[LINK] Mainframes

David dlochrin at key.net.au
Sat Mar 23 13:00:15 AEDT 2019

On Saturday, 23 March 2019 11:35:32 AEDT Bernard Robertson-Dunn wrote:

> It's not the programming language that counts it that the environment that guarantees transactions - In the case of IBM it's call CICS (Customer Information Control System) which supports on-line transaction processing. It makes sure that when you move money from one bank account to another it either complete of fails - there is no other outcome.
> This is very difficult to do in a distributed environment.

IBM's SNA Logical Unit 6.2 guaranteed proper communication of transactions between distributed systems with rollback on failure, for example if a transaction could not be secured on backup storage.  For example, BHP's modernisation of their steelworks at Port Kembla involved a large H/O mainframe which sent job orders to DEC systems in the hot-strip & slab mills with notification returned on completion, all using LU 6.2.

I think LU 6.2 was more typically used in pure IBM CICS-IMS environments.

But that was a long time ago on a distant star.  These days there are other TPEs, such as Tuxedo which was open-source but I think has now been digested by Oracle.

> COBOL was a transaction based system used for batch record processing.  There is so much COBOL around that it is cheaper and better to keep it - it is fit for purpose, more so than any other language.

That's why we still have Fortran!  It's now a modern TP language, and Wikipedia tells me the latest release was 3 months ago.

David L.

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