Path: utzoo!mnetor!uunet!husc6!think!ames!aurora!labrea!decwrl!decvax!ucbvax!LAUCOSC.BITNET!GRANT
From: GRANT@LAUCOSC.BITNET
Newsgroups: comp.os.vms
Subject: (none)
Message-ID: <8801201244.AA01767@ucbvax.Berkeley.EDU>
Date: 20 Jan 88 12:44:30 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 38
X-Unparsable-Date: 19-JAN-1988 09:07:14.71


Some recent experiences have led me to consider implementing
a new "feature" in my experimental/instructional operating system.
The idea, in brief, is to be able to "wait on a file".  For example,
a process could wait on a given directory: whenever that directory
is written upon the process would be resumed and could deal with new
files found there.

Some recent dialogue concerning the VMS SET WATCH command (which, though
related, is not quite what I have in mind) encouraged me to ask the
corporate experience of this list to comment.

1.  Has anyone heard of any operating system including this idea ?

2.  Clearly,  I have some particular applications in mind.  As a
    "blue sky" exercise, what applications come to mind for this
    facility ?

3.  Do you perceive any obvious weaknesses in the basic idea ?

4.  As far as I can tell, there is no efficient way to simulate this
    idea on VMS.  Can anybody contradict me ?

The problems which gave rise to this idea concern VMS programs (which
can't be modified) that write on known files.  A good example of such
a program is VMS MAIL.  The system on which I propose to test this idea
is LUMOS-2, a "toy" OS written in Modula-2.

I realise that this is not a VMS question, but any comments
would be appreciated.

Thanks

Grant Guenther                          Bitnet etc.:  GRANT@LAUCOSC

Department of Computer Science
Laurentian University
Sudbury, Ontario
CANADA   P3E 2C6