Browse Prior Art Database

Detecting Inter-Transaction Affinities

IP.com Disclosure Number: IPCOM000112706D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 180K

Publishing Venue

IBM

Related People

Davies, K: AUTHOR [+3]

Abstract

Disclosed is a utility program incorporating a way of detecting, classifying and hierarchically organising affinities between CICS transactions, so that a database of such affinities can be built from a running CICS system. It solves dynamically the problem of finding out what affinities exist in a running CICS system. That information cannot be found from program listings but only by either knowing the behaviour of the programs or by observing them as they run. This utility automates the job in a straight-forward and on-line manner.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 30% of the total text.

Detecting Inter-Transaction Affinities

      Disclosed is a utility program incorporating a way of
detecting, classifying and hierarchically organising affinities
between CICS transactions, so that a database of such affinities can
be built from a running CICS system.  It solves dynamically the
problem of finding out what affinities exist in a running CICS
system.  That information cannot be found from program listings but
only by either knowing the behaviour of the programs or by observing
them as they run.   This utility automates the job in a
straight-forward and on-line manner.

      The CICS workload manager component of CICSPlex attempts to
balance the work arriving in the CICSPlex across the CICS regions by
the use of dynamic transaction routing.  CICS transactions use many
different techniques to pass information from one to another and to
synchronise activity between them.  Some of these techniques require
that the transactions exchanging data or needing to synchronise
activity execute in the same CICS region and therefore impose
restrictions on the dynamic routing of the transactions.  For
CICSPlex to function correctly the workload manager must understand
these inter-transaction affinities for the workload to be managed.
Inter-transaction affinity can occur for the following reasons:

o   One transaction finishes leaving 'state data' which a second
    transaction will access in a place which requires the second CICS
    transaction to run in the same CICS system as the first
    transaction.

o   One transaction creates data which a second transaction accesses
    while the first transaction is still running.  For this to work
    safely the first transaction usually 'waits' on some event which
    the second transaction 'posts' when it has read data from the
    first transaction requiring both transaction to be run in the
    same CICS region.

o   Two transactions synchronise using a wait/post mechanism or
    serialise using an enqueue mechanism.  As CICS has no function
    shipping support for such mechanism events, this affinity
    constrains the two transactions to run in the same CICS system.

      The more affinity in a workload, the less effectively the
workload manager can balance the workload across the CICSPlex.   To
minimise this impact, an affinity may be considered to have a
'relation' and a 'lifetime'.  Relation and lifetime enable a bound to
be placed on the scope of an affinity.  A 'transaction group' is a
mechanism that could be used by the workload manager component of a
CICSPlex to group a set of logically related transactions.  An
'affinity transaction group', or affinity group for short, is a set
of transactions that have inter-transaction with one another.  The
workload manager component uses such affinity groups to determine
which CICS region to route transaction to.   So an affinity group
consists of a set of transaction identifiers, a...