On 12/12/06 11:30 AM, "Ivan Smahin" <IvanSmahin at public.kherson.ua> wrote:
Hi Charles,
Hi All,
> CY> Once you've established a connection to a VServer from a V4Rb client
> CY> and opened a database using the connection, VConnection.IsConnected
> CY> returns true, and VDatabase.IsOpen returns true. But what happens
> CY> when, say, the server shuts down? It turns out that IsConnected and
> CY> IsOpen still return true. So there doesn't appear to be a way to
> CY> determine whether a connection is actually working other than to try
> CY> something.
>
> Well, just for now we have "client-driven" system. So every
> activity in the server is result of some command issued by the client.
> I mean there is no client-callbacks registered in the server. So
> server is not able to issue some broadcast message like "I'm turning
> off". We don't use this way because it means multi-threaded vclient -
> it is not suitable for some our plugins.
>
> Now I will try to improve connection.IsOpen() method checking the
> socket state, but you know - it could be wrong result because of
> socket nature. So it is always good idea to catch "network exceptions"
> everywhere.
> CY> But if the server has quit, the result is not so good.
> CY> When I attempt to close a VDatabase object in this situation, I get
> CY> VException &h6050a, ERR_STREAM_READ_ERROR. Then the app quits
> CY> abruptly with only this entry in the console log.
>
> CY> terminate called after throwing an instance of 'fbl::xStreamError'
>
> Do you catch this exception in RB? If so - why you get abort?
What Ivan says is:
* when server gone, client computer still do not have info about this.
OS (mac and win) - still not close socket on client computer some time.
can be up to 2 minutes it seems.
So IsOpen() still answer true.
for now we think this is the only correct behavior and you
MUST live with this.
* Next, we do not see say you say: " Then the app quits abruptly "
you have got exception from Valentina about ERR_STREAM_READ_ERROR?
so what problems?
of course you will get troubles if you will continue
to use dead objects!
The CORRECT STEP is:
if you catch such exception, then you need
a) want user that network server have gone.
b) kill database objects
c) kill Vconnection objects
d) may be try create new Vconnection + Vdatabase.
YOU CANNOT reuse old Vconnection !!!
--
Best regards,
Ruslan Zasukhin
VP Engineering and New Technology
Paradigma Software, Inc
Valentina - Joining Worlds of Information
http://www.paradigmasoft.com
[I feel the need: the need for speed]