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Log-Based Algorithm for Efficient Archival Access to Messages

IP.com Disclosure Number: IPCOM000123384D
Original Publication Date: 1998-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 50K

Publishing Venue

IBM

Related People

Hastings, A: AUTHOR [+3]

Abstract

This disclosure relates to a method of indexing and accessing an archive of messages in an Encina(*) Publish/Subscribe system Log. The method maps the Publish/Subscribe identifiers of representative records to the Log Service identifiers.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 57% of the total text.

Log-Based Algorithm for Efficient Archival Access to Messages

   This disclosure relates to a method of indexing and
accessing an archive of messages in an Encina(*) Publish/Subscribe
system Log.  The method maps the Publish/Subscribe identifiers of
representative records to the Log Service identifiers.

   The Encina Publish/Subscribe system maintains a persistent
(on-disk) archive of published messages at the root distribution
server.  The archive is built on top of the Encina Log Service,
which provides a sequential-record data storage abstraction.  As
messages are published to the system, the contents of those messages
are written into records in the Encina Log Service.  Records are read
from this archive when a subscriber requests messages that are older
than those available in the Publish/Subscribe server's in-memory
storage.

   A problem arises in that both the Log Service and the
Publish/Subscribe system assign a different numeric identifier to
each record that is used to identify and access such a record.  When
the Publish/Subscribe system accesses a particular record in the Log
Service, it must map the Publish/Subscribe assigned identifier to the
Log assigned identifier in order to access the required Log record.
The two sets of identifiers do not have a well defined mapping - the
only guarantee is that both sets of identifiers are monotonically
increasing for successive records written to the Log.  This is a
fairly common problem in data processing, as...