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Expert Question of the Week 
August 20, 2001

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Welcome to Search390's Expert Question of the Week newsletter.
Remember, no question is too simple for Ask the Experts! If you have
a 390-related question, send it to [EMAIL PROTECTED] Selected
questions will be answered by our experts. 

This week's question was answered by Jim Keohane, search390's
Troubleshooting System 390 Expert.

THIS WEEK'S QUESTION:

Q:  I need to capture the last referenced date, time of a physical
sequential file in order to allocate and FTP a 0 byte new file with
timestamp as a node as delivery notification to an ip address. The
file which needs to checked for last change is changed by an ftp pgm.

A:  OS/390 does keep a "last referenced" date, but not time, for
sequential datasets in the format 1 DSCB.

You said the dataset is last "changed" by FTP. Last referenced date
is not same as last referenced date. If dataset was last changed
Monday but the next day some program or user later read or browsed
that dataset it's last referenced date would be Tuesday.

It sounds like you wish only the last date/time the dataset was
modified by FTP.

If FTP deleted old dataset and then allocated and wrote to new
dataset then the creation date would be more accurate than referenced
date but you would still not have the time.

Various SMF records are optionally written by FTP and by underlying
OS/390 access routines. One of them would probably contain enough
info to see a dataset of a specific name written to and closed by a
program named FTP or whatever. The SMF record would also contain a
date and time that should be awfully close to what you want. The
problem here, of course, is getting easy and timely access to these
SMF records. Every shop has their own procedures so it would be
fruitless for me to make suggestions without knowing more.

There are also FTP user exits. There should a user exit in OS/390
server to record or capture date/time of last write to specific
dataset(s). The exit could log that info somewhere that another
program could interrogate later and do the FTP of 0-byte file you use
as notification.

I wrote the code in IBM's older FTP client and server for SMF
records. There was also a user exit that was awoken when SMF record
was to be written. You could turn on SMF within FTP, have your exit
log the event and then return to FTP saying to SKIP writing of SMF
record. That is, if my memory hasn't failed me and that current IBM
FTP client/server have a similar capability.

Hmmmm, there are RACF/ACF2/TSS exits that are awaken when a file is
opened for output and/or when a file is allocated DISP=OLD or NEW (or
MOD if pre-existing?).

Hope this gives you enough ideas.

If you have a question for Jim, submit it here: 
http://search390.techtarget.com/ateQuestion/0,289624,sid10_tax285123,00.html

If you'd prefer to submit your question in one of our discussion
forums, you can do that as well.  We have four forums available for
your posting pleasure.

Also, stop by and see if you can answer some of the questions posed
by members of the 390 community.  For instance, search390 user
"steveg4432" posted the following in our Operating Systems forum: 
"Hello, we are getting ready to install Linux on 390. Which
distribution is the preferred (favorite) redhat, suse, turbo?"

What's your favorite?  Tell Steve and post your choice here:  
http://search390.discussions.techtarget.com/WebX?[EMAIL PROTECTED]^[email protected]

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