RE: [lemonade] I-D ACTION:draft-ietf-lemonade-reconnect-client-02.txt

["Ben Last" <Ben.Last at emccsoft.com>]

>From: Randall Gellens [mailto:randy at qualcomm.com] 
>>  Do we expect connections to drop during resync often enough to be 
>> worth handling it specially?

Randy: I think that was your quote - apologies if I have misattributed it.

In our testing of our mobile client, we use a range of mailbox sizes: some are test and some (the larger) are real-world mailboxes.  Like mine, which is embarrassingly large, and those of a group of test users who are evaluating the first release of the client.  We find that connection drop during synchronization is actually fairly common.  Naturally, the chances of losing the connection during sync increase with the size of the mailbox, especially since we find that the client often needs to do a state-comparison sync after first login, and actual cellular data rates can be very slow at times.  We await the availability of CONDSTORE with great anticipation...

Also: sometimes even a rare condition is worth special case treatment if the *consequences* of that condition are sufficiently expensive.  A full resync of an inbox with 1000+ email in counts as expensive :)

Just for interest, some stuff we've found through mobile phone client testing:

Connection drops occur somewhat more often when the connection is over WiFi.  We're typically finding that mobile phone connectivity over WiFi suffers because of coverage blackspots that are usually not noticed because they're in places where people don't take laptops, because blackspot effects are worse for a phone because transmission power is lower and because the human body is an effective shield when a phone is raised to the head or worn in a pocket!  Since WiFi is effectively free compared with cellular data, though, it's the preferred way to connect.

Aggressive battery-saving (and cost-saving) measures include dropping out of push mode during the night, or when roaming.  When re-establishing a connection after a pushless period it's often necessary to perform a state-comparison sync.

Yours meanderingly
Ben

Ben Last
R & D Manager
EMCC Software Ltd

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