[Tutor] Mainframe Technology (was: aBSOLUTE BEGINNER) (OT)

[Carroll, Barry]

> -----Original Message-----
> Date: Thu, 18 Oct 2007 10:53:22 +0100
> From: "Alan Gauld" <alan.gauld at btinternet.com>
> Subject: Re: [Tutor] aBSOLUTE BEGINNER
> To: tutor at python.org
> Message-ID: <ff7aej$vl8$1 at ger.gmane.org>
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> 	reply-type=original
> 
> "bhaaluu" <bhaaluu at gmail.com> wrote
> 
> > What does that mean... "mainframe technology"?
> 
> I'll take a guess at what it means.
> A true mainframe is usually one of (or a clone of) IBM
> or ICLmainframe hardware running an OS like OS/390. It is
> primarily used for large volume data crunching and the
> applications use text only screens such as 3270 terminals
> running LU6.2 protocol. LU6.2 is somewhat like CGI
> on the web(*). A user is presented with a form which they
> fill in and submit as a job to the mainframe. The job
> executes and presents the results in the shape of
> another form. The coordination between transactions
> is managed by a system such as IBM's CICS.
> 
> (*)I've often thought a mainframe wouldmake the ultimate
> web server, but sadly I'll never find out as web apps are
> usually considered far too trivial to waste a mainframe on...
> 
> For the programmer or 'operator'(sys admin) the system
> involves a lot of small executables (programs) each
> wrapped up as a "job" in a script written in JCL
> (Job Control Language) which will define how much
> memory should be allocated, when the job should start,
> when it should terminate (regardless of whether it has
> finished), its schedulling priority, and so on.
> 
> Any scripting in the python sense tends to be done
> using REXX, but it still needs to be wrapped in JCL.
> Everything is a job on a mainframe.
> 
> Mainframe people tend to regard Unix boxes in the
> same way Unix guys regard PCs - little more than
> grown up toys. Mainframes hardly ever fail, they run
> the world's top businesses. But they are expensive,
> they are used for data centric rathger than user-centric
> applications and so many people working on them
> find them a tad dull, or boring... I know I spent a very
> instructive year wotking on a mainframe project.
> I'm glad I did it, I learned a lot about writing super
> reliable programs , but I don't want to do another
> one - ever!
> 
> Now I may be assuming too much but I'm guerssing
> that's what the OP is referring to.
> 
> > Python is anything but boring! I doubt we can help you!
> 
> Well, Python is much more fun than either REXX or JCL so
> learning Python may well bring some light relief.
> 
> Alan G.
> 
> ------------------------------

Greetings:

An interesting side note:

IBM's mainframes are now constructed out of massively pararallel arrays
of MPUs.  In other words, all that number crunching is done by hundreds
or thousands of souped up PCs, all connected together and stuffed into a
single box.

Regards,
 
Barry
barry.carroll at datalogic.com
541-302-1107
________________________
We who cut mere stones must always be envisioning cathedrals.

-Quarry worker's creed