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Conference Information Data Model for Centralized Conferencing (XCON) :: RFC6501

Internet Engineering Task Force (IETF) O. Novo
Request for Comments: 6501 G. Camarillo
Category: Standards Track Ericsson
ISSN: 2070-1721 D. Morgan
Fidelity Investments
J. Urpalainen
Nokia
March 2012

Conference Information Data Model
for Centralized Conferencing (XCON)

Abstract

RFC 5239 defines centralized conferencing (XCON) as an association of
participants with a central focus. The state of a conference is
represented by a conference object. This document defines an XML-
based conference information data model to be used for conference
objects. A conference information data model is designed to convey
information about the conference and about participation in the
conference. The conference information data model defined in this
document constitutes an extension of the data format specified in the
Session Initiation Protocol (SIP) event package for conference State.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6501.

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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.

This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.

Table of Contents

1. Introduction ....................................................4
2. Terminology .....................................................4
3. Overview ........................................................4
3.1. Data Model Format ..........................................5
3.2. Data Model Namespace .......................................5
3.3. The Conference Object Identifier ...........................5
3.3.1. Conference Object URI Definition ....................7
3.3.2. Normalization and Conference Object URI Comparison ..7
3.4. Data Model Structure .......................................7
4. Data Model Definition ...........................................8
4.1. .........................................12
4.2. ..................................12
4.2.1. .........................................13
4.2.2. ...................................13
4.2.3. ...................................13
4.2.4. ...................................13
4.2.5. ..................................13
4.2.6. ........................................15
4.2.7. ..................................15

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4.3. ...............................................18
4.4. ........................................18
4.4.1. ..............18
4.5. .......................................18
4.5.1. ....................................19
4.5.2. ...............................19
4.5.3. ...........................19
4.5.4. ..........................20
4.6. ...................................................20
4.6.1. ....................................21
4.6.2. ............................21
4.6.3. ...............................22
4.6.4. ..................................23
4.6.5. and Its Sub-Elements .................24
4.6.5.1. .......................25
4.6.5.2. ...................................26
4.6.5.3. ...........26
4.6.5.4. ..........26
4.6.5.5. ..........26
4.6.5.6. ................................27
4.7. .........................................28
4.8. .........................................28
5. RELAX NG Schema ................................................28
6. XML Schema Extensibility .......................................39
7. XML Example ....................................................39
8. Security Considerations ........................................49
9. IANA Considerations ............................................51
9.1. RELAX NG Schema Registration ..............................51
9.2. XML Namespace Registration ................................52
9.3. Conference Object Identifier Registration .................52
9.4. Conference User Identifier Registration ...................53
10. Acknowledgements ..............................................53
11. References ....................................................53
11.1. Normative References .....................................53
11.2. Informative References ...................................54
Appendix A. Non-Normative RELAX NG Schema in XML Syntax ..........56
Appendix B. Non-Normative W3C XML Schema .........................84

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1. Introduction

There is a core data set of conference information that is utilized
in any conference, independent of the specific conference media.
This core data set, called the "conference information data model",
is defined in this document using an XML-based format. The
conference information data model defined in this document is
logically represented by the conference object.

Conference objects are a fundamental concept in centralized
conferencing, as described in the centralized conferencing framework
[RFC5239]. The conference object represents a particular
instantiation of a conference information data model. Consequently,
conference objects use the XML format defined in this document.

The Session Initiation Protocol (SIP) event package for conference
state, specified in [RFC4575], already defines a data format for
conferences. However, that model is SIP specific and lacks elements
related to some of the functionality defined by the centralized
conferencing framework [RFC5239] (e.g., floor control). The data
model defined in this document constitutes a superset of the data
format defined in [RFC4575]. The result is a data format that
supports more call signaling protocols (CSPs) besides SIP and that
covers all the functionality defined in the centralized conferencing
framework [RFC5239].

2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].

This document uses the terminology defined in the centralized
conferencing framework [RFC5239], the SIPPING conferencing framework
[RFC4353], and the BFCP (Binary Floor Control Protocol) specification
[RFC4582]. Readers of this document should be familiar with the
terminology used in those documents.

3. Overview

The data model specified in this document is the result of extending
the data format defined in [RFC4575] with new elements. Examples of
such extensions include scheduling elements, media control elements,
floor control elements, non-SIP URIs, and the addition of
localization extensions to text elements. This data model can be
used by conference servers providing different types of basic

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conferences. It is expected that this data model can be further
extended with new elements in the future in order to implement
additional advanced features.

3.1. Data Model Format

A conference object document is an XML [W3C.REC-xml-20081126]
document. Conference object documents MUST be based on XML 1.0 and
MUST be encoded using UTF-8.

The normative description of the syntax of the conference object
document, for use by implementers of parsers and generators, is found
in the RELAX NG schema provided in Section 5. Compliant messages
MUST meet the requirements of that schema.

3.2. Data Model Namespace

This specification defines a new namespace specification for
identifying the elements defined in the data model. This namespace
is as follows:

urn:ietf:params:xml:ns:xcon-conference-info

3.3. The Conference Object Identifier

The conference object identifier (XCON-URI) can be viewed as a key to
accessing a specific conference object. It can be used, for
instance, by the conference control protocol to access, manipulate
and delete a conference object. A conference object identifier is
provided to the conferencing client by the conference notification
service or through out-of-band mechanisms (e.g., email).

A conferencing system may maintain a relationship between the
conference object identifiers and the identifiers associated with
each of the complementary centralized conferencing protocols (e.g.,
call signaling protocol, BFCP, etc.). To facilitate the maintenance
of these relationships, the conference object identifier acts as a
top-level identifier within the conferencing system for the purpose
of identifying the interfaces for these other protocols. This
implicit binding provides a structured mapping of the various
protocols with the associated conference object identifier. Figure 1
illustrates the relationship between the identifiers used for the
protocols and the general conference object identifier (XCON-URI).

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+--------------------------+
| Conference |
| Object |
| Identifier |
+--------------------------+
| xcon:Ji092i@example.com |
+------+-------------------+
|
|
|
+-----------------+---------------+
| |
+-----------+-----------+ +----------+---------+
| CSP Conference IDs | |BFCP 'Conference ID'|
+-----------------------+ +--------------------+
| h323:i092@example.com | | i092 |
| tel:+44(0)2920930033 | +----------+---------+
| sip:i092@example.com | |
+-----------------------+ +-------+--------+
| BFCP 'Floor ID'|
+----------------+
| 543 |
| 236 |
+----------------+

Figure 1: Conference Object Mapping

In Figure 1, the conference object identifier acts as the top-level
key in the identification process. The call signaling protocols have
an associated conference user identifier, often represented in the
form of a URI. The BFCP, as defined in [RFC4582], defines the
'conference ID' identifier which represents a conference instance
within floor control. When created within the conferencing system,
the 'conference ID' has a 1:1 mapping to the unique conference object
identifier(XCON-URI). Operations associated with the conference
control protocols are directly associated with the conference object;
thus, the primary identifier associated with these protocols is the
conference object identifier(XCON-URI). The mappings between
additional protocols/interfaces is not strictly 1:1 and does allow
for multiple occurrences. For example, multiple call signaling
protocols will each have a representation that is implicitly linked
to the top-level conference object identifier, e.g., H323 and SIP
URIs that represent a conference instance. It should be noted that a
conferencing system is free to structure such relationships as
required, and this information is just included as a guideline that
can be used.

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Further elements can be added to the tree representation in Figure 1
to enable a complete representation of a conference instance within a
conferencing system.

3.3.1. Conference Object URI Definition

The syntax is defined by the following ABNF [RFC5234] rules.

XCON-URI = "xcon" ":" [conf-object-id "@"] host

conf-object-id = 1*( unreserved / "+" / "=" / "/" )

Note: host and unreserved are defined in RFC 3986 [RFC3986].

An XCON-URI is not designed to be resolved, and an application MUST
NOT attempt to perform a standard DNS lookup on the host portion of
such a URI in an attempt to discover an IP address or port at which
to connect.

3.3.2. Normalization and Conference Object URI Comparison

In order to facilitate the comparison of the XCON-URI identifiers,
all the components of the identifiers MUST be converted to lowercase.
After normalizing the URI strings, the URI comparison MUST be applied
on a character-by-character basis as prescribed by [RFC3986], Section
6.2.1.

The host construction, as defined in RFC 3986, can take the form of
an IP address, which is not conventionally compared on a character-
by-character basis. The host part of an XCON-URI serves only as an
identifier; that is, it is never used as an address. The character-
by-character comparison still applies.

3.4. Data Model Structure

The information in this data model is structured in the following
manner. All the information related to a conference is contained in
a element. The element contains
the following child elements:

o The element describes the conference as a
whole. It has, for instance, information about the URI of the
conference, maximum users allowed in the conference, media
available in the conference, or the time the conference will
start.

o The element contains information about the entity
hosting the conference (e.g., its URI).

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o The element informs the subscribers about the
changes in the overall conference information.

o The element contains information about the
status of the different floors in the conference.

o The element describes the membership information as a
whole. The element contains a set of child
elements, each describing a single participant in the conference.

o If a participant in the main conference joins a sidebar, a new
element is created in the conference referenced from the
element or under one of the
elements.

Note that some of the elements described above such as , , , or are not defined in the data model in this specification but are
defined in the data format of [RFC4575]. We describe them here
because they are part of the basic structure of the data model.

4. Data Model Definition

The following non-normative diagram shows the structure of conference
object documents. The symbol "!" preceding an element indicates that
the element is REQUIRED in the data model. The symbol "*" following
an element indicates that the element is introduced and defined in
this document. That is, elements without a "*" have already been
defined in [RFC4575].

!
|
|--
| |--*
| |--
| |--
| |--
| |--
| |--*
| |--*
| |--*
| |--*
| | |--*
| | | |--*
| | | |--*
| | | |--*
| | | |--*
| | | |--*

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| | | |--*
| | | |--*
| | | |--*
| | ...
| |--
| | |--
| | | |--
| | | |--
| | | |--
| | | |--*
| | ...
| |--
| | |--
| | | |--
| | | |--
| | | |--
| | ...
| |--
| | ...
| |--
| | |--
| | | |--
| | | |--
| | | |--
| | | |--*
| | | |--*
| | | | |--*
| | | | | |--*
| | | | |--*
| | | | | |--*
| | | | ...
| | | |--*
| | | | |--*
| | | | |--*
| | | | ...
| | |--
| | | |--
| | | |--
| | | |--
| | | |--*
| | | |--*
| | | | |--*
| | | | | |--*
| | | | |--*
| | | | | |--*
| | | | ...
| | | |--*
| | | | |--*

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| | | | |--*
| | | | ...
| | ...
|
|--
| |--
| |--
| |--
| | |--
| | | |--
| | | |--
| ...
|--
| |--*
| |--
| |--
| |--
|
|--*
| |--*
| |--*
| |--*
| |--*
| | |--*
| | | |--!*
| | | |--*
| | | |--*
| | | |--*
| | | ...
| | ...
|
|--
| |--*
| |--*
| |--*
| | |--*
| | |
| | |--*
| | | |--*
| | | | |-- *
| |
| |--*
| |
| |--
| | |--
| | |--
| | |--*
| | |--

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RFC 6501 Data Model Schema March 2012

| | | |
| | | ...
| | |--
| | |--
| | |--*
| | |--*
| | |--*
| | |--
| | | |--
| | | |--
| | | |--
| | | |--
| | | |--
| | | |--
| | | |--
| | | |--
| | | | |--
| | | | |--
| | | | |--
| | | | |--
| | | | |--
| | | | |--*
| | | | | |--*
| | | | | |--*
| | | | | | |--*
| | | | | | |--*
| | | | | | ...
| | | | |--*
| | | | | |--*
| | | | | |--*
| | | | | | |--*
| | | | | | ...
| | | | ...
| | | |--
| | | | |--
| | | | | |--
| | | | | |--
| | | | | |--
| | | | | |--
| ... ...
|--
| |--
| | |--
| | |--
| |--
| | |--
| | |--
| ...

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RFC 6501 Data Model Schema March 2012

|--
| |--
| | |
| | ...
| |--
| | |
| ... ...

The following sections describe these elements in detail. The full
RELAX NG schema is provided in Section 5.

4.1.

A conference object document begins with the root element
, which is defined in [RFC4575]. The 'state' and
'version' attributes of the element are defined in
[RFC4575] and are not used in the context of the XCON Conference
Information Model since they apply only to notification mechanisms.

In addition, [RFC4575] defines an 'entity' attribute that contains
the SIP URI identifier. This specification extends the meaning of
the 'entity' attribute to the conference object identifier (XCON-URI)
explained in Section 3.3.

This specification adds to the element the child
elements of the element.

4.2.

The element, which is defined in [RFC4575],
describes the conference as a whole. It SHOULD have an attribute
'lang' to specify the language used in the contents of this element.
It is comprised of , , , , , , , , , , , , and . The , ,
, , , and
elements are described in Section 5.3 of [RFC4575].

The following sections describe these elements in more detail. Other
child elements MAY be defined in the future to extend the
element.

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4.2.1.

The element indicates the predominant language that is
expected to be employed within a conference. This element contains
only one language. The possible values of this element are the
values of the 'Subtag' column of the "Language Subtag Registry" at
[IANA-Lan] originally defined in [RFC5646]. This element does not
enforce the language of the conference: it only informs the
participants about the desirable language that they should use in the
conference. Participants are free to switch to other languages if
they like.

4.2.2.

The element represents a boolean value. If set to
true or "1", the conference is allowed to create sidebar conferences.
If absent, or set to "false" or "0", the conference cannot create
sidebar conferences.

4.2.3.

When the is present, it indicates that the
conference object is a child of a parent conference. The element contains the conference object identifier (XCON-URI)
(different from the main XCON-URI) of the parent.

4.2.4.

When the is present, it indicates that the
conference object represents a sidebar of another conference. The
element contains the conference object identifier
(XCON-URI) (different from the main XCON-URI) of the parent.

4.2.5.

The element contains the information related to
time, policy, and duration of a conference. The
element contains one or more elements, each defining the time
and policy information specifying a single conference occurrence.
The element differs from the iCalendar objects
[RFC5545] in that it has the ability to define different policies
(, ) for the same
conference at different times.

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Every element contains the following child elements:

o : The child element specifies the iCalendar object of
the conference. The iCalendar object components are defined in
[RFC5545].

o : The child element
specifies when the conference media mixing starts before the
conference starts. The element specifies an
absolute value rather than an offset value. If the element is not present, it indicates that the conference
media mixing starts immediately. The MUST
include the 'required-participant' attribute. This attribute
contains one of the following values: "none", "administrator",
"moderator", "user", "observer", and "participant". The roles'
semantic definitions are out of the scope of this document and are
subject to future policy documents. More values can be specified
in the future. The 'required-participant' attribute allows a
privileged user to define when media mixing starts based on the
latter of the mixing start time and the time the first participant
arrives. If the value is set to "none", mixing starts according
to the mixing start time.

o : The child element
specifies the time conference media mixing stops after the
conference stops. If the element is not
present, it indicates that the conference occurrence is not
bounded. The element MUST include the
'required-participant' attribute. This attribute contains one of
the following values: "none", "administrator", "moderator",
"user", "observer", and "participant". More values can be
specified in the future. The 'required-participant' attribute
allows a privileged user to define when media mixing ends based on
the earlier of the and the time the last
participant leaves. If the value is set to "none", mixing stops
according to the . If the conference policy
was modified so that the last privileged user is now a normal
conference participant, and the conference requires a privileged
user to continue, that conference MUST terminate.

o : An administrator can indicate the time
when users can join a conference by populating the element.

o : An administrator can define the time
after which new users are not allowed to join the conference
anymore.

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o : This element defines the time when users or
resources on the are requested to join the
conference by using the element.

o : The element
defines in seconds when the system MUST send a notification that
the end of the conference is approaching. If the element is not present, this indicates that the system
does not notify the users when the end of the conference is
approaching.

o : The element indicates if the conference is allowed to be
extended. It has a boolean value.

4.2.6.

The contains a set of child elements -- each
containing a new element: . This element
contains the password(s) of the conference, for instance, Public
Switched Telephone Network (PSTN) conference will store the 'PIN
code' in this element. All the other child elements are
described in Section 5.3.1 of [RFC4575].

The RELAX NG schema in Section 5 allows to
appear anywhere uris-type is expanded. This document only provides
meaning for appearing as a descendant of the
element. Future standardization may give meaning to
appearing in other elements of type "uris-
type". In the absence of such standardization,
MUST NOT appear in elements of type "uris-type" other than .

4.2.7.

The element consists of a sequence of child
elements. Each element MAY contain the following child
elements:

o The , , and elements are described in
Section 5.3.4 of [RFC4575].

o The child element describes a default scheduling
policy by which the mixer will build the outgoing stream from the
incoming streams. Note that this policy is different than the
policy describing the floors for each media. The
child element MUST contain one and only one of the "moderator-
controlled", "FCFS", and "automatic" values, indicating the

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default algorithm to use with every media stream. The "moderator-
controlled" value indicates that the moderator of the conference
controls the media stream policy. The "FCFS" value indicates a
'first-come-first-served' policy. The "automatic" value means the
mixer must choose the best scheduling policy for the conference.

o The element specifies the allowed codecs in the
conference. It has an attribute 'decision' that specifies if the
focus decides the common codec automatically or needs the approval
of the moderator of the conference ("automatic", "moderator-
controlled"). The element contains elements. A
element can have the attribute 'name' and 'policy'. The
'name' attribute is a codec identifier assigned by the
conferencing server. The 'policy' attribute contains the policy
for that codec (allowed or disallowed). The element has
the child element , which stores the codec's name. The
possible values of this element are the values of the 'subtype'
column of the "RTP Payload Format media types" registry at [IANA]
originally defined in [RFC4855]. It is expected that future
conferencing specifications will define corresponding schema
extensions, as appropriate.

o The element contains the basic audio and video global
control elements for a conference. These controls are sufficient
for the majority of basic conferences. If the conference server
wants to support more-advanced controls, then it is RECOMMENDED
that an extension to the data model be used. In the
element, the schema is extensible; hence, new control types can be
added in the future. So, moderator controls that affect all media
output would go under the element. The
following child elements are defined for :

* The element is used in conjunction with an audio stream
to cease transmission of any audio from the associated stream.
That means that for the entire duration where mute is
applicable, all current and future participants of the
conference are muted and will not send any audio. It has a
boolean value. If this control is not specified, access to the
control is not available to the client.

* The element is used in conjunction with a video
stream to cease transmission of associated media. It has a
boolean value. If this control is not specified, the access to
the control is not available to the client.

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* The element is used in conjunction with a media output
stream to indicate the amount of amplification of an audio
stream. The value is an integer number that ranges from -127
to 127. If this control is not specified, access to the
control is not available to the client.

* The element is used in conjunction with a video
stream to specify how the video streams (of participants) are
viewed by each participant. Only one layout type can be
specified for each output stream. If there are fewer
participants than panels in the specified layout, then blanking
(black screen) MAY be mixed into the stream on the behalf of
the missing input streams. If unspecified, the
default type SHOULD be "single-view". The types
are as follows, although any number of custom layouts may be
specified in future extensions:

+ single-view: Only one stream is presented by the focus to
all participants in one panel.

+ dual-view: This dual-view option will present the video
side-by-side in two panels and not alter the aspect ratio of
the streams. This will require the focus to introduce
blanking on parts of the overall image as viewed by the
participants.

+ dual-view-crop: This side-by-side layout option instructs
the focus to alter the aspect ratio of the streams (alter-
aspect-ratio=true) so that blanking is not necessary. The
focus handles the cropping of the streams.

+ dual-view-2x1: This layout option instructs the focus to
place one stream above the other, in essence, with two rows
and one column. In this option, the aspect ratio is not
altered and blanking is introduced.

+ dual-view-2x1-crop: This layout option also instructs the
focus to place one stream above the other, in essence, with
two rows and one column. In this option, the aspect ratio
is altered and the video streams are cropped.

+ quad-view: Four equal-sized panels in a 2x2 layout are
presented by the focus to all participants. Typically, the
aspect ratio of the streams are maintained (alter-aspect-
ratio= FALSE).

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+ multiple-3x3: Nine equal-sized panels in a 3x3 layout are
presented by the focus to all participants. Typically, the
aspect ratio of the streams are preserved.

+ multiple-4x4: 16 equal-sized panels in a 4x4 layout are
presented by the focus to all participants. Typically, the
aspect ratio of the streams are preserved.

+ multiple-5x1: This option refers to a 5x1 layout where one
panel 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.

+ automatic: This option allows the focus to add panels as
streams are added.

4.3.

The element and its child elements are described in
[RFC4575], Section 5.4.

4.4.

The is introduced in [RFC4575]. The element contains the ,
, , and child elements. The , , and child elements are defined in
[RFC4575], Section 5.5.

4.4.1.

The element represents a
boolean action. If set to true, the focus is instructed to allow the
subscription to conference state events, such as 'SIP event package
for conference state' [RFC4575]. If set to FALSE, the subscription
to conference state events MUST be rejected. If this element is
undefined, it has a default value of true, causing the subscription
to conference state events to be accepted.

4.5.

The element contains the , , , and child elements. The absence of this element from an XML
document indicates that the conference does not have a floor.

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4.5.1.

The represents a conference instance within floor
control. When BFCP serves as the floor control protocol, the
is a 32-bit BFCP conference identifier defined in
[RFC4582], Section 5.1. Note that when created within the
conferencing system, there is a 1:1 mapping between this
and the unique conference object identifier (XCON-
URI).

4.5.2.

The element represents a boolean action. If set
to true, the focus is instructed to accept the subscription to floor
control events. If set to FALSE, the focus is instructed to reject
the subscription. If this element is undefined, it has a default
value of FALSE, causing the subscription to floor control events to
be rejected.

A conference participant can subscribe himself to a floor control
event in two different ways: one method is using an offer/answer
exchange mechanism ([RFC3264]) using SIP INVITE and BFCP parameters
in the SDP [RFC4583], the other method is a general authorization
mechanism described in Section 9 of [RFC4582] and in [RFC5018].
Future documentation may define additional connection mechanisms.

4.5.3.

The element defines the actions used by the
conference focus to control floor requests. This element defines the
action that the focus is to take when processing a particular request
to a floor within a conference. This element defines values of the
following:

o "block": This action instructs the focus to deny the floor
request. This action is the default action taken in the absence
of any other actions.

o "confirm": This action instructs the focus to allow the request.
The focus then uses the defined floor algorithm to further allow
or deny the floor. The algorithms used are outside the scope of
this document.

Note that this section discusses floor control information;
therefore, the value "block" in a element is
not related with the "block" value in the element
(see Section 4.6.1).

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4.5.4.

The element has one or more child
elements. Every child elements has an attribute 'id', which
uniquely identifies a floor within a conference. In the case of BFCP
[RFC4582], the 'id' attribute corresponds to the floor-id identifier
defined in [RFC4582], Section 5.2.2.

o : Every floor is identified for one or more mandatory
elements. If the information is
included in the conference document, the value of this element
MUST be equal to the "label" value of the corresponding media
stream in the container. The number of
those elements indicates how many floors the conference can have.
A floor can be used for one or more media types;

o : A floor can be controlled using many algorithms; the
mandatory element MUST be set to any of the
"moderator-controlled", "FCFS", or "random" values indicating the
algorithm. The "moderator-controlled" value indicates that the
moderator of the conference controls the floor. The "FCFS" value
indicates a 'first-come-first-served' policy.

o : The child element in the
element is OPTIONAL and, if present, dictates the maximum
number of users who can have the floor at one time.

o : The OPTIONAL indicates the "User
ID" of the moderator(s). It MUST be set if the element
is set to the "moderator-controlled" value. When the
floor is created within the conferencing system, the XCON-USERID
MAY be used as the . In the case where the BFCP is
the floor control protocol, the is defined in
[RFC4582], Section 3. Note that [RFC4582] refers to the moderator
role as a "floor chair".

4.6.

The element is described in [RFC4575] and contains the , , , and defined in this document and child elements
defined in [RFC4575]. When the element is used in the
context of the XCON Conference Information Model, the 'state' and
'version' attributes defined in [RFC4575] are not used, since they
apply only to notification mechanisms. The following sections
describe these elements in more detail. Other child elements and
attributes can be used to extend in the future.

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4.6.1.

The element defines the actions used by the
conference focus to control conference participation. This element
defines the action that the focus is to take when processing a
particular request to join a conference. This element defines values
of:

o "block": This action instructs the focus to deny access to the
conference. This action is the default action taken in the
absence of any other actions.

o "confirm": This action instructs the focus to place the
participant on a pending list (e.g., by parking the call on a
music-on-hold server), awaiting moderator input for further
actions.

o "allow": This action instructs the focus to accept the conference
join request and grant access to the conference within the
instructions specified in the transformations of this rule.

o "authenticate": This action instructs the focus that the user has
to provide a combination of username/password.

o "directed-operator": This action instructs the focus to direct the
user to an operator.

4.6.2.

The is an element that lets an organizer (or
a participant with appropriate rights) choose a policy for the
conference that controls how users are authenticated into the
conference, using a mechanism of the conference's choosing. Since a
variety of signaling protocols are possible, a variety of
authentication mechanisms -- determined by every individual
conference server -- may need to be mapped from the different
protocols. The specific types of authentication mechanisms are
beyond the scope of this document. The list of possible values are
as follows:

o "closedAuthenticated": A 'closedAuthenticated' policy MUST have
each conference participant in the allowed users list (listed
under the element) with each participant
being sufficiently (up to local policy) authenticated. Conference
join requests for users not in the allowed users list or
participants not authenticated should be rejected unless a action of 'confirm' is selected; in which case, the user
is placed on a pending list as indicated earlier. A

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'closedAuthenticated' policy MUST NOT include a .
If appears in the data model, it MUST be
ignored.

o "openAuthenticated": An 'openAuthenticated' policy requires each
conferencing participant to be sufficiently authenticated.
Typically, this implies that anyone capable of authenticating with
the conferencing system may join the conference. The
'openAuthenticated' policy permits the specification of "banned"
conferencing participants. Such banned users are prevented from
re-joining the conference until they have been un-banned. An
'openAuthenticated' policy SHOULD have a deny users list (listed
under the XML element) to support the banning of
conferencing participants from a conference. An
'openAuthenticated' policy MUST NOT include an . If appears in the data model, it MUST
be ignored.

o "anonymous": An 'anonymous' policy grants any join requests and is
the least restrictive policy. An 'anonymous' policy MUST NOT
include either an or a . If
any of these lists appear in the data model, they MUST be ignored.

In all other cases, the appearance of an and
MUST be ignored, except as otherwise described in a
future specification. Future specifications describing the use of
these lists must provide clear guidance on how to process the lists
when they occur concurrently, especially when both lists contain the
same user. For example, such a specification could disallow both
lists from appearing at the same time similar to values defined in this document.

4.6.3.

The child element contains a list of user URIs
(e.g., XCON-USERID, as defined in Section 4.6.5), roles (defined in
Section 4.6.5.2), or domains (e.g., *@example.com) that the focus
uses to determine who can join the conference, who can be invited to
join a conference, or who the focus needs to "refer to" the
conference. The element includes zero or more
child elements. This child element includes the mandatory
'uri' attribute and the mandatory 'method' attribute. The same 'uri'
attribute with different method values can appear in the list more
than once.

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The 'method' attribute is a list with the following values:

o "dial-in": The value "dial-in" is used by the focus to determine
who can join the conference.

o "dial-out": The value "dial-out" contains a list of resources with
which the focus will initiate a session.

o "refer": The value "refer" is used by the focus to determine the
resources that the focus needs to "refer to" the conference. In
SIP, this is achieved by the focus sending a REFER request to
those potential participants. In a different paradigm, this could
also mean that the focus sends an SMS or an email to the referred
user. This list can be updated during the conference lifetime so
it can be used for mid-conference refers as well.

The "refer" value differs from "dial-out" in that the resources on
the "refer" value are expected to initiate the session establishment
toward the focus themselves. It is also envisioned that different
users will have different access rights to those lists and therefore
a separation between the two is needed.

The element has a child
element as well. Some chat room systems allow -- and some require --
registration of detailed information about a user before they are
allowed to join a chat room. The child element
stores persistent information about users who are not actively part
of an ongoing chat room session. The element
stores the following information:

o user: The element stores the name, nickname, conference
user identifier (XCON-USERID), and email address of a user. It
has three attributes: 'name', 'nickname', and 'id' and an
element. Future extensions to this schema may define new elements
for the element.

Future extensions to this schema may define new elements for the
element.

4.6.4.

The child element contains a list of user URIs
(e.g., SIP URI, XCON-USERID defined in Section 4.6.5), roles (defined
in Section 4.6.5.2), or domains (e.g.: *@example.com) that the focus
uses to determine who has been 'banned' from the conference. Such
banned users are prevented from re-joining the chat room until the
ban has been lifted.

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4.6.5. and Its Sub-Elements

The element is described in [RFC4575] and describes a single
participant in the conference. The element has an attribute
'entity'. However, when the element is used in the context of
the XCON Conference Information Model, the 'state' and 'version'
attributes defined in [RFC4575] are not used, since they only apply
to notification mechanisms.

The attribute 'entity' contains a unique conference user identifier
(XCON-USERID) within the scope of the conference. The URI format of
this identifier is as follows (using ABNF [RFC5234]):

XCON-USERID = "xcon-userid" ":" conf-user-id

conf-user-id = 1*unreserved

Note: unreserved is defined in RFC 3986.

In order to facilitate the comparison of the XCON-USERID identifiers,
all the components of the identifiers MUST be converted to lowercase.

After normalizing the URI strings, the URIs comparison MUST be
applied codepoint-by-codepoint after conversion to a common character
encoding, as prescribed by [RFC3986], Section 6.2.1.

Other user identifiers can be associated with this conference user
identifier and enable the conferencing system to correlate and map
these multiple authenticated user identities to a single global user
identifier. Figure 2 illustrates an example using the conference
user identifier in association with the user identity defined for
BFCP, SIP, and H323 user identity. It should be noted that a
conferencing system is free to structure such relationships as
required, and this information is just included as a guideline.

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+----------------+
| Conference |
| User |
| Identifier |
+----------------+
|XCON-USERID:John|
+-------+--------+
|
|
|
+----------------------+-------------------------+
| | |
+-------+--------+ +-----------+-----------+ +-----------+-----------+
| BFCP User ID | | SIP User URI | | H323 User URI |
+----------------+ +-----------------------+ +-----------------------+
| 543 | |sip:851221@example.com | |h323:taeduk@example.com|
+----------------+ +-----------------------+ +-----------------------+

Figure 2: Conference User Mapping

The element element contains the , , , , , ,
, ,
, and . The following
sections describe these elements in more detail. The ,
, , and are defined in
[RFC4575], Section 5.6.

4.6.5.1.

The element specifies what level of anonymity the
server should provide to the user. In this case, the focus provides
the rest of the participants with an anonymous identity for that
user, for example, anonymousX, or it does not provide any information
for that user such that other users cannot see he is a participant in
the conference. This element only affects the way the user
information is provided to the other participants. The real user
information is stored in the data model but SHOULD NOT be provided to
the other participants of the conference. This can be achieved by
using the element. This element has three
values: "private", "semi-private", and "hidden". The "private" value
specifies that this user is completely anonymous in the conference.
The "semi-private" value specifies that this user is anonymous to all
users who have not been granted permission to see him. The "hidden"
value specifies that other users cannot see this participant in the
conference.

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4.6.5.2.

A provides the context for the set of conference operations
that a participant can perform. This element can contain one or more
of the following values: "administrator", "moderator", "user",
"participant", "observer", and "none". A role of "none" indicates
that any role is assigned. The semantic definition is out of
the scope of this document and is subject to future policy documents.
This element can be extended with new roles in future documents.

4.6.5.3.

The element represents a boolean
value. If set to true, a participant is allowed to instruct the
focus to refer a user to the conference without modifying the
(in SIP terms, a participant is allowed to send
a REFER request [RFC3515] to the focus, which results in the focus
sending a REFER request to the user the referrer wishes to join the
conference). If set to FALSE, the REFER request is rejected. If
this element is undefined, it has a value of FALSE, causing the REFER
request to be rejected.

4.6.5.4.

The element represents a boolean
action. If set to true, a participant is allowed to instruct the
focus to invite a user to the conference without modifying the
list (in SIP terms, a participant is allowed to
send a REFER request [RFC3515] to the focus, which results in the
focus sending an INVITE request to the user the referrer wishes to
join the conference). If set to FALSE, the REFER request is
rejected. If this element is undefined, it has a value of FALSE,
causing the REFER request to be rejected.

4.6.5.5.

The element represents a boolean
action. If set to true, a participant is allowed to instruct the
focus to remove a user from the conference without modifying the
ruleset (in SIP terms, a participant is allowed to send a REFER
request [RFC3515] to the focus, which results in the focus sending a
BYE request to the user the referrer wishes to leave the conference).
If set to FALSE, the REFER request is rejected. If this element is
undefined, it has a value of FALSE, causing the REFER request to be
rejected.

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4.6.5.6.

The child element is identical to the element with the
same name in [RFC4575] except that the 'state' attribute is not
included. When the element is used in the context of the
XCON Conference Information Model, the 'state' and 'version'
attributes defined in [RFC4575] are not used, since they apply only
to notification mechanisms. The element can provide the
desired level of detail about the user's devices and their signaling
sessions taking part in the conference.

The element has the following child elements: , , , , ,
, , , and . All the child elements are defined in [RFC4575]
with the exception of the element and the
element.

The / element has two other child elements defined
in this document: the and the :

o , : These are controls that apply to a
user's media stream being sent from the mixer to the participant's
endpoint or to the mixer from the participant's endpoint. The
element details properties associated with the incoming
streams to the mixer (streams sent to the mixer from the
participant). The element details properties
associated with the outgoing streams from the mixer (sent from the
mixer to the participant). Both of these elements have the
attribute 'name'. The 'name' attribute has the values "VideoIn",
"VideoOut", "AudioOut", and "AudioIn". The "VideoOut" and
"AudioOut" media streams detail properties associated with the
outgoing video and audio from the mixer. The "VideoIn" and
"AudioIn" media stream details properties associated with the
incoming video and audio to the mixer. Both of these elements can
have the child element defined:

* The element refers to the floor assigned to a certain
participant in the conference. If a participant, for instance,
needs to talk in the conference, it first needs to get the
floor from the chair of the conference. The element
has an attribute 'id', which uniquely identifies a floor within
a conference. The 'id' attribute corresponds to the floor-id
identifier defined in [RFC4582], Section 5.2.2. The
element has a boolean value. A value of FALSE indicates that
this user does not hold the floor in this moment. If this
control is not specified, this user SHOULD NOT specify the
floor option.

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The and elements can have the
child element:

* Controls that apply to a specific user would appear under the
element.

o More values can be defined in the future.

4.7.

The element contains a set of child
elements. This element is described in [RFC4575], Section 5.9.1.
When the element is used in the context of the XCON
conference information model, the 'state' and 'version' attributes
defined in [RFC4575] are not used, since they apply only to
notification mechanisms.

4.8.

The element contains a set of child
elements each containing information about a single sidebar. This
element is described in [RFC4575], Section 5.9.2. When the
element is used in the context of the XCON
conference information model, the 'state' and 'version' attributes
defined in [RFC4575] are not used, since they apply only to
notification mechanisms.

5. RELAX NG Schema

In accordance with the centralized conferencing framework document
[RFC5239], the conference object is a logical representation of a
conference instance. The conference information schema contains core
information that is utilized in any conference. It also contains the
variable information part of the conference object.

The normative schema is backwards compatible with [RFC5239], in other
words, valid [RFC5239] instance documents are also valid according to
this RELAX NG schema [RELAX]. In addition to approximately similar
RELAX NG [RELAX] definitions of [RFC5239], this schema contains
extension elements in the
"urn:ietf:params:xml:ns:xcon-conference-info" namespace.

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default namespace = "urn:ietf:params:xml:ns:conference-info"
namespace xcon = "urn:ietf:params:xml:ns:xcon-conference-info"

start = element conference-info { conference-type }
# CONFERENCE TYPE
conference-type =
attribute entity { text }
& anyAttribute
& conference-description-type?
& element host-info { host-type }?
& element conference-state { conference-state-type }?
& element users { users-type }?
& element sidebars-by-ref { uris-type }?
& element sidebars-by-val { sidebars-by-val-type }?
& element xcon:floor-information { floor-information-type }?
& anyElement*
# CONFERENCE DESCRIPTION TYPE
conference-description-type =
element conference-description {
attribute xml:lang { xsd:language }?
& anyAttribute
& element display-text { text }?
& element subject { text }?
& element free-text { text }?
& element keywords {
list { xsd:string* }
}?
& element conf-uris { uris-type }?
& element service-uris { uris-type }?
& element maximum-user-count { xsd:int }?
& element available-media { conference-media-type }?
& element xcon:language { xsd:language }?
& element xcon:allow-sidebars { xsd:boolean }?
& element xcon:cloning-parent { xsd:anyURI }?
& element xcon:sidebar-parent { xsd:anyURI }?
& element xcon:conference-time { conferencetime-type }?
& anyElement*
}
# HOST TYPE
host-type =
element display-text { text }?
& element web-page { xsd:anyURI }?
& element uris { uris-type }?
& anyElement*
& anyAttribute
# CONFERENCE STATE TYPE
conference-state-type =
anyAttribute

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& element user-count { xsd:unsignedInt }?
& element active { xsd:boolean }?
& element locked { xsd:boolean }?
& element xcon:allow-conference-event-subscription { xsd:boolean }?
& anyElement*
# CONFERENCE MEDIA TYPE
conference-media-type =
anyAttribute
& element entry { conference-medium-type }*
& anyElement*
# CONFERENCE MEDIUM TYPE
conference-medium-type =
attribute label { text }
& anyAttribute
& element display-text { text }?
& element type { text }?
& element status { media-status-type }?
& element xcon:mixing-mode { mixing-mode-type }?
& element xcon:codecs { codecs-type }?
& element xcon:controls { control-type }?
& anyElement*
# URIs TYPE
uris-type =
anyAttribute
& element entry { uri-type }*
& anyElement*
# URI TYPE
uri-type =
element uri { xsd:anyURI }
& element display-text { text }?
& element purpose { text }?
& element modified { execution-type }?
& element xcon:conference-password { text }*
& anyElement*
& anyAttribute
# USERS TYPE
users-type =
anyAttribute
& element user { user-type }*
& element xcon:join-handling { join-handling-type }?
& element xcon:user-admission-policy { user-admission-policy-type }?
& element xcon:allowed-users-list { allowed-users-list-type }?
& element xcon:deny-users-list { deny-user-list-type }?
& anyElement*
# USER TYPE
user-type =
attribute entity { xsd:anyURI }
& anyAttribute

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& element display-text { text }?
& element associated-aors { uris-type }?
& element roles {
element entry { single-role-type }+
}?
& element languages {
list { xsd:language }
}?
& element cascaded-focus { xsd:anyURI }?
& element endpoint { endpoint-type }*
& element xcon:provide-anonymity { provide-anonymity-type }?
& element xcon:allow-refer-users-dynamically { xsd:boolean }?
& element xcon:allow-invite-users-dynamically { xsd:boolean }?
& element xcon:allow-remove-users-dynamically { xsd:boolean }?
& anyElement*
# ENDPOINT TYPE
endpoint-type =
attribute entity { text }
& anyAttribute
& element display-text { text }?
& element referred { execution-type }?
& element status { endpoint-status-type }?
& element joining-method { joining-type }?
& element joining-info { execution-type }?
& element disconnection-method { disconnection-type }?
& element disconnection-info { execution-type }?
& element media { media-type }*
& element call-info { call-type }?
& anyElement*
# ENDPOINT STATUS TYPE
endpoint-status-type =
"pending"
| "dialing-out"
| "dialing-in"
| "alerting"
| "on-hold"
| "connected"
| "muted-via-focus"
| "disconnecting"
| "disconnected"
| free-text-extension
# JOINING TYPE
joining-type =
"dialed-in" | "dialed-out" | "focus-owner" | free-text-extension
# DISCONNECTION TYPE
disconnection-type =
"departed" | "booted" | "failed" | "busy" | free-text-extension
# EXECUTION TYPE

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execution-type =
element when { xsd:dateTime }?
& element reason { text }?
& element by { xsd:anyURI }?
& anyAttribute
# CALL TYPE
call-type =
element sip { sip-dialog-id-type }
& anyElement*
& anyAttribute
# SIP DIALOG ID TYPE
sip-dialog-id-type =
element display-text { text }?
& element call-id { text }
& element from-tag { text }
& element to-tag { text }
& anyElement*
& anyAttribute
# MEDIA TYPE
media-type =
attribute id { xsd:int }
& anyAttribute
& element display-text { text }?
& element type { text }?
& element label { text }?
& element src-id { text }?
& element status { media-status-type }?
& element xcon:to-mixer { mixer-type }?
& element xcon:from-mixer { mixer-type }?
& anyElement*
# MEDIA STATUS TYPE
media-status-type =
"recvonly"
| "sendonly"
| "sendrecv"
| "inactive"
| free-text-extension
# SIDEBARS-BY-VAL TYPE
sidebars-by-val-type =
anyAttribute
& element entry { conference-type }*
& anyElement*
# CONFERENCE TIME
conferencetime-type =
anyAttribute
& element xcon:entry {
element xcon:base { text },
element xcon:mixing-start-offset {

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time-type,
attribute required-participant { single-role-type },
anyAttribute
}?,
element xcon:mixing-end-offset {
time-type,
attribute required-participant { single-role-type },
anyAttribute
}?,
element xcon:can-join-after-offset { time-type }?,
element xcon:must-join-before-offset { time-type }?,
element xcon:request-user { time-type }?,
element xcon:notify-end-of-conference { xsd:nonNegativeInteger }?,
element xcon:allowed-extend-mixing-end-offset { xsd:boolean }?,
anyElement*
}*
# TIME TYPE
time-type = xsd:dateTime { pattern = ".+T.+Z.*" }
# SINGLE ROLE TYPE
single-role-type =
xsd:string "none"
| xsd:string "administrator"
| xsd:string "moderator"
| xsd:string "user"
| xsd:string "observer"
| xsd:string "participant"
| free-text-extension
# MIXING MODE TYPE
mixing-mode-type =
xsd:string "moderator-controlled"
| xsd:string "FCFS"
| xsd:string "automatic"
| free-text-extension
# CODECS TYPE
codecs-type =
attribute decision { decision-type }
& anyAttribute
& element xcon:codec { codec-type }*
& anyElement*
# CODEC TYPE
codec-type =
attribute name { text }
& attribute policy { policy-type }
& anyAttribute
& element xcon:subtype { text }?
& anyElement*
# DECISION TYPE
decision-type =

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xsd:string "automatic"
| xsd:string "moderator-controlled"
| free-text-extension
# POLICY TYPE
policy-type =
xsd:string "allowed" | xsd:string "disallowed" | free-text-extension
# CONTROL TYPE
control-type =
anyAttribute
& element xcon:mute { xsd:boolean }?
& element xcon:pause-video { xsd:boolean }?
& element xcon:gain { gain-type }?
& element xcon:video-layout { video-layout-type }?
& anyElement*
# GAIN TYPE
gain-type = xsd:int { minInclusive = "-127" maxInclusive = "127" }
# VIDEO LAYOUT TYPE
video-layout-type =
xsd:string "single-view"
| xsd:string "dual-view"
| xsd:string "dual-view-crop"
| xsd:string "dual-view-2x1"
| xsd:string "dual-view-2x1-crop"
| xsd:string "quad-view"
| xsd:string "multiple-3x3"
| xsd:string "multiple-4x4"
| xsd:string "multiple-5x1"
| xsd:string "automatic"
| free-text-extension
# FLOOR INFORMATION TYPE
floor-information-type =
anyAttribute
& element xcon:conference-ID { xsd:unsignedLong }?
& element xcon:allow-floor-events { xsd:boolean }?
& element xcon:floor-request-handling { floor-request-type }?
& element xcon:conference-floor-policy { conference-floor-policy }?
& anyElement*
# FLOOR REQUEST TYPE
floor-request-type =
xsd:string "block" | xsd:string "confirm" | free-text-extension
# CONFERENCE FLOOR POLICY
conference-floor-policy =
anyAttribute
& element xcon:floor {
attribute id { text }
& anyAttribute
& element xcon:media-label { xsd:nonNegativeInteger }+
& element xcon:algorithm { algorithm-type }?

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& element xcon:max-floor-users { xsd:nonNegativeInteger }?
& element xcon:moderator-id { xsd:nonNegativeInteger }?
& anyElement*
}+
# ALGORITHM POLICY
algorithm-type =
xsd:string "moderator-controlled"
| xsd:string "FCFS"
| xsd:string "random"
| free-text-extension
# USERS ADMISSION POLICY
user-admission-policy-type =
xsd:string "closedAuthenticated"
| xsd:string "openAuthenticated"
| xsd:string "anonymous"
| free-text-extension
# JOIN HANDLING TYPE
join-handling-type =
xsd:string "block"
| xsd:string "confirm"
| xsd:string "allow"
| xsd:string "authenticate"
| xsd:string "directed-operator"
| free-text-extension
# DENY USERLIST
deny-user-list-type =
anyAttribute
& element xcon:target {
attribute uri { xsd:anyURI },
anyAttribute
}*
& anyElement*
# ALLOWED USERS LIST TYPE
allowed-users-list-type =
anyAttribute
& element xcon:target { target-type }*
& element xcon:persistent-list { persistent-list-type }?
& anyElement*
# PERSISTENT LIST TYPE
persistent-list-type =
element xcon:user {
attribute name { text }
& attribute nickname { text }
& attribute id { text }
& anyAttribute
& element xcon:e-mail { text }*
& anyElement*
}*

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& anyElement*
# TARGET TYPE
target-type =
attribute uri { xsd:anyURI },
attribute method { method-type },
anyAttribute
# METHOD TYPE
method-type =
xsd:string "dial-in"
| xsd:string "dial-out"
| xsd:string "refer"
| free-text-extension
# ANONYMITY TYPE
provide-anonymity-type =
"private" | "semi-private" | "hidden" | free-text-extension
# MIXER TYPE
mixer-type =
attribute name { mixer-name-type }
& anyAttribute
& element xcon:controls { control-type }*
& element xcon:floor {
attribute id { text },
anyAttribute,
xsd:boolean
}*
& anyElement*
# MIXER NAME TYPE
mixer-name-type =
"VideoIn" | "VideoOut" | "AudioOut" | "AudioIn" | free-text-extension

# FREE TEXT EXTENSION
#

free-text-extension = text

# *********************************
# EXTENSIBILITY OF THE SCHEMA
# *********************************

# EXTENSIBILITY ELEMENTS
#

anyElement =
element * - (conference-description
| host-info
| conference-state
| users
| sidebars-by-ref

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| xcon:e-mail
| xcon:user) { anyExtension }
anyExtension =
(attribute * { text }
| any)*
any =
element * {
(attribute * { text }
| text
| any)*
}

# EXTENSIBILITY ATTRIBUTES
#

anyAttribute =
attribute * - (xml:lang
| entity
| required-participant
| label
| decision
| name
| policy
| uri
| method
| id
| nickname) { text }*

6. XML Schema Extensibility

The conference information data model defined in this document is
meant to be extensible. Extensions are accomplished by defining
elements or attributes qualified by namespaces other than
"urn:ietf:params:xml:ns:conference-info" and
"urn:ietf:params:xml:ns:xcon-conference-info" for use wherever the
schema allows such extensions (i.e., where the RELAX NG definition
specifies "anyAttribute" or "anyElement").

Elements or attributes from unknown namespaces MUST be ignored.

7. XML Example

The following is an example of a conference information document.
The conference starts on October 17, 2007, at 10:30 a.m. in New York
City and finishes the same day at 12:30 p.m. every week and repeats
every week. In this example, there are currently three participants
in the conference: one administrator, one moderator, and one
participant. Sidebars are allowed in this conference and,

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consequently, there is one sidebar in the conference. In addition,
Alice and Carol are using a floor in the main conference to manage
the audio and video resources. At the moment, Alice is assigned to
use the floor.

Discussion of Formula-1 racing
Sports:Formula-1
This is a conference example
Formula-1 cars

tel:+3585671234
Conference Bridge
participation
5678

http://www.example.com/live.ram
streaming

mailto:bob@example.com
email

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main audio
audio
sendrecv
automatic

PCMU

true
50

main video
video
sendrecv
automatic

H.263

single-view

En-us

true

BEGIN:VCALENDAR
PRODID:-//LlamaSpinner Inc.//NONSGML CamelCall//EN
VERSION:2.0

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BEGIN:VEVENT
DTSTAMP:20071003T140728Z
UID:20071003T140728Z-345FDA-carol@example.com
ORGANIZER:MAILTO:carol@example.com
DTSTART:20071017T143000Z
RRULE:FREQ=WEEKLY
DTEND:20071217T163000Z
END:VEVENT
END:VCALENDAR
2007-10-17T14:29:00Z
2007-10-17T16:31:00Z
2007-10-17T15:30:00Z

Formula1
http://www.example.com/formula1/

sip:alice@example.com

sip:carol@example.com

3
true

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false
true

Bob Hoskins

mailto:bob@example.com
email

participant

en-us

Bob's Laptop

2007-10-17T14:00:00Z
expert required
sip:alice@example.com

connected
dialed-out

2007-10-17T14:00:00Z
invitation
sip:alice@example.com

video
10235

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432424
sendrecv

single-view

full info
hsjh8980vhsb78
vav738dvbs
8954jgjg8432

semi-private
false
false
false

Alice Kay

mailto:alice@example.com
email

moderator

en-us

Alice's Desktop
connected
dialed-in

2007-10-17T13:35:08Z
invitation
sip:conference@example.com

video
10235
432424
sendrecv

single-view

audio
10234
532535
sendrecv

full info
truy45469123478

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asd456cbgt
3456jgjg1234

true

private
true
true
true

Carol More

mailto:carol@example.com
email

administrator

en-us

Carol's Computer
connected
dialed-in

2007-10-17T13:30:05Z
invitation
sip:conference@example.com

video
10235

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432424
sendrecv

single-view

audio
10234
532535
sendrecv

full info
wevb12562321894
asw456wedf
2365dfrt3497

false

private
true
true
true

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allow
openAuthenticated

xcon:conf223
private with Bob

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567
true
confirm

10234
10235
moderator-controlled
1
234

Note that due to RFC formatting conventions, this documents splits
lines whose content would exceed 72 characters.

8. Security Considerations

There are numerous security considerations for this document.
Overall, the security considerations for authentication and the
Security and Privacy of Identity described in Sections 11 and 11.2,
respectively, of the centralized conferencing framework document
[RFC5239] apply to this document.

This specification defines a data model for conference objects.
Different conferencing systems may use different protocols to provide
access to these conference objects. This section contains general
security considerations for the conference objects and for the
protocols. The specification of each particular protocol needs to
discuss how the specific protocol meets the security requirements
provided in this section.

A given conferencing system usually supports different protocols in
order to implement different functions (e.g., SIP for session control
and BFCP for floor control). Each of these protocols may use its own
authentication mechanism. In cases where a user is authenticated
using multiple authentication mechanisms, it is up to the
conferencing system to map all the different authentications to the
same user. Discussing the specifics of different authentication
mechanism is beyond the scope of this document.

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Furthermore, users may use different identifiers to access a
conference, as explained in Section 4.6.5. These different
namespaces can be associated with a unique conference user identifier
(XCON-USERID). A mapping database is used to map all these
authenticated user namespaces to the XCON-USERID. There are several
threats against this database. In order to minimize these threats,
the administrator of the conferencing system MUST ensure that only
authorized users can connect to this database (e.g., by using access
control rules). In particular, the integrity of the database MUST be
protected against unauthorized modifications. In addition, the XCON-
USERID or XCON-URI SHOULD be hard to guess. It is critical that the
URI remain difficult to "guess" via brute force methods. Generic
security considerations for usage of URIs are discussed in [RFC3986].

It is RECOMMENDED that the database uses encryption mechanisms if the
information is stored in long-term storage (e.g., disk). If the
database contains sensitive elements (e.g., passwords), the
confidentiality of the database MUST be protected from unauthorized
users. If no sensitive elements are present, then confidentiality is
not needed. In addition to implementing access control, as discussed
above, it is RECOMMENDED that administrators of conferencing systems
only provide access to the database over encrypted channels (e.g.,
using TLS encryption) in order to avoid eavesdroppers.
Administrators of conferencing systems SHOULD also avoid disclosing
information to unauthorized parties when a conference is being cloned
or when a sidebar is being created. For example, an external sidebar
as defined in [RFC5239], Section 9.4.2, may include participants who
were not authorized for the parent conference.

The security considerations for authentication described in Section
11.1 of the centralized conferencing framework document [RFC5239]
also apply to this document. Similarly, the security considerations
for authorization described in Section 5.2 of the Session Initiation
Protocol (SIP) REFER Method [RFC3515] apply to this document as well.

Note that the specification of the privacy policy is outside the
scope of this document. Saying that, a privacy policy will be needed
in the real implementation of the data model and, therefore, is
subject to future policy documents.

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9. IANA Considerations

9.1. RELAX NG Schema Registration

This specification registers a schema. The schema can be found
as the sole content of Section 5.

URI: urn:ietf:params:xml:schema:xcon-conference-info

Registrant Contact: IETF XCON working group ,
Oscar Novo

RELAX NG Schema: The RELAX NG schema to be registered is contained
in Section 5. Its first line is as follows:

default namespace = "urn:ietf:params:xml:ns:conference-info"

and its last line is as follows:

anyAttribute = attribute * - (xml:lang | entity
| required-participant | label | decision | name
| policy | uri | method | id | nickname) { text }*

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9.2. XML Namespace Registration

This section registers a new XML namespace.

URI: urn:ietf:params:xml:ns:xcon-conference-info

Registrant Contact: IETF XCON working group ,
Oscar Novo

XML:

BEGIN

Centralized Conferencing Namespace

Namespace for Centralized Conferencing
urn:ietf:params:xml:ns:xcon-conference-info
See
RFC 6501.

END

9.3. Conference Object Identifier Registration

URI scheme name: xcon
Status: permanent
URI scheme syntax: see Section 3.3.1.
URI schema semantics: see Section 3.3
Encoding considerations: see Section 8
Intended usage: see Section 3.3
Applications and/or protocols that use this URI scheme name:
Centralized Conferencing systems
Interoperability considerations: none
Security considerations: see Section 8
Relevant publications: conference information data model for
Centralized Conferencing (XCON)
Contact: Oscar Novo
Author/Change controller: Oscar Novo

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9.4. Conference User Identifier Registration

URI scheme name: XCON-USERID
Status: permanent
URI scheme syntax: see Section 4.6.5
URI schema semantics: see Section 4.6.5
Encoding considerations: see Section 8
Intended usage: see Section 4.6.3 and 4.6.5
Applications and/or protocols that use this URI scheme name:
Centralized Conferencing systems.
Interoperability considerations: none
Security considerations: see Section 8
Relevant publications: conference information data model for
Centralized Conferencing (XCON)
Contact: Oscar Novo
Author/Change controller: Oscar Novo

10. Acknowledgements

This document is really a distillation of many ideas discussed over a
long period of time. These ideas were contributed by many different
documents in the XCON working group and the SIPPING working group.
We would like to thank Orit Levin, Roni Even, Adam Roach, Mary
Barnes, Chris Boulton, Umesh Chandra, Hisham Khartabil, Petri
Koskelainen, Aki Niemi, Rohan Mahy, Jonathan Lennox, Sean Duddy,
Richard Barnes, and Henning Schulzrinne for their comments. Also, we
would like to thank Mary Barnes and Chris Boulton for letting us use
the conference and user identifier information of their XCON
documents. Last but not least, we would like to express our
gratitude to all those reviewers for their invaluable contributions:
Simon Pietro Romano, Lorenzo Miniero, Tobia Castaldi, Miguel Garcia,
Mary Barnes, Srivatsa Srinivasan, Avshalom Houri, Pierre Tane, and
Ben Campbell.

11. References

11.1. Normative References

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

[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.

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[RFC4575] Rosenberg, J., Schulzrinne, H., and O. Levin, "A Session
Initiation Protocol (SIP) Event Package for Conference
State", RFC 4575, August 2006.

[RFC4582] Camarillo, G., Ott, J., and K. Drage, "The Binary Floor
Control Protocol (BFCP)", RFC 4582, November 2006.

[RFC4583] Camarillo, G., "Session Description Protocol (SDP) Format
for Binary Floor Control Protocol (BFCP) Streams",
RFC 4583, November 2006.

[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.

[RFC5239] Barnes, M., Boulton, C., and O. Levin, "A Framework for
Centralized Conferencing", RFC 5239, June 2008.

[RFC5545] Desruisseaux, B., "Internet Calendaring and Scheduling
Core Object Specification (iCalendar)", RFC 5545,
September 2009.

11.2. Informative References

[IANA] IANA, "RTP Payload Types",
.

[IANA-Lan] IANA, "Language Subtag Registry",
.

[RELAX] "RELAX NG Home Page", ISO/IEC 19757-2:2008.

[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264,
June 2002.

[RFC3515] Sparks, R., "The Session Initiation Protocol (SIP) Refer
Method", RFC 3515, April 2003.

[RFC4353] Rosenberg, J., "A Framework for Conferencing with the
Session Initiation Protocol (SIP)", RFC 4353,
February 2006.

[RFC4855] Casner, S., "Media Type Registration of RTP Payload
Formats", RFC 4855, February 2007.

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[RFC5018] Camarillo, G., "Connection Establishment in the Binary
Floor Control Protocol (BFCP)", RFC 5018, September 2007.

[RFC5646] Phillips, A. and M. Davis, "Tags for Identifying
Languages", BCP 47, RFC 5646, September 2009.

[W3C.REC-xml-20081126]
Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and
F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
Edition)", World Wide Web Consortium Recommendation REC-
xml-20081126, November 2008,
.

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Appendix A. Non-Normative RELAX NG Schema in XML Syntax

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pending
dialing-out
dialing-in
alerting
on-hold
connected
muted-via-focus
disconnecting
disconnected

dialed-in
dialed-out
focus-owner

departed
booted
failed
busy

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recvonly
sendonly
sendrecv
inactive

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.+T.+Z.*

none
administrator
moderator
user
observer
participant

moderator-controlled
FCFS
automatic

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automatic
moderator-controlled

allowed
disallowed

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-127
127

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single-view
dual-view
dual-view-crop
dual-view-2x1
dual-view-2x1-crop
quad-view
multiple-3x3
multiple-4x4
multiple-5x1
automatic

block
confirm

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moderator-controlled
FCFS
random

closedAuthenticated
openAuthenticated
anonymous

block
confirm
allow
authenticate
directed-operator

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dial-in
dial-out
refer

private
semi-private
hidden

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VideoIn
VideoOut
AudioOut
AudioIn

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conference-description
host-info
conference-state
users
sidebars-by-ref
sidebars-by-val
display-text
subject
free-text
keywords
conf-uris
service-uris
maximum-user-count
available-media
web-page
uris
uri
user-count
active
locked
entry
type
status
purpose
modified
user
associated-aors
roles
languages
cascaded-focus
endpoint
referred
joining-method
joining-info
disconnection-method
disconnection-info

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media
call-info
when
reason
by
sip
call-id
from-tag
to-tag
label
src-id
xcon:conference-password
xcon:mixing-mode
xcon:codecs
xcon:controls
xcon:language
xcon:allow-sidebars
xcon:cloning-parent
xcon:sidebar-parent
xcon:allow-conference-event-subscription
xcon:to-mixer
xcon:provide-anonymity
xcon:allow-refer-users-dynamically
xcon:allow-invite-users-dynamically
xcon:allow-remove-users-dynamically
xcon:from-mixer
xcon:join-handling
xcon:user-admission-policy
xcon:allowed-users-list
xcon:deny-users-list
xcon:floor-information
xcon:conference-time
xcon:provide-anonymity
xcon:floor
xcon:entry
xcon:mixing-start-offset
xcon:mixing-end-offset
xcon:can-join-after-offset
xcon:must-join-before-offset
xcon:request-user
xcon:notify-end-of-conference
xcon:allowed-extend-mixing-end-offset
xcon:codec
xcon:subtype
xcon:mute
xcon:pause-video
xcon:gain
xcon:video-layout

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xcon:conference-ID
xcon:allow-floor-events
xcon:floor-request-handling
xcon:conference-floor-policy
xcon:media-label
xcon:algorithm
xcon:max-floor-users
xcon:moderator-id
xcon:target
xcon:persistent-list
xcon:e-mail
xcon:user

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lang

entity
required-participant
label
decision
name
policy
uri
method
id
nickname

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Appendix B. Non-Normative W3C XML Schema

The non-normative W3C XML schema defines extension elements in the
"urn:ietf:params:xml:ns:xcon-conference-info" namespace. Note that
extensions in this schema are stricter than in the normative
RELAX NG schema [RELAX], and the normative RELAX NG schema [RELAX]
allows unordered child elements unlike this schema (and the [RFC4575]
schema). Also, note that this schema allows otherwise valid
extension elements to appear in the non-allowed positions. Likewise,
the cardinalities of these extension elements cannot be constrained
with this schema.

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Authors' Addresses

Oscar Novo
Ericsson
Hirsalantie 11
Jorvas 02420
Finland

EMail: Oscar.Novo@ericsson.com

Gonzalo Camarillo
Ericsson
Hirsalantie 11
Jorvas 02420
Finland

EMail: Gonzalo.Camarillo@ericsson.com

David P. Morgan
Fidelity Investments
82 Devonshire St, MZ V3C
Boston, MA 02109-3614
USA

EMail: Dave.Morgan@fmr.com

Jari Urpalainen
Nokia
Itamerenkatu 11-13
Helsinki 00180
Finland

Phone: +358 7180 37686
EMail: jari.urpalainen@nokia.com

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RFC, FYI, BCP