Managing a message subscription in a publish/subscribe messaging system

• US 8,954,504 B2
• Filed: 05/22/2012
• Issued: 02/10/2015
• Est. Priority Date: 05/18/2011
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Banks, Andrew D., Beardall, Gavin D., Dick, Adrian D., Homewood, Brian C.
• Primary Examiner(s): Hussain, Tauqir
• Application Number:
  US13/477,249
• Publication Number:
  US 20130138737A1
• Time in Patent Office: 994 Days
• Field of Search: 709/204
• US Class Current: 709/204
• CPC Class Codes: H04L 51/00 User-to-user messaging in packet-switching networks, transmitted according to store-and-forward or real-time protocols, e.g. e-mail
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]

Abstract

A method and computer program product is disclosed for managing a message broker and subscriber application programs in a publish/subscribe messaging system so as to maintain the state of the subscriber application program on the broker subscriber application program.

Claims

1. A method for managing a message subscription in a message subscription application program of a publish/subscribe messaging system, the method comprising:

subscribing, via a message subscriber, to a subscription provided in parallel by each of a set of message brokers, said subscription comprising a common sequence of messages, each common message being associated with a common sequential message identifier (SMI);

retrieving a message from a selected one of said message brokers and triggering a saving of the associated common SMI for said subscription at said message broker;

in response to a restart of said message subscriber, determining whether all of said message brokers are available, and when all of said message brokers are not available, reverting to said set of message brokers to determine a latest saved SMI for said subscription at any one of said message brokers; and

resuming said subscription by requesting a subsequent message associated with said latest saved SMI, from a selected one of said message brokers.

2. The method according to claim 1 comprising:

in response to said resuming of said subscription from said selected message broker, instructing each of the remaining message brokers in said set to discard any queued message in said sequence prior to and including the message associated with said determined latest saved SMI.

3. The method according to claim 1, wherein acknowledgement of a receipt of a given message triggers the saving of said associated common SMI.

4. The method according to claim 1, wherein said messages are requested in sequence from each broker in turn in accordance with a predetermined protocol.

5. The method according to claim 4, in which said protocol is a round robin protocol.

6. A method for managing a message subscription in a message broker application program of a publish/subscribe messaging system, the method comprising:

subscribing, via a set of message brokers, to a subscription provided in parallel in response to a subscription request from a message subscriber, said subscription comprising a common sequence of messages, each common message being associated with a common sequential message identifier (SMI);

sending a message to said message subscriber and recording the associated common SMI in association with said subscription at said message broker;

in response to a restart of said message subscriber, determine whether all of said message brokers are available, and when all of said message brokers are not available, determine a latest saved SMI for said subscription at any one of said message brokers; and

sending said associated common SMI to said message subscriber in response to a request therefrom.

7. The method according to claim 6, further comprising:

in response to a request for a subsequent message to a given SMI, sending said subsequent message.

8. The method according to claim 7, further comprising:

in response to said sending of said subsequent message, discarding said subsequent message and any queued prior messages in said sequence.

9. The method according to claim 6, wherein said sending of said message to said message subscriber and said recording of said associated common SMI for said subscription are performed in a single unit of work.

10. The method according to claim 6, wherein said associated common SMI is saved to persistent storage.

11. A computer program product comprising;

a computer readable storage medium; and

computer usable code stored in the computer readable storage medium, wherein if executed by a processor, the computer usable code causes a computer to;

subscribe to a subscription provided in parallel by each of a set of message brokers, said subscription comprising a common sequence of messages, each common message being associated with a common sequential message identifier (SMI);

retrieve a message from a selected one of said message brokers and triggering a saving of the associated common SMI for said subscription at said message broker;

in response to a restart of said message subscriber, determine whether all of said message brokers are available, and when all of said message brokers are not available, revert to said set of message brokers to determine a latest saved SMI for said subscription at any one of said message brokers; and

resume said subscription by requesting a subsequent message associated with said latest saved SMI, from a selected one of said message brokers.

12. The computer program product according to claim 11 wherein if executed, the computer usable code further causes a computer to:

in response to said resuming of said subscription from said selected message broker, instruct each of the remaining message brokers in said set to discard any queued message in said sequence prior to and including the message associated with said determined latest saved SMI.

13. The computer program product according claim 11, wherein acknowledgement of a receipt of a given message triggers the saving of said associated SMI.

14. The computer program product according to claim 11, wherein said messages are requested in sequence from each broker in turn in accordance with a predetermined protocol.

15. The computer program product according to claim 14, in which said protocol is a round robin protocol.

16. A computer program product comprising;

a computer readable storage medium; and

computer usable code stored in the computer readable storage medium, wherein if executed by a processor, the computer usable code causes a computer to;

subscribe to a subscription in response to a subscription request from a message subscriber, said subscription comprising a common sequence of messages, each common message being associated with a common sequential message identifier (SMI);

send a message to said message subscriber and recording the associated common SMI in association with said subscription at said message broker;

in response to a restart of said message subscriber, determine whether all of said message brokers are available, and when all of said message brokers are not available, determine a latest saved SMI for said subscription at any one of said message brokers; and

send said associated common SMI to said message subscriber in response to a request therefrom.

17. The computer program product according to claim 16 wherein if executed, the computer usable code causes a computer to:

in response to a request for a subsequent message to a given SMI, send said subsequent message.

18. The computer program product according to claim 17 wherein if executed, the computer usable code causes a computer to:

in response to said sending of said subsequent message, discard said subsequent message and any queued prior messages in said sequence.

19. The computer program product according to claim 16, wherein said sending of said message to said message subscriber and said recording of said associated common SMI for said subscription are performed in a single unit of work.

20. The computer program product according to claim 16, wherein said associated common SMI is saved to persistent storage.