Recent Work on Distributed Commit Protocolls, and Recoverable Messaging and Queuing

This paper briefly summarizes some recent IBM work in the areas of distributed commit protocols, and recoverable messaging and queuing. We discuss the original presumed nothing commit protocol of SNA LU 6.2 and the current industry standard presumed abort (PA) protocol which we originally developed in IBM’s R* project. We also discuss generalized presumed abort (GPA) which resulted from the integration of PA into LU 6.2. GPA has been implemented in DB2 V3. We provide a brief introduction to the Message Queue Interface (MQI), an architected application programming interface, and Message Queue Manager (MQM) MVS/ESA, one of the IBM MQSeries products that implements MQI. Some internal design features of MQM are also described.