant is assigned, the
following priority assignment mechanism applies:
1. Each participant has an (positive integer) priority value: the
lower the value, the higher the priority. The priority value is
determined by the <priority> child element (Section 5.2.2.5.4) of
<stream>. If not explicitly specified, the default priority
value is 100.
2. The MS uses priority values to assign participants to regions in
the video layout which remain unfilled after application of the
video switching policy. The MS MUST dedicate larger and/or more
prominent portions of the layout to participants with higher
priority values first (e.g. first all participants with priority
1, then those with 2, 3, etc).
3. The policy for displaying participants with the same priority is
implementation-specific.
The MS applies this priority policy each time the video layout is
changed or updated. It is RECOMMENDED that the MS does not move a
participant from one region to another unless required by the video
switching policy when an active video layout is updated.
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This model allows the MS to apply default video layouts after
applying the video switch policy. For example, region 2 is
statically assigned to Bob, so the priority mechanism only applies to
regions 1, 3, 4, etc.
5.2.1.4.4. <subscribe>
The <subscribe> element is a container for specifying conference
notification events to which a controlling entity subscribes.
Notifications of conference events are delivered using the <event>
element (see Section 5.2.4).
The <subscribe> element has no attributes, but has the following
child element:
<active-talkers-sub>: subscription to active talker events
(Section 5.2.1.4.4.1). The element is optional.
The MS SHOULD support a <active-talkers-sub> subscription. It MAY
support other event subscriptions. If the MS does not support a
requested subscription, it MUST send a <response> with a 422 status
code.
5.2.1.4.4.1. <active-talkers-sub>
The <active-talkers-sub> element has the following attributes:
interval: the minimum amount of time (in seconds) that must elapse
before further active talker events can be generated. A valid
value is a non-negative integer (see Section 5.7.2). A value of 0
suppresses further notifications. The attribute is optional. The
default value is 3 (seconds).
The <active-talker-sub> element has no child elements.
Active talker notifications are delivered in the <active-talker-
notify> element (Section 5.2.4.1).
5.2.2. Joining Elements
5.2.2.1. Joining Model
The <join> operation creates a media stream between a connection and
a conference, between connections, or between conferences. This sub-
section describes the model of conferences and connections and
specifies the behavior for join requests to targets that already have
an associated media stream.
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Conferences support multiple inputs and have resources to mix them
together. A media server conference in essence is a mixer that
combines media streams. A simple audio mix simply sums its input
audio signals to create a single common output. Conferences however
use a more complex algorithm so that participants do not hear
themselves as part of the mix. That algorithm, sometimes called an
n-minus mix, subtracts each participants input signal from the summed
input signals, creating a unique output for each contributing
participant. Each <join> operation to a conference uses one of the
conferences available inputs and/or outputs, to the maximum number of
supported participants.
A connection is the termination of a RTP session(s) on a media
server. It has a single input and output for each media session
established by its SIP dialog. The output of a connection may feed
several different inputs such as both a conference mix and a
recording of that participants audio.
Joining two connections which are are not joined to anything else
simply creates a media stream from the outputs(s) of one connection
to the corresponding inputs(s) of the other connection. It is not
necessary to combine media from multiple sources in this case. There
are however several common scenarios where combining media from
several sources to create a single input to a connection is needed.
In the first case, a connection may be receiving media from one
source, for example a conference, and it is necessary to play an
announcement to the connection so that both the conference audio and
announcement can be heard by the conference participant. This is
sometimes referred to as a whisper announcement. An alternative to a
whisper announcement is to have the announcement pre-empt the
conference media.
Another common case is the call center coaching scenario where a
supervisor can listen to the conversation between an agent and a
customer, and provide hints to the agent, which are not heard by the
customer.
Both of these cases can be solved by having the controlling AS create
one or more conferences for audio mixing and to join and unjoin the
media streams as required. A better solution is to have the media
server automatically mix media streams that are requested to be
joined to a common input when only the simple summing of audio
signals as described above is required. This is the case for both
the use cases presented above.
Automatically mixing streams has several benefits. Conceptually, it
is straight forward and simple, requiring no indirect requests on the
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part of the controlling AS. This increases transport efficiency and
reduces the coordination complexity and the latency of the overall
operation. Therefore, it is RECOMMENDED that a media server be able
to automatically mix at least two audio streams where only the simple
summing of signals is required.
When a media server receives a <join> request, it MUST automatically
mix all of the media streams included in the request with any streams
already joined to one of the entities identified in the request, or
it MUST fail the request and MUST NOT join any of the streams. A
controlling AS MUST use the <createconference> request for generic
conferences where the complex mixing algorithm is required.
Specifications which extend this package to handle additional media
types such as text or video, MUST define the semantics of the join
operation when multiple streams are requested to be joined to a
single input, such as that for a connection with a single RTP session
per media type.
5.2.2.2. <join>
The <join> element is sent to the MS to request creation one or more
media streams either between a connection and a conference, between
connections, or between conferences. The two entities to join are
specified by the attributes of <join>.
Streams may be of any media type, and may be bi-directional or uni-
directional. A bi-directional stream is implicitly composed of two
uni-directional streams that can be manipulated independently. The
streams to be established are specified by child <stream> elements
(see Section 5.2.2.5).
The <join> element has the following attributes:
id1: an identifier for either a connection or a conference. The
identifier MUST conform to the syntax defined in Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework] The attribute is
mandatory.
id2: an identifier for either a connection or a conference. The
identifier MUST conform to the syntax defined in Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework] The attribute is
mandatory.
Note: Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework]
defines the semantics for a conference identifier but not its syntax.
Media server implementations need to distinguish between conferences
and connections based upon the values of the "id1" and "id2"
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attributes.
The <join> element has the following child element (0 or more):
<stream>: an element that both identifies the media streams to join
and defines the way that they are to be joined (see
Section 5.2.2.5). The element is optional.
If no <stream> elements are specified, then the default is to join
all streams between the entities according to the media configuration
of the connection or conference.
One or more <stream> elements may be specified so that individual
media streams can be controlled independently. For example, if a
connection supports both audio and video streams, a <stream> element
could be used to indicate that only the audio stream is used in
receive mode. In cases where there are multiple media streams of the
same type for a connection or conference, it is RECOMMENDED that the
configuration is explicitly specified using <stream> elements.
It is an error if a <stream> element is in conflict with (a) another
<stream> element, (b) with specified connection or conference media
capabilities, (c) with a SDP label value as part of the connection-id
(see Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework]) or
(d) if the media stream configuration is not supported by the MS.
If the MS is unable to execute the join as specified in <stream>
elements, the MS MUST report an error (407) and MUST NOT join the
entities.
If the MS is unable to join an entity to a conference because it is
full, then the MS MUST report an error (410).
If the specified entities are already joined, then the MS MUST report
an error (408).
If the MS does not support joining two specified connections
together, the MS MUST report an error (426).
If the MS does not support joining two specified conferences
together, the MS MUST report an error (427).
If the MS is unable to join the specified entities for any other
reason, the MS MUST report an error (411).
When the MS has finished processing a <join> request, it MUST reply
with an <response> element (Section 5.2.3).
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For example, a request to join two connection together:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<join id1="connnection1" id2="connection2"/>
</mscmixer>
and the response if the MS doesn't support joining media streams
between connections:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<response status="426" reason="mixing connections not supported"/>
</mscmixer>
5.2.2.3. <modifyjoin>
The <modifyjoin> element is sent to the MS to request changes in the
configuration of media stream(s) that were previously established
between a connection and a conference, between two connections, or
between two conferences.
The <modifyjoin> element has the following attributes:
id1: an identifier for either a connection or a conference. The
identifier MUST conform to the syntax defined in Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework] The attribute is
mandatory.
id2: an identifier for either a connection or a conference. The
identifier MUST conform to the syntax defined in Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework] The attribute is
mandatory.
The <modifyjoin> element has the following child elements (1 or
more):
<stream>: an element that both identifies the media streams to
modify and defines the way that each stream should now be
configured (see Section 5.2.2.5).
The MS MUST support <modifyjoin> for any stream that was established
using <join>.
The media server MUST configure the streams that are included within
<modifyjoin> to that stated by the child elements. It MUST NOT
change the configuration of any streams not included as child
elements.
If the MS is unable to modify the join as specified in <stream>
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elements, the MS MUST report an error (407) and MUST NOT modify the
join between the entities.
If the specified entities are not already joined, then the MS MUST
report an error (408).
If the MS is unable to modify the join between the specified entities
for any other reason, the MS MUST report an error (411).
When an MS has finished processing a <modifyjoin> request, it MUST
reply with an appropriate <response> element (Section 5.2.3).
5.2.2.4. <unjoin>
The <unjoin> element is sent to the MS to request removal of
previously established media stream(s) from between a connection and
a conference, between two connections, or between two conferences.
The <unjoin> element has the following attributes:
id1: an identifier for either a connection or a conference. The
identifier MUST conform to the syntax defined in Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework] The attribute is
mandatory.
id2: an identifier for either a connection or a conference. The
identifier MUST conform to the syntax defined in Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework] The attribute is
mandatory.
The <unjoin> element has the following child element (0 or more
occurrences):
<stream>: an element that identifies the media stream(s) to remove
(see Section 5.2.2.5). The element is optional. When not
present, all currently established streams between "id1" and "id2"
are removed.
The MS MUST support <unjoin> for any stream that was established
using <join> and has not already been removed by a previous <unjoin>
on the same stream.
If the MS is unable to terminate any join as specified in <stream>
elements, the MS MUST report an error (407) and MUST NOT terminate
the join between the entities.
If the specified entities are not already joined, then the MS MUST
report an error (409).
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If the MS is unable to terminate the join between the specified
entities for any other reason, the MS MUST report an error (411).
When an MS has successfully processed a <unjoin> request, it MUST
reply with a successful <response> element (Section 5.2.3).
5.2.2.5. <stream>
<join>, <modifyjoin> and <unjoin> require the identification and
manipulations of media streams. Media streams represent the flow of
media between a participant connection and a conference, between two
connections, or between two conferences. The <stream> element is
used (as a child to <join>, <modifyjoin> and <unjoin) to identify the
media stream(s) for the request and to specify the configuration of
the media stream.
The <stream> element has the following attributes:
media: a string indicating the type of media associated with the
stream. It is strongly recommended that the following values are
used for common types of media: "audio" for audio media, and
"video" for video media. The attribute is mandatory.
label: a string indicating the SDP label associated with a media
stream ([RFC4574]). The attribute is optional.
direction: a string indicating the allowed media flow of the stream
relative to the value of the "id1" attribute of the parent
element. Defined values are: "sendrecv" (media can be sent and
received), "sendonly" (media can only be sent), "recvonly" (media
can only be received) and "inactive" (stream established but no
media flow). The default value is "sendrecv". The attribute is
optional.
The <stream> element has the following sequence of child elements:
<volume>: an element (Section 5.2.2.5.1) to configure the volume or
gain of the media stream. The element is optional.
<clamp>: an element (Section 5.2.2.5.2) to configure filtering and
removal of tones from the media stream. The element is optional.
<region>: an element (Section 5.2.2.5.3) to configure a region
within a video layout where the media stream is displayed. The
element is optional.
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<priority>: an element (Section 5.2.2.5.4) to configure priority
associated with the stream in the media mix. The element is
optional.
In each child element, the media stream affected is from the value of
the "id1" attribute of the parent element.
If the "media" attribute does not have the value of "audio", then the
MS MUST ignored <volume> and <clamp> elements.
If the "media" attribute does not have the value of "video", then the
MS MUST ignored <region> element.
5.2.2.5.1. <volume>
The <volume> element is used to configure the volume of an audio
media stream. It may be set to a specific gain amount, to
automatically adjust the gain to a desired target level, or to mute
the volume.
The <volume> element has no child elements but has the following
attributes:
controltype: a string indicating the type of volume control to use
for the stream. Defined values are: "automatic" (the volume will
be adjusted automatically to the level specified by the "value"
attribute), "setgain" (use the value of the "value" attribute as a
specific gain measured in dB to apply), "setstate" (set the state
of the stream to "mute" or "unmute" as specified by the value of
the "value" attribute). The attribute is mandatory.
value: a string specifying the amount or state for the volume
control defined by the value of the "controltype" attribute. The
attribute is optional. There is no default value.
5.2.2.5.2. <clamp>
The <clamp> element is used to configure whether tones should be
filtered and removed from a media stream.
The <clamp> element has no child elements but has the following
attributes:
tones: A space-separated list of the tones to remove. The attribute
is mandatory.
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5.2.2.5.3. <region>
The <region> element is used to explicitly specify the region within
a video layout where the media stream is displayed.
The <region> element has no attributes and its content model
specifies the name of the region layout.
5.2.2.5.4. <priority>
The <priority> element is used to explicitly specify the priority of
a participant. The MS uses this priority to determine where the
media stream is displayed within a video layout
(Section 5.2.1.4.3.1).
The <priority> element has no attributes and its content model
specifies a positive integer (see Section 5.7.3). The lower the
value, the higher the priority.
5.2.3. <response>
Responses to requests are indicated by a <response> element.
The <response> element has following attributes:
status: numeric code indicating the response status. Valid values
are defined in Section 5.6. The attribute is mandatory.
reason: string specifying a reason for the response status. The
attribute is optional.
conferenceid: string identifying the conference (see Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework]). The attribute is
optional.
connectionid: string identifying the SIP dialog connection (see
Section 17.1 of [I-D.ietf-mediactrl-sip-control-framework]). The
attribute is optional.
For example, a response when a conference was created successfully:
<response code="200">
<reason>Success</reason>
</response>
The response if conference creation failed due to the requested
conference id already existing:
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<response code="403">
<reason>Conf already exists</reason>
</response>
5.2.4. <event>
When a mixer generates a notification event, the MS sends the event
using an <event> element.
The <event> element has no attributes, but has the following sequence
of child elements (0 or more instances of each child):
<active-talkers-notify> specifies an active talkers notification
(Section 5.2.4.1).
<unjoin-notify> notifies that a connection or conference has been
completely unjoined (Section 5.2.4.2).
<conferenceexit> notifies that a conference has exited
(Section 5.2.4.3).
5.2.4.1. <active-talkers-notify>
The <active-talkers-notify> element describes zero or more speakers
that have been active in a conference during the specified interval
(see Section 5.2.1.4.4.1).
The <active-talkers-notify> element has the following attributes:
conferenceid: string indicating the name of the conference from
which the event originated. This attribute is mandatory.
The <active-talkers-notify> element has the following sequence of
child elements (0 or more occurrence's):
<active-talker> element describing an active talker
(Section 5.2.4.1.1).
5.2.4.1.1. <active-talker>
The <active-talker> element describes an active talker, associated
with either a connection or conference participant in a conference.
The <active-talker> element has the following attributes:
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connectionid: string indicating the connectionid of the active
talker. This attribute is optional. There is no default value.
conferenceid: string indicating the conferenceid of the active
talker. This attribute is optional. There is no default value.
It is an error (400) if both the connectionid and conferenceid
attributes are specified.
The <active-talker> element has no child elements.
5.2.4.2. <unjoin-notify>
The <unjoin-notify> element describes a notification event where a
connection and/or conference have been completely unjoined.
The <unjoin-notify> element has the following attributes:
status: a status code indicating why the unjoin occurred. A valid
value is a non-negative integer (see Section 5.7.2). A value of 1
indicates that the join has been terminated by a <unjoin> request.
A value of 2 indicates that the unjoin occurred because the a
connection or conference has terminated. A value of 3 indicates
the join terminated due to an internal error. Any other value
indicates an error defined by the MS. The attribute is mandatory.
reason: a textual description providing a reason for the status
code; e.g. details about an error. A valid value is a string (see
Section 5.7.4). The attribute is optional. There is no default
value.
id1: an identifier for either a connection or a conference. The
identifier MUST conform to the syntax defined in Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework] The attribute is
mandatory.
id2: an identifier for either a connection or a conference. The
identifier MUST conform to the syntax defined in Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework] The attribute is
mandatory.
The <unjoin-notify> element has no child elements.
5.2.4.3. <conferenceexit>
The <conferenceexit> element indicates that a conference has exited
because it has been terminated or because a error occurred (for
example, a hardware error in the conference mixing unit). This event
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MUST be sent by the MS whenever a successfully created conference
exits.
The <conferenceexit> element has the following attributes:
conferenceid: string indicating the name of the conference. This
attribute is mandatory.
status: a status code indicating why the conference exited. A valid
value is a non-negative integer (see Section 5.7.2). A value of 1
indicates that the conference has been terminated by a
<destroyconference> request. Any other value indicates an error
defined by the MS. The attribute is mandatory.
reason: a textual description providing a reason for the status
code; e.g. details about an error. A valid value is a string (see
Section 5.7.4). The attribute is optional. There is no default
value.
The <conferenceexit> element has no child elements.
When a MS sends a <conferenceexit> event, the identifier for the
conference (conferenceid attribute) is no longer valid on the MS and
can be reused for another conference.
For example, the following notification event would be sent from the
MS when the conference with identifier "conference99" exits due to a
successful <destroyconference/>:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<event>
<conferenceexit conferenceid="conference99"
status="1"/>
</event>
</mscmixer>
5.3. Audit Elements
The audit elements defined in this section allow the MS to be audited
for package capabilities as well as mixers managed by the package.
Auditing is particularly important for two use cases. First, it
enables discovery of package capabilities supported on an MS before
an AS creates a conference mixer or joins connections and
conferences. The AS may then use this information to create request
elements using supported capabilities and, in the case of codecs, to
negotiate an appropriate SDP for a user agent's connection. Second,
auditing enables discovery of the existence and status of mixers
currently managed by the package on the MS. This allows one AS to
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take over management of mixers when the AS which initiated the mixers
fails or is no longer available.
5.3.1. <audit>
The <audit> request element is sent to the MS to request information
about the capabilities of, and mixers currently managed with, this
control package. Capabilities include supported conference codecs
and video layouts. Mixer information includes the status of managed
mixers as well as codecs.
The <audit> element has the following attributes:
capabilities: indicates whether package capabilities are to be
audited. A valid value is a boolean (see Section 5.7.1). A value
of true indicates that capability information is to be reported.
A value of false indicates that capability information is not to
be reported. The attribute is optional. The default value is
true.
mixers: indicates whether mixers currently managed by the package
are to be audited. A valid value is a boolean (see
Section 5.7.1). A value of true indicates that mixer information
is to be reported. A value of false indicates that mixer
information is not to be reported. The attribute is optional.
The default value is true.
conferenceid: string identifying a specific conference mixer to
audit. It is an error (406) if the conferenceid attribute is
specified and the conference identifier is not valid. The
attribute is optional. There is no default value.
If the mixers attribute has the value true and conferenceid attribute
is specified, then only audit information about the specified
conference mixer is reported. If the mixers attribute has the value
false, then no mixer audit information is reported even if a
conferenceid attribute is specified.
The <audit> element has no child elements.
When the MS receives an <audit> request, it MUST reply with a
<auditresponse> element (Section 5.3.2) which includes a mandatory
attribute describing the status in terms of a numeric code. Response
status codes are defined in Section 5.6. If the request is
successful, the <auditresponse> contains (depending on attribute
values) a <capabilities> element (Section 5.3.2.1) reporting package
capabilities and a <mixers> element (Section 5.3.2.2) reporting
managed mixer information. If the MS is not able to process the
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request and carry out the audit operation, the audit request has
failed and the MS MUST indicate the class of failure using an
appropriate 4xx response code. Unless an error response code is
mandated for a specific class of error within this section,
implementations follow Section 5.6 in determining the appropriate
status code for the response.
For example, a request to audit capabilities and mixers managed by
the package:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<audit/>
</mscmixer>
In this example, only capabilities are to be audited:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<audit mixers="false"/>
</mscmixer>
With this example, only a specific conference mixer is to be audited:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<audit capabilities="false" conferenceid="conf4"/>
</mscmixer>
5.3.2. <auditresponse>
The <auditresponse> element describes a response to a <audit>
request.
The <auditresponse> element has the following attributes:
status: numeric code indicating the audit response status. The
attribute is mandatory. Valid values are defined in Section 5.6.
reason: string specifying a reason for the status. The attribute is
optional.
The <auditresponse> element has the following sequence of child
elements:
<capabilities> element (Section 5.3.2.1) describing capabilities of
the package. The element is optional.
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<mixers> element (Section 5.3.2.2) describing information about
managed mixers. The element is optional.
For example, a successful response to a <audit> request requesting
capabilities and mixer information:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<auditresponse status="200">
<capabilities>
<codecs>
<codec>
<subtype>H263</subtype>
</codec>
<codec>
<subtype>H264</subtype>
</codec>
<codec>
<subtype>PCMU</subtype>
</codec>
<codec>
<subtype>PCMA</subtype>
</codec>
</codecs>
</capabilities>
<mixers>
<conferenceaudit conferenceid="conf1">
<codecs>
<codec>
<subtype>PCMA</subtype>
</codec>
</codecs>
<participants>
<participant id="connection1"/>
</participants>
</conferenceaudit>
<joinaudit id1="connection1" id2="conf1"/>
<joinaudit id1="connection2" id2="connection3"/>
<joinaudit id1="connection4" id2="connection5"/>
</mixers>
</auditresponse>
</mscmixer>
5.3.2.1. <capabilities>
The <capabilities> element provides audit information about package
capabilities.
The <capabilities> element has no attributes.
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The <capabilities> element has the following sequence of child
elements:
<codecs>: element (Section 5.4) describing codecs available to the
package. The element is mandatory.
For example, a fragment describing capabilities:
<capabilities>
<codecs>
<codec>
<subtype>H263</subtype>
</codec>
<codec>
<subtype>H264</subtype>
</codec>
<codec>
<subtype>PCMU</subtype>
</codec>
<codec>
<subtype>PCMA</subtype>
</codec>
</codecs>
</capabilities>
5.3.2.2. <mixers>
The <mixers> element provides audit information about mixers.
The <mixers> element has no attributes.
The <mixers> element has the following sequence of child elements (0
or more occurrences, any order):
<conferenceaudit>: audit information for a conference mixer
(Section 5.3.2.2.1). The element is optional.
<joinaudit>: audit information for a join mixer (Section 5.3.2.2.2).
The element is optional.
5.3.2.2.1. <conferenceaudit>
The <conferenceaudit> element has the following attributes:
conferenceid: string identifying the conference (see Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework]). The attribute is
mandatory.
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The <conferenceaudit> element has the following sequence of child
elements:
<codecs> element describing codecs used in the conference. See
Section 5.4. The element is optional.
<participants> element listing connections or conferences joined to
the conference. See Section 5.3.2.2.1.1. The element is
optional.
<video-layout> element describing the active video layout for the
conference. See Section 5.2.1.4.2.1. The element is optional.
For example, a fragment describing a conference which has been
created but has no participants:
<conferenceaudit conferenceid="conference1"/>
And a fragment when the same conference has three participants (two
connections and another conference) joined to it:
<conferenceaudit conferenceid="conference1">
<codecs>
<codec>
<subtype>PCMU</subtype>
</codec>
</codecs>
<participants>
<participant id="connection1"/>
<participant id="connection2"/>
<participant id="conference2"/>
</participants>
</conferenceaudit>
5.3.2.2.1.1. <participants>
The <participants> element is a container for <participant> elements
(Section 5.3.2.2.1.1.1).
The <participants> element has no attributes, but the following child
elements are defined (0 or more):
<participant>: specifies a participant (Section 5.3.2.2.1.1.1).
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5.3.2.2.1.1.1. <participant>
The <participant> element describes a participant.
The <participant> element has the following attributes:
id: an identifier for either a connection or a conference. The
identifier MUST conform to the syntax defined in Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework]. The attribute is
mandatory.
The <participant> element has no children.
5.3.2.2.2. <joinaudit>
The <joinaudit> element has the following attributes:
id1: an identifier for either a connection or a conference. The
identifier MUST conform to the syntax defined in Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework] The attribute is
mandatory.
id2: an identifier for either a connection or a conference. The
identifier MUST conform to the syntax defined in Section 17.1 of
[I-D.ietf-mediactrl-sip-control-framework] The attribute is
mandatory.
The <joinaudit> element has no children.
For example, a fragment describing an audit of two join mixers, one
between connections and the second between conferences:
<mixers>
<joinaudit id1="connection1" id2="connection2"/>
<joinaudit id1="conference1" id2="conference2"/>
</mixers>
5.4. <codecs>
The <codecs> element is a container for one or more codec
definitions. Codec definitions are used by an AS to specify the
codecs allowed for a conference (e.g. when used as a child of
<createconference> or <modifyconference). Codec definitions are used
by an MS to provide audit information about the codecs supported by
an MS and used in specific conferences.
The <codecs> element has no attributes.
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The <codecs> element has the following sequence of child elements (0
or more occurrences):
<codec>: defines a codec and optionally its policy(Section 5.4.1).
The element is optional.
For example, a fragment describing two codecs:
<codecs>
<codec>
<subtype>PCMA</subtype>
</codec>
<codec>
<subtype>H263</subtype>
</codec>
</codecs>
5.4.1. <codec>
The <codec> element describes a codec. The element is modeled on the
<codec> element in the XCON conference information data model
([I-D.ietf-xcon-common-data-model]) and allows addition information
(e.g. rate, speed, etc) to be specified.
The <codecs> element has no attributes.
The <codecs> element has the following sequence of child elements:
<subtype>: element describing the codec's name. The possible values
of this element are the values of the 'subtype' column of the RTP
Payload Format media types per [RFC4855] defined in IANA ([IANA]).
The element is mandatory.
<params>: element (Section 5.5) describing additional information
about the codec. This package is agnostic to the names and values
of the codec parameters supported by an implementation. The
element is optional.
For example, a fragment with a <codec> element describing the H263
codec:
<codec>
<subtype>H263</subtype>
</codec>
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5.5. <params>
The <params> element is a container for <param> elements
(Section 5.5.1).
The <params> element has no attributes, but the following child
elements are defined (0 or more):
<param>: specifies a parameter name and value (Section 5.5.1).
5.5.1. <param>
The <param> element describes a parameter name and value.
The <param> element has the following attributes:
name: a string indicating the name of the parameter. The attribute
is mandatory.
type: specifies a type indicating how the inline value of the
parameter is to be interpreted. A valid value is a MIME media
type (see Section 5.7.6). The attribute is optional. The default
value is "text/plain".
The <param> element content model is the value of the parameter.
Note that a value which contains XML characters (e.g. "<") needs to
be escaped following standard XML conventions.
5.6. Response Status Codes
This section describes the response codes in Table 1 for the status
attribute of mixer management <response> (Section 5.2.3) and audit
<auditresponse> (Section 5.3.2) responses. The MS MUST support these
status response codes. The MS MAY support other response codes. The
AS MUST treat any responses it does not recognize as being equivalent
to the x00 response code for all classes. For example, if an AS
receives an unrecognized response code of 499, it can safely assume
that there was something wrong with its request and treat the
response as if it had received a 400 (Syntax error) response code.
4xx responses are definite failure responses from a particular MS.
The reason attribute in the response SHOULD identify the failure in
more detail, for example, "Mandatory attribute missing: id2 join
element" for a 400 (Syntax error) response code.
The AS SHOULD NOT retry the same request without modification (for
example, correcting a syntax error or changing the conferenceid to
use one available on the MS). However, the same request to a
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different MS might be successful; for example, if another MS supports
a capability required in the request.
4xx failure responses can be grouped into three classes: failure due
to a syntax error in the request (400); failure due to an error
executing the request on the MS (405-419); and failure due to the
request requiring a capability not supported by the MS (420-435).
In cases where more than one request code could be reported for a
failure, the MS SHOULD use the most specific error code of the
failure class for the detected error. For example, if the MS detects
that the conference identifier in the request is invalid, then it
uses a 406 status code. However, if the MS merely detects that an
execution error occurred, then 419 is used.
+-------+---------------+----------------------+--------------------+
| Code | Summary | Description | Informational: AS |
| | | | Possible Recovery |
| | | | Action |
+-------+---------------+----------------------+--------------------+
| 200 | OK | request has | |
| | | succeeded | |
| | | | |
| 400 | Syntax error | request is | Change the request |
| | | syntactically | so that it is |
| | | invalid: it is not | syntactically |
| | | valid with respect | valid. |
| | | to the XML schema | |
| | | specified in | |
| | | Section 6 or it | |
| | | violates a | |
| | | co-occurrence | |
| | | constraint for a | |
| | | request element | |
| | | defined in | |
| | | Section 5. | |
| | | | |
| 401 | Reserved for | | |
| | future use | | |
| | | | |
| 402 | Reserved for | | |
| | future use | | |
| | | | |
| 403 | Reserved for | | |
| | future use | | |
| | | | |
| 404 | Reserved for | | |
| | future use | | |
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| 405 | Conference | request uses an | Send an <audit> |
| | already | identifier to create | request |
| | exists | a new conference | (Section 5.3.1) |
| | | (Section 5.2.1.1) | requesting the |
| | | which is already | list of conference |
| | | used by another | mixer identifiers |
| | | conference on the | already used by |
| | | MS. | the MS and then |
| | | | use a conference |
| | | | identifier which |
| | | | is not listed. |
| | | | |
| 406 | Conference | request uses an | Send an <audit> |
| | does not | identifier for a | request |
| | exist | conference which | (Section 5.3.1) |
| | | does not exist on | requesting the |
| | | the MS. | list of conference |
| | | | mixer identifiers |
| | | | used by the MS and |
| | | | then use a |
| | | | conference |
| | | | identifier which |
| | | | is listed. |
| | | | |
| 407 | Incompatible | request specifies a | Change the media |
| | stream | media stream | stream |
| | configuration | configuration which | configuration to |
| | | is in conflict with | match the |
| | | itself, or the | capabilities of |
| | | connection or | the connection or |
| | | conference | conference |
| | | capabilities (see | |
| | | Section 5.2.2.2) | |
| | | | |
| 408 | joining | request attempts to | Send an <audit> |
| | entities | create a join mixer | request |
| | already | (Section 5.2.2.2) | (Section 5.3.1) |
| | joined | where the entities | requesting the |
| | | are already joined | list of join |
| | | | mixers on the MS |
| | | | and then use |
| | | | entities which are |
| | | | not listed. |
| | | | |
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| 409 | joining | request attempts to | Send an <audit> |
| | entities not | manipulate a join | request |
| | joined | mixer where entities | (Section 5.3.1) |
| | | which are not joined | requesting the |
| | | | list of join |
| | | | mixers on the MS |
| | | | and then use |
| | | | entities which are |
| | | | listed. |
| | | | |
| 410 | Unable to | request attempts to | |
| | join - | join a participant | |
| | conference | to a conference | |
| | full | (Section 5.2.2.2) | |
| | | but the conference | |
| | | is already full | |
| | | | |
| 411 | Unable to | request attempts to | |
| | perform join | create, modify or | |
| | mixer | delete a join | |
| | operation | between entities but | |
| | | fails | |
| | | | |
| 412 | Reserved for | | |
| | future use | | |
| | | | |
| 413 | Reserved for | | |
| | future use | | |
| | | | |
| 414 | Reserved for | | |
| | future use | | |
| | | | |
| 415 | Reserved for | | |
| | future use | | |
| | | | |
| 416 | Reserved for | | |
| | future use | | |
| | | | |
| 417 | Reserved for | | |
| | future use | | |
| | | | |
| 418 | Reserved for | | |
| | future use | | |
| | | | |
| 419 | Other | requested operation | |
| | execution | cannot be executed | |
| | error | by the MS. | |
| | | | |
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| 420 | Conference | request to create a | |
| | reservation | new conference | |
| | failed | (Section 5.2.1.1) | |
| | | failed due to | |
| | | unsupported | |
| | | reservation of | |
| | | talkers or | |
| | | listeners. | |
| | | | |
| 421 | Unable to | request to create or | |
| | configure | modify a conference | |
| | audio mix | failed due to | |
| | | unsupported audio | |
| | | mix. | |
| | | | |
| 422 | Unable to | request to create or | |
| | create | modify a conference | |
| | subscription | failed due to | |
| | | unsupported | |
| | | subscription. | |
| | | | |
| 423 | Unable to | request to create or | |
| | configure | modify a conference | |
| | video layouts | failed due to | |
| | | unsupported video | |
| | | layout | |
| | | configuration. | |
| | | | |
| 424 | Unable to | request to create or | |
| | configure | modify a conference | |
| | video switch | failed due to | |
| | | unsupported video | |
| | | switch | |
| | | configuration. | |
| | | | |
| 425 | Unable to | request to create or | |
| | configure | modify a conference | |
| | codecs | failed due to | |
| | | unsupported codec. | |
| | | | |
| 426 | Unable to | request to join | |
| | join - mixing | connection entities | |
| | connections | (Section 5.2.2.2) | |
| | not supported | failed due lack of | |
| | | support for mixing | |
| | | connections. | |
| | | | |
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| 427 | Unable to | request to join | |
| | join - mixing | conference entities | |
| | conferences | (Section 5.2.2.2) | |
| | not supported | failed due lack of | |
| | | support for mixing | |
| | | conferences. | |
| | | | |
| 428 | Unsupported | the request contains | |
| | foreign | attributes or | |
| | namespace | elements from | |
| | attribute or | another namespace | |
| | element | which the MS does | |
| | | not support | |
| | | | |
| 429 | Reserved for | | |
| | future use | | |
| | | | |
| 430 | Reserved for | | |
| | future use | | |
| | | | |
| 431 | Reserved for | | |
| | future use | | |
| | | | |
| 432 | Reserved for | | |
| | future use | | |
| | | | |
| 433 | Reserved for | | |
| | future use | | |
| | | | |
| 434 | Reserved for | | |
| | future use | | |
| | | | |
| 435 | Other | request requires | |
| | unsupported | another capability | |
| | capability | not supported by the | |
| | | MS | |
+-------+---------------+----------------------+--------------------+
Table 1: status codes
5.7. Type Definitions
This section defines types referenced in attribute definitions.
5.7.1. Boolean
The value space of boolean is the set {true, false}.
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5.7.2. Non-Negative Integer
The value space of non-negative integer is the infinite set
{0,1,2,...}.
5.7.3. Positive Integer
The value space of positive integer is the infinite set {1,2,...}.
5.7.4. String
A string in the character encoding associated with the XML element.
5.7.5. Time Designation
A time designation consists of a non-negative real number followed by
a time unit identifier.
The time unit identifiers are: "ms" (milliseconds) and "s" (seconds).
Examples include: "3s", "850ms", "0.7s", ".5s" and "+1.5s".
5.7.6. MIME Media Type
A string formated as a IANA MIME media type ([MIME.mediatypes]).
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6. Formal Syntax
This section defines the XML schema for the Mixer Control Package.
The schema defines datatypes, attributes, and mixer elements in the
urn:ietf:params:xml:ns:msc-mixer namespace. In most elements the
order of child elements is significant. The schema is extensible:
elements allow attributes and child elements from other namespaces.
Elements from outside this package's namespace can occur after
elements defined in this package.
The schema is dependent upon the schema (framework.xsd) defined in
Section 17.1 of the Control Framework
[I-D.ietf-mediactrl-sip-control-framework].
<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema targetNamespace="urn:ietf:params:xml:ns:msc-mixer"
xmlns:fw="urn:ietf:params:xml:ns:control:framework-attributes"
elementFormDefault="qualified"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns="urn:ietf:params:xml:ns:msc-mixer"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<xsd:annotation>
<xsd:documentation>
IETF MediaCtrl Mixer 1.0 (20081010)
This is the schema of the Mixer control package. It
defines request, response and notification elements for
mixing.
The schema namespace is urn:ietf:params:xml:ns:msc-mixer
</xsd:documentation>
</xsd:annotation>
<!--
#############################################################
SCHEMA IMPORTS
#############################################################
-->
<xsd:import
namespace="urn:ietf:params:xml:ns:control:framework-attributes"
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schemaLocation="framework.xsd">
<xsd:annotation>
<xsd:documentation>
This import brings in the framework attributes for
conferenceid and connectionid.
</xsd:documentation>
</xsd:annotation>
</xsd:import>
<!--
#####################################################
Extensible core type
#####################################################
-->
<xsd:complexType name="Tcore">
<xsd:annotation>
<xsd:documentation>
This type is extended by other component types to
allow elements and attributes from other namespaces
to be added.
</xsd:documentation>
</xsd:annotation>
<xsd:sequence>
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:anyAttribute namespace="##other" processContents="lax" />
</xsd:complexType>
<!--
#####################################################
TOP LEVEL ELEMENT: mscmixer
#####################################################
-->
<xsd:complexType name="mscmixerType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:choice>
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<xsd:element ref="createconference" />
<xsd:element ref="modifyconference" />
<xsd:element ref="destroyconference" />
<xsd:element ref="join" />
<xsd:element ref="unjoin" />
<xsd:element ref="modifyjoin" />
<xsd:element ref="response" />
<xsd:element ref="event" />
<xsd:element ref="audit" />
<xsd:element ref="auditresponse" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:choice>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="mscmixer" type="mscmixerType" />
<!--
#####################################################
CONFERENCE MANAGEMENT TYPES
#####################################################
-->
<!-- createconference -->
<xsd:complexType name="createconferenceType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="codecs" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="audio-mixing" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="video-layouts" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="video-switch" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="subscribe" minOccurs="0"
maxOccurs="1" />
<xsd:any namespace="##other"
processContents="lax" minOccurs="0" maxOccurs="unbounded" />
</xsd:sequence>
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<xsd:attribute name="conferenceid" type="xsd:string" />
<xsd:attribute name="reserved-talkers"
type="xsd:nonNegativeInteger" default="0" />
<xsd:attribute name="reserved-listeners"
type="xsd:nonNegativeInteger" default="0" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="createconference" type="createconferenceType" />
<!-- modifyconference -->
<xsd:complexType name="modifyconferenceType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="codecs" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="audio-mixing" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="video-layouts" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="video-switch" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="subscribe" />
<xsd:any namespace="##other"
processContents="lax" minOccurs="0" maxOccurs="unbounded" />
</xsd:sequence>
<xsd:attribute name="conferenceid" type="xsd:string"
use="required" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="modifyconference" type="modifyconferenceType" />
<!-- destroyconference -->
<xsd:complexType name="destroyconferenceType">
<xsd:attribute name="conferenceid" type="xsd:string"
use="required" />
</xsd:complexType>
<xsd:element name="destroyconference"
type="destroyconferenceType" />
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<!--
#####################################################
JOIN TYPES
#####################################################
-->
<xsd:complexType name="joinType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="stream" minOccurs="0"
maxOccurs="unbounded" />
<xsd:any namespace="##other"
processContents="lax" minOccurs="0" maxOccurs="unbounded" />
</xsd:sequence>
<xsd:attribute name="id1" type="xsd:string"
use="required" />
<xsd:attribute name="id2" type="xsd:string"
use="required" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="join" type="joinType" />
<xsd:complexType name="modifyjoinType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="stream" minOccurs="0"
maxOccurs="unbounded" />
<xsd:any namespace="##other"
processContents="lax" minOccurs="0" maxOccurs="unbounded" />
</xsd:sequence>
<xsd:attribute name="id1" type="xsd:string"
use="required" />
<xsd:attribute name="id2" type="xsd:string"
use="required" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="modifyjoin" type="modifyjoinType" />
<xsd:complexType name="unjoinType">
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<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="stream" minOccurs="0"
maxOccurs="unbounded" />
<xsd:any namespace="##other"
processContents="lax" minOccurs="0" maxOccurs="unbounded" />
</xsd:sequence>
<xsd:attribute name="id1" type="xsd:string"
use="required" />
<xsd:attribute name="id2" type="xsd:string"
use="required" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="unjoin" type="unjoinType" />
<!--
#####################################################
OTHER TYPES
#####################################################
-->
<xsd:complexType name="eventType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:choice>
<xsd:element ref="active-talkers-notify"
minOccurs="0" maxOccurs="1" />
<xsd:element ref="unjoin-notify"
minOccurs="0" maxOccurs="1" />
<xsd:element ref="conferenceexit"
minOccurs="0" maxOccurs="1" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:choice>
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="event" type="eventType" />
<xsd:complexType name="activetalkersnotifyType">
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<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="active-talker" minOccurs="0"
maxOccurs="unbounded" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:attribute name="conferenceid" type="xsd:string"
use="required" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="active-talkers-notify"
type="activetalkersnotifyType" />
<xsd:complexType name="activetalkerType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:attributeGroup ref="fw:framework-attributes" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="active-talker" type="activetalkerType" />
<xsd:complexType name="unjoinnotifyType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:attribute name="status" type="status.datatype"
use="required" />
<xsd:attribute name="reason" type="xsd:string" />
<xsd:attribute name="id1" type="xsd:string"
use="required" />
<xsd:attribute name="id2" type="xsd:string"
use="required" />
</xsd:extension>
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</xsd:complexContent>
</xsd:complexType>
<xsd:element name="unjoin-notify" type="unjoinnotifyType" />
<!-- conferenceexit-->
<xsd:complexType name="conferenceexitType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:attribute name="conferenceid" type="xsd:string"
use="required" />
<xsd:attribute name="status"
type="xsd:nonNegativeInteger" use="required" />
<xsd:attribute name="reason" type="xsd:string" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="conferenceexit" type="conferenceexitType" />
<xsd:complexType name="responseType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:attribute name="status" type="status.datatype"
use="required" />
<xsd:attribute name="reason" type="xsd:string" />
<xsd:attributeGroup ref="fw:framework-attributes" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="response" type="responseType" />
<xsd:complexType name="subscribeType">
<xsd:complexContent>
<xsd:extension base="Tcore">
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<xsd:sequence>
<xsd:element ref="active-talkers-sub"
minOccurs="0" maxOccurs="1" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="subscribe" type="subscribeType" />
<xsd:complexType name="activetalkerssubType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:attribute name="interval"
type="xsd:nonNegativeInteger" default="3" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="active-talkers-sub"
type="activetalkerssubType" />
<xsd:complexType name="streamType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="volume" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="clamp" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="region" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="priority" minOccurs="0"
maxOccurs="1" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:attribute name="media" type="media.datatype"
use="required" />
<xsd:attribute name="label" type="label.datatype" />
<xsd:attribute name="direction"
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type="direction.datatype" default="sendrecv" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="stream" type="streamType" />
<xsd:complexType name="volumeType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:attribute name="controltype"
type="volumecontroltype.datatype" use="required" />
<xsd:attribute name="value" type="xsd:string" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="volume" type="volumeType" />
<xsd:complexType name="clampType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:attribute name="tones" type="xsd:string"
use="required" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="clamp" type="clampType" />
<!-- region -->
<xsd:simpleType name="regionType">
<xsd:restriction base="xsd:NMTOKEN" />
</xsd:simpleType>
<xsd:element name="region" type="regionType" />
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<!-- priority -->
<xsd:simpleType name="priorityType">
<xsd:restriction base="xsd:positiveInteger" />
</xsd:simpleType>
<xsd:element name="priority" type="priorityType" />
<xsd:complexType name="audiomixingType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:attribute name="type" type="audiomix.datatype"
default="nbest" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="audio-mixing" type="audiomixingType" />
<!-- video-switch -->
<xsd:complexType name="videoswitchType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:attribute name="type"
type="videoswitchtype.datatype" default="vas" />
<xsd:attribute name="interval"
type="xsd:nonNegativeInteger" default="3" />
<xsd:attribute name="activespeakermix"
type="boolean.datatype" default="false" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="video-switch" type="videoswitchType" />
<!-- video-layouts -->
<xsd:complexType name="videolayoutsType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="video-layout" minOccurs="0"
maxOccurs="unbounded" />
<xsd:any namespace="##other" minOccurs="0"
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maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="video-layouts" type="videolayoutsType" />
<!-- video-layout -->
<!-- doesn't extend tCore since its content model is mixed -->
<xsd:complexType name="videolayoutType" mixed="true">
<xsd:sequence>
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:attribute name="min-participants"
type="xsd:positiveInteger" default="1" />
</xsd:complexType>
<xsd:element name="video-layout" type="videolayoutType" />
<xsd:complexType name="auditType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:attribute name="capabilities"
type="boolean.datatype" default="true" />
<xsd:attribute name="mixers" type="boolean.datatype"
default="true" />
<xsd:attribute name="conferenceid" type="xsd:string" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="audit" type="auditType" />
<xsd:complexType name="auditresponseType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="capabilities" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="mixers" minOccurs="0"
maxOccurs="1" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
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</xsd:sequence>
<xsd:attribute name="status" type="status.datatype"
use="required" />
<xsd:attribute name="reason" type="xsd:string" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="auditresponse" type="auditresponseType" />
<!-- mixers -->
<xsd:complexType name="mixersType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="conferenceaudit" minOccurs="0"
maxOccurs="unbounded" />
<xsd:element ref="joinaudit" minOccurs="0"
maxOccurs="unbounded" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="mixers" type="mixersType" />
<!-- joinaudit -->
<xsd:complexType name="joinauditType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:any namespace="##other"
processContents="lax" minOccurs="0" maxOccurs="unbounded" />
</xsd:sequence>
<xsd:attribute name="id1" type="xsd:string"
use="required" />
<xsd:attribute name="id2" type="xsd:string"
use="required" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="joinaudit" type="joinauditType" />
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<!-- conferenceaudit -->
<xsd:complexType name="conferenceauditType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="codecs" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="participants" minOccurs="0"
maxOccurs="1" />
<xsd:element ref="video-layout" minOccurs="0"
maxOccurs="1" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:attribute name="conferenceid" type="xsd:string"
use="required" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="conferenceaudit" type="conferenceauditType" />
<!-- participants -->
<xsd:complexType name="participantsType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="participant" minOccurs="0"
maxOccurs="unbounded" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="participants" type="participantsType" />
<!-- participant -->
<xsd:complexType name="participantType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:any namespace="##other" minOccurs="0"
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maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
<xsd:attribute name="id" type="xsd:string"
use="required" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="participant" type="participantType" />
<!-- capabilities -->
<xsd:complexType name="capabilitiesType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="codecs" minOccurs="1"
maxOccurs="1" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="capabilities" type="capabilitiesType" />
<!-- codecs -->
<xsd:complexType name="codecsType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="codec" minOccurs="0"
maxOccurs="unbounded" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="codecs" type="codecsType" />
<!-- codec -->
<xsd:complexType name="codecType">
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<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="subtype" minOccurs="1"
maxOccurs="1" />
<xsd:element ref="params" minOccurs="0"
maxOccurs="1" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="codec" type="codecType" />
<!-- subtype -->
<xsd:simpleType name="subtypeType">
<xsd:restriction base="xsd:string" />
</xsd:simpleType>
<xsd:element name="subtype" type="subtypeType" />
<!-- params -->
<xsd:complexType name="paramsType">
<xsd:complexContent>
<xsd:extension base="Tcore">
<xsd:sequence>
<xsd:element ref="param" minOccurs="0"
maxOccurs="unbounded" />
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
</xsd:sequence>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:element name="params" type="paramsType" />
<!-- param -->
<!-- doesn't extend tCore since its content model is mixed -->
<xsd:complexType name="paramType" mixed="true">
<xsd:sequence>
<xsd:any namespace="##other" minOccurs="0"
maxOccurs="unbounded" processContents="lax" />
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</xsd:sequence>
<xsd:attribute name="name" type="xsd:string" use="required" />
<xsd:attribute name="type" type="mime.datatype"
default="text/plain" />
<xsd:anyAttribute namespace="##other" processContents="lax" />
</xsd:complexType>
<xsd:element name="param" type="paramType" />
<!--
####################################################
DATATYPES
####################################################
-->
<xsd:simpleType name="eventname.datatype">
<xsd:restriction base="xsd:NMTOKEN">
<xsd:pattern value="[a-zA-Z0-9\.]+" />
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="audiomix.datatype">
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="nbest" />
<xsd:enumeration value="controller" />
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="media.datatype">
<xsd:restriction base="xsd:string" />
</xsd:simpleType>
<xsd:simpleType name="label.datatype">
<xsd:restriction base="xsd:string" />
</xsd:simpleType>
<xsd:simpleType name="status.datatype">
<xsd:restriction base="xsd:positiveInteger">
<xsd:pattern value="[0-9][0-9][0-9]" />
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="direction.datatype">
<xsd:restriction base="xsd:NMTOKEN">
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<xsd:enumeration value="sendonly" />
<xsd:enumeration value="recvonly" />
<xsd:enumeration value="sendrecv" />
<xsd:enumeration value="inactive" />
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="boolean.datatype">
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="true" />
<xsd:enumeration value="false" />
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="mime.datatype">
<xsd:restriction base="xsd:string" />
</xsd:simpleType>
<xsd:simpleType name="videoswitchtype.datatype">
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="vas" />
<xsd:enumeration value="controller" />
</xsd:restriction>
</xsd:simpleType>
<xsd:simpleType name="volumecontroltype.datatype">
<xsd:restriction base="xsd:NMTOKEN">
<xsd:enumeration value="automatic" />
<xsd:enumeration value="setgain" />
<xsd:enumeration value="setstate" />
</xsd:restriction>
</xsd:simpleType>
</xsd:schema>
Figure 10: Mixer Package XML Schema
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7. Examples
This section provides examples of the Mixer Control package.
7.1. AS-MS Framework Interaction Examples
The following example assume a control channel has been established
and synced as described in the Media Control Channel Framework
([I-D.ietf-mediactrl-sip-control-framework]).
The XML messages are in angled brackets (with the root <mscmixer> and
other details omitted for clarity); the REPORT status is in round
brackets. Other aspects of the protocol are omitted for readability.
7.1.1. Creating a conference mixer and joining a participant
A conference mixer is created successfully and a participant is
joined.
Application Server (AS) Media Server (MS)
| |
| (1) CONTROL: <createconference> |
| ----------------------------------------> |
| |
| (2) 202 |
| <--------------------------------------- |
| |
| |
| (3) REPORT: <response status="200"/> |
| (terminate) |
| <---------------------------------------- |
| |
| (4) 200 |
| ----------------------------------------> |
| |
| (5) CONTROL: <join id1=.. id2=..> |
| ----------------------------------------> |
| |
| (6) 202 |
| <--------------------------------------- |
| |
| (7) REPORT: <response status="200"/> |
| (terminate) |
| <---------------------------------------- |
| |
| (8) 200 |
| ----------------------------------------> |
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7.1.2. Receiving active talker notifications
An active talker notification event is sent by the MS.
Application Server (AS) Media Server (MS)
| |
| (1) CONTROL: <event ...> |
| <--------------------------------------- |
| |
| (4) 200 |
| ----------------------------------------> |
| |
7.1.3. Conference termination
The MS receives a request to terminate the conference, resulting in
conferenceexit and participant unjoined notifications.
Application Server (AS) Media Server (MS)
| |
| (1) CONTROL: <destroyconference> |
| ----------------------------------------> |
| |
| (2) 200: <response status="200"/> |
| <--------------------------------------- |
| |
| (3) CONTROL: <event ..> |
| (unjoin-notify) |
| <---------------------------------------- |
| |
| (4) 200 |
| ----------------------------------------> |
| |
| (5) CONTROL: <event ..> |
| (conferenceexit) |
| <---------------------------------------- |
| |
| (6) 200 |
| ----------------------------------------> |
7.2. Mixing Examples
The following examples show how the mixing package can be used to
create audio conferences, bridge connections and video conferences.
The examples do not specify all messages between the AS and MS.
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7.2.1. Audio conferencing
The AS sends a request to create a conference mixer:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<createconference conferenceid="conf1"
reserved-talkers="2" reserved-listeners="3">
<audio-mixing type="nbest"/>
<subscribe>
<active-talkers-sub interval="5"/>
</subscribe>
</createconference>
</mscmixer>
The request specifies that the conference is assigned the conference
id "conf1" and is configured with 2 reserved talkers, 3 reserved
listener slots, audio mixing policy set to nbest and with active
talkers notifications set to 5 seconds.
If the MS is able to create this conference mixer, it sends 200
response:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<response status="200" reason="conference created"
conferenceid="conf1"/>
</mscmixer>
The AS is now able to join connections to the conference as
participants. A participant able to contribute to the audio mix
would be joined as follows:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<join id1="1536067209~913cd14c" id2="conf1">
<stream media="audio" direction="sendrecv"/>
</join>
</mscmixer>
If the MS can join the participant 1536067209~913cd14c to the
conference conf1 with audio in both directions, then it sends a
successful response:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<response status="200" reason="join successful"/>
</mscmixer>
The AS could also join listener-only participants to the conference
by setting the stream direction to receive only:
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<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<join id1="9936067209~914cd14c" id2="conf1">
<stream media="audio" direction="recvonly"/>
</join>
</mscmixer>
If the MS can join the participant 9936067209~914cd14c to the
conference conf1 then it would send a successful response (not
shown).
As the active talker changes, the MS sends an active talker
notification to the AS:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<event>
<active-talker-notify conferenceid="conf1">
<active-talker connectionid="1536067209~913cd14c"/>
</active-talker-notify>
</event>
</mscmixer>
The AS could decide to change the status of a talker connection so
that they can only listen:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<modifyjoin id1="1536067209~913cd14c" id2="conf1">
<stream media="audio" direction="recvonly"/>
</modifyjoin>
</mscmixer>
Where the participant 1536067209~913cd14c is no longer able to
contribute to the audio mix on the conference. If the MS is able to
execute this request, it would send a 200 response.
The AS could decide to remove this participant from the conference:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<unjoin id1="1536067209~913cd14c" id2="conf1"/>
</mscmixer>
Again, if the MS can execute this request, a 200 response would be
sent.
Finally, the AS terminates the conference:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<destroyconference conferenceid="conf1"/>
</mscmixer>
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If the MS is able to destroy the conference conf1, it sends a 200
response:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<response status="200" conferenceid="conf1"/>
</mscmixer>
For each participant attached to the conference when it is destroyed,
the MS sends an unjoin notification event:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<event>
<unjoin-notify status="1" id1="9936067209~914cd14c"
id2="conf1"/>
</event>
</mscmixer>
And the MS sends a conferenceexit notification event when the
conference finally exits:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<event>
<conferenceexit status="1" conferenceid="conf1"/>
</event>
</mscmixer>
7.2.2. Bridging connections
The mixer package may be used to join connections to one another. In
a call center scenario, for example, this package can be used to set
up and modify connections between a caller, agent and supervisor.
A caller is joined to an agent with bi-directional audio:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<join id1="caller~001" id2="agent~002">
<stream media="audio" direction="sendrecv"/>
</join>
</mscmixer>
If the MS is able to establish this connection, then it would send a
200 response:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<response status="200"/>
</mscmixer>
Now assume that the AS wants a supervisor to listen into the agent
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conversation with the caller and provide whsipered guidance to the
agent. First the AS would send a request to join the supervisor and
the caller connections:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<join id1="supervisor~003" id2="caller~001">
<stream media="audio" direction="recvonly"/>
</join>
</mscmixer>
If this request was successful, audio output from the caller
connection would now be sent to both the agent and the supervisor.
Second, the AS would send a request to join the supervisor and the
agent connections:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<join id1="supervisor~001" id2="agent~002">
<stream media="audio" direction="sendrecv"/>
</join>
</mscmixer>
If this request was successful, the audio mixing would occur on both
the agent and supervisor connections: the agent would hear the caller
and supervisor, and the supervisor would hear the agent and caller.
The caller would only hear the agent. If the MS is unable to join
and mix connections in this way, it would send a 426 response.
7.2.3. Video conferencing
In this example, an audio video-conference is created with the
loudest participant has the most prominent region in the video
layout.
The AS sends a request to create an audio-video conference:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<createconference conferenceid="conf2">
<audio-mixing type="nbest"/>
<video-switch type="vas"/>
<video-layouts>
<video-layout min-participants="1">single-view</video-layout>
<video-layout min-participants="2">dual-view</video-layout>
<video-layout min-participants="3">quad-view</video-layout>
<video-layout min-participants="5">multiple-5x1</video-layout>
</video-layouts>
</createconference>
</mscmixer>
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In this configuration, the conference uses a nbest audio mixing
policy and a vas video switch policy, so that the loudest speaker
receives the most prominent region in the layout. Multiple video
layouts are specified and active one depends on the number of
participants.
Assume that 4 participants are already joined to the conference. In
that case, the video layout will be quad-view (Figure 6) with the
most active speaker displayed in region 1. When a fifth participant
joins, the video layout automatically switches to a multiple-5x1
layout (Figure 9), again with the most active speaker in region 1.
The AS can manipulate which participants are displayed in the
remaining regions. For example, it could force an existing
conference participant to be displayed in region 2:
<mscmixer version="1.0" xmlns="urn:ietf:params:xml:ns:msc-mixer">
<modifyjoin id1="1536067209~913cd14c" id2="conf2">
<stream media="video">
<region>2</region>
</stream>
</modifyjoin>
</mscmixer>
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8. Security Considerations
As this control package processes XML markup, implementations MUST
address the security considerations of [RFC3023].
As a Control Package of the Media Control Channel Framework,
security, confidentiality and integrity of messages transported over
the control channel MUST be addressed as described in Section 11 of
the Media Control channel Framework
([I-D.ietf-mediactrl-sip-control-framework]), including Session
Establishment, Transport Level Protection and Control Channel Policy
Management.
The Media Control Channel Framework permits additional policy
management, including resource access and control channel usage, to
be specified at the control package level beyond that specified for
the Media Control Channel Framework (see Section 11.3 of
[I-D.ietf-mediactrl-sip-control-framework]).
Since creation of conferences and other mixers is associated with
media mixing resources on the MS, policy management for this control
package MUST address how such mixers are managed across multiple
control channels. This includes which channels are used to deliver
mixer event notifications, and whether channels are permitted to
originate requests managing a mixer which was not created through
that channel (e.g. a conference mixer has been created via channel X
and a request to terminate the conference, or join a participant,
originates from channel Y).
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9. IANA Considerations
This specification instructs IANA to register a new Media Control
Channel Framework Package, a new XML namespace and a new MIME type.
9.1. Control Package Registration
Control Package name: msc-mixer/1.0
9.2. URN Sub-Namespace Registration
XML namspace: urn:ietf:params:xml:ns:msc-mixer
9.3. MIME Registration
Mime type: application/msc-mixer+xml
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10. Change Summary
Note to RFC Editor: Please remove this whole section.
The following are the major changes between the -02 and -01 versions.
o Section 4: Aligned Control Package definitions with requirements
in Section 8 of the Control Framework.
o Following October Interim meeting discussion on response codes,
generally clarified usage of error status codes, modified some
codes and re-organized the response codes section (Section 5.6)
with more guidance and details.
o MIXER-006. No action required following October 2008 interim
discussion.
o MIXER-008. No action required following October 2008 interim
discussion.
o MIXER-009. No action required for control package - addressed in
-05 framework draft following interim October 2008 discussion.
o MIXER-010/5.2.2.5: Clarified that in the <stream> element, an
"inactive" direction value indicates the stream is established but
there is no media flow. Such a stream can be manipulated by
<modifyjoin> and <unjoin>.
o 5.2.2.5: <stream>: Clarified that the media stream specified in
child elements <volume>, <clamp>, <region> and <priority> is the
stream originating from the entity identified as id1.
o 5.2.1.4.3: <video-switch>: Clarified that it is not an error if a
<stream> specifies a region which is not defined for the currently
active video layout.
o 5.2.1.4.2.1: <video-layout>: Added descriptions and ASCII art for
layout and regions of XCON video layouts.
o Added examples of audio conferencing, connection bridging and
video conferencing.
The following are the major changes between the -01 and -00 versions.
o [MIXER-001]/5.2.4.3: Added <conferenceexit> notification event.
o [MIXER-003]/5.2.1.4.2.1: Added ASCII diagrams for video layouts.
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o [MIXER-004]/5.3.2.2.1: Added active <video-layout> information to
<conferenceaudit>.
o [MIXER-007]/5.4.1: Added <params> inside <codec> so additional
codec information can be specified.
o 5.2.1.1: Fixed <createconference> example with missing min-
participants attributes.
o 5: Changed handling of unsupported foreign namespace elements and
attributes. The MS send a 427 error response if it encounters
foreign elements and attributes it does not support.
o 5.2.1.4.3: <video-switch>. Clarified that the VAS policy is
implementation-specific if a participant provides more than one
audio stream.
o 5.2.2.2/5.2.2.3/5.2.2.4: Clarified that joining behavior so that
streams which have previously been <modifiedjoin>ed or <unjoin>ed
are not affected by a general <unjoin>.
o 5.2.1.4.3: <video-switch>: Added support for whether active
speaker is displayed on their video layout ('activespeakermix'
attribute) and clarified that personal video mixes are out of
scope for this package.
o 5.2.1.4.3/5.2.2.5.4: <video-switch>: Added support for a priority
mechanism in video switching policy and a <priority child element
on <stream>.
o 8:Updated security section
o 13:Updated references
o 5.2.1.4.4.1: Added default of 3 seconds for <active-talkers-sub>
interval.
o 5.2.2.5.1: <volume> controltype attribute set to mandatory.
o Updated schema
The following are the major changes between the -00 of this work
group item draft and the individual submission -04 version.
o Control package name is now 'msc-mixer/1.0'. Namespace is now
'urn:ietf:params:xml:ns:msc-mixer'. Mime type is now
'application/msc-mixer+xml'.
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o Added XML root element <mscmixer>.
o Editorial tidy up of sections.
o Added audit request/response elements.
o Added video layout and switching conference configuration.
o <audio-mixing>: changed 'mix-type' attribute to 'type'
(consistency with video-switch)
o Added "inactive" as value of <stream>'s direction attribute.
o Added <region> child to <stream> element.
o <createconference>: <audio-mixing> element is no longer mandatory;
added <video-layouts> and <video-switch> child elements. reserved-
talkers and reserved-listeners as attributes.
o replaced conf-id attribute with conferenceid attribute.
o Removed <data> element. Active talkers subscription and
notifications used dedicated elements now.
o Added <unjoin-notify> notification event to indicate when
(un)expected joins occur. Use case: connection or conference
joined to a conference and conference exits (either by request or
runtime error.
The following are the major changes between the -04 of the draft and
the -03 version.
o Updated reference for Media Control Channel Framework
The following are the major changes between the -03 of the draft and
the -02 version.
o None
The following are the major changes between the -02 of the draft and
the -01 version.
o clarified the model for join operations and introduced several new
package error codes
o added definition for MS connection
The following are the major changes between the -01 of the draft and
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the -00 version.
o restructured into single request response model for non-trivial
operations
o aligned with XML structure of other control framework packages
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11. Contributors
Asher Shiratzky from Radvision provided valuable support and
contributions to early versions of this document.
The authors would like to thank the Mixer design team consisting of
Roni Even, Lorenzo Miniero, Adnan Saleem, Diego Besprosvan and Mary
Barnes who provided valuable feedback, input, diagrams and text to
this document.
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12. Acknowledgments
The authors would like to thank Roni Even, Lorenzo Miniero and Steve
Buko for expert reviews of this work.
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13. References
13.1. Normative References
[I-D.ietf-mediactrl-sip-control-framework]
Boulton, C., Melanchuk, T., and S. McGlashan, "Media
Control Channel Framework",
draft-ietf-mediactrl-sip-control-framework-06 (work in
progress), October 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3023] Murata, M., St. Laurent, S., and D. Kohn, "XML Media
Types", RFC 3023, January 2001.
[RFC4574] Levin, O. and G. Camarillo, "The Session Description
Protocol (SDP) Label Attribute", RFC 4574, August 2006.
[XML] Bray, T., Paoli, J., Sperberg-McQueen, C M., Maler, E.,
and F. Yergeau, "Extensible Markup Language (XML) 1.0
(Third Edition)", W3C Recommendation, February 2004.
13.2. Informative References
[I-D.ietf-xcon-common-data-model]
Novo, O., Camarillo, G., Morgan, D., Even, R., and J.
Urpalainen, "Conference Information Data Model for
Centralized Conferencing (XCON)",
draft-ietf-xcon-common-data-model-12 (work in progress),
October 2008.
[IANA] "IANA registry for RTP Payload Types",
<http://www.iana.org/assignments/rtp-parameters>.
[MIME.mediatypes]
"IANA registry for MIME Media Types",
<http://www.iana.org/assignments/media-types/>.
[MSML] Saleem, A., Xin, Y., and G. Sharratt, "Media Session
Markup Language (MSML)", draft-saleem-msml-07 (work in
progress), August 2008.
[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.
Melanchuk, et al. Expires May 7, 2009 [Page 86]
Internet-Draft Mixer Control Package November 2008
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC4855] Casner, S., "Media Type Registration of RTP Payload
Formats", RFC 4855, February 2007.
[RFC5022] Van Dyke, J., Burger, E., and A. Spitzer, "Media Server
Control Markup Language (MSCML) and Protocol", RFC 5022,
September 2007.
[RFC5167] Dolly, M. and R. Even, "Media Server Control Protocol
Requirements", RFC 5167, March 2008.
Melanchuk, et al. Expires May 7, 2009 [Page 87]
Internet-Draft Mixer Control Package November 2008
Authors' Addresses
Tim Melanchuk
Rain Willow Communications
Email: tim.melanchuk@gmail.com
Scott McGlashan
Hewlett-Packard
Gustav III:s boulevard 36
SE-16985 Stockholm, Sweden
Email: scott.mcglashan@hp.com
Chris Boulton
Avaya
Building 3
Wern Fawr Lane
St Mellons
Cardiff, South Wales CF3 5EA
Email: cboulton@avaya.com
Melanchuk, et al. Expires May 7, 2009 [Page 88]
Internet-Draft Mixer Control Package November 2008
Full Copyright Statement
Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
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Melanchuk, et al. Expires May 7, 2009 [Page 89]
