Am 20.04.2014 23:27, schrieb Clark Morris:
On 19 Apr 2014 18:51:09 -0700, in bit.listserv.ibm-main you wrote:
IMO, programming language and file organizations are
complete different things and should be discussed seperately.
Furthermore, you have direct access on all platforms, including
Windows and Unix; this is not a matter of programming language at all.
And: you have keyed access, because it is easy to implement keyed access
by software on top of the hardware supported direct access; you don't
need hardware support for keyed access ... this was one of the design
errors in history.
While this is true in the sense that there are both indexed and direct
files in the Unix and Windows worlds, so far as I know there is no
common format and access routines provided with those operating
systems such as BDAM, ISAM (remember that?), VSAM RRDS and VSAM KSDS
are provided by VSE and MVS. As I understand it most if not all of
the BUNCH provided similar facilities. Also my understanding is that
in the Windows environment separate facilities such as Btrieve and
COBOL vendor provided routines were needed with no general readability
except as provided by those packages. This has meant in at least one
UNIX shop that I worked at, all mainframe VSAM KSDS files had been
converted to Oracle tables as part of the migration from the MVS
system to HP-UX. It is the requirement for each shop to construct or
purchase separately their own routines for this and various packages
may use different routines with resulting incompatible file formats.
As klutzy as the IBM utilities are they are still more than what is
available on my Windows 7 computer.
Clark Morris
It is not clear to me if such things like keyed access to files have to be
part of the operating system.
The scope of "what is part of the operating system" has changed over time.
In historic times even compilers (or text editors) were part of the
operating system, but
today compilers are considered to be just another kind of application
program
that can be bought from third parties or even be public domain.
Same goes for file systems etc.; for a Linux system you can get different
file systems on your hard disc with different properties.
BTW: is VSAM part of the operating system? I don't think so.
It's just quite common; (almost) every site uses it. Just like DB2 ...
The nice thing about my index file system I mentioned in the other post:
it works on all platforms in the same way, because it is written in ANSI C,
no difference, if you use it on Windows, Unix or z/OS. It is just a
portable
replacement for VSAM ... before we migrated it from Windows/Unix to
z/OS, we had a DB2 based solution on z/OS, but it had performance problems
(DB2 was too expensive for the given workload). Since we migrated the
file system to z/OS, we have no problems any more.
Kind regards
Bernd
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