Browse Prior Art Database

Message Filtering Method

IP.com Disclosure Number: IPCOM000123386D
Original Publication Date: 1998-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 54K

Publishing Venue

IBM

Related People

Dixit, A: AUTHOR [+5]

Abstract

This disclosure relates to an improved method of filtering messages in the Encina(*) Publish/Subscribe system. One step of the method is to evaluate each filter expression once and to store the results using hash tables. A second step is to parse each incoming message once and to evaluate it by means of the hash tables to determine where the message should be distributed. The Encina Publish/Subscribe system routes messages based on their content. This allows the system to minimize the use of network and computational resources by only transmitting those published messages that a subscriber is interested in seeing. In the Publish/Subscribe system, messages are arbitrary collections of name-value pairs of data of various types.

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Message Filtering Method

   This disclosure relates to an improved method of filtering
messages in the Encina(*) Publish/Subscribe system.  One step of the
method is to evaluate each filter expression once and to store the
results using hash tables.  A second step is to parse each incoming
message once and to evaluate it by means of the hash tables to
determine where the message should be distributed.  The Encina
Publish/Subscribe system routes messages based on their content.
This allows the system to minimize the use of network and
computational resources by only transmitting those published
messages that a subscriber is interested in seeing.  In the
Publish/Subscribe system, messages are arbitrary collections of
name-value pairs of data of various types.  Subscribers specify the
content of messages of interest using a filter expression made up of
logical and relational operations defined against message value names
and string and numeric constants.  The Publish/Subscribe server
programs must be able to evaluate each message they receive against a
(potentially large) number of filter expressions to determine which,
if any, of their subscribers are interested in receiving the message.
This operation is on the critical path for delivering messages to
subscribers, and so directly impacts the throughput and latency of
the total system.  The proposed solution is the use of a filtering
method that has the following desirable behavior:
  o  It requires parsing of the m...