Browse Prior Art Database

Two-Phase Commit Resynchronization

IP.com Disclosure Number: IPCOM000038511D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 3 page(s) / 49K

Publishing Venue

IBM

Related People

Treiber, RK: AUTHOR

Abstract

A method is described for resynchronizing two systems that were cooperating to accomplish an atomic unit of work when a communications failure occurred, comprising, upon detection of a communications failure, the steps of (a) determining the processing state of each system and (b) allowing processing to continue to completion unless one or both systems had backed-out processing. Presently, resynchronization of two systems can be achieved via a well-known, two-phase commit process which is supported by communication protocols, such as IBM's System Network Architecture (SNA). The systems, however, are resynchronized to a backed-out status.

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Two-Phase Commit Resynchronization

A method is described for resynchronizing two systems that were cooperating to accomplish an atomic unit of work when a communications failure occurred, comprising, upon detection of a communications failure, the steps of (a) determining the processing state of each system and (b) allowing processing to continue to completion unless one or both systems had backed-out processing. Presently, resynchronization of two systems can be achieved via a well-known, two-phase commit process which is supported by communication protocols, such as IBM's System Network Architecture (SNA). The systems, however, are resynchronized to a backed-out status. According to the method herein disclosed, the resynchronization capacity can be extended so that work that was in progress when a communications failure occurred may be continued instead of being backed out and restarted. When resynchronization occurs, each system will be in one of the following seven states: State 0: The system is in a cold or reset state and has no state information. State 1: The system is in Phase 0 state for a transaction occurrence. State 2: The system is in Phase 1 state for a transaction occurrence (able to back out or commit), waiting for direction. State 3: The system was in Phase 1 state for a transaction occurrence, but a user decision was made to force back out of changes and free resources. State 4: The system was in Phase 1 state for a transaction occurrence, but a user decision was made to force commit of changes and free resources. State 5: A transaction occurrence has been committed and backed out. State 6: This is a state where the system has committed the occurrence of a transaction and, having not received anything from the other system, has sent...