3. Maintenance Policies and Procedures › 3.2 User Maintenance Procedures › 3.2.2 User Change Control Procedure › 3.2.2.3 Design and Review

3.2.2.3 Design and Review

The authorization phase of modification development includes
an implied feasibility study.  Having done that groundwork,
the next step is the design of the modification and a
thorough review of the design.

General design of the modification is usually a very short
process.  This is true because most modifications to CA MICS
are small in nature, even though the impact of the intended
change may be great.

The most important factor in general design of a CA MICS
modification is identifying all the areas affected by the
change.  For example, adding an element to one file of the
CA MICS database may involve coding a piece of CA MICS file
exit logic to construct contents of the data element.  This,
in turn, may involve additional record selection and data
element verification logic.  It may also require that
additional records be passed through the intermediate files,
and that the intermediate data sets be resized.

The general design of larger projects, such as adding
user-written components, requires more effort.  Besides the
"ripple" effect noted above, an entire spectrum of design
must be done.  This covers the input data through the output
reports and database, and identification of exception
conditions.

The general design should be reviewed before detail design
takes place.  The CA MICS Product Support Group is well able
to comment on summaries of such general designs.  Also, user
involvement at this stage in modification development can be
valuable in terms of short-term design refinement and
long-term acceptance of CA MICS (if user involvement is
needed for the change).

Detail design of the modification should be done next.
Detail design involves, at a minimum:

    - Identifying each point in all modules to be modified.

    - Producing logic diagrams or pseudocode for each
      modification point.

    - Producing a code implementation plan, defining the
      order in which module modifications have to be made.

    - Producing a test plan.  This defines what debugging
      tools will be used, what debugging output must be
      examined to determine if the modification is working,
      and what checking must be done to determine that the
      modification is not interfering with normal system
      operation.