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O'Reilly on the Virtues of Rexx
gaijincory writes "O'Reilly's ONLamp has written an interesting article on the history and virtues of Rexx, the first widely used scripting language concocted 25 years ago. According to the review, 'Rexx employs decimal rather than binary arithmetic' and 'You don't need to declare or predefine your variables. Rexx automatically allocates them when you first refer to them.'
I'd be interested to hear about any success (or failure) implementation stories."
We tried working with Rexx
An employee suggested to me that we load Rexx on a few machines here as an evaluation. I was skeptical at first but he explained the benefits of using it for our employee's day-to-day scripting. So I decided to let him install the interpreter onto 5 machines to see how the users got on. Besides, our IT manager had been using it on his system and it seemed to work fine, why not try it on the client machines?
Once he'd got the machines up and running with Rexx we let the users try it out. It all seemed fine to start with: Rexx was a pretty good replacement for batch files and the users could still do their work as normal.
Alas it did not stay that way. After a few days, I had lost count of the number of complaints received from users who could find things they were used to or tasks they could not perform that they previously could with batch files. The final straw came when one employee lost several hours work when Rexx suddenly had an error reading from our intranet file server and corrupted his project.
Needless to say, the Rexx team offered no support whatsoever. I made the employee uninstall Rexx from the machines and lets just say he's not with us anymore, because we had him killed.
Rexx employs decimal rather than binary arithmetic. [...] You don't need to declare or predefine your variables. Rexx automatically allocates them when you first refer to them. Are these supposed to be positive points? Because it kind of flies in the face of coding best practices...
Okay, I'm probably dating myself here (illegal in Nebraska, btw), but I remember REXX when it emerged as a replacement for EXEC which I had coded extensively in (written entire app systems) on IBM mainframes. There were a lot of benefits to REXX back then, notably it cleaned up and made transparent a lot of garbage and system management chores required to write clean EXEC code (e.g., strings tokenized at 8 chars, awkward variable interpolation)... I used REXX for a while on the mainframe and can't remember why I abandoned it.
Fast forward 2 or 3 hundred years, and I found myself dropped into a Unix universe, and quickly self taught myself the ins and outs of shell. Haven't looked back since. Now, I'm looking back and am intrigued... REXX really does have some interesting features. And, since I have a little free time on my hands, maybe I'll re-visit REXX, but from userland out there, any feedback would be useful:
>You don't need to declare or predefine your variables.
Isn't this a bad thing? You would never catch typos when using variables. I start using a variable named "myBigNumber" then the next day I mistakenly start using a "myBigNum" variable even though I mean the same thing.
The surprise isn't how often we make bad choices; the surprise is how seldom they defeat us.
I used to be the VM/ESA systems programmer (king geek) for a state university (I'm still at that university, it's been over 21 years).
REXX was the first serious scripting language that IBM delivered for VM (EXEC was awful and EXEC2 not much better). Our systems development (applications) staff wrote quite a number of in-house REXX applications interfaced to DMS/CMS (this was before ISPF was very usable under VM). Most of these were working with CUFS (later Advantage). I used REXX extensively to match-merge two files, generate reports, and reformat data. I also rewrote some programs in REXX that had originally been implemented in SNOBAT (a snobol4 dialect for System/370).
Roll forward a few years. All the sudden, I'm responsible for Unix servers as well as VM. Although I installed regina on our Unix servers, I figured out pretty quickly that perl was the preferred script language for Unix (I first installed 4.0.36). I saw that there were a lot of facilities and working scripts in perl that I'd have to build for myself in REXX, so I made a point to learn perl. I still used REXX for things that interacted with our VM/ESA and z/OS & TSO/ISPF environment.
Roll forward a few more years. IBM drops HESC, and VM becomes prohibitively expensive to keep. Meanwhile, our academia is moving to Unix and PC-based teaching, and a Unix-based ERP is on the horizon. We decided to eliminate VM. I spent quite a few hours writing perl scripts to parse DMS/CMS panel sources and REXX programs, to build ISPF panels and generate ISPF-friendly REXX from the DMS/CMS REXX code (fortunately most of the code was cookie-cutter so it was easy to do a find/replace). I knew these programs would be eliminated when the ERP was in place.
Now I'm so neck-deep in Oracle (database, application server, and other toys) and SCT Banner that I maybe spend 10 minutes a day on our z/OS system, and haven't written a new program there (in any language, much less REXX) in six months. I still maintain or help debug a REXX program now-and-then.
REXX was a success, but for us VM died. I still like REXX, but perl has pretty-well replaced it for me. The last time I wrote a REXX program I caught myself writing perl-isms into it that I had to fix.
Doug
REXX's history isn't even really mentioned.
First of all, REXX is hardly the first popular scripting language, there were lots of them before it. REXX was designed as an alternative to EXEC2 which was a replacement for EXEC and that's just on IBM's VM mainframe systems. Listing other scripting systems prior to REXX is left as an exercise for the reader.
As for history, REXX wasn't developed as an official IBM project. It was developed as an internal tools project by Mike Cowlishaw at IBM's research lab in Hursley, England (the VENTA lab) because EXEC2 basically sucked. It was distributed on IBM's internal tools system (VMTOOLS and IBMVM) and became hugely popular inside IBM.
It was made available as an unsupported tool through the IBM VM user group and became so popular that despite IBM managment wanting EXEC2 to be the "official" scripting language, nobody in their right minds used EXEC2 and REXX became almost universal. Pressure from their commercial VM/CMS and VM/XA users forced IBM to make REXX a supported product.
In the mid 1980s, a PC version became available internally on the IBMPC and PCTOOLS systems and quite a few internal tools were written in REXX but despite internal popularity, IBM didn't release the PC version of REXX until much later when a vastly expanded (some would say bloated) version was released as a fairly expensive commercial product.
As a side note, REXX was released as a scripting language for PCs with later versions of OS/2 but by that time OS/2 was insignificant in the PC industry.
One unrelated note, Cowlishaw is also famous as the keeper of the IBM Jargon Dictionary - a tongue firmly in cheek listing of IBMisms.