Reliable multicast with automatic session startup and client backfil support

• US 20090003342A1
• Filed: 06/27/2007
• Published: 01/01/2009
• Est. Priority Date: 06/27/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Sadler, Jeremy, Yaqoob, Asad, Syed, Saad, Abdelhalim, Alaa H., Dickens, Christopher Scott
• Granted Patent: US 8,018,933 B2
• Time in Patent Office: Days
• US Class Current: 370/390
• CPC Class Codes: H04L 12/185 with management of multicast group membership

Abstract

A form of multicast, referred to as “on-demand multicast,” provides a methodology that allows for “on demand” multicasting of data. On-demand multicast allows clients to join or leave a transmission at any point. There is no transmission session start or end time—the session is continuously available, although data is not necessarily continuously transmitted. Data blocks missed by late-joining clients are retransmitted per amalgamated client requests through multiple transmission cycles until all clients that have joined the transmission session receive all content. Once a client has received all data blocks comprising the content for the session, the client may exit the ongoing session.

Claims

1. A method on a computer server for multicasting data to a number of client devices comprising

receiving a number of requests from one or more requesting client devices for respective blocks of a set of data;

if there is no current transmission session corresponding to the requests,

creating a transmission session of the blocks of the data set;

joining the requesting client devices to the transmission session; and

transmitting the blocks to the requesting client devices;

if there is a current transmission session corresponding to the requests,

allowing additional requesting client devices to join the transmission session; and

continuing the transmission session until all requests from any joined client devices are satisfied.

2. The method of claim 1 further comprising

configuring parameters for the transmission session of the data set;

determining, based upon the parameters, whether and how the client devices can join the transmission session; and

transmitting authorizations to the requesting client devices allowing the requesting client devices to join the transmission session.

3. The method of claim 1 further comprising transmitting a value to the requesting client devices indicating a number of the blocks in the data set.

4. The method of claim 3 further comprising

polling the joined client devices at the end of a transmission cycle to determine whether all requests have been satisfied;

and

receiving updated requests from the joined client devices indicating which of the number of blocks the joined clients devices did not receive; and

wherein

the transmitting operation continues the transmission session by transmitting the blocks not previously received in a further transmission cycle.

5. The method of claim 4, wherein the transmission cycle ends upon completion of transmission of blocks of the data set corresponding to an initial request or any updated requests.

6. The method of claim 4 further comprising amalgamating the updated requests to determine which of the number of blocks to transmit in the further transmission cycle.

7. The method of claim 4, wherein the transmitting operation transmits the blocks not previously received according to a prioritization scheme for determining a transmission order for the blocks in the further transmission cycle.

8. The method of claim 1, wherein the transmitting operation transmits the blocks of the data set in a non-sequential order.

9. The method of claim 1 further comprising

receiving a request from one or more of the client devices for blocks of a second set of data;

and

creating a second transmission session of the blocks of the second data set according to the operations of claim 1.

10. A computer-readable medium having computer-executable instructions for performing a computer process implementing a multicasting session on a computer server, the instructions comprising causing the computer server to

acknowledge a number of requests from one or more requesting client devices for respective blocks of a set of data;

if there is no current transmission session corresponding to the requests,

create a transmission session of the blocks of the data set;

join the requesting client devices to the transmission session; and

transmit the blocks to the requesting client devices;

if there is a current transmission session corresponding to the requests,

join additional requesting client devices the transmission session; and

continue the transmission session until all requests from any joined client devices are satisfied.

11. The computer-readable medium of claim 10 further comprising instructions for causing the computer server to

configure parameters for the transmission session of the data set;

determine, based upon the parameters, whether and how the client devices can join the transmission session; and

transmit authorizations to the requesting client devices allowing the requesting client devices to join the transmission session.

12. The computer-readable medium of claim 10 further comprising instructions for causing the computer server to transmit a value to the requesting client devices indicating a number of the blocks in the data set.

13. The computer-readable medium of claim 12 further comprising instructions for causing the computer server to

poll the joined client devices at the end of a transmission cycle to determine whether all requests have been satisfied;

acknowledge updated requests from the joined client devices indicating which of the number of blocks the joined clients devices did not receive; and

continue the transmission session by transmitting the blocks not previously received in a further transmission cycle.

14. The computer-readable medium of claim 13 further comprising instructions for causing the computer server to end each transmission cycle upon completion of transmission of blocks of the data set corresponding to an initial request or any updated requests.

15. The computer-readable medium of claim 13 further comprising instructions for causing the computer server to amalgamate the updated requests to determine which of the number of blocks to transmit in the further transmission cycle.

16. The computer-readable medium of claim 13 further comprising instructions for causing the computer server to transmit the blocks not previously received according to a prioritization scheme for determining a transmission order for the blocks in the further transmission cycle.

17. The computer-readable medium of claim 10 further comprising instructions for causing the computer server to transmit the blocks of the data set in a non-sequential order.

18. A method on a client computer device for receiving multicast data comprising

sending a request to an on-demand multicast server to receive a set of data;

receiving an authorization to join a transmission session transmitting the data set;

receiving a value indicating a number of blocks in the data set;

sending a request to join the transmission session;

receiving one more of the blocks in a transmission cycle;

responding to a poll by requesting a subset of the blocks not received in the transmission cycle.

19. The method of claim 18 further comprising exiting the transmission session upon receipt of all subsets of the data set.

20. A computer readable medium having computer-executable instructions for performing a computer process according to the method of claim 18.