Subject: RE: [lemonade] Mobile messaging clients barriers

From: "Vaudreuil, Greg M (Greg)" <[email-masked]>
Date: Fri, 13 Jun 2003 14:59:10 -0500

It sounds like you are asking for an IMAP "session" to extend across multiple short-lived TCP connections?   Can you elaborate on why leaving the TCP connection open is a burden for the client.... is it that a wireless circuit must be maintained?  The cost of the TCP keep-alives?    
 
If the desire is to reduce the cost of "checking messages" over a circuit data session, then something like a suspend command that would return from the server a session token would be useful.  A new message-checking action could rapid-start with this token as a means to access the last shared state.... maybe check for new messages in just 3-4 round-trips.
 
Greg V.
 
-----Original Message-----
From: Mendelovich Meir [mailto:[email-masked]]
Sent: Friday, June 13, 2003 4:55 AM
To: IETF LEMONADE (E-mail)
Subject: [lemonade] Mobile messaging clients barriers

Hi, 
 I'm very happy to see that a consensus is forming about the need to add message submission to IMAP4. 
 But, this is only one of several barriers that prevent us from building good mobile messaging clients. I want to raise two major problems. All the details are in section 7.1 of the requirements document that was presented by Wong and me in San-Francisco (  <http://www.ietf.org/internet-drafts/draft-wong-umcli-02.txt> http://www.ietf.org/internet-drafts/draft-wong-umcli-02.txt).

1. As Alan Stebbens mentioned, server-side processing of media is crucial. We can't download 3 mega pixel image with 30bit color depth to device that has 100X100 pixels screen and 8bit color depth. We don't expect mail servers to implement image processing but it is needed to allow IMAP4 servers or mobile messaging gateways to use external transcoding engines to provide their mobile client better experience. 

In the MMS arena it is very hot issue. OMA prepares now a standard interface for transcoding servers. 

2. It is very hard to maintain long sessions in mobile networks. The current statefull nature of IMAP4 prevent many clients from providing good experience. Most of the mobile handsets that has IMAP4 client open and close new session for each command. This kind of behaviour cause enormous load on the server and spend lots of bandwidth. We MUST solve this problem if we want to see real mobile e-mail solution in GPRS and CDMA1X networks.

From our experience in mobile messaging clients these two problems must be solve to fulfill the LEMONADE goals. 

        Meir :-> 

__________________________________ 

Meir Mendelovich 
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