Re: Separation of Presentation, BL, and I/O Tiers

Jon,

There is a big advantage in having a middle layer that handles
the allocation etc. That takes the I/O part out of the allocation
business and allows much greater flexibility in the caller. I would
call that middle piece a Mediator. The main purpose is to decouple
the I/O and Application so that either can be changed independently.
Having the I/O routine allocate its own storage is dangerous when
you start writing generic routines (for example a validation that
reads a record and overlays storage required by an application)
and is likely to impose some serious design limitations.

David Morris

>>> Jon.Paris@Partner400.com 04/10/02 06:28PM >>>
...First of all the IO routine would just increase its allocation as
required as I
explained above.  Second, when the caller received the pointer it
would
simply use it to base its own version of the MODS.  It would never own
any
storage or have to resize anything.  It would just reference the
storage
owned by the IO routine.

Jon Paris
Partner400