Browse Prior Art Database

Publish/Subscribe System

IP.com Disclosure Number: IPCOM000123769D
Original Publication Date: 1999-Apr-01
Included in the Prior Art Database: 2005-Apr-05
Document File: 1 page(s) / 46K

Publishing Venue

IBM

Related People

Bolam, SW: AUTHOR [+5]

Abstract

In a publish/subscribe system, if the processing and delivery of publications is on the critical path, as much processing as possible is needed prior to publication, this being mainly identifying the relevant set of subscribers requiring a certain publication. Where wildcard topics are supported (a subscription to a wildcard topic may result in publications on multiple different topics being published to the subscriber), the process of matching the wildcard topic to real (non-wildcard) topics is costly and performing this task out of the publish-time path would be beneficial. In IBM's *MQSeries Publish/Subscribe function the number of topics published is finite and multiple publications are usually published on the same topics.

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Publish/Subscribe System

   In a publish/subscribe system, if the processing and
delivery of publications is on the critical path, as much processing
as possible is needed prior to publication, this being mainly
identifying the relevant set of subscribers requiring a certain
publication.  Where wildcard topics are supported (a subscription to
a wildcard topic may result in publications on multiple different
topics being published to the subscriber), the process of matching
the wildcard topic to real (non-wildcard) topics is costly and
performing this task out of the publish-time path would be
beneficial.  In IBM's *MQSeries Publish/Subscribe function the number
of topics published is finite and multiple publications are usually
published on the same topics.  Knowing this, as much processing as
possible is performed on the first occurrence of a topic on a broker
(either by a subscriber or publisher registration or a publish).  A
record of the topic is created and stored dynamically, and is added
to a hash table for quick access.  All existing subscriptions to the
topic are directly linked to this topic record and can be accessed
without further processing after locating the topic.  Thus, when a
publication is published on a topic a single hash lookup is required
to find the topic and if it exists the publication is published to
all the subscribers linked to the topic.  When a real topic
(non-wildcard) is created all existing wildcard topics known to the
broker are pr...