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Use of a Mirror Queue for the Collection of Accurate Status Information

IP.com Disclosure Number: IPCOM000123468D
Original Publication Date: 1998-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 44K

Publishing Venue

IBM

Related People

Smith, GC: AUTHOR

Abstract

Problem When using a queuing system as the underlying communication system for a set of applications, there is often a need to know the status of the items on a queue. For example, if a queue held messages that denoted a piece of work that must be completed, one might want a list of those pieces of work.

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Use of a Mirror Queue for the Collection of Accurate Status Information

   Problem

   When using a queuing system as the underlying
communication system for a set of applications, there is often a need
to know the status of the items on a queue.  For example, if a queue
held messages that denoted a piece of work that must be completed,
one might want a list of those pieces of work.

   An obvious way to do this would be to browse through a
queue, and record the contents.  This method, however, does not take
into account any pieces of work that an application might currently
be working on, as they would have been removed from the queue.  If
the application that removed the piece of work were unable to
complete it, the piece of work would be replaced in the original
queue.  If one were monitoring the list of jobs in the queue, it
would appear as though the piece of work had vanished and then
reappeared.

   What is needed was a way to determine what all of the
current work is, whether queued or in progress, with as little extra
overhead as possible for the applications responsible for doing the
work.

   Solution

   The solution is to add an extra queue that is a copy of
the original queue.  Whenever an item or a piece of work is placed on
the original queue, a copy of the item or piece of work is also
placed on the copy, or mirror, queue.  It is important that there is
some mechanism for removing the copy from the mirror queue given only
the information availab...