Re: Database applications over VPN

"r042wal" <rob@xxxxxxxxxxxxxxxx> wrote in message
news:mddHj.4532$9X3.4477@xxxxxxxxxxx
Why do database applications not work well over VPN?

There is no specific reason - database apps can be written to work well over
a WAN.

I have tried a few
proprietary applications that are SQL driven and they are painfully slow,
but even something as simple as ACT or QuickBooks will not work well over
VPN.

These apps use SQL queries - but there is an "old saying" - any programmer
can defeat good tools and networks.....

what seems to cause the issue is writing the app so that there are large
numbers of separate transactions that happen serially - add latency within a
transaction and everything slows down in proportion.

now consider that a LAN may have turnaround times well below 1 mSec, and a
typical broadband link will have 10s or 100s of mSec, and slower equipment
to traverse such as home routers, multiple firewalls, VPN gear, and you see
where the difference comes from.

i have seen lots of apps that could have been written so that 1 query is
sent, and then the results are streamed back (which means 1 turnaround for a
set of results) - but they do a "give the next record" type query (1 per
record).

What is the reason behind this?


bad programming, and more seriously, poor or inappropriate testing.

the biggest single reason i come across is that the developers always seem
to have the latest machines, modern fast servers with few other users and
and access on a local LAN.

and then you roll it out and suddenly realise it doesnt like your old
machines, slow WAN links, remote workers......

Make them work on a remote broadband link and your apps will suddenly get
better :)

--
Regards

stephen_hope@xxxxxxxxxxxx - replace xyz with ntl


.

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