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Event Signalling to Multiple Processes

IP.com Disclosure Number: IPCOM000014693D
Original Publication Date: 1999-Dec-01
Included in the Prior Art Database: 2003-Jun-20

Publishing Venue


Related People

Geoffrey Winn Brian Mihell


This invention solves the problem of efficiently notifying a set of processes of the occurence of an event, where the membership of the set is not known to the entity signalling the event. The solution is applicable to the OpenVMS* operating system. The invention uses OpenVMS mailboxes and write-attention (WRTATTN) ASTs. A mailbox is a pseudo-device, normally used for OpenVMS processes to exchange data. A write attention AST is effectively a process-private interrupt. A process with an interest in a mailbox can declare that a named procedure within the process (referred to as an AST routine) is to be run when data is written to the mailbox. The process then continues executing, without having to poll the mailbox or otherwise stall, knowing that the AST routine will execute when data is available in the mailbox. The normal use of this mechanism is for one process to write data into a mailbox and another to read from it, prompted to do so by the AST mechanism. The mailbox then functions as a buffer.