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Simulation of a Replaced System Component Disclosure Number: IPCOM000114449D
Original Publication Date: 1994-Dec-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 4 page(s) / 96K

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Hausmann, F: AUTHOR [+4]


Disclosed is a method for avoiding adaption effort for a replaced component in VSE/ESA 2.1.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Simulation of a Replaced System Component

      Disclosed is a method for avoiding adaption effort for a
replaced component in VSE/ESA 2.1.

      An operating system like VSE/ESA is composed of multiple
components.  Some of the functions of such components can be
activated via commands of an interpreter language.

      Sometimes it becomes necessary to withdraw such a component and
replace it with a functionally compatible new component.  It is not
unusual that the functions of the new component, although
semantically compatible to the old component, must be activated via a
different syntax.

      This usually means that all customer or IBM supplied procedures
of the interpreter language, which activate functions of the replaced
component, have to be adapted.

      In VSE/ESA an old assembler was replaced by new High Level
Assembler (HLASM).  The functions of the assembler can be activated
via two interpreter languages, a Job Control Language (JCL) for
Batch, and a ICCF Command Language for foreground execution.  For the
rest of this text we concentrate on JCL, the solution works similar
in ICCF.

      The assembler is activated via the 'EXEC ASSEMBLY' statement,
certain parameters define the functions to be executed.  HLASM is
executed by coding a different name with the EXEC and in part
different parameters have to be specified.

      JCL passes an internal representation of the information on the
EXEC statement to the operating system in order to have the desired
functions processed.

      For the old EXEC ASSEMBLY statements, the operating system
reports an error back to JCL since that component is no more
available in the system.

      Instead of reporting this error to the user, JCL internally
maps this statement to the new assembler, creating a modified EXEC
statement with the name and required parameters for HLASM and
automatically feeds this statement into the interpretation process
again, from where it is passed in an internal format back to the
operating system.

      Processing now continues as if the user would have included the
changed statement in his/her command procedure.

The new method has the following advantages:
  o  Users and IBM need not change their command procedures.
  o  Feeding the generated command back into the interpretation
      process gives more information to the user about what is
      happening sinc...