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Hello World on z/OS

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Re: Hello World on z/OS

#11

Post by wolfgke »

userbinator wrote: post #4

The reason why things are the way they are on mainframes, and how you should think intuitively, becomes a lot clearer once you realise that they are a long-evolved version of the very first mechanical punched-card processors: https://en.wikipedia.org/wiki/Unit_record_equipment In fact, I'm almost willing to bet that the foreignness of mainframes to the average developer is due to mini/microcomputers having become dom…

> Linux and DOS/Windows have far more in common with each other than mainframe OSes, despite their huge differences, because they evolved from mini/microcomputers and UNIX.

Surely Linux and the Windows NT line (don't confuse the Windows 9x line, which evolved indirectly from DOS with the Windows NT line) have much more in common with each other than mainframe OSes, but Windows did not evolve from UNIX:

The Windows 9x line evolved indirectly from DOS (cf. [1]). DOS was inspired a lot by CP/M.

The Windows NT line is a spiritual succesor to VMS (cf. [2]). The kernels of both operating systems were designed by Dave Cutler, who did not like UNIX (cf. [3]). Indeed, Windows NT has I/O Completion Port (IOCP, [4]) as an - in my opinion - better I/O system than the UNIX process input/output model.

[1] https://blogs.msdn.microsoft.com/oldnewthing/20071224-00/?p=...

[2] https://www.itprotoday.com/management-mobility/windows-nt-an...

[3] https://en.wikipedia.org/w/index.php?title=Dave_Cutler&oldid...

[4] https://en.wikipedia.org/w/index.php?title=Input/output_comp...

Re: Hello World on z/OS

#12

Post by tony-allan »

api wrote: post #6
etaioinshrdlu wrote: post #3

IBM is a special company that seems to not want anyone to use its products. They sure go out of there way to make things hard to access. But they keep them around forever. Happy to sell them to the right customer. So many overlapping products that don't make sense in aggregate. The company seems to be marketing-driven the last 10+ years, selling all manner of snake oil. Possibly the worst big co in these factors?

They're not interested in anyone but people willing to write million dollar plus checks using their products. Those same giant customers have large legacy investments and plenty of money to hire teams of people to deal with things that are hard to use. Those kinds of customers care much more about things working for 30+ years without downtime than they care about UX. There's a whole world of solid, reliable, but unbe…

Sure z/OS is boring if your job is to write Cobol programs but if you are interested in sophisticated operating systems packed with very smart algorithms then it's a different matter.

You can read about amazing hardware and IBM's ability to fuse hardware, microcode and software capabilities that keep pushing the ability to solve business problems. Yes, most of this is needed to extract value out of incredibly expensive technology.

Re: Hello World on z/OS

#13

Post by wolfgke »

api wrote: post #6
etaioinshrdlu wrote: post #3

IBM is a special company that seems to not want anyone to use its products. They sure go out of there way to make things hard to access. But they keep them around forever. Happy to sell them to the right customer. So many overlapping products that don't make sense in aggregate. The company seems to be marketing-driven the last 10+ years, selling all manner of snake oil. Possibly the worst big co in these factors?

They're not interested in anyone but people willing to write million dollar plus checks using their products. Those same giant customers have large legacy investments and plenty of money to hire teams of people to deal with things that are hard to use. Those kinds of customers care much more about things working for 30+ years without downtime than they care about UX. There's a whole world of solid, reliable, but unbe…

> There's a whole world of solid, reliable, but unbelievably boring "institutional computing" out there that hackers usually don't touch because it's... well... boring.

I can imagine if the salaries would be sufficiently (i.e. very) high and the complete culture would not be openly hostile towards the values of the hacker culture, I can easily imagine that hackers would be willing to touch it.

Re: Hello World on z/OS

#14

Post by AnIdiotOnTheNet »

> IBM uses special and completely unintuitive names for basic concepts…. because OF COURSE THEY DO.

As I recall, it's called "Bluespeak", and that sort of thing is pretty common actually. I was educated in networking at a Cisco netacad, so I use Cisco terminology that is apparently not universal.

Programming languages do this too for some reason: Sum type, tagged union, discriminated union, variant...

Re: Hello World on z/OS

#15

Post by marbletiles »

I find this sort of complexity absolutely fascinating: I imagine it is similar intellectually to learning of a new order or family in biology: you understand the mechanisms and underpinning goals, but the mechanisms and results are wholly foreign to you.

Had a similar experience with the Bloomberg terminal, which is a similar evolutionary offshoot. (Think "what if the GUI had never happened, but the 3270 form-style CLI had gained a mouse and graphical representations?")

Re: Hello World on z/OS

#16

Post by mattzito »

The mainframe infrastructure is both the core feature and showstopper bug of the platform. On the plus side, it has empowered countless core business applications to scale years, even decades, beyond their original development lifecycle. On the negative side, it has created a stagnant cult of mainframe “priests” who oversee a platform that most businesses would rather get rid of, if they could only figure out how.

My startup was acquired by BMC software, one of the largest third party providers of mainframe software, and I also worked for EMC for a time early in my career, so I spent a lot of time hanging around the mainframe space. Two quick anecdotes:

- working on a giant data center move for a big bank, there was a break room filled on a Saturday with operations people from the “open systems” (non-mainframe) and mainframe teams. I was struck by the contrast: the Unix/windows operations folks were tattooed, pierced, jeans and t-shirts, late 20s. The mainframe folks were short hair, polos and jeans, mid-50s. The two groups self segregated into clusters on opposite ends of the room, not speaking to each other.

- at a BMC leadership offsite, I found myself st the dinner table with a couple of mainframe engineering and product directors. After a few drinks, we got on the subject of why more tech companies weren’t using mainframes. “They’re so reliable! Why wouldn’t you just go out and rent one from IBM, and then you don’t have to worry about uptime or stability?”. I explained that the fashion had become to build the reliability into the application and assume that the hardware was not reliable. This confused them. “That sounds like a huge pain in the ass, why would you bother dealing with that?” So I explained that the cost per compute cycle was so much cheaper that it made it worth it, plus open source, etc etc

One of them kept pressing: “but Facebook could just take all the engineers they’re devoting to building reliable infrastructure and shift those people to writing customer facing code!”

The other director stopped him and said, “don’t you see? They’ve already done it. There’s no reason for them to go back now. People have figured out that they don’t need mainframes to get mainframe reliability”. The other director just kept shaking his head and we moved to other subjects.

This conversation happened in 2014.

Re: Hello World on z/OS

#17

Post by rayiner »

wolfgke wrote: post #13
api wrote: post #6

Earlier quoted context omitted.

They're not interested in anyone but people willing to write million dollar plus checks using their products. Those same giant customers have large legacy investments and plenty of money to hire teams of people to deal with things that are hard to use. Those kinds of customers care much more about things working for 30+ years without downtime than they care about UX. There's a whole world of solid, reliable, but unbe…

> There's a whole world of solid, reliable, but unbelievably boring "institutional computing" out there that hackers usually don't touch because it's... well... boring. I can imagine if the salaries would be sufficiently (i.e. very) high and the complete culture would not be openly hostile towards the values of the hacker culture, I can easily imagine that hackers would be willing to touch it.

But would you want hackers to touch it?

Re: Hello World on z/OS

#18

Post by JdeBP »

Whilst the ways that one does command-line stuff and full-screen editing with block-oriented (rather than character-oritented) terminals are an important difference to learn, there are, of course, things here that are not different.

* There's still "object" code, and a "link (edit)" step.

* The function key mappings such as F3 for Exit are Common User Access standards, and were to be found in some Microsoft and IBM softwares for PC operating systems in the 1980s; most prominently perhaps in the various "E" editors and clones thereof available on PC-DOS and OS/2.

* The underlines for the menu item hotkeys are also Common User Access things, as is F10 for bringing focus to the menu.

M. Bellotti would gain by learning about the "TE" line command. Xe would also gain by not abusing the word "legacy", especially since the so-called "legacy paradigm" of IBM's "panels" on block-oriented terminals is pretty much the same paradigm as forms on a WWW browser. (-:

* http://jdebp.info./FGA/legacy-is-not-a-pejorative.html

And the doco, IBM's and others', is not really wildly different, in both range and content, to other platforms'.

* Gary DeWard Brown (2002). zOS JCL. John Wiley & Sons. ISBN 9780471426738.

* https://www-01.ibm.com/servers/resourcelink/svc00100.nsf/pag...

* Mike Ebbers, John Kettner, Wayne O'Brien, and Bill Ogden (2012). Introduction to the New Mainframe: z/OS Basics. IBM Redbooks. ISBN 9780738435343.

Re: Hello World on z/OS

#19

Post by jareds »

sien wrote: post #10
wereHamster wrote: post #5

Earlier quoted context omitted.

Sure, that's certainly important to keep in mind. But that doesn't mean IBM shouldn't invest in usability.

They and others have. There are ways to develop in Eclipse that can target z/OS. https://developer.ibm.com/zsystems/documentation/java/jzos/j... https://www.ikanalm.com/solutions/devops-and-toolchain-orche... However, the people who develop for z/OS are often people who are familiar with Interactive System Productivity Facility (ISPF). It's a bit like whether people who are proficient in Vim or Emacs really benefit t…

I've been working on Mainframes for the passed 8 years full time, and several internships before that. I often go several days with out needing to use ISPF. I use https://compuware.com/workbench-mainframe-modernization/ for dataset editing, job submission, etc. I find the Unix shell you access through ISPF to be very difficult to use. Luckily SSH is available on z/OS, so if I need to do Unix stuff I can just SSH in with the client of my choice. The biggest difficulty I had when getting started was understanding JCL. I had come from a Linux background, so was used to executing commands with arbitrary file names, looping, etc. It took me a while to understand how JCL worked. Once I understood that you have to define datasets with things such as space allocation and disposition before using them, and that JCL was a series of sequential steps with the output from a prior step available to a later step a switch flipped and I went from struggling with JCL to fairly comfortable in a couple days. I'm not sure how much of this was the fact that I was an intern at the time so didn't have a lot of programming experience and how much of it is the platform. I find that once you get comfortable with the basics of JCL the structure it forces you into actually makes it easier, even though it is limiting in some ways. The issue I still have with the Mainframe is documentation. Unlike most programming questions a google search does not turn up Stackoverflow results. I find I spend a lot of time going through random forums or reading the IBM doc. I don't find IBM doc easy to understand, but the more I have to deal with it the easier it gets.

Re: Hello World on z/OS

#20

Post by JdeBP »

wolfgke wrote: post #11
userbinator wrote: post #4

The reason why things are the way they are on mainframes, and how you should think intuitively, becomes a lot clearer once you realise that they are a long-evolved version of the very first mechanical punched-card processors: https://en.wikipedia.org/wiki/Unit_record_equipment In fact, I'm almost willing to bet that the foreignness of mainframes to the average developer is due to mini/microcomputers having become dom…

> Linux and DOS/Windows have far more in common with each other than mainframe OSes, despite their huge differences, because they evolved from mini/microcomputers and UNIX. Surely Linux and the Windows NT line (don't confuse the Windows 9x line, which evolved indirectly from DOS with the Windows NT line) have much more in common with each other than mainframe OSes, but Windows did not evolve from UNIX: The Windows 9x…

MS/PC/DR-DOS was also inspired by Unix. It's where the handle-based API, the hierarchical directory structure, and indeed ioctl, came from that appeared in MS/PC-DOS version 2.
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