[maemo-developers] Modest/TinyMail problems (continue from the blog comments)

[From: Philip Van Hoof]

On Wed, 2008-06-25 at 00:33 +0200, Luca Olivetti wrote:
> En/na Marius Gedminas ha escrit:
> > On Tue, Jun 24, 2008 at 11:24:24PM +0200, Andrea Grandi wrote:
 
> > I want all the messages, and I want them in threaded view.  I believe
> > Modest does the former, but not the latter.
> 
> Claws does both, however it also downloads *all* the headers.
> Mulberry (that's not available on the tablet) uses a different approach: 
> it only downloads enough headers to fill the screen. You scroll down (or 
> up), it fetches more headers. Latency is higher and it cannot use the 
> same mechanism for offline operation, otherwise it's pretty efficient, 
> especially on a constrained device.

Polymer does a similar thing to Mulberry. The technique is indeed very
interesting and could be adapted to work with offline operations too, if
downloading is allowed to take place in the background and if when
scrolling up and down a higher priority task to get the visible items
can be scheduled upfront.

To make this perform good, with few latency problems, we'd need to
implement full pipelining. This is something Tinymail's IMAP code can't
do at this moment. For it to do such pipelining would require an almost
rewrite of the IMAP code (not a trivial task, but planned nonetheless).

> On a pc with a relatively slow connection to the imap server is way 
> faster than thunderbird on the same pc.

That's for Mulberry mostly due to the fact that just visible envelopes
are downloaded, and for Polymer on top of and Tinymail mostly due to the
fact that CONDSTORE and QRESYNC can be used (if the IMAP server supports
it).

What could help a lot is to use very recent OpenSSL or NSS libraries
with your IMAP server and on your device and keep tracking the latest
versions. I have not investigated this fully but in theory can the SSL
layer do compression. With IMAP data that would compress at a very high
compression rate indeed.

Certain IMAP servers also have the COMPRESS capability, but since the
SSL layer should eventually support compression too, relatively few IMAP
servers are implementing this capability.


Cheers,

-- 
Philip Van Hoof, freelance software developer
home: me at pvanhoof dot be 
gnome: pvanhoof at gnome dot org 
http://pvanhoof.be/blog
http://codeminded.be