International Business Machines Corporation

Jeffery M Mick

David Arlen Elko

Jeffrey Alan Frey

Michael D Swanson

Brian B Moore

Jimmy Paul Strickland

Audrey A Helffrich

John F Isenberg, Jr

A Structured External Storage (SES) device/processor is connected to two or more DP systems, thereby loosely coupling the systems. The SES is capable of holding data objects of two distinct types (List objects and Cache objects), and communicates commands and command responses with the systems using a message protocol. A support facility within a processor on which a system is executing receives status indications from the SES without interrupting mainline system execution. Within the SES, a serialization mechanism allows more than one command to execute in parallel without loss of data object integrity, or command consistency. A forward completion mechanism sends to systems early notification of completion of certain commands, without permitting results inconsistent with this notification to be obtained by the systems. And a restart mechanism permits interrupted commands to be restarted by the initiating system or, in certain cases, by another system.

Method and apparatus for coupling data processing systems

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Fishkill, NY, United States of America

Jeffery M Mick