Re: [MacPerl-WebCGI] query

[Peta Adams - John Murray <jmnc@lis.net.au>]

My thoughts.

A user clicks on a thumbnail. Rather than a thumbnail link calling another
html text page, it calls a perl script with the ID of that picture along
with it.

That script writes to a file:
picsinuse.txt:
picID	datetime
pc0237	07091999-12:18:36
pc1426	07091999-12:24:13
etc.

This takes care of how to flag to a more recent user that a particular page
is in use. [The script that builds the index page checks if picID in
picsinuse.txt, or if datetime to now > say 15mins,(see in use refresh
below) and if it is substitutes "In Use" graphic for thumb]

Now to existing other users. The refresh idea I think would be neat. You
could annotate each index page with "The status of images in use
represented on this page is correct as at Jul 27 1999 at 3:37:23 pm. The
page will automatically reload updating status for you. Alternativiely you
can click on the "Any Changes?" button" [obviously you would need to be
more succint or communicate concept in another way than words].

You'll need to check when an existing user clicks a thumbnail whether the
pic has become in use since the page the thumb is being clicked on was
loaded.

The last point is to capture that the user of the graphic has actually
finished using it. If they keep making requests of your server you should
be able to track it with picsinuse.txt. [e.g.a "New Image" link could drive
a script that first deletes that picID from picsinuse]

It's when a user just logs off or moves to another site that requires
another strategy. I'd probably go for a refresh on each page that is an
enlarged graphic each say 10 minutes that stated "You have had possession
of this graphic for 15 mins. Keep using it?". If there is a response feed
original page back via your script and also rewrite datetime for that picID
in picsinuse.txt. If there is no response within a minute, that page could
have a refresh that pulled up "Graphic Handed Back" message.

Can the on window close event in javascript request a URL. If so, you can
drive a script when the window is closed that deletes picID from
picsinuse.txt.

There's a few issues still left to resolve [How long can refresh be set to?].

However I can see something workable from using:
* a "picsinuse" file
* refreshes that give an opportunity to have user cause "picsinuse" file to
be updated

Sorry mate, above is a bit of an ideas dump than clean concise debugged
method. But I hope it adds something to your endeavours.

John.

John



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