Recovery guarantees for general multi-tier applications

• US 20040255182A1
• Filed: 07/08/2004
• Published: 12/16/2004
• Est. Priority Date: 09/04/2001
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Lomet, David B., Weikum, Gerhard, Barga, Roger
• Granted Patent: US 7,478,277 B2
• Time in Patent Office: Days
• US Class Current: 714/2
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 11/1474 in transactions G06F16/20 takes precedence

Abstract

A technique is described for guaranteeing recovery in a computer system comprising of recovery contracts with a plurality of obligations for a message exchange between a first component and a second component. Three forms of contract are described, governing interactions between three types of components. Each contract is bilateral, i.e. between a first component and a second component. The first and second components have mutual agreement on when the contract will be released to facilitate log truncation, and independent and/or autonomous recovery.

Claims

1. A system for guaranteeing recovery in a computer system, comprising:

a first persistent component; and

a second persistent component that interacts with the first persistent component via a committed interaction contract (CIC) that comprises a plurality of obligations for a message exchange between the first persistent component and the second persistent component, the obligations comprising;

the first persistent component provides recreatability of a message and its state as of an interaction time, and ensures message uniqueness, and

the second persistent component detects and suppresses a message duplicate, and eventually guarantees the persistence of its state as of an interaction time; and

the first and second persistent components have a mutual agreement on when the CIC will be released.

2. The system of claim 1, further comprising an external component that interacts with at least one of the first persistent component and the second persistent component via an external interaction contract (XIC) that comprises a plurality of obligations for a message exchange between the external component and one of the persistent components, the obligations comprising:

the one of the persistent components provides an output message to the external component and logs in a log that the message has been sent, and re-sends the message if a failure occurs before the log is stable, and

the external component attempts to provide an input message to the one of the persistent components and the one of the persistent components logs the message, such that if a failure occurs before the log is stable, the input message is lost and may be sent again by the external component.

3. The system of claim 1, further comprising a transactional component that interacts with at least one of the first persistent component and the second persistent component via a transactional interaction contract (TIC) that comprises a plurality of obligations for a message exchange between the transactional component and one of the persistent components, the obligations comprising:

the transactional component promises persistent atomic state transition in which the transactional component eventually proceeds to one of a committing state and an aborting state, and promises a faithful reply message in which the transactional component reply message to the one of the persistent components'"'"' commit-transaction or rollback-transaction request faithfully reports the state transition, and promises a persistent commit reply message in which, once the transaction commits, the transactional component replies acknowledging the commit request, and guarantees persistence of this reply, and

the one of the persistent components promises persistent state and commit request message at the time that the commit request is made.

4. The system of claim 1, wherein each of the first component and the second component is piecewise deterministic.

5. The system of claim 1, wherein first and second persistent components comprise an autonomous component ensemble that guarantees recovery with exactly-once execution semantics.

6. The system of claim 5, wherein the system further comprises an immediately committed interaction contract that provides autonomous recovery for the component ensemble.

7. A method of providing recovery in a computer system, comprising:

receiving a recovery contract between the first component and the second component; and

implementing the recovery contract, wherein the first and second components have a mutual agreement on when the contract will be released.

8. The method of claim 7, wherein the recovery contract comprises one of a committed interaction contract (CIC), an immediately committed interaction contract (ICIC), an external interaction contract (XIC), and a transactional interaction contract (TIC).

9. The method of claim 7, wherein the first component and the second component each comprise one of a persistent component and either an external component or a transactional component.

10. The method of claim 7, further comprising:

generating a component ensemble comprising a plurality of the components that guarantees recovery with exactly-once execution semantics; and

providing autonomous recovery for the component ensemble responsive to immediately committed interaction contracts with components outside of the component ensemble.

11. The method of claim 7, wherein each of the plurality of persistent components is piecewise deterministic.

12-13. -13. (Canceled).

14. A computer readable medium having computer-executable instructions for performing the steps comprising:

receiving a recovery contract between the first component and the second component; and

implementing the recovery contract, wherein the first and second components have a mutual agreement on when the contract will be released.

15. The computer readable medium of claim 14, wherein the recovery contract comprises one of a committed interaction contract (CIC), an immediately committed interaction contract (ICIC), an external interaction contract (XIC), and a transactional interaction contract (TIC).

16. The computer readable medium of claim 14, wherein the first component and the second component each comprise one of a persistent component, an external component, and a transactional component.

18. The computer readable medium of claim 14, having further computer executable instructions for:

generating a component ensemble comprising a plurality of the components that guarantees recovery with exactly-once execution semantics; and

providing autonomous recovery for the component ensemble responsive to an immediately committed interaction contract.

19. The computer readable medium of claim 14, wherein each of the plurality of components is piecewise deterministic.

17. (Canceled)

20-21. -21. (Cancelled).

22. In a computer implemented device having a computer readable storage medium having computer executable components, the computer executable components comprising:

a data store for storing a recovery contract comprising a plurality of obligations for a message exchange between a first component and a second component, the obligations comprising;

the first persistent component provides recreatability of a message and its state as of an interaction time, and ensures message uniqueness, and

the second persistent component detects and suppresses a message duplicate, and eventually guarantees the persistence of its state as of an interaction time, wherein the first and second persistent components have a mutual agreement on when the recovery contract will be released; and

a processor for reading the data store and directing the first and second components to operate in accordance with the recovery contract.

23. The device of claim 22, wherein the recovery contract comprises one of a committed interaction contract (CIC), an immediately committed interaction contract (ICIC), an external interaction contract (XIC), and a transactional interaction contract (TIC).

24. The device of claim 22, wherein the first component and the second component each comprise one of a persistent component, an external component, and a transactional component.

25. The device of claim 22, wherein each of the first component and the second component comprises one of a client, an application server, a data server, and an external user.

26. A system for guaranteeing recovery in a computer system, comprising:

a recovery contract comprising a plurality of obligations for a message exchange between a first component and a second component, the obligations comprising;

the first persistent component provides recreatability of a message and its state as of an interaction time, and ensures message uniqueness, and

the second persistent component detects and suppresses a message duplicate, and eventually guarantees the persistence of its state as of an interaction time, wherein the first and second persistent components have a mutual agreement on when the recovery contract will be released.

27. The system of claim 26, wherein the recovery contract comprises one of a committed interaction contract (CIC), an immediately committed interaction contract (ICIC), an external interaction contract (XIC), and a transactional interaction contract (TIC).

28. The system of claim 26, wherein the first component and the second component each comprise one of a persistent component, an external component, and a transactional component.