Tom Brandt writes,

> The same cannot be said about NT, which is frequently touted
> as an "open" system.

Actually NT does have a POSIX layer as well, again, not as robust as MPE's.

In addition, there is a purchasable product (the name of which escapes me at
the moment), which gives NT darn-near full Unix compatibility.  NT is a
proprietary OS (as is OS/400, MVS, and other OSes, as well as MPE) - it's the
level of POSIX implemented in the OS that determines how "open" it is.  People
would be surprised as to how much POSIX is in NT.  People will be more
surprised to see how far Microsoft has come with Win2000.

I love when people bandy about the term "open systems" - as there is no such
thing.  Anyone who has ported any code will tell you that even Unix isn't
open - there are many different flavors.  In essence, each manufacturer of Unix
has their own proprietary extensions within it.  Even languages - people say
COBOL is COBOL is COBOL... which is true to a point - but every system
manufacturer that offers a COBOL compiler has placed their own extensions into
it, and even the SELECT clause has differing syntaxes.

Basically, the term "open system" (at least IMHO) means that one can port a
program from System 1 running one OS, to System 2 running another, with minimal
effort.  Sometimes we get lucky and it'll port over, compile clean and run
without any work at all other than extracting it from a tarball... but they are
not the rule, they are the exception.  Most ports will require some work,
however minimal.

HP's attempted port of the Netscape FastTrack server is a classic example.  It
was *supposed* to be a POSIX compatible app.  It wasn't - it was written to
Unix, not POSIX.  It turned out to be, from what I understand, less than POSIX
compliant -- so much less that the time invested in the port was considerable,
and would have taken considerably more time than to take a BETTER server
(Apache/iX) over to MPE.  Apache/iX is written to POSIX, not Unix... and that's
the key.  If it's written to POSIX, the better chance of a clean port.  If it's
written to Unix, it's a crapshoot - you could get lucky, or you could get into
a quagmire.

Regards,
Joe

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