Re: The Design of Design

Tim Rentsch wrote:

"Stephen Fuld" <SFuld@alumni.cmu.edu.invalid> writes:
 

Tim Rentsch wrote:
 

"Stephen Fuld" <SFuld@alumni.cmu.edu.invalid> writes:

 
snip
 
 

The biggest fault of JCL is that it
is trying to solve the wrong problem.

 
What problem was it trying to solve and what was the "right"
problem?

 
The problem it was trying to solve is contained in its name:  Job
Control Language.  It tacitly accepted the non-interactive batch
model for what it needed to address.

 
You may be right, but correct me if I am wrong, there was no
non-interactive model in the mid 1960s

 
I'm having trouble making sense of this question.  Did you mean
there was no interactive model?  Certainly there was a
non-interactive model, which is in the batch approach to the
world.

Sorry, my error.  I meant interactive (i.e. Time Sharing), not
non-interactive.  But as others have pointed out, there were such
models, but IBM chose to ignore them.

 

when JCL was devised.

 
OS/360 was announced in April 1964, at the same time as System/360.
Surely there had been significant thought put into what JCL would
look like by that time, which puts it in the early 1960s.
 

They didn't address it because they couldn't forcast
(obviouslyincorrectly), that it would be a problem to solve.

 
Talking about System/360 and OS/360 in The Design of Design, Brooks
distinguishes between teleprocessing and interactive use, aka
time-sharing.

Good.

Teleprocessing is for remote submission of batch jobs
and for fixed applications such as airline reservation systems.

Agreed.

He
doesn't say why time-sharing was given short shrift but there is
this interesting statement:  "There was no conscious decision to
cater to two use modes [namely, batch and interactive];  it merely
reflected subgroups holding differing use models."  It seems clear
that the design team, including Brooks himself, expected that the
primary use mode would be batch-like (which includes teleprocessing
applications such as airline reservation systems).

Yes, that is consistend with what happened.

 

The problem that was in need of addressing is interactive use.  I
think there are two reasons why JCL was so poor at that.  One is
that they knew that teleprocessing would be important, but they
tried to cram it into the batch processing model, rather than
understanding a more interactive work style.  The second reason is
that the culture at IBM, at least at that time, never understood

the >> idea that using computers can be (and should be) easy and fun.
The >> B in IBM is Business, and Business isn't supposed to be fun.
And I >> think that's part of why JCL was not viewed (at IBM) as a
failure, >> because their Business customers didn't mind.  Needless
to say, I am >> speculating, but for what it's worth those are my
speculations.

I don't think we have a major disagreement that IBM didn't address the
interactive user.  We may have a slight disagreement as to the reason
for that.  I believe you think that they considered it, but rejected it
because it was too much like fun.  I don't attribute that motivation,
and don't know what the resons for the rejection were, but we both
agree that they underestimated its importance for non-fun uses.



--
 - Stephen Fuld
(e-mail address disguised to prevent spam)