While I know of no careful study I think there is considerable
anecdotal evidence (well at least folklore) that holding the
connection open is a bad idea. It may reduce network traffic but
increases the load on the server.
We should distinguish between two ways of holding a connection open.
One is what ftp does, holding it open for some large amount of time,
on the order of minutes, so the user can figure out what to do next.
The other is holding it open for a short time, on the order of
seconds, so clients and fast users can figure out what additional
documents to get.
Not holding connections open also increases load on the server since
the overhead of opening and closing connections counts for something.
Somewhere in the middle is the optimum setting. The amount of time
that a server holds a connection open could be automatically adjusted
based on load; it should not drop the threshold any lower or raise it
any higher than the point at which it would increase load on itself if
it did so.
Daniel LaLiberte
National Center for Supercomputing Applications
liberte@ncsa.uiuc.edu
(Fight interface copyrights and software patents.
Join the League for Programming Freedom: lpf@uunet.uu.net)