>I have taken on a project in which satellite offices will
>collect data, and at regular intervals send this data
>to a main office. The satellite offices may also request
>data from the main office.
>
>Both the main office and the satellite offices may send or
>receive data from each other, or the sattelite offices may
>send data back and forth at any time.
>
>Some offices will be using dial-up connections, some may use
>more fixed connections like cable modem or DSL. There is no
>network in place.
>
>Once the data is collected, the main office will process it
>and the send this data to other organizations.
>
>My question is this: Whats the preferred method for sending
>and receiving data? I am leaning towards having my application
>ZIP up the required records and send it via modem upon user
>request.
>
>Should I do this via email? Or is there some way to actually
>transmit the data to another PC via IP address?
>
>Any input would be really helpfull.
>
>Thanks


from my experience doing this, whatever details you settle on, i strongly
recommend writing all the synchronization code yourself.

i would start with a wholesale transfer of the tables.
if you expect to accumulate a lot of data, you should consider from the
beginning, to incorporate some fields to serve as version info so you
can implement a transactional sync versus a wholesale transfer and replacement
style sync. otherwise the transfer latency will eat you alive.
keep the whole-table transfer method available, which is handy to
update table structures. you could implement a table structure update
procedure too, but of course, the more elaborate you get, the longer
it takes to write and the more complicated to maintain.

if you are using dial up networking, you can map to a share on your
server and transfer files. to invoke a program on the server you can
use RPC to incorporate your transactions into the warehouse and/or
extract your transactions for transfer to a remote machine.
this arrangement affords you very good security (if that is an issue).

the problem with transferring to a mapped share, is the requirement to
log in to the 'host' server. if your remote computers participate in a
network, i've found it necessary to create and boot into a non-network
hardware profile to be able to log into an NT server. this is not a
big deal if your clients are part of your company, but to have to do
this for non-employee clients, it's a pain. ftp transfer of
the files would avoid this problem. wish this had occured to me before
i started.

right now, i have the luxury of opening server files exclusively for
update. if you can't do that, you will resort to table-level or record-level
locking to do updates. someday i may upscale to oracle backend to avoid this
issue entirely.