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Browse Prior Art Database

Method of Notifying Multiple Database Agent Processes that a Database Application has Received Control Break

IP.com Disclosure Number: IPCOM000109736D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 2 page(s) / 89K

Publishing Venue

IBM

Related People

Hidalgo, DS: AUTHOR [+3]

Abstract

Disclosed is an algorithm which solves the problem of notifying multiple database agent processes in a distributed database system when a database application process has received a control break signal. In the Database Manager Distributed Database System version 2.0 (DBM 2.0), many database agent processes may service requests from one or more database applications. When an application receives a control break, the database agent processing any request from this application must be notified so that appropriate cleanup or rollback action can be taken.

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Method of Notifying Multiple Database Agent Processes that a Database Application has Received Control Break

       Disclosed is an algorithm which solves the problem of
notifying multiple database agent processes in a distributed database
system when a database application process has received a control
break signal.  In the Database Manager Distributed Database System
version 2.0 (DBM 2.0), many database agent processes may service
requests from one or more database applications.  When an application
receives a control break, the database agent processing any request
from this application must be notified so that appropriate cleanup or
rollback action can be taken.

      In the DBM 2.0 system, there is a set of database agent
processes which service the database requests on behalf of the
application programs.  Each DBM agent process may service requests
from any of the applications at any time.  While the database Agent
process is servicing a request from an application, the application
process may receive a control break signal.

      Although it is relatively straightforward to handle the control
break signal in the application process, the database agent process
must be notified immediately so that any transactions in progress can
be aborted cleanly.  The added complication in DBM 2.0 results from
the separation of database application and database service agent
into two distinct processes.

      The control break mechanism invented for DBM 2.0 employs
interprocess communications using message queues and shared memory.
The database application process installs a control break signal
handler when the first database request is made.  This control break
handler is installed as part of the application registration that
must take place between the application process and the database
system before the first database request from the application can be
serviced.  The control break handler will gain control of the
application whenever a control break signal is received.

      This control break handler will package and sen...