Porting from Mainframe to PC 
Author Message
 Porting from Mainframe to PC

We have a large legacy application on an IBM mainframe with significant PL/1
content for middleware (parser, database, control), but with most business
tasks done in fortran. How easy would it be to port the entire application
to Windows?
I believe there are certain addressing peculiarities re mainframes,
particularly of character data and arrays in Fortran ENTRY statements.


Fri, 08 Apr 2005 17:13:55 GMT  
 Porting from Mainframe to PC
My personal opinion is that while you might be able to convert the code
(possibly by writing a generic interface module to solve the
inter-language problems), it would be much more cost effective in the
long run to do a complete rewrite, using a Windows (how was that
determined to be the best platform, as opposed to UNIX/LINUX/MAC OS X
etc?) based development platform. The initial costs would be greatly
offset by having a Windows looking interface, reducing user training
costs, and having a code base which is more maintainable, both in terms
of its modernity and the availability of trained and experienced
programmers.

I would need to know lots more about the application to make any
recommendations about which development tool(s) to use, including which
language to program in.

I would definitely start on the project soon because us old timers with
mainframe, FORTRAN, and especially PL/I expertise are a rapidly
disappearing breed.

Quote:

> We have a large legacy application on an IBM mainframe with significant PL/1
> content for middleware (parser, database, control), but with most business
> tasks done in Fortran. How easy would it be to port the entire application
> to Windows?
> I believe there are certain addressing peculiarities re mainframes,
> particularly of character data and arrays in Fortran ENTRY statements.



Fri, 08 Apr 2005 22:00:56 GMT  
 Porting from Mainframe to PC

Quote:
> > We have a large legacy application on an IBM mainframe with significant
PL/1
> > content for middleware (parser, database, control), but with most
business
> > tasks done in Fortran. How easy would it be to port the entire
application
> > to Windows?
> > I believe there are certain addressing peculiarities re mainframes,
> > particularly of character data and arrays in Fortran ENTRY statements.

PLI's not much of a problem. If you use a database that's also available on
Windows, or equivalent.
We used DB2 on the mainframe and now use DB2/UDB in Windows NT. No problem.
Tim.


Fri, 08 Apr 2005 22:45:03 GMT  
 Porting from Mainframe to PC
Both languages port readily (I assume you're using VS Fortran II or later).
The only area that may be awkward is the PL/I - Fortran interface for
non-nul terminated string variables; this will be highly dependent upon the
Fortran compiler you choose.
You should check this with a test program before starting. I am not aware of
any addressing peculiarites in host Fortran compilers [VS Fortran II and
later].

DB2 embedded SQL is the easiest to port. For other databases, you'll need to
speak to the manufacturer for availability of precompilers for both
languages.

The complexity of the task is highly dependent upon the code "quality". If
it's clean code, it'll port fast. If it's full of "low-level" tricks that
rely upon byte ordering (big-endian), floating point formats, or EBCDIC
encoding conventions, you'll have more work as you'll need to consider these
and add suitable attributes or recode the affected parts of the application.
Even worse if it is full of ISPF logic or such-like, where you cannot
migrate [CICS is OK, as CICS exists on NT/2000].

I have successfully ported large (250KLOC) mainframe applications to the
Windows NT / 2000 platform.

---

Aside: I assume you mean Windows 2000 (or NT or XP) and have no plans on
supporting 95/98/ME. Targeting the DOS-based Windows platforms is asking for
catastrophic failure and can only be described as foolhardiness.


Quote:
> We have a large legacy application on an IBM mainframe with significant
PL/1
> content for middleware (parser, database, control), but with most business
> tasks done in Fortran. How easy would it be to port the entire application
> to Windows?
> I believe there are certain addressing peculiarities re mainframes,
> particularly of character data and arrays in Fortran ENTRY statements.



Sat, 09 Apr 2005 14:05:26 GMT  
 
 [ 4 post ] 

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