Urgent replication facility

• US 6,412,017 B1
• Filed: 07/01/1996
• Issued: 06/25/2002
• Est. Priority Date: 07/01/1996
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Contorer, Aaron M., Straube, Dave D., Miller, Arnold S., Misra, Pradyumna K., Raman, Balan S., Seaman, Michael R. C.
• Primary Examiner(s): Oberley, Alvin E.
• Assistant Examiner(s): LAO, SUE X
• Application Number:
  US08/673,929
• Time in Patent Office: 2,185 Days
• Field of Search: 395/712, 395/683, 395/619, 395/617, 707/201, 707/203, 707/511, 707/202, 709/206, 709/207, 709/313, 709/315, 717/170
• US Class Current: 719/313
• CPC Class Codes: G06F 16/1844 Management specifically adapted to replicated file systems
• CPC Class Codes: G06F 9/54 Interprogram communication

Abstract

A system and method for expediting the replication of at least one specified object to a replica in a distributed computer system. A source object of a source replica determines that it has an urgent change to propagate through the distributed system, and informs a replication facility at the source replica of the urgent change. The facility extracts, or is provided with, the change information from that object, and the source replica communicates information representative of the change to a destination replica. A replication facility at the destination replica provides the change information to a destination replica object, which uses the information to make itself consistent with the source replica object.

Claims

1. In a distributed computer system, a method of expediting the replication of a source object in a source computer to a destination replica object in a destination replica in the system wherein the state of the source object has changed from a first to a second state, comprising the steps of:

notifying a source replication facility that the source object has changed state,

requesting, by the source replication facility in response to the notifying step, a difference generated with regard to the source object changed state and receiving the difference,

transmitting, by the source replication facility, the difference to the destination replica,

receiving, by the destination replica, the transmitted difference,

applying, by the destination replica, the difference to the destination replica object, and

assigning an urgency value to the change in the source object state, and sending the urgency value to the source replication facility, wherein the source replication facility delays for a time interval having a duration corresponding to the urgency value of the change before requesting or transmitting the difference.

2. The method of claim 1, further comprising the step of applying the difference to the destination replica object such that the destination replica object is consistent with the changed source object.

3. The method of claim 1, wherein the step of notifying the source replication facility includes invoking a method of a replication framework.

4. The method of claim 1, wherein the step of transmitting the difference includes a duplication of the entire source object.

5. The method of claim 1, wherein the step of requesting the difference comprises the source object generating differencing information.

6. The method of claim 1, further comprising the step of:

the source replication facility reassigning the urgency value of the change, wherein the source replication facility uses the reassigned urgency value in determining the duration of the time interval.

7. The method of claim 1, further comprising the steps of:

transmitting information to a second destination replica corresponding to the change to the source object;

receiving the transmitted information at the second destination replica;

extracting the change information from the received information at the second destination replica; and

providing the change information to a replica object of the second destination replica.

8. The method of claim 1, further comprising the steps of:

extracting destination change information from the replica object of the destination replica;

transmitting information to a second destination replica corresponding to the destination change information;

receiving the transmitted information at the second destination replica;

extracting the change information from the received information at the second destination replica;

providing the change information to a replica object of the second destination replica; and

applying the destination change information to a destination replica object.

10. The method of claim 1, further comprising the steps of:

when communication between the source and the destination is unavailable, storing the received information and a received timestamp value;

then after communication between the source and the destination becomes available, and if the received information corresponds to a relatively recent change, then expediting the replication of the object which has changed at the source.

25. The method of claim 1 wherein the source object initiates the notifying step.

9. In a system of distributed computers, a system for expediting the replication of a source object which has changed at a source node to a counterpart object at a destination node, comprising:

signaling means associated with the source object for initiating generating a signal at the source node indicating that the source object at the source node has changed and assigning an urgency value to the change with respect to a predetermined criteria, and wherein the urgency value indicates changes as either urgent or non-urgent, and wherein urgent changes are pushed to the destination and non-urgent changes are pulled from the source,

a control means connected to the signaling means for receiving the signal generated by the signaling means and in response communicating to request information representative of the change to the source object, and to receive the change information,

a data communication mechanism at the source node connected to a data communication mechanism at the destination node for communicating information, representative of the change to the source object, from the source node to the destination node, and

means at the destination node for applying the received change information to the counterpart object at the destination node such that the counterpart object at the destination node is consistent with the changed source object at the source node.

26. The system of claim 9 wherein the source object comprises the signaling means.

11. In a distributed computer system, a method of expediting the replication of changes to at least one source object in a source to a destination replica in the system wherein the state of the source object has changed, comprising the steps of:

recognizing a change in state of a source object;

first notifying a source replication facility that the source object has changed and providing a value reflecting the urgency of the change,

second notifying the destination replica that the source object has changed and the urgency of the change,

transmitting from the destination replica to the source a request for change information after a time interval whose duration varies as a function of the value of the urgency of the change,

extracting change information at the source from the source object representative of the change to the source object wherein the source object generates the change information,

transmitting information from the source to the destination, the transmitted information including the extracted change information,

receiving the transmitted information at the destination replica,

extracting the change information from the received information, and

providing the change information to a replica object of the destination.

12. The method of claim 11, wherein the time interval is substantially zero.

27. The method of claim 11 wherein the source object initiates the first notifying step.

13. A computer-readable medium having computer-executable instructions for a method of expediting the replication of a source object in a source computer to a destination replica object in a destination replica in the system wherein the state of the source object has changed from a first to a second state, the method steps comprising:

notifying a source replication facility that the source object has changed its state,

requesting, by the source replication facility in response to the notifying step, a difference generated with regard to the source object changed state and receiving the difference,

transmitting, by the source replication facility, the difference to the destination replica,

receiving, by the destination replica, the transmitted difference,

applying, by the destination replica, the difference to the destination replica object, and

assigning an urgency value to the change in the source object state, and sending the urgency value to the source replication facility, wherein the source replication facility delays for a time interval having a duration corresponding to the urgency value of the change before requesting or transmitting the difference.

14. The computer-readable medium of claim 13, further comprising computer-executable instructions for performing the step of applying the difference to the destination replica object such that the destination replica object is consistent with the changed source object.

15. The computer-readable medium of claim 13, wherein the step of notifying the source replication facility includes invoking a method of a replication framework.

16. The computer-readable medium of claim 13, wherein the step of transmitting the difference includes a duplication of the entire source object.

17. The computer-readable medium of claim 13, wherein the step of requesting the difference comprises the source object generating differencing information.

18. The computer-readable medium of claim 13, further comprising computer-executable instructions for performing the step of:

the source replication facility reassigning the urgency value of the change, wherein the source replication facility uses the reassigned urgency value in determining the duration of the time interval.

19. The computer-readable medium of claim 13, further comprising computer-executable instructions for performing the steps of:

transmitting information to a second destination replica corresponding to the change to the source object;

receiving the transmitted information at the second destination replica;

extracting the change information from the received information at the second destination replica; and

providing the change information to a replica object of the second destination replica.

20. The computer-readable medium of claim 13, further comprising computer-executable instructions for performing the steps of:

extracting destination change information from the replica object of the destination replica;

transmitting information to a second destination replica corresponding to the destination change information;

receiving the transmitted information at the second destination replica;

extracting the change information from the received information at the second destination replica;

providing the change information to a replica object of the second destination replica; and

applying the destination change information to a destination replica object.

21. The computer-readable medium of claim 13, further comprising computer-executable instructions for performing the steps of:

when communication between the source and the destination is unavailable, storing the received information and a received timestamp value;

then after communication between the source and the destination becomes available, and if the received information corresponds to a relatively recent change, then expediting the replication of the object which has changed at the source.

28. The computer-readable medium of claim 13 wherein the source object initiates the notifying step.

29. The computer-readable medium of claim 28 wherein the source object comprises the signaling means.

22. A computer-readable medium having computer-executable instructions for a system for expediting the replication of a source object which has changed at a source node to a counterpart object at a destination node, the system comprising:

signaling means associated with the source object for initiating generating a signal at the source node indicating that the source object at the source node has changed and assigning an urgency value to the change with respect to a predetermined criteria, and wherein the urgency value indicates changes as either urgent or non-urgent, and wherein urgent changes are pushed to the destination and non-urgent changes are pulled from the source,

a control means connected to the signaling means for receiving the signal generated by the signaling means and in response communicating to request information representative of the change to the source object, and to receive the change information,

a data communication mechanism at the source node connected to a data communication mechanism at the destination node for communicating information, representative of the change to the source object, from the source node to the destination node, and

means at the destination node for applying the received change information to the counterpart object at the destination node such that the counterpart object at the destination node is consistent with the changed source object at the source node.

23. A computer-readable medium having, computer-executable instructions for a method of expediting the replication of changes to at least one source object in a source to a destination replica in the system wherein the state of the source object has changed, the steps comprising:

recognizing a change in state of a source object;

first notifying a source replication facility that the source object has changed and providing a value reflecting the urgency of the change,

second notifying the destination replica that the source object has changed and the urgency of the change,

transmitting from the destination replica to the source a request for change information after a time interval whose duration vanes as a function of the value of the urgency of the change,

extracting change information at the source from the source object representative of the change to the source object wherein the source object generates the change information,

transmitting information from the source to the destination, the transmitted information including the extracted change information,

receiving the transmitted information at the destination replica,

extracting the change information from the received information, and

providing the change information to a replica object of the destination.

24. The computer-readable medium of claim 23, wherein the time interval is substantially zero.

30. The computer-readable medium of claim 23 wherein the source object initiates the first notifying step.