System for terminating multicast channel and data broadcast when at least two second endpoints do not transmit positive acknowledgement message to first endpoint
A method and apparatus for optimizing transmission of data to a plurality of second endpoints in a system wherein a first endpoint is providing data to the plurality of second endpoints each connected by a point-to-point communication channels. This may be useful in teleconferencing applications with a plurality of participants (endpoints) or broadcast server applications. The first endpoint activates a multicast communication channel having a first multicast address and commences broadcast of the data over the multicast communication channel. The first endpoint transmits a request message to each of the plurality of second endpoints in order to query each of the second endpoints whether they can receive transmissions broadcast to the first multicast address. Certain of the plurality of second endpoints transmit an acknowledgment message if they can receive transmissions broadcast to the first multicast address, and the first endpoint receives the acknowledgment message. Then, for each acknowledgment message received from certain of the plurality of second endpoints, the first endpoint deactivates the point-to-point communication channel and the certain of the plurality of second endpoints.
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This application is a reissue application of U.S. Pat. No. 5,999,977, issued Dec. 7, 1999, which is a continuation of U.S. patent application Ser. No. 08/468,715, now abandoned, filed Jun. 5, 1995, which is a continuation of U.S. patent application Ser. No. 08/396,198, filed Feb. 24, 1995, now U.S. Pat. No. 5,854,898 issued Dec. 29, 1998. Notice: More than one reissue application has been filed for the reissue of U.S. Pat. No. 5,999,977. The reissue applications are application Ser. Nos. 10/857,798 (now U.S. Pat. No. RE40,704), 10/857,799, 10/857,805, 10/857,806, and 12/210,847.
This application is related to copending reissue patent application Ser. No. 10/857,799, for “System for Terminating Multicast Channel and Data Broadcast When at Least Two Second Endpoints Do Not Transmit Positive Acknowledgement Message to First Endpoint”, filed May 28, 2004.
This application is related to copending reissue patent application Ser. No. 10/857,798, for “System for Terminating Multicast Channel and Data Broadcast When at Least Two Second Endpoints Do Not Transmit Positive Acknowledgement Message to First Endpoint”, filed May 28, 2004.
This application is related to copending reissue patent application Ser. No. 10/857,806, for “System for Terminating Multicast Channel and Data Broadcast When at Least Two Second Endpoints Do Not Transmit Positive Acknowledgement Message to First Endpoint”, filed May 28, 2004.
This application is related to copending reissue patent application Ser. No. 10/857,805, for “System for Terminating Multicast Channel and Data Broadcast When at Least Two Second Endpoints do not Transmit Positive Acknowledgement Message to First Endpoint”, filed May 28, 2004.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to teleconferencing systems.
More specifically, the present invention relates to the addition of a data stream, such as an auxiliary data stream to a teleconference.
2. Background Information
Teleconferencing is increasingly becoming a popular application in personal computer systems. Such applications typically allow the transfer of audio and video data between users so that they can speak and otherwise communicate with one another. Such applications sometimes also include data sharing wherein various types of data such as documents, spreadsheets, graphic data, or other types of data, can be shared and manipulated by all participants in the teleconference. Different teleconference applications perhaps residing on different hardware platforms have different capabilities. Moreover, a wide variety of features has been implemented in different teleconference applications, and the proliferation of different types of computer systems with different capacities, and different networking media has created challenges for teleconferencing.
For example, for most teleconferencing applications, it is assumed that the sender and the receiver have certain minimum capabilities. However, with the wide diversity of systems having different computation capacities, and in addition, the wide variety of networking media, that certain systems may not have certain capabilities. For example, the first system may be a high performance workstation coupled to a high performance communication medium whereas a second system may employ an earlier generation processor, operate at a substantially slower clock rate, and/or be coupled to a lower capacity communication medium. Certain network capabilities such as multicast or other optimization features, may not be present in certain networking media. Thus, in order for some teleconference applications to function, the participants in the conference can only operate at the fastest possible configuration provided by any minimum system which may participate in the teleconference. Of course, this results in certain inefficiencies, especially if both of the participants are capable of transmitting in a higher capacity than the system with the least possible capability.
Another issue in teleconference applications is the ability of certain stations to participate in more than one teleconference. In fact, in certain circumstances, multiple individual conferences may be desired to be merged by a user according to operating circumstances. Due to the distributed nature of certain networks, during this merge operation, certain circumstances may change. That is, that while a single station is merging more than one conference it is participating in, a second station at a remote location may further have other operating circumstances changing (e.g., participants leaving, entering, or otherwise joining an on-going teleconference), and thus, the management of such merging operations becomes unduly burdensome.
Yet another shortcoming of certain prior art teleconference applications is the ability to associate an independent data stream with an on-going teleconference. For example, a source participant may desire to provide an additional data stream to other participants in a teleconference. This additional source may include, but not be limited to, video, data, audio or any other type of data available to the source participant. For example, such an additional source may include other audio information for a receiver. Other types of data may also be desired to be associated with an on-going teleconference, which may be accessible to other participant in the teleconference. Certain prior art teleconferencing applications lack these abilities.
SUMMARYA method and apparatus for optimizing transmission of data to a plurality of second endpoints in a system wherein a first endpoint is providing data to the plurality of second endpoints each connected by point-to-point communication channels. This may be useful in teleconferencing applications with a plurality of participants (endpoints) or broadcast server applications. The first endpoint activates a multicast communication channel having a first multicast address and commences broadcast of the data over the multicast communication channel. The first endpoint transmits a request message to each of the plurality of second endpoints in order to query each of the second endpoints whether they can receive transmissions broadcast to the first multicast address. Certain of the plurality of second endpoints transmit an acknowledgement message if they can receive transmissions broadcast to the first multicast address, and the first endpoint receives the acknowledgement message. Then, for each acknowledgement message received from certain of the plurality of second endpoints, the first endpoint deactivates the point-to-point communication channel and the certain of the plurality of second endpoints.
The broadcast of the data and the multicast communication channel is terminated if at least two of the plurality of second endpoints do not transmit the acknowledgement messages containing a positive acknowledgement. In this instance, communication channels are maintained as point-to-point. Subsequent to commencing broadcast of the data to the multicast address, the first endpoint can receive detach messages from certain of the plurality of second endpoints, and if at least two of the plurality of second endpoints are not receiving the data, then the first endpoint can terminate the broadcast of the data and the multicast communication channel. Communication of the data in this instance also reverts to point-to-point communication channels.
In implemented embodiments, the acknowledgement message includes a response code which indicates whether the second endpoint can receive transmissions broadcast to the first multicast address. Also, in implemented embodiments, prior to the first endpoint activating the multicast communication channel having the first multicast address, it is determined whether the single communication medium supports broadcasting to the first multicast address, and if not, multicast cannot be activated.
The present invention is illustrated by way of example and not limitation in the figures of the accompanying in which like references indicate similar elements and in which:
The present invention relates to networking systems, more specifically, the present invention describes a messaging protocol for establishing and maintaining teleconference connections between a plurality of participants in a networking system. Applications for this include, transmitting application and/or system capabilities between participants or potential participants in a teleconference, notifying participants of a teleconference that more than one teleconference should be merged, and addition of an auxiliary data stream to an on-going teleconference. Although the present invention will be described with reference to certain specific embodiments thereof, especially, with relation to certain hardware configurations, data structures, packets, method steps, and other specific details, these should not be viewed as limiting the present invention. Various modifications and other may be made by one skilled in the art, without departing from the overall spirit and scope of the present invention.
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever. Copyright Apple Computer, Inc.
A typical system configuration in which a teleconference may take place is illustrated as 100 in
A teleconference display is shown at 200 at
In implemented embodiments of the present invention, a general purpose computer system is used for implementing the teleconferencing applications and associated processes to be described here. Although certain of the concepts to be described here will be discussed with reference to teleconferencing, it is apparent that the methods and associated apparatus can be implemented for other applications, such as file sharing, real time data acquisition, or other types of applications which sends data from a first participant to a second participant or set of participants. A computer system such as that used for implementing embodiments of the present invention will now be described.
A computer system, such as a workstation, personal computer or other processing apparatus 150c or 155c as shown in
System 150c may further be coupled to a display device adapter display 321 such as a cathode ray tube (CRT) or liquid crystal display (LCD) coupled to bus 301 for displaying information to a computer user. Such a display 321 may further be coupled to bus 301 for the receipt of video or image information. An alphanumeric input device 322, including alphanumeric and other keys may also be coupled to bus 301 for communicating information and command selections to processor 302. An additional user input device is cursor control 323, such as a mouse, a trackball, stylus, or cursor direction keys, coupled to bus 301 for communicating direction information and command selections to processor 302, and for controlling cursor movement on display 321. For teleconferencing applications, system 150c may also have coupled to it a sound output device 324, a video input device 325, and sound input device 326, along with the associated D/A (Digital-to-Analog) and A/D (Analog-to-Digital) converters for inputting or outputting media signal bitstreams. System 150c may further be coupled to communication device 327 which is coupled to network adapter 160 for communicating with other teleconferencing stations.
Note, also, that any or all of the components of system 150c and associated hardware may be used in various embodiments, however, it can be appreciated that any configuration of the system may be used for various purposes according to the particular implementation.
In one embodiment, system 150c is one of the Apple Computer® brand family of personal computers such as the Macintosh 8100 brand personal computer manufactured by Apple Computer, Inc. of Cupertino, Calif. Processor 302 may be one of the PowerPC brand microprocessors manufactured by Motorola, Inc. of Schaumburg, Ill.
Note that the following discussion of various embodiments discussed herein will refer specifically to a series of routines which are generated in a high-level programming language (e.g., the C or C++ programming language) and compiled, linked, and then run as object code in system 150c during run-time within main memory 304 by processor 302. For example the object code may be generated by the C++ Compiler available from Symantec, Inc. of Cupertino, Calif.
Although a general purpose computer system has been described, it can be appreciated by one skilled in the art, however, that the following methods and apparatus may be implemented in special purpose hardware devices, such as discrete logic devices, large scale integrated circuits (LSI's), application-specific integrated circuits (ASIC's), or other specialized hardware. The description here has equal application to apparatus having similar function.
The transport component 402 and the networking component 403 provide the necessary operations for communication over the particular type of network adapter 160 and networking medium 170 according to implementation. For example, networking component 402 may provide the TCP or ADSP protcols and packetizing, according to those respective standards.
A more detailed view of the conference component 400 is shown in
The conference component's main function is to establish and maintain a bi-directional connection between every member of a conference. Conferencing applications use a pre-established control channel to exchange control data that is pertinent to the conference. This data might include user identification information or other information that is germane to the application's operation. Conferencing applications (e.g., 401) define the format and content of these control messages by establishing their own control protocols. The conferencing component further establishes communication channels between a first endpoint and a second endpoint, using the underlying transport component 402. Thus, once a media channel has been established, the conference component uses the transport component 402's media channel which is provided for transmission of media and non-media information. For the remainder of this application, however, the focus will be on the establishment of communication between a first and second participant (referred to as endpoints) or group of participants which may participate in a teleconference.
Application Program Interface (API)The application program 401 controls the conference component 400 by the issuance of MovieTalk application API calls. The conference component operates using an event-driven model wherein events pertinent to the application are issued to the application program. The application program can then take appropriate action either by modifying internal data structures within (creating a source or sink), and/or issuance of appropriate messages over the network to other connected participants, or potential participants. According to messages received by the conference component, a current context and API calls from the application, the conference component can take appropriate action.
A typical series of events which occur after the establishment of a teleconference by the conference component in an application is illustrated in
A typical application's initialization is shown as process 700 of
-
- 1. optional;
- 2. desired;
- 3. required; or
- 4. a negotiation message.
These types of capabilities are included in a capabilities list which is transmitted to endpoints, as will be described below. An “optional” capability is a message which is not required to be exchanged before setting up a conference. A “desired” capability is one which is not required that it be exchanged before setting up a conference, however, it is preferred that it is. A “required” capability is one which requires that a message be exchanged before setting up a conference. This may include access control or other messages which are transferred prior to setting up a conference. An access control capability may include the transmission of a account number and password prior to the commencement of a teleconference. A “negotiation message” is a capability which indicates that the application wishes to query the receiving application. In the case of a negotiation message capability, the type field associated with the capability allows the requests of information about the applications prior to the establishment of a conference (e.g. about the type of software and hardware components the application is interested in, such as sound). Any other types of exchanges which require negotiated information between applications may be set.
Once all individual capabilities have been set by the issuance of “Set Capabilities” API calls (e.g. MTConferenceSetCapabilities) to the conference component at step 702, a member may set its operating mode at step 704. The mode will be contained within a mode mask value which is sent in the API call to the conference component, and moreover, is included in certain messages transmitted from the conference component in the sender to the conference component in the receiver. The mode mask specifies the characteristics of a conference that the member makes available. Different capabilities, modes, and other initialization operations shown in
-
- 1. send media;
- 2. receive media;
- 3. shareable; and
- 4. joiner.
The “send media” mode flag indicates that the member intends to send media data in its conferences. Most members will want to send media, however, there will be instances where the member will be a receive-only member, thus the send media mode flag will not be set. The receive media mode flag indicates that the member intends to receive media in conferences. In the case of a send-only member (e.g., a server providing a real-time video and/or audio source), will have the receive media mode flag set to “off” (e.g., a numeric value ‘0’). The “shareable” mode flag indicates that the member is willing to share the conference media data with new conference members. Thus, in the instance of a send-only media server, the shareable mode flag would be set indicating that new members can receive the conference data.
The “joiner” mode flag indicates that all conference members are allowed to interact. This would allow two-way transmission between each of the conference members. However, the setting of this flag to “off” (e.g., a numeric value ‘0’) results in broadcast type conferences wherein one member sends media data to other conference members, but the individual conference members do not exchange any media data among themselves. Each of these mode flags is transmitted at the beginning of a connection (e.g., contained within the “hello” message 1400 in
By default, the conference component establishes conferences that are fully two-way media data capable, shareable, and joinable. If different characteristics are desired, then the application must call “set mode” (e.g. MTConferenceSetMode) at step 704, along with the appropriate flag(s) set. Conference mode settings are stored and associated with a particular conference ID in the sender's conference component so that when messages are created for that conference ID, the appropriate mode flags are transmitted along with the initialization or other messages sent before any other communications.
In addition to the capabilities and mode settings at steps 702 and 704, a time-out value associated with calls placed from the member may be set (e.g. using the API call MTConferenceSetTimeOut). The time-out value is then included at the beginning of certain messages preceding a conference in order to enable a recipient to determine when the caller will stop listening for responses. This allows certain features to be incorporated into participant conference components such as the smart triggering of events based upon context. For example, if the recipient is receiving a call, but a user does not wish to take the call at that time, the recipient's conference knows the time-out occurs and can take certain context-dependent action (e.g., forward the call, send a message, etc.).
The application can then invoke an API call “Listen for Call” (e.g. MTConferenceListen) which implements steps 708 and 710. At step 708, using the underlying transport to which the system is connected, a high level address is registered and published. This then allows other potential participants in the system to call the member. The registration and publication of the address is implementation-dependent, depending upon the media to which the system is connected. Then, at step 710, the conference component waits for incoming calls.
The conference component in the member enters an idle state wherein incoming messages, alerts for the transport component, API and calls will be detected and acted upon. Note that the capabilities, mode, and time-out values are all optional, and the default settings may be used by the member if none of these functions is required by the application. In the call to the MTConferenceListen function, the application must specify the networks on which the member is willing to accept calls. The conference component proceeds to register the member on those networks, doing whatever is appropriate in the various network contexts, and sends an mtListenerStatusEvent to the application to specify whether the registration attempt was successful. After listeners are operational, if another application desires to establish communication with the application, then an mtIncomingCallEvent is forwarded to the application.
As shown in
Conference components exchange a number of messages in order to establish, maintain, and terminate conferences. Conference components also send messages that encapsulate user data, that is, the data that is exchanged by the programs that are using the conference.
After establishing a transport connection but prior to establishing a conference channel with a remote system, a conference member may send either a Capabilities message 1300 or an Auxiliary message 1700. The member then sends a Hello message 1400 to identify itself, specifically its mode of operation (send media, receive media, shareable, or joiner) followed by a Call message 1500 (to set up a conference) or a Join message 1800 (to join to an ongoing conference). The remote member sends a Response message 1600 in answer to the Call or a Join message 1800. Once a conference is established, a member can combine calls or conferences by sending a Merge message 1900. Conference members may send or receive a Terminate message 2300 to end a conference. Connections initially are point-to-point between members of a conference. If the transport medium supports multicast addresses and more than one member is participating in a conference, a broadcast to a multicast address can be used as an optimization. The conference component uses the BroadcastRequest and BroadcastAck messages 2400 and 2500 to negotiate the transition from point-to-point to multipoint connections using multicast addresses.
All messages supported in the conference messaging protocol are preceded by a 2-byte character identifying the message type. For example for a capabilities message shown in
- capabilitiesList 1306
- The member's capabilities. This field is optional. If specified, it contains a list of the member's capablilities. An application specifies its capabilities by calling the conference component's MTConferenceSetMessageCapabilities function.
The Capabilities message 1300 shown in
In response to a negotiation Capabilities message, the remote member formats a user data message, for example, containing available component subtypes. Note that this list may contain duplicate entries and entries with a value of NULL. To parse this array, a member must determine the array's size. After sending a Capabilities message 1300, the member sends a Hello message 1400 to establish a conference.
A Hello message (e.g., 1400 of
- minimumVersion 1404
- The oldest version of the conference protocol supported by the sending component
- maximumVersion 1408
- The newest version of the conference protocol supported by the sending component.
- conferenceMode 1412
- The desired conference operating mode. This field contains a value that corresponds to the operating mode the sender desires for this conference. Applications specify their desired mode by a SetMode API call (e.g. MTConferenceSetMode discussed above).
- name 1416
- The name of the prospective conference member. This name identifies the entity that wants to join the conference, and may represent either an auxiliary data source or a new user. Applications specify a user name by calling the MTConferenceListen API call. The auxiliary name is specified in a MTAttachAuxiliary API call.
The Hello message 1400 is the first step in establishing a conference. This message allows conference components on different systems to exchange basic identification and capability information. Before sending a Hello message 1400, a conference component may send either a Capabilities 1300 or an Auxiliary message 1700. The type of message sent depends upon the role the member anticipates playing in the conference. If the member is looking to join or start a conference, the conference component sends a Capabilities message. If the member is setting up an auxiliary media data source, the component sends an Auxiliary message 1700. Following this message, the conference component can enter the call setup phase by sending the Call message 1500. If the member wants to provide an auxiliary data source to an existing conference, or join an existing conference, the component sends the Join message 1800.
Call message 1500 of
- callTime-out 1504
- The amount of time the calling component is willing to wait for an answer. This field specifies the number of ticks ( 1/60 of a second) the calling component will wait before deciding that the call has not been answered. Called components must respond within this time period. This value may be used by a potential responder for taking some automatic action if the user doesn't answer before the timeout.
- ConferenceName 1508
- The conference name. If the caller is establishing a conference, this is the name the caller has assigned to the conference. If the caller is connecting to a conference server, the is the name of the server's conference. Applications set the conference name by calling the MTConferenceCall function.
- callingConfID 1512
- The caller's unique conference identifier. This field uniquely identifies the caller's conference endpoint on the network. Conference components create conference identifiers on behalf of calling applications which are unique within the conference component. Call ID's are discussed with reference to 2200 of
FIG. 22 .
- The caller's unique conference identifier. This field uniquely identifies the caller's conference endpoint on the network. Conference components create conference identifiers on behalf of calling applications which are unique within the conference component. Call ID's are discussed with reference to 2200 of
The Call message 1500 shown in
The response message 1600 of
- callResponse 1604
- The result. This field indicates the result of the preceding Call request. This field is set to ‘0’ if the request was successful. Otherwise, it contains an appropriate result code.
- destinationConfID 1608
- The other endpoint's unique identifier. This field identifies the other participant in the conference.
The Response message 1600 allows the caller to determine the success of a Call or Join request. The Response message 1600 indicates how the user at the remote system reacted to the call (for example, whether the user answered the call). The callResponse field 1604 contains the request's result code. If non-zero, an error occurred and the request was not successful. Otherwise, the destinationConfID field 1608 identifies the endpoint with which the caller may now communicate.
- The other endpoint's unique identifier. This field identifies the other participant in the conference.
The auxiliary message 1700 allows one member to alert the other members of a conference that it is about to provide an auxiliary media data source (a source associated with an ongoing conference). This message may be used in place of the Capabilities message 1300 if a participant is being alerted about the presence of an auxiliary media source. The member sends this message before sending the Hello and Join Messages 1400 and 1800, and then proceeds to adding an auxiliary data source to the conference.
- parentConfID 1704
- The member's conference identifier. This field identifies the member's existing conference endpoint (the conference identifier the member supplied in the Call message when it first joined the conference). This allows other conference participants to identify the source of the auxiliary data within each participant.
The Auxiliary message 1700 informs other conference participants that a member is about to provide an auxiliary conference data source. For auxiliary data sources, this message replace the Capabilities message during early interactions. The member must send this message to each conference participant. The member then sends a Hello 1400 and a Join message 1800 to each participant. Other participants then accept the new data source by accommodating the Join request.
A Join message 1800 of
- destinationConf ID 1804
- The remote endpoint's unique conference identifier. This field identifies the conference to join on.
- callingConfID 1808
- Unique conference identifier. This field uniquely identifies the caller's conference endpoint on the network. Conference components create conference identifiers on behalf of calling applications. If the message is adding an auxiliary media data source, this is the auxiliary's identifier.
- memberList 1812
- A list of other conference participants. This list identifies all other known conference participants that are willing to exchange data with new participants (that is, they have the Joiner Mode Mask [e.g. mtJoinerModeMask] set in their conference mode). The conference component can connect with each participant with whom it is not already connected. If the message is adding an auxiliary (via the issuance of an auxiliary message 1700), this list contains the endpoint identifier of each participant to which the caller is making the auxiliary available. It is up to each of them to respond.
- This is a list of conference endpoint identifiers; each element in the list is followed by a newline character.
The Join message 1800 allows a member to add an auxiliary data source to an existing conference or to merge two existing conferences. The caller sends this message to members of the conference in response to a merge or join request instead of a call message.
The Merge message 1900 of
- conferenceName 1904
- The new conference name resulting from the merge. This is the name that was assigned to the conference when the conference was established. Applications specify the conference name by calling the MTConferenceCall API function.
- myConfID 1908
- Unique conference identifier. This field uniquely identifies the caller's conference endpoint in the target conference. Conference components create conference identifiers on behalf of calling applications.
- memberList 1912
- A list of other conference participants. This list identifies other current conference participants. This list contains the endpoint identifier of each new participant. This is a list of conference endpoint identifiers; each element in the list is followed by a newline character.
The Merge message causes the combination of two conferences. This is the mechanism for creating conferences with more than two participants. The caller sends this message to each existing conference member, specifying the conference's name. Each endpoint establishes communications with any new endpoints. By convention, the endpoint with the higher conference identifier value establishes the connection (to avoid duplicate or missed connections). Members of the conference receive a Join message 1900 instead of a Call message 1500 when contacted by each new member.
Field SpecificsA capabilities list such as shown in
- type 2002
- Identifies a message by reference to a unique type value.
- version 2006
- Message version number. Specifies the most-recent version of the message that the application supports.
- desires 2010
- Support level. This field indicates the level of support required by the application. Possible values are:
- mtMessageOptionalCapability
- Optional. Indicates that the message is optional. The value corresponding to this option is ‘O’.
- mtMessageDesiredCapability
- Desired. While still optional, this value indicates that the application prefers to receive this message early in the call (e.g. prior to establishing a call, one member may request that the recipient send his business card for long-term storage). The value corresponding to this option is ‘D’.
- mtMessageRequiredCapability
- Required. The application must receive this message. The value corresponding to this option is ‘R’.
- mtNegotiationMessageCapability
- Negotiate. The application wants to learn about the recipient's facilities. The value corresponding to this option is ‘N’.
- mtMessageOptionalCapability
- Support level. This field indicates the level of support required by the application. Possible values are:
Conference identifiers such as 2200 shown in
- UniqueID 2202
- Unique numeric identifier. This field contains a unique numeric endpoint identifier. Each conference component assigns its own identifiers in order to guarantee uniqueness within the context of a given name specified in the name field 2206.
- name 2206
- A unique name. Identifies the system on the network. The name is unique within the context of a given transport interface. It includes the type of the selected transport and network interface.
A member list such as 1812 of
The Terminate message 2300 of
The Terminate message 2300 is the last step in ending a member's participation in a conference. This message ends the member's conference communication with all participants to which it sends the message. If a member is leaving a conference altogether, it must send this message to each conference participant.
The BroadcastRequest message 2400 allows a member to find out if another conference member can accept broadcast (multicast) messages.
- subtype 2406
- The broadcast message subtype. This field must be set to ‘R’.
- multicastAddress 2410
- The proposed multicast address. This field contains the multicast address on which the member proposes to send broadcast messages.
The BroadcastRequest message 2400 allows a member to determine whether another conference member can accept broadcast messages over a given multicast network address. The recipient indicates its ability to support the broadcast messages by sending a BroadcastAck message 2500 (described below). If the recipient cannot support broadcast messaging or cannot access this particular broadcast transmission, the calling member should continue to send point-to-point messages to the recipient.
The BroadcastRequest message 2400 is typically uses as part of the negotiation process that follows merging two conferences or the joining of any new members to a conference. As an optimization, conference participants may choose to set up broadcast capabilities as a more-efficient alternative to maintaining several different point-to-point connections.
The BroadcastAck message 2500 allows a member to respond to a BroadcastRequest message 2400.
- subtype 2504
- The broadcast message subtype. This field must be set to ‘A’.
- broadcastResponse 2508
- The result. This field indicates whether the member can support the multicast address proposed in the BroadcastRequest message 2500.
The BroadcastAck message 2500 allows a member to indicate whether it can receive messages over a proposed multicast address. Another conference participant proposes a multicast address by sending a BroadcastRequest message 2408. If the recipient can support that address, it sets the broadcastResponse field 2508 to ‘0’. Otherwise, the broadcastResponse field 2580 contains an appropriate non-zero result code. This message is typically used as part of the negotiation process that follows merging two conferences. As an optimization, conference participants may choose to set up broadcast capabilities as a more-efficient alternative to maintaining several different point-to-point connections.
Join operations have the protocol illustrated in
The merge membership function 2664 is shown in more detail in
Merge operations are initiated using a “Merge” message (e.g., 1900 of
In addition to using conference ID's for performing merge and subsequent join operations, contained within each Merge and Join message is a list of members of the conferences being merged or joined. These are included in the memberList fields 1812 or 1912 of messages 1800 or 1900. For example, due to propagation delays in a networking system, old conference ID's may still exist in peripheral participants, and therefore during merging and or joining operations, conference ID's may become invalid due to members merging conferences, etc. . . . , or reference conference ID's which no longer exist. Thus, contained within each conference component in a member is a current conferences table such as 2900 shown in
An auxiliary media source can become part of an ongoing conference. The media source is associated with an ongoing conference by a invoking reference to the main conference stored in each conference component (e.g. by the API call MTConferenceAttachAuxiliarySource), however, it is treated as a separate conference in each conference component. For example, as illustrated with reference to
An example session using the protocols described above is shown in
Subsequent to the exchange of capabilities, hello, and call and response, a merge message 3514 is received by the first endpoint including the conference name “Some Conference”, a conf ID=137 “mtlkatlk Hillary Rodham: Video Phone: Video Zone” and a member list. The endpoint then processes the merge, placing a call sending capabilities, and hello to a member of the old conference, and a join along with the member list as shown by messages 3516, 3518, and 3520. Once the connection has been established, capabilities and hello messages 3524 and 3526 are received from the recipient. Responsive to the join the recipient sends a response message 3528 with the result=0 (request successful). Subsequent thereto, the endpoint then attempts to use a multicast address by transmitting broadcast request messages 3530 and 3532. The other members respond with broadcast Acks 3534 and 3536, allowing the use of multicast. The conference can then be terminated at any time by any of the members via the transmission of terminate messages to all of the members, such as 3538 and 3540.
Thus, by use of the foregoing, connections between endpoints, such as for teleconferences between teleconferencing systems, can be enabled. This includes, but is not limited to, the exchange of capabilities and notification of connections between endpoints, the addition of auxiliary data streams to such connections, and the merging of existing connections. It will be appreciated that though the foregoing has been described especially with reference to
Claims
1. In a system wherein a first endpoint is providing data to a plurality of second endpoints each connected by a point-to-point communication channel with said first endpoint, an automatic method for optimizing the transmission of said data to said plurality of second endpoints comprising the following steps:
- a. said first endpoint activating a multicast communication channel having a first multicast address and commencing broadcast of said data over said multicast communication channel;
- b. Said first endpoint transmitting a request message to each of said plurality of second endpoints in order to query each of said second endpoints whether they can receive transmissions broadcast to said first multicast address;
- c. certain of said plurality of second endpoints transmitting an acknowledgment message and said first endpoint receiving said acknowledgment message;
- d. for each said acknowledgment message received from said certain of said plurality of second endpoints which indicates that said certain of said plurality of second endpoints can receive transmissions broadcast to said first multicast address, deactivating said point-to-point communication channel with said first endpoint and said certain of said plurality of second endpoints; and
- e. terminating said broadcast of said data and said multicast communication channel if at least two of said plurality of second endpoints do not transmit said acknowledgment messages containing a positive acknowledgment.
2. The method of claim 1 further comprising the step of receiving detach messages from certain of said plurality of second endpoints, and if at least two of said plurality of second endpoints are not receiving said data, then terminating said broadcast of said data and said multicast communication channel.
3. The method of claim 1 wherein said each acknowledgment message includes a response code.
4. The method of claim 3 wherein said response code indicates whether each said certain of said plurality of second endpoints can receive transmissions broadcast to said first multicast address.
5. The method of claim 1 wherein said data includes teleconference data.
6. The method of claim 1 further comprising, prior to said step of said first endpoint activating said multicast communication channel having a first multicast address, determining whether more than one of said plurality of second endpoints is coupled to said first endpoint on a single communication medium, and if not, aborting said method.
7. The method of claim 6 further comprising, prior to said first endpoint activating said multicast communication channel having said first multicast address, determining whether said single communication medium supports broadcasting to said first multicast address.
8. The method of claim 1 wherein said data includes teleconference data between said first endpoint and said plurality of second endpoints.
9. An apparatus in a first endpoint for transmitting data to a plurality of second endpoints receiving said data from said first endpoint on point-to-point communication channels comprising:
- a. a circuit for activating a multicast communication channel having a first multicast address and commencing broadcast of said data over said multicast communication channel;
- b. a circuit for transmitting a request message to each of said plurality of second endpoints in order to query each of said second endpoints whether they can receive transmissions broadcast to said first multicast address;
- c. a circuit for receiving acknowledgment messages, if any, from certain of said plurality of second endpoints;
- d. a circuit for deactivating each said point-to-point communication channel with said certain of said plurality of second endpoints responsive to receiving each said acknowledgment message; and
- e. a circuit for terminating said broadcast of said data and said multicast communication channel if at least two of said acknowledgment messages containing a positive acknowledgment are not received.
10. The apparatus of claim 9 further comprising a circuit for receiving detach messages from others of said plurality of second endpoints, and if at least two of said plurality of second endpoints are not receiving said data, then terminating said broadcast of said data and said multicast communication channel.
11. The apparatus of claim 9 wherein said each acknowledgment message includes a response code.
12. The apparatus of claim 11 wherein said response code indicates whether each of said certain of said plurality of second endpoints can receive transmissions broadcast to said first multicast address.
13. The apparatus of claim 9 wherein said data includes teleconference data.
14. The apparatus of claim 9 further comprising a detection circuit operative prior to said first endpoint activating said multicast communication channel having said first multicast address for determining whether more than one of said plurality of second endpoints is coupled to said first endpoint on a single communication medium, and if not, not activating said circuits b and c.
15. The apparatus of claim 14 further comprising, prior to activation of said detection circuit a circuit for determining whether said single communication medium supports broadcasting to said first multicast address.
16. In a system wherein a first endpoint is providing data to a plurality of second endpoints each connected by a point-to-point communication channel with said first endpoint, an automatic method for optimizing the transmission of said data to said plurality of second endpoints comprising the following steps:
- a. said first endpoint activating a multicast communication channel having a first multicast address and commencing broadcast of said data over said multicast communication channel;
- b. said first endpoint transmitting a multicast transmission to each of said plurality of second endpoints in order to query each of said second endpoints whether they can receive transmissions broadcast to said first multicast address;
- c. certain of said plurality of second endpoints transmitting an acknowledgement message;
- d. for each said acknowledgement message received from said certain of said plurality of second endpoints which indicates that said certain of said plurality of second endpoints can receive transmissions broadcast to said first multicast address, deactivating said point-to-point communication channel with said first endpoint and said certain of said plurality of second endpoints; and
- e. terminating said broadcast of said data and said multicast communication channel if at least two of said plurality of second endpoints do not transmit said acknowledgment messages containing a positive acknowledgment.
17. In a system wherein a first entity and a plurality of second entities in a network are operating in a point-to-point mode, with each of said second entities connected by a point-to-point communication channel with said first entity, an automatic method for optimizing a mode of transmission of data between said plurality of second entities and said first entity, the method comprising the following steps:
- a. said first entity transmitting a multicast transmission to said plurality of second entities over a multicast communication channel, said multicast transmission being used to initiate transition from said point-to-point mode to a multicast mode;
- b. receiving from certain of said plurality of second entities an acknowledgment message, said acknowledgement message indicating that corresponding ones of said certain of said plurality of entities was able to receive said multicast transmission;
- c. for each said acknowledgment message received from said certain of said plurality of second entities which indicates that said corresponding ones of said certain of said plurality of second entities can receive said multicast transmission, deactivating said point-to-point communication channel between said first entity and said corresponding ones of said certain of said plurality of second entities; and
- d. terminating said multicast communication channel if at least two of said plurality of second entities do not transmit said acknowledgment messages containing a positive acknowledgment.
18. The method of claim 17, wherein said each acknowledgment message includes a response code.
19. The method of claim 18, wherein said response code indicates whether each of said certain of said plurality of second entities can perform an action requested in the request message.
20. The method of claim 17, wherein said data comprises audio data and video data.
21. The method of claim 17, further comprising operating each of said certain of said plurality of second entities in a multicast mode.
22. The method of claim 17, further comprising, for any of said plurality of second entities which do not send an acknowledgement, continuing to operate said first entity in a point-to-point mode with such non-acknowledging second entities.
23. The method of claim 17, further comprising retrieving, using said first entity, a multicast address which is used for said act of transmitting the request message.
24. The method of claim 17, further comprising, prior to said step of transmitting, determining whether a same communication medium couples each of said plurality of second entities to said first entity.
25. The method of claim 17, further comprising said first entity transmitting a first message comprising capabilities of said first entity to at least a portion of said plurality of second entities.
26. The method of claim 25, further comprising said at least a portion of said second entities transmitting a second message comprising respective capabilities of said at least a portion of said second entities to said first entity substantially in response to said first entity transmitting said first message.
27. The method of claim 26, wherein said first message from said first entity, and said second messages from said respective ones of said at least a portion of said plurality of second entities, are both transmitted before said act of transmitting the request message.
28. The method of claim 26, wherein said first message from said first entity, and said second messages from said respective ones of said at least a portion of said plurality of second entities, are both transmitted before establishing said point-to-point mode.
29. An apparatus for optimizing a mode of transmission of data between a first entity and a plurality of second entities in a network, said network capable of operating in a point-to-point mode, with each of said second entities connected by a point-to-point communication channel with said first entity, the apparatus comprising:
- a. a first apparatus configured to transmit a multicast transmission to said plurality of second entities over a multicast communication channel, said multicast transmission being used to initiate transition from said point-to-point mode to a multicast mode;
- b. a second apparatus in data communication with said first apparatus and configured to receive from certain of said plurality of second entities an acknowledgment message, said acknowledgement message indicating that corresponding ones of said certain of plurality of second entities was able to receive said multicast transmission;
- c. a third apparatus in data communication with said second apparatus and configured so that, for each said acknowledgment message received from said certain of said plurality of second entities which indicates that said corresponding ones of said certain of said plurality of second entities can receive said multicast transmission, said point-to-point communication channel between said first entity and said corresponding ones of said certain of said plurality of second entities is deactivated; and
- d. a fourth apparatus in data communication with said third apparatus and configured so that, if at least two of said plurality of second entities do not transmit said acknowledgment messages containing a positive acknowledgment, said multicast communication channel is terminated.
30. In a system wherein a first entity and a plurality of second entities in a network are operating in a point-to-point mode, with each of said second entities connected by a point-to-point communication channel with said first entity, an automatic method for changing a mode of transmission of data between said plurality of second entities and said first entity, the method comprising the following steps:
- a. said first entity transmitting a multicast transmission to said plurality of second entities over a multicast communication channel, said multicast transmission being used to initiate transition from said point-to-point mode to a multicast mode;
- b. said first entity receiving from certain of said plurality of second entities an acknowledgment message, said acknowledgement message indicating that corresponding ones of said certain of said plurality of entities was able to receive said multicast transmission;
- c. for each said acknowledgment message received from said certain of said plurality of second entities which indicates that said corresponding ones of said certain of said plurality of second entities can receive said multicast transmission, transitioning communications between said first entity and said corresponding ones of said certain of said plurality of second entities from said point-to-point mode to said multicast mode; and
- d. terminating said multicast communication channel if at least two of said plurality of second entities do not transmit said acknowledgment messages containing a positive acknowledgment.
31. The method of claim 30, wherein said each acknowledgment message includes a response code.
32. The method of claim 31, wherein said response code indicates whether each of said certain of said plurality of second entities can perform an action requested in the request message.
33. The method of claim 30, wherein said data comprises audio data and video data.
34. The method of claim 30, further comprising operating each of said certain of said plurality of second entities in a multicast mode.
35. The method of claim 30, further comprising, for any of said plurality of second entities which do not send an acknowledgement, continuing to operate said first entity in a point-to-point mode with such non-acknowledging second entities.
36. The method of claim 30, further comprising retrieving, using said first entity, a multicast address which is used for said act of transmitting the request message.
37. The method of claim 30, further comprising, prior to said step of transmitting, determining whether a same communication medium couples each of said plurality of second entities to said first entity.
38. The method of claim 30, further comprising said first entity transmitting a first message comprising capabilities of said first entity to at least a portion of said plurality of second entities.
39. The method of claim 38, further comprising said at least a portion of said second entities transmitting a second message comprising respective capabilities of said at least a portion of said second entities to said first entity substantially in response to said first entity transmitting said first message.
40. The method of claim 39, wherein said first message from said first entity, and said second messages from said respective ones of said at least a portion of said plurality of second entities, are both transmitted before said act of transmitting the request message.
41. The method of claim 40, wherein said first message from said first entity, and said second messages from said respective ones of said at least a portion of said plurality of second entities, are both transmitted before establishing said point-to-point mode.
42. An apparatus for automatically changing a mode of transmission of data between a first entity and a plurality of second entities in a network, said network being capable of operating in a point-to-point mode, with each of said second entities connected by a point-to-point communication channel with said first entity, the apparatus comprising:
- a. a first apparatus configured to transmit a multicast transmission to said plurality of second entities over a multicast communication channel, said multicast transmission being used to initiate transition from said point-to-point mode to a multicast mode;
- b. a second apparatus in data communication with said first apparatus and configured to receive from certain of said plurality of second entities an acknowledgment message, said acknowledgement message indicating that corresponding ones of said certain of said plurality of entities was able to receive said multicast transmission;
- c. a third apparatus in data communication with said second apparatus and configured to, for each said acknowledgment message received from said certain of said plurality of second entities which indicates that said corresponding ones of said certain of said plurality of second entities can receive said multicast transmission, transition communications between said first entity and said corresponding ones of said certain of said plurality of second entities from said point-to-point mode to said multicast mode; and
- d. a fourth apparatus in data communication with said third apparatus and configured to, if at least two of said plurality of second endpoints do not transmit said acknowledgment messages containing a positive acknowledgment, terminate said multicast communication channel.
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Type: Grant
Filed: Dec 7, 2001
Date of Patent: Jun 7, 2011
Assignee: Apple Inc. (Cupertino, CA)
Inventor: Guy G. Riddle (Los Gatos, CA)
Primary Examiner: Kenny S Lin
Attorney: Fenwick & West LLP
Application Number: 10/020,515
International Classification: G06F 15/16 (20060101);
