U.S. patent application number 14/228604 was filed with the patent office on 2014-08-07 for third-party session modification.
This patent application is currently assigned to Core Wireless Licensing, S.a.r.I.. The applicant listed for this patent is Core Wireless Licensing, S.a.r.I.. Invention is credited to Arto LEPPISAARI, Jari MUTIKAINEN.
Application Number | 20140222921 14/228604 |
Document ID | / |
Family ID | 38620741 |
Filed Date | 2014-08-07 |
United States Patent
Application |
20140222921 |
Kind Code |
A1 |
MUTIKAINEN; Jari ; et
al. |
August 7, 2014 |
THIRD-PARTY SESSION MODIFICATION
Abstract
The present invention relates to a method, system, client
device, conference server device and computer program product of
controlling media composition in a multi-party conversation
involving a central control point (50). At a participant (10) of
said multi-party conversation, a scope information (SoM) which
specifies members of said multi-party conversation is selected and
added to a session modifying request. The session modifying request
is transmitted to the central control point (50) which initiates a
media modification at the specified members in response to the
scope information (SoM). Thereby, a client can control whether
media modification is applied to the whole conference, selected
participants or only between the client itself and the conference
server.
Inventors: |
MUTIKAINEN; Jari; (Lepsama,
FI) ; LEPPISAARI; Arto; (Kangasala, FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Core Wireless Licensing, S.a.r.I. |
Luxembourg |
|
LU |
|
|
Assignee: |
Core Wireless Licensing,
S.a.r.I.
Luxembourg
LU
|
Family ID: |
38620741 |
Appl. No.: |
14/228604 |
Filed: |
March 28, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11485391 |
Jul 13, 2006 |
8719342 |
|
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14228604 |
|
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Current U.S.
Class: |
709/204 |
Current CPC
Class: |
H04L 12/1818 20130101;
H04L 65/1006 20130101; H04L 65/1089 20130101; H04L 12/1822
20130101; H04L 29/06421 20130101; H04L 65/4038 20130101; H04L
29/06197 20130101; H04L 65/403 20130101; H04L 29/06027 20130101;
H04W 4/16 20130101 |
Class at
Publication: |
709/204 |
International
Class: |
H04L 12/18 20060101
H04L012/18 |
Claims
1. A method comprising: receiving scope information at a client
device participating in a multi-party conversation session, wherein
the scope information identifies one or more parties participating
in the multi-party conversation session for whom a modification of
a media type is to be applied; generating, by the client device, a
session modifying request based on the scope information; and
determining, by the client device, to transmit the session
modifying request from the client device to a central control point
to apply the modification of the media type identified by the scope
information.
2. The method of claim 1, wherein the scope information is a header
parameter or an attribute of the session modifying request.
3. The method of claim 1, wherein the media type comprises push to
talk over cellular (PoC) audio, instant messaging, full-duplex
audio, full-duplex video, or some combination thereof.
4. The method of claim 1, wherein the scope information is
specified within the session modifying request as a session
description protocol (SDP) attribute.
5. The method of claim 1, wherein the scope information is
specified within the session modifying request as an a-line
value.
6. The method of claim 1, wherein the modification of the media
type is applied only between the client device and the central
control point without affecting other parties of the multi-party
conversation session.
7. The method of claim 1, comprising adding a list of addresses of
all parties to whom the modification of the media type is to be
applied.
8. The method of claim 7, wherein the list of addresses includes a
session initiation protocol (SIP) uniform resource indicator (URI)
list.
9. The method of claim 7, wherein the list of addresses includes at
least one uniform resource indicator (URI) of the session
initiation protocol (SIP).
10. The method of claim 1, wherein the session modifying request is
a re-INVITE request of a session initiation protocol (SIP).
11. The method of claim 1, wherein the session modifying request
identifies a recipient to contact a third party using the scope
information.
12. The method of claim 11, wherein the session modifying request
includes a header parameter used to inform the central control
point that an existing dialog is to be modified, instead of
creating a new dialog.
13. The method of claim 12, wherein the session modifying request
includes a callee capability information which indicates in which
way the existing dialog is to be modified.
14. The method of claim 11, wherein the scope information is added
as an address list.
15. The method of claim 14, wherein the address list comprises at
least one uniform resource indicator (URI) of a session initiation
protocol (SIP).
16. An apparatus comprising: at least one processor; and at least
one memory including computer program code; wherein the at least
one memory and the computer program code are configured to, with
the at least one processor, direct the apparatus to perform at
least the following: receive scope information at the apparatus
while the apparatus is participating in a multi-party conversation
session, wherein the scope information identifies one or more
parties participating in the multi-party conversation session for
whom a modification of a media type is to be applied; generate a
session modifying request based on the scope information; and
determine to transmit the session modifying request from the
apparatus to a central control point to apply the modification of
the media type identified by the scope information.
17. The apparatus of claim 16, wherein the scope information is a
header parameter or a message attribute of the session modifying
request.
18. The apparatus of claim 17, wherein the message attribute is a
session initiation protocol (SIP) attribute, and the scope
information is added as an a-line value.
19. A tangible non-transitory computer-readable storage medium
carrying one or more sequences of one or more instructions, which
when executed by one or more processors, direct an apparatus to:
receive scope information corresponding to a multi-party
conversation session, wherein the scope information identifies one
or more parties participating in the multi-party conversation
session for whom a modification of a media type is to be applied;
generate a session modifying request based on the scope
information; and determine to transmit the session modifying
request to a central control point to apply the modification of the
media type identified by the scope information.
20. The computer-readable storage medium of claim 19, wherein the
apparatus is directed to provide a user agent for a client device.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of US Publication No.
2007/0250569 (U.S. patent application Ser. No. 11/485,391 filed on
Jul. 13, 2006), the entirety of which is incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a method, system, client
device, conference server and computer program product for
controlling media composition in a multi-party conversation.
According to a specific example, the present invention relates to
media modification in a Session Initiation Protocol (SIP)
conferencing framework.
BACKGROUND OF THE INVENTION
[0003] The SIP conferencing framework (as defined in
draft-ietf-sipping-conferencing-framework-05.txt) defines basic
procedures, functionalities and architecture how participants may
create and join a SIP multimedia conference session, invite other
participants to the session, remove participants from the session,
become aware of other participants in the session, and so on. The
conferencing framework has been then adopted to many SIP based
conferencing standards, like 3GPP R6 IMS (3rd Generation
Partnership Project Release 6 Internet Protocol (IP) Multimedia
Subsystem) conferencing service (as specified e.g. in TS 24.147),
OMA-PoC (Open Mobile Alliance--Push-to-talk over Cellular), and
OMA-IM (Open Mobile Alliance--Instant Messaging).
[0004] The above framework describes how a SDP (Service Description
Protocol) offer/answer mechanism specified in the IETF (Internet
Engineering Task Force) specification RFC (Request for Comments)
3264 can be used to add, remove and modify media streams and their
attributes in the multimedia conferencing session.
[0005] In a Multimedia conference session a user should be able to
start the session with one particular media (e.g. PoC audio, IM,
full-duplex audio, full-duplex video, etc) and add another media
later on. The conferencing control function should then communicate
the added media to other participants in the conference session,
e.g., via an SDP offer in a SIP re-INVITE or a SIP UPDATE request
which are described in the IETF RFC 3311. In this way the other
participants learn that a new media has been added and they can
start to use it in the session.
[0006] On the other hand, the same SDP offer/answer mechanism can
be used also by a participant to modify the connection portion,
i.e., call leg, between this participant and the central control
point (e.g., focus in SIP conferencing terminology) of the
conference, only. In this kind of session modification of the SIP
conferencing framework, the focus should not modify the other
participant's media sessions. For example, in the SIP conferencing
framework, if one participant wants to put the full duplex audio
media on hold, this is done by SDP offer/answer in re-INVITE/200 OK
between this participant and the focus, but the focus should not
send re-INVITE to other participants, since they are not put on
hold and should thus be able to continue communicating as
before.
[0007] Thus, the central control point needs to be able to
determine, what SDP offers should be communicated to other
participants and what are kept between a requesting participant and
the focus only. In some media modifications, the central control
point can determine this based on the SDP offer attributes. For
example, if one participant puts the media in a conference session
to "on hold", typically the central control point should not put
the other participants to hold, but instead keep the media
modification within this particular SIP dialog, i.e. between the
participant and the focus. But with some SDP offers the central
control point has no means to know whether the media modification
should be sent further. For example, if the conferencing session
includes audio and video media and some participant wants to remove
the video from his/her leg only (e.g. moves to a cell which cannot
offer enough bandwidth for video), but the other participants do
not have this limitation, i.e., they would like to continue with
both audio and video.
[0008] The current SDP offer/answer mechanism in SIP conferencing
framework is not enough to distinguish whether the media
manipulation should be limited to one call leg or communicated to
all participants. IETF XCON is solving a similar use case at the
moment. There, a framework for media control protocol is defined,
which a participant can use to control the media policies of the
other participants, e.g. remove video from certain participant,
mute one participant (remove the audio sending capability) and so
on. However, the XCON work has been very slow, and the result
anyhow will be a new protocol between the participant and the
focus.
[0009] What OMA-IM and OMA-PoC would need is a simple SIP based
solution for adding and removing media, from standardization time
schedule point of view, the IM and POC are not able to wait results
from XCON, and they don't need the complex XCON framework and the
other more advanced capabilities of the media policy control
protocol.
SUMMARY OF THE INVENTION
[0010] It is therefore an object of the present invention to
provide a simple session manipulation scheme by means of which
media components can be added and removed in a simple and flexible
manner.
[0011] This object is achieved by a method of controlling media
composition in a multi-party conversation involving a central
control point, said method comprising the steps of: [0012]
selecting at a participant of said multi-party conversation a scope
information which specifies members of said multi-party
conversation; [0013] adding said selected scope information to a
session modifying request; [0014] transmitting said session
modifying request to said central control point; and [0015]
initiating a media modification at said specified members in
response to said scope information.
[0016] Furthermore, the above object is achieved by a client device
for controlling media composition in a multi-party conversation
involving a central control point, said client device comprising:
[0017] selecting means for selecting a scope information which
specifies members of said multi-party conversation; [0018] adding
means for adding said selected scope information to a session
modifying request; and [0019] transmitting means for transmitting
said session modifying request to said central control point.
[0020] Additionally, the above object is achieved by a conference
server device for providing central control for a multi-party
conversation, said conference server device comprising: [0021]
detecting means for detecting a scope information, which specifies
members of said multi-party conversation, in a received session
modifying request; and [0022] initiating means, responsive to said
scope information, for initiating a media modification towards said
members specified by said scope information.
[0023] Further, the above object is achieved by a computer program
product comprising code means for generating the selecting, adding
and transmitting steps of the above method when run on a computer
device. Moreover, the above object is achieved by a computer
program product comprising code means for generating the initiating
step of the above method when run on a computer device.
[0024] Finally, the above object is achieved by a system for
controlling media composition in a multi-party conversation, said
system comprising at least one client device as defined above and a
conference server device as defined above.
[0025] Accordingly, a client or participant can individually
control the scope of media modification, i.e. to which members of a
multi-party conversation the requested media modification shall be
applied. For example, it can be selected by the requesting
participant whether the media modification is applied to the whole
conference or only between the client and the conference server
(i.e. central control point). In this case, one or more media
components can be dropped by the requesting client locally or for
the whole conference.
[0026] According to first aspect, the scope information may be
added as a new header parameter of the session modifying
request.
[0027] According to a second aspect, the scope information may be
added as an attribute of the session modifying request. This
attribute may for example be an SDP attribute and the scope
information may then be added as an a-line value.
[0028] In a specific example, the scope may information specify
whether the media modification is to be applied to the participant
only or to all members of the multi-party conversation.
[0029] According to a third aspect, the scope information may be
added as a list of addresses of those participants to whom the
media modification shall be applied. This list of addresses may
comprise, for example, at least one SIP Uniform Resource Indicator
(URI).
[0030] In the above first to third aspect, the session modifying
request may be a SIP re-INVITE or a SIP UPDATE request.
[0031] According to a fourth aspect, the session modifying request
may identify a recipient which should contact a third party using
the scope information. Here, the session modifying request may
comprise a header parameter used to inform the central control
point that an existing dialog is to be modified, instead of
creating a new dialog. As an additional option, the session
modifying request may comprise a callee capability information
which indicates in which way the existing dialog is to be modified.
In the fourth aspect, the scope information may then be added as an
address list. This address list may comprise for example at least
one SIP URI.
[0032] Further advantageous modifications are defined in the
dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] In the following, the present invention will be described in
greater detail based on embodiments with reference to the
accompanying drawings in which:
[0034] FIG. 1 shows a schematic diagram indicating a multi-party
conferencing architecture in which the present invention can be
implemented;
[0035] FIG. 2 shows a schematic block diagram of a media
modification system according to the preferred embodiments;
[0036] FIG. 3 shows a listing of example of a re-INVITE request as
used in a second embodiment;
[0037] FIG. 4 shows a listing of an example of an SDP attribute as
used in a third embodiment;
[0038] FIG. 5 shows a listing of an example of a REFER request as
used in a first example of a fourth embodiment; and
[0039] FIG. 6 shows a listing of an example of a nested REFER
request as used in a second example of the fourth embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0040] The preferred embodiments will now be described on the basis
of a SIP multi-party conferencing architecture as shown in FIG.
1.
[0041] In this specification, the term "conference" is intended to
designate an instance of a multi-party conversation, in which a
single control point which may be a SIP user agent, referred to as
a focus 50, maintains a dialog via respective call legs 70 with
each participant P1 10 to P4 40. Each participant is a software
element or routine running on a client computer device or terminal
device, that connects a user or apparatus to a conference. It
implements, at a minimum, a SIP user agent, but may also implement
non-SIP-specific mechanisms for additional functionality. This SIP
user agent can be a PC application, a SIP hard-phone, or a PSTN
(Public Switched Telephone Network) gateway. It can also be another
focus.
[0042] The focus 50 plays the role of a centralized manager of the
conference, and is addressed by a conference URI, e.g., a URI,
usually a SIP URI, which identifies the focus 50 of a conference.
The focus 50 is a logical role that maintains a SIP signaling
relationship with each participant, e.g., P1 10 to P4 40, in the
conference. The focus 50 is responsible for ensuring, in some way,
that each participant receives the media that make up the
conference. The focus 50 also implements conference policies.
[0043] The state of the conference includes the state of the focus
50, the set of participants 10-40 connected to the conference, and
the state of their respective dialogs. A conference notification
service is provided as a logical function of the focus 50 which can
thus act as a notifier, accepting subscriptions to the conference
state, and notifying subscribers about changes to that state.
[0044] Furthermore, a conference policy server 60 may be provided
as a logical function which can store and manipulate the conference
policy. This logical function is not specific to SIP, and may not
physically exist. It refers to the component that interfaces a
protocol to the conference policy which is a complete set of rules
governing a particular conference.
[0045] Additionally, a mixer (not shown) may be provided which
receives a set of media streams of the same type, and combines
their media in a type-specific manner, redistributing the result to
each participant 10-40.
[0046] A conference server is a physical server which contains, at
a minimum, the focus functionality. It may also include the
conference policy server and mixer functionalities.
[0047] As can be gathered from FIG. 1, the central component of the
SIP conferencing architecture is the focus 50, which results in a
star topology. The focus 50 is responsible for making sure that the
media streams which constitute the conference are available to the
participants 10-40 in the conference. It does that through the use
of one or more mixers, each of which combines a number of input
media streams to produce one or more output media streams. The
focus 50 uses a media policy to determine the proper configuration
of the mixers.
[0048] The focus 50 has access to the conference policy of each
conference. Effectively, the conference policy can be thought of as
a database which describes the way that the conference should
operate. It is the responsibility of the focus 50 to enforce those
policies. Not only does the focus need read access to the database,
but it needs to know when it has changed. Such changes might result
in SIP signaling (for example, the ejection of a user from the
conference using the SIP BYE method), and those changes with affect
the conference state will require a notification to be sent to
subscribers using the conference notification service.
[0049] Each conference has a unique focus 50 and a unique URI
identifying that focus 50. Requests to the conference URI are
routed to the focus 50 for that specific conference. Users usually
join the conference by sending an INVITE request to the conference
URI. As long as the conference policy allows, the INVITE request is
accepted by the focus 50 and the user is brought into the
conference. Users can leave the conference by sending a BYE
message, as they would in a normal call.
[0050] Similarly, the focus 50 can terminate a dialog with a
participant, should the conference policy change to indicate that
the participant is no longer allowed in the conference. The focus
50 can also initiate an INVITE method to bring a participant into
the conference.
[0051] A participant can communicate with the conference policy
server 60 using some kind of non-SIP-specific mechanism by which it
can affect the conference policy. This is indicated in FIG. 1 by
the arrow between participant P4 40 and the conference policy
server 60 which need not be available in any particular conference,
although there is always a conference policy.
[0052] The interfaces between the focus 50 and the conference
policy, and the conference policy server 60 and the conference
policy are non-SIP-specific. For the purposes of SIP-based
conferencing, they serve as logical roles involved in a conference,
as opposed to representing a physical decomposition.
[0053] The conference URI is unique, such that no two conferences
have the same conference URI. It can be a SIP URI. Contextual
information surrounding the URI (for example, SIP header
parameters) may indicate that the URI represents a conference. When
a SIP request is sent to the conference URI, that request is routed
to the focus 50. The conference URI can represent a long-lived
conference or interest group, such as
"sip:discussion-on-dogs@example.com". The focus identified by this
URI would always exist, and always be managing the conference for
whatever participants are currently joined. Other conference URIs
can represent short-lived conferences, such as an ad-hoc
conference. Callee capability parameters are also be used to
indicate that the focus 50 supports the conference notification
service. This may be achieved by declaring support for the SIP
SUBSCRIBE method and the relevant package(s) in the caller
preferences feature parameters associated with the conference
URI.
[0054] As already mentioned and shown in FIG. 1, the focus 50 is
the center of the conference. All participants 10-40 in the
conference are connected to it by a SIP dialog. The focus 50 is
responsible for maintaining the dialogs connected to it. It ensures
that the dialogs are connected to a set of participants who are
allowed to participate in the conference, as defined by the
membership policy. The focus 50 also uses SIP to manipulate the
media sessions, in order to make sure each participant obtains all
the media for the conference. To do that, the focus 50 makes use of
the mixers. Through that interaction, it makes sure that all valid
participants 10-40 received a copy of the media streams, and that
each participant sends media to an IP address and port on the mixer
that cause it to be appropriately mixed with the other media in the
conference.
[0055] Each conference is composed of a particular set of media
that the focus 50 is managing. For example, a conference might
contain a video stream and an audio stream. The set of media
streams that constitute the conference can be changed by the
participants 10-40. When the set of media in the conference change,
the focus 50 will need to generate a re-INVITE to each participant
in order to add or remove the media stream to each participant. A
SIP re-INVITE can be used by a participant to add or remove a media
stream. This is accomplished using the standard offer/answer
techniques for adding media streams to a session. This will trigger
the focus to generate its own re-INVITEs towards the other
participants 10-40 of the conference.
[0056] FIG. 2 shows a schematic block diagram indicating units or
functionalities of a participant 10 or its respective client
hardware device and the focus 50 or its respective conference
server hardware device, participating at a proposed third party
session modification scheme, by means of which media components can
be easily manipulated in a flexible manner by the participant
10.
[0057] According to FIG. 2, the participant 10 comprises a
selection unit or functionality 102 for selecting a scope of a
desired media modification, i.e., specific conference participants
to which the media modification shall be applied. This selection my
be controlled by a software functionality or by a hardware input
function provided at the respective client device. In response to
such a control or input operation, the selection functionality 102
generates a scope information SoM Scope of Modification) which is
added by a message generation unit or functionality 104 to a
session modifying request. This request may be any suitable request
which can be used to initiate any kind of session modifications.
Examples of such request are explained later based on the exemplary
SIP conferencing architecture.
[0058] The enhanced session modifying request with the added scope
information SoM is then signaled or routed to the focus 50 based on
the conference URI by a message signaling unit or functionality 106
of the participant 10. At the focus 50, the enhanced session
modifying request is received by a similar message signaling unit
or functionality 506 and supplied to a scope detection unit or
functionality 502 which detects the scope information SoM. The
detected scope information SoM is supplied to a message generation
unit or function 504 of the focus, the requested media modification
is initiated via the message signaling functionality 506 in
combination with respective mixer functionalities (not shown)
towards those participants specified in the scope information
SoM.
[0059] It is noted that the above units or functionalities 102,
104, and 106 of the participant 10 and the above units or
functionalities 502, 504, and 506 of the focus 50 may be
implemented as software routines or components cooperating with or
integrated in the respective control programs (e.g. SIP user agents
or the like) of the participant 10 and the focus 50, respectively.
As an alternative the above listed units or functionalities may be
implemented as hardware units of the respective client device or
conference server device, respectively. Of course, the above units
or functionalities 102, 104, and 106 may be provide in some or all
of the other participants 20-40, as well.
[0060] In the following, different embodiments are described which
can be distinguished based on the message type and message portion,
which conveys the above scope information SoM.
[0061] According to the first to third embodiments re-INVITE or
UPDATE requests are modified to provide an easy and flexible way to
a participant to selectively modify media compositions of a
conference. These mechanisms are used when an existing session is
to be modified and participants are not added or removed.
[0062] Re-INVITE or UPDATE requests are used to modify medias in
the session. The support of the UPDATE method is optional for the
network and a participant or client can learn the network
capability during session establishment. Although, for reasons of
simplicity, the UPDATE method is not always mentioned herein as an
alternative method to re-INVITE, it should be understood as an
alternative to all use cases of re-INVITE in connection with the
first to third embodiments.
[0063] As a specific example, it is proposed here that the
re-INVITE request contains as the scope information SoM a parameter
indicating if the media modification proposed by the client should
be applied to the whole session or only to the requesting client.
This indication can be conveyed either in the SIP headers or in the
SDP payload of the INVITE or UPDATE requests.
[0064] In the first embodiment, a new SIP header e.g.,
Media-Handling (Conference/Client) is introduced. Since one INVITE
request can be used for modifying several medias, the SIP header
parameter value is applied to all medias negotiated in the
re-INVITE. In case some media modification of the re-INVITE request
is aimed for the whole conference and some for the participant's
own media or call leg only, the participant needs to send a
separate re-INVITE request.
[0065] As another option for the first embodiment, some already
existing SIP header, e.g., the Request-Disposition SIP header could
be utilized for conveying the scope information SoM.
[0066] In the second embodiment, a SIP URI-list service is proposed
for conveying the scope information SoM. In this case, the SIP
INVITE/UPDATE request contains the SIP URI-list as request payload.
The SIP URI-list is used to tell to which participants the media
modification should be applied. The SIP URI-list can also contain
the conference URI indicating that media modifications are applied
to all conference participants. Similar to the first embodiment, by
default, all proposed media modifications (multiple m-lines in FIG.
3) are applied to participants given in SIP URI-list. If the
participant wants to add some media to the whole conference, but
other media only for a subset of participants, two separate
re-INVITEs/UPDATES are needed.
[0067] In addition to SIP URI-list as specified in
"draft-ietf-sipping-uri-services-05.txt", some additional
indication might be needed in the re-INVITE/UPDATE request to
inform the focus 50 how it should use the SIP URI-list information.
The SIP URI-list might already be included in the re-INVITE/UPDATE
request for some other reasons. Therefore, combinations of proposed
mechanisms are possible, such as SIP URI-list and SIP header, SIP
URI-list and SDP attribute, or additionally SIP URI-list itself
could contain new field indicating that this list is used for this
particular purpose.
[0068] FIG. 3 shows an exemplary listing of a re-INVITE request
according to the second embodiment, which contains two bodies, SDP
and SIP URI-list for a PoC service.
[0069] In the third preferred embodiment, a new SDP attribute e.g.,
Conference/Client-only or media-treatment:Conference/Client-only,
is introduced for conveying the scope information SoM, e.g., as an
a-line value.
[0070] FIG. 4 shows a listing of an example of the proposed SDP
attribute. In this case new a-line value "conference" indicates
that this media modification applies for the whole conference and a
new value "client-only", indicates that the media modification
shall be applied only between this particular requesting
participant and the conference server.
[0071] This new SDP attribute is more flexible, since the
participant can include several medias into the same re-INVITE and
request different handling for each of the medias. The conference
server, i.e. the focus 50, can negotiate own leg modifications
immediately, while new media for the whole conference may take some
time.
[0072] According to the fourth embodiment, the REFER method as
specified in IETF RFC 3515 is used as session modifying request, to
which the scope information is added.
[0073] In particular, a new SIP header "Alternates" could be
introduced (as compared to "Replaces"). This header is used in the
SIP REFER method to notify the referee, i.e. the focus 50, that the
INVITE sent due to the reception of the REFER is supposed to modify
the existing dialog, instead of creating a new dialog. In addition,
the callee capabilities could be used along the contact URI in the
Refer-to header in the REFER method. These callee capabilities
together with the new Alternates header indicate to the focus 50 in
what way the dialog should be modified.
[0074] As an additional option, the SIP URI list service could be
used for REFER to generate the re-INVITE to all participants 10-40
of the conference session. With the SIP URI list service, it is
also possible to request that re-INVITE is generated and sent to
only some of conference participants. In this case, the requesting
participant or client can include the list of participants into the
REFER request as SIP-URI list.
[0075] This new REFER based mechanism utilizing the Alternates
header can be used always when the participant wants to modify the
sessions of other participants. If the participant wants to modify
its own call leg 70 to the focus 50, it uses the regular SDP
offer/answer mechanism as explained in the third preferred
embodiment.
[0076] FIG. 5 shows a listing of a first example of a REFER request
according to the fourth embodiment, where user A wants to drop
video from all participants in the audio/video multimedia
conferencing session. User A sends a REFER request to the focus 50.
The REFER request contains a Refer-to header with the focus URI.
The focus URI in the Refer-to indicates that the method should be
sent to all participants currently in the session with this focus
50.
[0077] The focus 50 then generates a re-INVITE to each participant
currently in the session. Additionally, the focus 50 adds an SDP
offer to the re-INVITE based on the currently negotiated media in
each participant's session. Based on the callee capabilities (audio
in this example) given in the Refer-To header of the REFER request,
the focus 50 generates an SDP offer that includes only the audio
media. As a response from each participant, the video is dropped
from all participants.
[0078] Another way to drop the video in a second example of the
fourth embodiment is to send a nested REFER to the focus.
[0079] FIG. 6 shows a listing of the REFER request according to the
second example. The nested focus generates a REFER to each
participant. This second REFER includes the new Alternates header,
based on that the participant generates a re-INVITE back to the
focus. This re-INVITE includes an SDP offer that drops the video
media from the ongoing dialog.
[0080] As a specific example, the simple and flexible media
modification mechanisms introduced above in connection with the
first to fourth embodiments can be implemented in OMA PoC 2.0.
Thereby, a new media for a PoC feature is provided, in which one
session can contain several medias.
[0081] In summary, a method, system, client device, conference
server device and computer program product for controlling media
composition in a multi-party conversation involving a central
control point have been described. At a participant of said
multi-party conversation, a scope information which specifies
members of said multi-party conversation is selected and added to a
session modifying request. The session modifying request is
transmitted to the central control point which initiates a media
modification at the specified members in response to the scope
information. Thereby, a client can control whether media
modification is applied to the whole conference, selected
participants or only between the client itself and the conference
server.
[0082] It is noted that the present invention is not restricted to
the above preferred SIP-based embodiments, but can be applied in
connection with any type of media modification for multi-party
conversations, where session modifying requests can be used for
modifying media components. Any header or payload portion or
parameter can be used or newly introduced to add and convey the
proposed scope information. The preferred embodiments may thus vary
within the scope of the attached claims.
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