Centralized Conferencing Manipulation Protocol (CCMP) Call Flow Examples
Nortel2201 Lakeside BlvdRichardsonTXmary.barnes@nortel.comNS-Technologieschris@ns-technologies.comMeetechoVia Carlo Poerio 89/a80121NapoliItalylorenzo@meetecho.comUniversity of NapoliVia Claudio 2180125NapoliItalyroberta.presta@unina.itUniversity of NapoliVia Claudio 2180125NapoliItalyspromano@unina.it
RAI
XCON Working GroupCCMPCentralized Conferencing Manipulation Protocol
This document provides detailed
call flows for the scenarios documented in the Centralized Conferencing
(XCON) Framework and the XCON Scenarios.
The call flows document the use of the interface
between a conference control client and a conference control server using the
Centralized Conferencing Manipulation Protocol (CCMP). The objective is to
provide a base reference for both
protocol researchers and developers.
This document provides detailed
call flows for the scenarios documented in the Framework for Centralized Conferencing
(XCON Framework) and the XCON Scenarios
. The XCON scenarios describe a broad range of use cases
taking advantage of the advanced conferencing capabilities provided by a system realization
of the XCON framework.
The call flows document the use of the interface
between a conference control client and a conference control server using the
Centralized Conferencing Manipulation Protocol (CCMP).
Due to the broad range of functionality provided by the XCON Framework and the flexibility of
the CCMP messaging, these call flows should not be considered inclusive of all the functionality
that can provided
by the XCON Framework and protocol implementations. These flows represent a sample to
provide an overview of the feature rich capabilities of the XCON framework and CCMP messaging for
protocol developers, software developers and researchers.
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT
RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as
described in BCP 14, RFC 2119 and
indicate requirement levels for compliant implementations. In this document,
these key words are used when describing normative functionality based on the
XCON Framework and CCMP.
Note that due to RFC formatting conventions, this document often splits
message details whose content would exceed 72 characters.
A backslash character marks where this line folding has taken place. This
backslash and its trailing CRLF and whitespace would not appear in the actual
protocol contents.
This document uses the same terminology as
found in the referenced documents, with the following
terms and abbreviations used in the call
flows. Also, note that the term "call flows" is used in a very generic
sense in this document since the media is not limited to voice. The calls supported by the
XCON framework and CCMP can consist
of media such as text, voice and video, including multiple media types in a single active conference.
As defined in the XCON Framework.
In the flows in this document, the CMCC is logically equivalent to
the use of UAC as the client notation in the media control call flows
.
As defined in the XCON Framework.
In this document, the conferencing server is used interchangeably with the term
Application Server (AS) as used in the
Media Control Architectural Framework .
However, these need not be the same entities in an
implementation.
As defined in the Media Control Architectural Framework .
This document provides a sampling of detailed call flows that can be implemented based on
a system realization of and implementation of .
This is intended to be a simple guide on the use of the conference control protocol between
the Conference Server and the Conference Control Client. The objective is to provide
an informational base reference
for protocol developers, software developers and researchers.
This document focuses on the
interaction between the Conference (and Media) Control Client and the Conferencing system, specifically
the Conference Server. The scenarios are based on those described in the XCON framework, many
of which are based on the advanced conferencing capabilities described in the XCON scenarios.
Additional scenarios
have been added to provide examples of other real life scenarios that are anticipated to be supported
by the framework. With the exception of an initial example with media control messaging, the examples
do not include the details for the media control ,
call signaling
or binary floor control protocols.
This document
references the scenarios in the Media Control call flows ,
SIP Call Control Conferencing
and binary floor control protocol documents.
This section provides the details associated with the various ways in which a conference can be created
using CCMP and the XCON framework constructs. As previously mentioned the details of the
media control, call signaling and floor control protocols, where
applicable, are annotated in the flows without showing all the details.
However, for clarification purposes, the first example provides the details of the
media control messaging along with an
example of the standard annotation used throughout the remainder of this document.
In subsequent flows, only this
annotation (identified by lower case letters) is included and the reader is encouraged to
refer to the call flows in the relevant documents for details for the other protocols.
The annotations for the
call signaling are on the left side of the conferencing server vertical bar and those for the media control
messaging are on the right side.
The simplest manner in which a conference can be created is accomplished by the client sending
a "confRequest" message with the "create" operation as the only parameter to the conference server,
together with the "confUserID" associated with the requesting client itself.
This results in the creation of a default conference, with an
XCON-URI in the form of the "confObjID" parameter, the XCON-UserID in the form of the
"confUserID" parameter (the same already present in the request) and
the data for the conference object in the "confInfo" parameter all returned in the
"confResponse" message. According to the implementation of the framework, this
example may also add the user that invoked the conference upon creation to the
conference object (e.g., "method" attribute in the "target" element of
"allowed-users-list" may be set to "dial out" for this
client based on the particular conferencing systems default). This is exactly
the case depicted in the figure, which is presented to enrich the scenario.
Note that, depending upon the conferencing system, this default conference could
be specific to the client requesting the conference and thus may be different
for the initiator than other participants (e.g., IVR interactions
in this case which are not shown).
The specific data for the conference object is returned in the
"confResponse" message in the "confInfo"
parameter. This allows the client (with the appropriate authorization)
to manipulate this
data and add additional participants to the conference,
as well as change the data during the conference.
In addition, the client may distribute the conferencing
information to other participants allowing them to join,
the details of which are provided in additional
flows.
Please notice that, according to CCMP specification,
the restitution of the new conference data in the "confInfo"
parameter is not mandatory: if the "confInfo" parameter of the successful
confResponse/create is void, a following confRequest/retrieve of the
returned "confObjID" can be triggered to provide the requesting client
with the detailed conference description.
Clients that are not XCON-aware
may join the conference using a specific signaling interface such as SIP ,
using the signaling
interface to the conference focus as described in . However, these
details are not shown in the message flows. The message flows in this document
identity the point in the message flows
at which this signaling occurs via the lower case letter items (i.e., (a)...(x)) along with the
appropriate text for the processing done by the conferencing server.
A conference can also be created by the client sending a "confRequest" message
with the "create" operation, along with the desired data in the form of the "confInfo" parameter
for the conference to be created. The request also
includes the "confUserID" of the requesting entity.
If the conferencing system can support that specific type
of conference (capabilities, etc.), then the request results in the creation of a
conference. In this success case, an
XCON-URI in the form of the "confObjID" parameter and the XCON-UserID in the form of the
"confUserID" parameter (again, the same as the requesting entity)
are returned in the "confResponse" message. In this example,
we choose not to return the created conference object in the successful
"confResponse" in the "confInfo" parameter.
This example also activates the conference upon creation (i.e., "method" attribute is set
to "dial out" for this client based on the particular conferencing systems default). Just as
before, this is not to be considered mandatory, since it depends on the implementation
choices of the framework.
Note that, depending upon the conferencing system, this default conference could
be specific to the client requesting the conference and thus may be different
for the initiator than other participants (e.g., IVR interactions
in this case which are not shown).
A client can also create another conference by cloning an existing conference, such as an active conference
or conference reservation. In this example, the client sends a "confRequest" message
with the "create" operation, along with the "confUserID" and a specific "confObjID", from which a new conference is to be
created by cloning an existing conference.
An example of how a client can create a conference based on a blueprint
is provided in . The manner by which a client in this example might learn
about a conference reservation or active conferences is similar to the first step in the blueprint example, with
the exception of specifying querying for different types of conference objects supported by the specific
conferencing system.
For example, in this example, the client clones a conference reservation (i.e., an inactive conference).
If the conferencing system can support a new instance of the specific type
of conference(capabilities, etc.), then the request results in the creation of a
conference, with an
XCON-URI in the form of a new value in the "confObjID" parameter to reflect the newly cloned conference object
returned in the "confResponse" message.
"Alice" sends a confRequest message to clone a conference based on an
existing conference reservation. "Alice" indicates this conference should be
cloned from the specified parent conference represented by the "confObjID" in the request.
Upon receipt of the confRequest message containing a
"create" operation and "confObjID", the
conferencing system ensures that the "confObjID" received is valid.
The
conferencing system determines the appropriate read/write access of
any users to be added to a conference based on this "confObjID" (using
membership, roles, etc.). The conferencing system uses the received
"confObjID" to clone a conference reservation. The conferencing system
also reserves or allocates a new "confObjID" (called "confObjID*" in
) to be used for the cloned conference object.
This new identifier is of course different from the one associated with the
conference to be cloned, since it represents a different conference object. Any
subsequent protocol requests from any of the members of the
conference must address this new identifier. The conferencing system maintains the mapping between this
conference ID and the parent conference object ID associated with the
reservation through the conference instance, and this mapping is explicitly
addressed through the "cloning-parent" element of the "conference-description"
in the new conference object.
provides an example of one client
"Alice" determining the conference blueprints available for a
particular conferencing system and creating a conference based on the
desired blueprint.
"Alice" first sends a "blueprintsRequest" message to the conferencing system identified by
the conference server discovery process. Upon receipt of the
"blueprintsRequest", the conferencing system would first authenticate "Alice"
and then
ensure that "Alice" has the appropriate authority based on system
policies to receive any blueprints supported by that system.
Any
blueprint that "Alice" is authorized to use are returned in a
"blueprintsResponse" message in the "blueprintsInfo" attribute.
Upon receipt of the "blueprintsResponse" containing
the blueprints, "Alice" determines which blueprint to use for the
conference to be created. "Alice" sends a "blueprintRequest" message to
get the specific blueprint as identified by the "confObjID".
The conferencing system returns the "confInfo" associated with the specific blueprint as
identified by the 'confObjID' in the "blueprintResponse" message.
"Alice" then sends a "confRequest" with a
"create" operation to the
conferencing system to create a conference reservation,
including the appropriate "blueprintName" and associated
"confObjID".
Upon receipt of the "confRequest" message with a "create" operation, the conferencing system uses the
received
blueprint to clone a conference, allocating a new "confObjID" (again called "confObjID* in the example).
The conferencing server then
sends a "confResponse" message including the new "confObjID*" associated with the newly created
conference instance.
Upon receipt of the "confResponse" message, "Alice" can now add other users to the conference .
The following scenarios are based on those documented in the XCON framework.
The examples assume that a conference has already been
correctly established, with media, if applicable, per one of the examples in
.
In this example, as
shown in "Alice" is joining "Bob"'s conference that requires that she
first enter a pass code. After successfully entering the passcode, an announcement prompts "Alice
to speak her name so it can be recorded. When "Alice" is added to the active conference, the
recording is played back to all the existing participants. A very similar example is presented in
Figure 33 of .
Upon receipt of the userRequest from
"Alice" to be added to "Bob's" conference (i.e., an "update" operation on "Bob's"
conference object), the conferencing system
determines that a password is required for this specific conference.
Thus an announcement asking "Alice" to enter the password is provided
to "Alice". This may be achieved by means of typical IVR fucntionality.
Once "Alice" enters the password, it is validated against
the policies associated with "Bob's" active conference. The
conferencing system then connects to a server which prompts and
records "Alice's" name. The conferencing system must also determine
whether "Alice" is already a user of this conferencing system or
whether she is a new user.
In this case, "Alice" is a new user for this conferencing system, so a conference
user identifier is created for "Alice". Based upon the addressing
information provided by "Alice", the call signaling to add "Alice" to
the conference is instigated through the Focus.
The conference server sends "Alice" a userResponse message which includes
the "confUserID" assigned by the
conferencing system for "Alice". This would allow "Alice" to later perform
operations on the conference (if she were to have the appropriate policies),
including registering for event notifications associated with the conference.
Once the call signaling indicates that "Alice" has been
successfully added to the specific conference, per updates to the
state, and depending upon the policies, other participants (e.g.,
"Bob") are notified of the addition of "Alice" to the conference via
the conference notification service and an announcement is provided to
all the participants indicating that "Alice" has joined the
conference.
The conferencing system also needs the capability to monitor for
DTMF from each individual participant. This would typically be used to
enter the identifier and/or access code for joining a specific
conference.
An example of DTMF monitoring, within the context of the framework
elements, is shown in . A typical
way for the conferencing system to be aware of all the DTMF interactions
within the context of conferences it is responsible for, is making
use of the MEDIACTRL architecture for what regards media manipulation.
Examples in that sense (specifically for what concerns DTMF interception
in conference instances) are presented in .
In this example, "Alice" wants to
add "Bob" to an established conference. In the following example we assume
"Bob" is a new user to the system, which means "Alice" also needs to provide
details about him. In fact, the case of "Bob" already present as a user
in the conferencing system is much easier to address, and will be
discussed later on.
"Alice" sends a userRequest message with an operation of "create" to
add "Bob" to the specific conference as identified by the
confObjID. The "create" operation also makes sure that "Bob" is created
as a user in the whole conferencing system. This is done by adding
a "userInfo" element describing "Bob" as a user. This is needed in
order to let the conferencing system be aware of "Bob"'s characteristics.
In case Bob was already a registered user, "Alice" would just have referenced him through his
XCON UserID, without providing the additional "userInfo". In fact, that information
(including, for instance, "Bob"'s SIP URI to be used subsequently for dial-out)
would be obtained by referencing the extant registration.
The conference server ensures that "Alice" has
the appropriate authority based on the policies associated with that
specific conference object to perform the operation.
As mentioned before, a new Conference User Identifier is created for Bob,
and the "userInfo" is used to update the conference object accordingly.
In the presented example, the call signaling to add
"Bob" to the conference is instigated through the Focus as well. Please
notice that this is implementation specific. In fact, a conferencing
system may accomplish different actions after the user creation, just
as it may do nothing at all. Among the possible actions,
for instance "Bob" may be added as a "target" element to the
"allowed-users-list" element, whose joining "method" may be either
"dial-in" or "dial-out". Besides, out-of-band notification mechanisms
may be involved as well, e.g. to notify "Bob" via mail of the new
conference, including details as the date, password, expected
participants and so on.
To conclude the overview on this scenario, once "Bob" has been successfully
added to the specified conference, per updates to the state, and
depending upon the policies, other participants (including "Bob" himself) may
be notified of the addition of "Bob" to the conference via the
Conference Notification Service.
This section provides an example of the muting of a party in an
active conference. The unmuting would involve the identical CCMP message
flow. Although, in the case that floor control is involved, whether or
not a particular conference client can unmute itself must be
considered by the conferencing system.
Please notice that interaction between CCMP and floor control should
be carefully considered. In fact, handling CCMP- and BFCP-based media
control has to be considered as multiple layers: i.e., a
participant may have the BFCP floor granted, but be muted by means of CCMP.
If so, he would still be muted in the conference, and would only be unmuted if
both the protocols allowed for this.
provides an example of one client
"Alice" impacting the media state of another client "Bob". This
example assumes an established conference. In this example, the
client, "Alice" whose Role is "moderator" of the conference, wants to
mute "Bob" on a medium-size multi-party conference, as his device is
not muted (and he's obviously not listening to the call) and
background noise in his office environment is disruptive to the
conference. BFCP floor control is assumed not to be involved.
Upon receipt of userRequest message with an update operation and
the userInfo with the "status" field in the "media" element for "Bob"
set to "revconly".
The Conference Server ensures that "Alice" has
the appropriate authority based on the policies associated with that
specific conference object to perform the operation and updates the userInfo in the
conference object reflect
that "Bob"s media is not to be mixed with the conference media.
In case the Conference Server relies on a remote Media Server for
its multimedia functionality, it subsequently changes "Bob"'s media
profile accordingly by means of the related protocol interaction
with the MS. An example describing a possible way of dealing with
such a situation using the Media Server Control architecture is
described in ,
at "Simple Bridging: Framework Transactions (2)".
A userResponse message with a responseCode of "success" is then sent to "Alice".
Depending upon the policies, tne conference server may notify
other participants (including "Bob")
of this update via the Conference Notification
Service.
provides an example of one
client "Alice" involved in active conference with "Bob" and "Carol".
"Alice" wants to create a sidebar to have a side discussion with
"Bob" while still viewing the video associated with the main
conference. Alternatively, the audio from the main conference could
be maintained at a reduced volume. "Alice" initiates the sidebar by
sending a request to the conferencing system to create a conference
reservation based upon the active conference object. "Alice" and
"Bob" would remain on the roster of the main conference, such that
other participants could be aware of their participation in the main
conference, while an internal-sidebar conference is occurring.
Besides, "Bob" decides that he is not interested in still
receiving the conference audio in background (not even at a lower
volume as "Alice" configured) and so modifies the sidebar in
order to make that stream inactive for him.
Upon receipt of CCMP sidebarByValRequest message to
"reserve" a new sidebar conference based upon the confObjID
received in the request, the conferencing system uses the confObjID
to clone a conference reservation for the sidebar.
The sidebar reservation is NOT independent
of the active conference (i.e., parent).
The conferencing system
also reserves or allocates a new confObjID to be used for any
subsequent protocol requests from any of the members of the
conference.
The relationship information is provided in the sidebarByValResponse
message, specifically in the "sidebar-parent" element. A dump of
the complete representation of the main/parent conference is
provided below as well to show how the cloning process for the creation
of the sidebar could take place.
Upon receipt of the sidebarByValResponse
message to
reserve the conference, "Alice" can now create an active conference
using that reservation, or create additional reservations based upon
the existing reservations. In this example, "Alice" wants only "Bob"
to be involved in the sidebar, thus she manipulates the membership
so that only the two of them appear in the "allowed-users-list" section.
"Alice" also wants both audio and the video from the original conference
to be available in the sidebar. For what concerns the media
belonging to the sidebar itself, "Alice" wants the audio to be
restricted to the participants in the sidebar (that is, her and "Bob").
Additionally, "Alice" manipulates the media values to recieve
the audio from the main conference at a reduced volume, so that
the communication between her and "Bob" isn't affected. "Alice"
sends a sidebarByValRequest message with an operation of "update" along
with the sidebarByValInfo
in the reservation, to create an active
conference.
Upon receipt of the sidebarByValRequest to update
the reservation to create an active conference for the sidebar,
as identified by the sidebar conference object ID, the conference server
ensures that "Alice" has the appropriate authority based on the
policies associated with that specific conference object to perform
the operation. The conference server must also validate the
updated information in the reservation, ensuring that a member like
"Bob" is already a user of this conference server. Once the data for the
confObjID is updated, the conference server sends a sidebarByValResponse to
"Alice".
Depending upon the policies, the initiator of the request (i.e.,
"Alice") and the participants in the sidebar (i.e., "Bob") may be
notified of his addition to the sidebar via the conference
notification service.
At this point, "Bob" sends a userRequest message to the conference server
with an operation of "update" to
completely disable the background audio from the parent conference,
since it prevents him from understanding what "Alice" says in the
sidebar.
Notice that "Bob's" request only changes the media perspective for
"Bob". "Alice" keeps on receiving both the audio from "Bob" and
the background from the parent conference. This request may be
relayed by the conference server to the Media Server handling
the mixing, if present. Upon completion of the change, the conference server
sends a "userResponse" message to "Bob".
Depending upon the policies, the initiator of the request (i.e.,
"Bob") and the participants in the sidebar (i.e., "Alice") may be
notified of this change via the conference
notification service.
That said, let's consider the following conference object:
This is the representation of the conference the sidebar is going to
be created in. As such, it will be used by the conferencing system
in order to create the new conference object associated with the sidebar.
In fact, the sidebar creation happens through a cloning of the parent conference.
Once the sidebar is created, an "update" makes sure that the sidebar
is customized as needed. The following protocol dump makes the process
clearer.
provides an example of
a different approach towards sidebar. In this scenario, one
client, "Alice", is involved in an active conference with "Bob", "Carol",
"David" and "Ethel". "Alice" gets an important text message via a
whisper from "Bob" that a critical customer needs to talk to
"Alice", "Bob" and "Ethel". "Alice" creates a sidebar to have a side
discussion with the customer "Fred" including the participants in
the current conference with the exception of "Carol" and "David",
who remain in the active conference. The difference from the previous
scenario is that "Fred" is not part of the parent conference: this means
that different policies might be involved, considering that "Fred"
may access information coming from the parent conference, in case the
sidebar was configured accordingly. For this reason, in this scenario
we assume that "Alice" disables all the media from the original (parent)
conference within the sidebar. This means that, while in the previous
example "Alice" and "Bob" still heard the audio from the main conference
in background, this time no background is made available. "Alice" initiates the sidebar
by sending a request to the conferencing system to create a
conference reservation based upon the active conference object.
"Alice", "Bob" and "Ethel" would remain on the roster of the main
conference in a hold state. Whether or not the hold state of these
participants is visible to other participants depends upon the
individual and local policy.
Upon receipt of the "sidebarByRefRequest" message to
create a new sidebar conference, based upon the active conference
specified by "confObjID" in the request, the conferencing system uses the received
active conference to clone a conference reservation for the sidebar.
The sidebar reservation is NOT independent
of the active conference (i.e., parent). The conferencing system
as before reserves or allocates a conference ID (confObjID*) to be used for any
subsequent protocol requests from any of the members of the
conference. The conferencing system maintains the mapping between
this conference ID and the conference object ID associated with the
sidebar reservation through the conference instance. Just as before,
this mapping is mantained in "sidebar-parent".
Upon receipt of the "sidebarByRefResponse" message, which acknowledges the
successful creation of the sidebar object, "Alice" decides that only "Bob"
and "Ethel", along with the new participant "Fred" are to be involved in
the sidebar. Thus she manipulates the membership accordingly. "Alice" also sets the
media in the "conference-info" such that the participants in the sidebar don't receive any
media from the main conference. All these settings are provided to the conferencing
system by means of a new "sidebarByRefRequest" message, with an "update"
operation.
"Alice" sends the aforementioned "sidebarByRefRequest" to update the information in the reservation and to
create an active conference.
Upon receipt of the "sidebarByRefRequest" with an operation of "update",
the conferencing system
ensures that "Alice" has the appropriate authority based on the
policies associated with that specific conference object to perform
the operation. The conferencing system also validates the
updated information in the reservation. Since "Fred" is a new user for this
conferencing system, a conference user identifier is created for
"Fred". Specifically, "Fred" is added to the conference by only providing
his SIP URI. Based upon the addressing information provided for "Fred" by
"Alice", the call signaling to add "Fred" to the conference may be
instigated through the Focus (e.g. if "Fred" had a "dial-out" method set
as the target for him) at the actual activation of the sidebar.
The conference server sends a "sidebarByRefResponse" message and, depending upon the policies,
the initiator of the request (i.e.,
"Alice") and the participants in the sidebar (i.e., "Bob" and
"Ethel") may be notified of his addition to the sidebar via the
conference notification service.
Floor control with sidebars can be used to realize conferencing
scenario such as an analyst briefing. In this scenario, the conference
call has a panel of speakers who are allowed to talk in the main
conference. The other participants are the analysts, who are not
allowed to speak unless they have the floor. To request access to the
floor, they have to join a new sidebar with the moderator and ask
their question. The moderator can also whisper to each analyst what
their status/position in the floor control queue, similar to the
example in . It should be noted that other
mechanisms which don't make use of sidebars could be used for floor control
such as those detailed in BFCP.
provides an example of the
configuration involved for this type of conference. As in the previous
sidebar examples, there is the main conference along with a sidebar.
"Alice" and "Bob" are the main participants in the conference, with
"A1", "A2" and "A3" representing the analysts. The sidebar remains
active throughout the conference, with the moderator, "Carol", serving
as the chair. As discussed previously, the sidebar conference is NOT
independent of the active conference (i.e., parent). The analysts are
provided the conference object ID associated with the active sidebar
when they join the main conference. The conferencing system also
allocates a conference ID to be used for any subsequent manipulations
of the sidebar conference. The conferencing system maintains the
mapping between this conference ID and the conference object ID
associated with the active sidebar conference through the conference
instance. The analysts are permanently muted while in the main
conference. The analysts are moved to the sidebar when they wish to
speak. Only one analyst is given the floor at a given time. All
participants in the main conference receive audio from the sidebar
conference, as well as audio provided by the panelists in the main
conference.
"A1" wishes to ask a question, so he sends a Floor Request
message to the floor control server.
Upon receipt of the request, the
floor control server notifies the moderator, "Carol" of the active
sidebar conference, whose serving as the floor chair.
Since no other analysts
have yet requested the floor, "Carol" indicates to the floor control
server that "A1" may be granted the floor.
The case of private messages can be handled as a sidebar with just
two participants, similarly to the example in section . Unlike the previous example, anyway, rather than using audio within the
sidebar, "Alice" could just add an additional text based media stream to
the sidebar in order to convey her whisper. From the protocol point of view, with reference to the
messages described in , only
the third CCMP message (a sidebarByValRequest/update) changes, as depicted
in .The other context, referred to as whisper, in this
document refers to situations involving one time media targetted to
specific user(s). An example of a whisper would be an announcement
injected only to the conference chair or to a new participant joining
a conference. Please notice that such an announcement would not be
conveyed by means of CCMP, while rather by means of a notification
protocol related to it, e.g. a SIP event package, XMPP, or even a
multimedia announcement. CCMP would only be involved with respect
to the creation of an ad-hoc sidebar, as it will be clearer in the
following lines.
provides an example of one user
"Alice" who's chairing a fixed length conference with "Bob" and
"Carol". The configuration is such that only the chair is providing a
warning when there is only 10 minutes left in the conference. At that
time, "Alice" is moved into a sidebar created by the conferencing
system and only "Alice" receives the announcement.
When the conferencing system determines that there is only 10
minutes left in the conference which "Alice" is chairing, the conferencing system directly
creates an active sidebar conference, based on the active conference
associated with "Alice". This sidebar
conference is NOT independent of the active conference (i.e., parent).
The conferencing system also allocates a conference ID to be used for
any subsequent manipulations of the sidebar conference.
Immediately upon creation of the active sidebar conference, the
announcement media is provided to "Alice". Depending upon the
policies, Alice may be notified of her addition to the sidebar via the
conference notification service. "Alice" continues to receive the
media from the main conference.
Upon completion of the announcement, "Alice" is removed from the
siebar and the sidebar conference is deleted.
"Alice" is notified of her removal from the sidebar via
the conference notification service.
An example of observing and coaching is shown in figure . In this example, call center agent "Bob" is
involved in a conference with customer "Carol". Since "Bob" is a new
agent and "Alice" sees that he has been on the call with "Carol" for
longer than normal, she decides to observe the call and coach "Bob" as
necessary.
Consider the following as the conference document associated with the video conference
involving Bob (the call agent) and Carol (the customer)
():
Upon receipt of the sidbarByRefRequest/create from
"Alice" to "create" a new sidebar conference from the confObjID
received in the request, the conferencing system uses the
received active conference to clone a conference reservation for the
sidebar. The conferencing system also allocates a
conference ID to be used for any subsequent protocol requests from any
of the members of the conference. The conferencing system maintains
the mapping between this conference ID and the confObjID
associated with the sidebar reservation through the conference
instance. The conference server sends a sidebarByRefResponse message with the
new confObjID and relevant confInfo.
Upon receipt of the confResponse message,
"Alice" manipulates the data received in the confInfo in the response.
"Alice" wants only "Bob" to be involved
in the sidebar, thus she updates the "allowed-users-list" to include
only "Bob". "Alice" also
wants the audio to be received by herself and "Bob" from the original
conference, but wants any outgoing audio from herself to be restricted
to the participants in the sidebar, whereas "Bob's" outgoing audio
should go to the main conference, so that both "Alice" and the
customer "Carol" hear the same audio from "Bob".
"Alice" sends a
sidebarByRefRequest message with an "update" operation including the updated conference
information.
Upon receipt of the sidbarByRefRequest message with an "update" operation,
the conferencing system
ensures that "Alice" has the appropriate authority based on the
policies associated with that specific conference object to perform
the operation.
After validating the data, the conference server sends a sidebarByRefResponse message.
Based upon the addressing information provided for
"Bob" by "Alice", the call signaling to add "Bob" to the sidebar with
the appropriate media characteristics is instigated through the
Focus.
"Bob" is notified of his addition to the sidebar via the conference
notification service, thus he is aware that "Alice" the supervisor is
available for coaching him through this call.
The following scenarios detail the basic operations associated with removing participants from conferences
and entirely deleting conferences. The examples assume that a conference has already been
correctly established, with media, if applicable, per one of the examples in
.
provides an example of one client
"Alice" removing another participant "Bob" from a conference. This example
assumes an established conference with "Alice", "Bob", "Claire" and "Duck".
In this example, "Alice" wants to
remove "Bob" from the conference so that the group can continue in the same conference without
"Bob"'s participation.
"Alice" sends a userRequest message, with a "delete" operation.
The conference server ensures that "Alice" has
the appropriate authority based on the policies associated with that
specific conference object to perform the operation.
Based upon the addressing and media
information in the conference object for "Bob" in the "user" element, the conference
instigates the process
to remove "Bob" (e.g., the call signaling to remove
"Bob" from the conference is instigated through the Focus).
The conference server updates the data in the conference object,
thus removing "Bob" from the "users" list.
After updating the data, the conference server sends a userResponse message
to "Alice". Depending upon the policies, other participants (e.g. "Claire") may
be notified of the removal of "Bob" from the conference via the
Conference Notification Service.
Details to be added.
(Text description to be added).
The following are additional scenarios making use of the XCON framework and
associated protocols. In some cases, these examples make use of some of the building
block scenarios detailed in the previous example sections, in which case the appropriate
scenario is referenced rather than duplicating details. In addition, in cases where the scenarios
make use of other protocols, as in the previous section, the appropriate reference in the form of a title
to the specific flow in the appropriate protocol document is included.
The chat functionality described in this section of the document
allows clients that use the XCON framework and protocols
for other media types (e.g. voice/video) to utilize the same conference
control mechanisms and conferencing system to establish, update and
delete a conference instance associated with an Instant Messaging (IM)
chat session,
independent of the IM chat protocol. In some cases(e.g., Message Session
Relay Protocol (MSRP) chat),
this would provide additional capabilities, such as sidebars.
This approach also allows the
conferencing system to provide a natural interworking point for various
IM protocols, the details of the interworking are outside the scope of
this document.
An IM client wishing to join a conference uses standardized
centralized conferencing mechanisms for creating and joining a
conference, as identified in the previous sections.
The request to send an IM to an IM media session is specific to the
IM protocol (e.g., MSRP SEND), just as there is specific media control
messaging for other types of sessions. An IM client connecting to
a conferencing system has a 1:1 relationship with the IM media signaling
entity in the conferencing system. This relationship is referred to as an
IM session. Further details of the correlation of the IM session identifiers
with the XCON session identifiers is provided in .
The IM media signaling entity is responsible for distribution of all
the messages to the other participants.
As with the other example conferences created, each IM session is logically
associated with a
specific conference.
The conference itself has a specific identifier in the
form of the XCON-URI, which is passed in the "confObjID" element in the
CCMP messages.
This provides the relevant
association between IM session and a centralized conference.
An IM client wishing to delete a chat room uses standardized
mechanisms for deleting a conference instance, such as those detailed in
.
This section provides details of the realization of the Multi-party
IM (chat) within the context of the centralized conferencing framework.
A brief discussion and diagrams are provided for creating, joining, and
deleting a chat based conference. The discovery of chat rooms available
on a specific conferencing system is inherent in the blueprint
capability provided by the conferencing system. The objective of this
section is to further illustrate the model, mechanisms and protocols
presented in the previous sections and also serves to validate that the
model, mechanisms and protocols are sufficient to support IM chat.
It should be noted that not all entities impacted by the
request are shown in the diagram (e.g., Focus), but rather the emphasis
is on the new entities introduced by this centralized conferencing
framework.
There are different ways to create a conference. A participant can
create a conference using call signaling means only, such as SIP, as
detailed in . For a conferencing client
to have more flexibility in defining the charaterisitics and
capabilities of a chat based conference, a conferencing client would
implement a conference control protocol client. By using a conference
control protocol, the client can determine the capabilities of a
conferencing system and its various resources.
provides an example of one client
"Alice" determining the conference blueprints available to support
various types of chat rooms for a particular conferencing system and
creating a chat based conference using the desired blueprint.
Upon receipt of the Conference Control Protocol request for
blueprints associated with chat rooms, the conferencing system would
first authenticate "Alice" (and allocate a conference user identifier,
if necessary) and then ensure that "Alice" has the appropriate
authority based on system policies to receive any chat room based
blueprints supported by that system. Any blueprints that "Alice" is
authorized to use are returned in a response, along with the
conference user ID.
Upon receipt of the Conference Control Protocol response containing
the blueprints, "Alice" determines which blueprint to use for the
conference to be created. "Alice" creates a conference object based on
the blueprint (i.e., clones) and modifies applicable fields, such as
membership list, topic details, and start time. "Alice" then sends a
request to the conferencing system to create a conference reservation
based upon the updated blueprint.
Upon receipt of the Conference Control Protocol request to "create"
a conference based upon the blueprint in the request, the conferencing
system ensures that the blueprint received is a valid blueprint (i.e.
the values of the various field are within range). The conferencing
system determines the appropriate read/write access of any users to be
added to a conference based on this blueprint (using membership,
roles, etc.). The conferencing system uses the received blueprint to
clone a conference reservation. The conferencing system also reserves
or allocates a conference ID to be used for any subsequent protocol
requests from any of the members of the conference. The conferencing
system maintains the mapping between this conference ID and the
conference object ID associated with the reservation through the
conference instance.
Upon receipt of the conference control protocol response to reserve
the conference, "Alice" now creates an active chat room using that
reservation. "Alice" provides the conference information, including
the necessary conference ID, to desired participants to allow them to
join the chat room. "Alice" may also add other users to the chat room.
When the first participant, including "Alice", requests to be added to
the conference, an active conference and focus are created. The focus
is associated with the conference ID received in the request.
A participant can join and leave the conference using call
signaling means only, such as SIP. However, in order to perform richer
conference control a user client can implement a conference control
protocol client. By using a conference control protocol, the client
can affect its own state and the state of other participants,
depending upon policies, which may indirectly affect the state of any
of the conference participants.
In the example in section ,
"Alice" has reserved a chat room . "Alice" has also already joined the
conference and made the chat room active. "Alice" can either add
additional participants to the chat room or provide the conference
information, including the necessary conference ID, to desired
participants and allow them to request to join themselves. Any
participants that have the authority to manipulate the conference
would receive the conference object identifier of the active
conference object in the response to their request to join.
provides an example of "Bob" joining
the chat room using the conference ID provided by "Alice" (e.g., in an
IM).
Upon receipt of the Conference Control Protocol request to "add" a
party ("Bob") in the specific conference as identified by the
conference object ID, the conferencing system must determine whether
"Bob" is already a user of this conferencing system or whether he is a
new user. If "Bob" is a new user for this conferencing system, a
Conference User Identifier is created for Bob. The conferencing system
must also ensure that "Bob" has the appropriate authority based on the
policies associated with that specific conference object to perform
the operation.
Once "Bob" has been successfully added to the chat room, a response
is sent to "Bob". Depending upon the policies, other participants
(including "Bob") may be notified of the addition of "Bob" to the
conference via the Conference Notification Service.
Depending upon the conferencing system policies and policies
specific to the chat room, the creator of the chat would typically be
the participant authorized to delete the chat room.
In the example in section ,
"Alice" has created a chat room and provided the conference
information, including the necessary conference ID, to desired
participants and allow them to request to join themselves. "Bob" and
others are participants in the chat.
provides an example of "Alice" later deleting this same chat room.
Upon receipt of the Conference Control Protocol request to "delete"
the specific chat room as identified by the conference object ID, the
conferencing system must determine whether "Alice" has the authority
to delete this conference. Since "Alice" is the creator of the
conference, the "delete" operation is performed, with the appropriate
signaling sent to the participants, including a response to "Alice"
indicating that the chat room has been deleted.
One step in the deletion of the chat room may include notifitying
the participants (including "Bob") that they have been removed via the
Conference Notification Service.
This section provides details of the realization of advanced chat
features, such as sidebars and private messages, within the context of
the centralized conferencing framework. As with , the objective of this section is
to further illustrate the model, mechanisms and protocols presented in
the previous sections and also serves to validate that the model,
mechanisms and protocols are sufficient to support advance IM chat
features.
The concept of a 'sidebar' in conferencing system is fully
described in the Sidebar section and related subsections within the
Conferencing Scenarios Realization section of the centralized
conferencing framework document . The creation, manipulation
and deletion of sidebars for chat rooms follows the same
principles.
A conference object representing a sidebar is created by cloning
the parent associated with the existing conference and updating any
information specific to the sidebar. A sidebar conference object is
implicitly linked to the parent conference object (i.e. it is not an
independent object) and is associated with the parent conference
object identifier. A conferencing system manages and enforces the
parent and appropriate localized restrictions on the sidebar
conference object (e.g., no members from outside the parent conference
instance can join, sidebar conference can not exist if parent
conference is terminated, etc.).
provides an example of one
client "Alice" involved in active chat room with "Bob" and "Carol".
"Alice" wants to create a sidebar to have a side discussion with "Bob"
while still receiving the session based messaging associated with the
main chat room. Whether the text is interleaved with the main chat or
whether a separate window is created for the sidebar is implementation
specific. "Alice" initiates the sidebar by sending a request to the
conferencing system to create a conference chat reservation based upon
the active chat conference object. "Alice" and "Bob" would remain on
the roster of the main conference, such that other participants could
be aware of their participation in the main conference, while the text
sidebar conference is occurring.
Upon receipt of the Conference Control Protocol request to
"reserve" a new sidebar chat conference, based upon the active chat
conference received in the request, the conferencing system uses the
received active chat conference to clone a conference chat reservation
for the sidebar. As discussed previously, the sidebar reservation is
NOT independent of the active conference (i.e., parent). The
conferencing system also reserves or allocates a conference ID to be
used for any subsequent protocol requests from any of the members of
the conference. The conferencing system maintains the mapping between
this conference ID and the conference object ID associated with the
sidebar reservation through the conference instance.
Upon receipt of the conference control protocol response to reserve
the conference, "Alice" can now create an active chat conference using
that reservation or create additional reservations based upon the
existing reservations. In this example, "Alice" wants only "Bob" to be
involved in the sidebar, thus she manipulates the membership. "Alice"
also only wants the text from the original conference, but wants the
text within the sidebar to be restricted to the participants in the
sidebar. "Alice" sends a conference control protocol request to update
the information in the reservation and to create an active
conference.
Upon receipt of the conference control protocol request to update
the reservation and to create an active chat conference for the
sidebar, as identified by the conference object ID, the conferencing
system ensures that "Alice" has the appropriate authority based on the
policies associated with that specific conference object to perform
the operation. The conferencing system must also validate the updated
information in the reservation, ensuring that a member like "Bob" is
already a user of this conferencing system.
Depending upon the policies, the initiator of the request (i.e.,
"Alice") and the participants in the sidebar (i.e., "Bob") may be
notified of his addition to the sidebar via the conference
notification service.
The case of private messages can be handled as a sidebar with just
two participants, identical to the example in section . The other context, referred to as
whisper, in this document refers to situations involving one time
media targetted to specific user(s). An example of a whisper would be
a text message injected only to the conference chair or to a new
participant joining a conference.
provides an example of one user
"Alice" who's chairing a fixed length conference with "Bob" and
"Carol". The configuration is such that only the chair is providing a
warning when there is only 10 minutes left in the conference. At that
time, "Alice" is moved into a sidebar created by the conferencing
system and only "Alice" receives that text message announcing the 10
minute warning.
When the conferencing system determines that there is only 10
minutes left in the conference which "Alice" is chairing, rather than
creating a reservation as was done for the sidebar in , the conferencing system directly
creates an active chat sidebar conference, based on the active chat
conference associated with "Alice". As discussed previously, the
sidebar conference is NOT independent of the active conference (i.e.,
parent). The conferencing system also allocates a conference ID to be
used for any subsequent manipulations of the sidebar chat conference.
The conferencing system maintains the mapping between this conference
ID and the conference object ID associated with the active sidebar
conference through the conference instance.
Immediately upon creation of the active chat sidebar conference,
the text announcement is provided to "Alice". Depending upon the
policies, Alice may be notified of her addition to the sidebar via the
conference notification service. "Alice" continues to receive the text
messages from the main conference.
Upon delivery of the text announcement, "Alice" is removed from the
sidebar and the sidebar conference is deleted. Depending upon the
policies, "Alice" may be notified of her removal from the sidebar via
the conference notification service.
This document has no IANA considerations.
The security considerations applicable to the implementation of these call flows is
documented in the XCON Framework, with
additional security considerations documented in the CCMP document.
Where applicable, statements with regards to the necessary security are
discussed in particular flows, however, since
this is only an informational document, readers are strongly
recommended to carefully consider the security considerations
defined in the XCON Framework and the CCMP document.
NOTE TO THE RFC-Editor: Please remove this section prior to
publication as an RFC.
The following are the major changes between the
01 and the 02 versions of the draft:
updated the call flows in order to take into account the new versioning
mechanism of the CCMP;clarified, per agreement in Stockholm, that cloning from a blueprint does not
need a cloning-parent to be made available in the response;clarified that BFCP and CCMP-based media control are neither in conflict nor
one the wrapper of the other; they act at different levels, and when both are involved,
it is required that both grant a resource before it can be used by an interested participant;changed all the domains involved in the flows to make them compliant
with ;clarified that a successful creation of a new conference object may or may not
contain the whole confInfo object in the response; in case it doesn't, a retrieve
of the updated object can be achieved by issuing a confRequest/retrieve;clarified that the scenario in only involves CCMP in adding the
user to a conference; this includes requiring the use of a password only in adding the user
to the conference object; the actual request for PIN/Password when joining thw conference is
handled by means of out-of-band mechanisms
(in this case at the media level, with the help of the MEDIACTRL framework);added and corrected Sidebars-related scenarios;added flows for some previously missing scenarios: Private Message/Whisper, Coaching Scenario, Removing a Party, Deleting a Conference;
The following are the major changes between the
00 and the 01 versions of the draft:
Updates to reflect change of CCMP to HTTP transport model.
The following are the major changes between the
individual 01 version to the WG 00:
Updates to reflect most recent version of CCMP, including parameter names, etc. Added protocol details to many of the examples. Editorial: Simplifying intro, terms, etc.
The detailed content for this document is derived from the prototype work of
Lorenzo Miniero, Simon Pietro-Romano,
Tobia Castaldi and their colleagues at the University of Napoli.