On Tue, Jun 10, 2003 at 09:27:13PM -0400, Ken Murchison wrote: > > Gary Mills wrote: > >Does anyone know of an e-mail web application that doesn't abuse the > >IMAP server by making short connections? Most of them simply connect > >and disconnect with each HTTP transaction. Is there one that behaves > >the same as an IMAP client, using one connection for the duration of > >the session. An IMAP proxy is not adequate because most of them only > >cache TCP connections and perhaps authentication. These are generally > >not the source of most of the transaction overhead. > > So what part of the connection to you perceive as the most expensive? > The selection of the mailbox? This might be cacheable, but that depends > on how the webmail client is written (ie, simply caching it might screw > up some of the client's logic).
I haven't determined that. I suspect, though, that there are limits to what can be cached by a proxy. A better design might involve a persistent portion of the webmail application, that maintains some state across HTTP transactions. The communications between the two portions need not involve IMAP. > FWIW, Dave McMurtrie's imapproxy (http://www.imapproxy.org/) works quite > well with IMP/Cyrus, and is very well written. It doesn't cache the > selected mailbox, but it does keep an authenticated (and optionally > encrypted) connection open with the server. We do use that, and it probably does improve performance. It does have a problem with idle browser connections that accumulate with time. This also ties up a lot of `imapd' and `httpd' processes. It probably needs a client timeout someplace. I haven't had time to investigate further. -- -Gary Mills- -Unix Support- -U of M Academic Computing and Networking-