Re: Re: GPE syncing

> > 2. keep trace of modifications, with a modified flag.
I'm not sure this is sufficient for modifications. it doesn't allow you
to apply sensible policies for collisions (where client and host are
modified).

a better approach would be a timestamp associated with each field.
unfortunately this is quite expensive in terms of space +at least 4
bytes for every individual entry you want to sync.

the even better alternative is to use a modification log, which
unfortunately adds a bit more complexity to either the client program or
to the DB handler.

> > * For the 3, I guess we need some RPC solution to communicate between
> > the synchronization applications and the SyncML client, I guess in
> > the same way the «Today» application would do. Which one do GPE
> > use? If there is no one used right now, which do you plan to use?
>
> This probably wants to be handled in the database layer (ie usqld)
> rather than by a more general IPC mechanism. I don't know if anything
> like that exists right now. At any rate, no applications are using it.

at present opening a transaction on a sqlite database locks the whole
underlying file anyway, so as long as sync was done within a transaction
you are alright on this leve.

usqld has fallen a bit by the wayside recently due to Ph.D/work
commitments and lack of functioning develoment box, i did start to
re-write protocol driver to support multiple handles over a single
connection, with a view to having an asynchronous mode for the client
(which would also with a bit more work allow server-client notifications
if that were called for)

In its current state there isn't really any need for GPE apps to use
usqld locally as it does the same thing (actually less :() than sqlite.

sqlite now includes loadable modules etc. i thought it would be very
useful, if there were a given subset of database side functionality that
could be applied across the board, to have a gpe_sqlite module
encapsulating all of this functionality. (this would work for both
sqlite or usqld based apps) somebody was also talking about stored
procedures, but i can't remember what happened to that thread.

owen

 
Owen Cliffe <occ_at_cs.bath.ac.uk>
Received on Sat Oct 12 2002 - 14:23:44 EDT