Comments inline - prefaced by '>>'
NOTE: I am not a Network architect but believe my understanding as
described below is correct.
Steffen Winkler wrote:
Thank you Stan.
We come closer to the solution:
Application, database and Network server is installed on the same computer
(Laptop).
Url contains computername (e.g. danxpu73).
If the network-cable is plugged off, the connection closes with following
error:
-4499: A communications error has been detected: Connection reset by peer:
socket write error.
>> OK, the Client or the Server (whomever printed the error) noticed
that the connection had been broken and probably marked the connection
as disabled.
Restart the application and ping leads to the error:
DRDA_NoIO.S:Es konnte keine Verbindung zu Derby Network Server auf dem Host
danxpu73, Port 1527, hergestellt werden.
That means "no connection possible".
>> Sounds like the network cable is still unplugged so there is not way
to address the network and so this error makes sense.
Shutdown the server leads to the error:
-4499 java.net.NoRouteToHostException : Error connecting to server danxpu73
on port 1527 with message No route to host: connect.
Restarting the Network-Sever solves this problem.
>> No route because the network cable is still unplugged?
If the network-cable is plugged off and re-plugged in, then new connection
of the application is possible.
>> So now the network is back and you can connect again.
Similar problems occur, when I use IP-Number instead of computername.
>> OK, using IP or hostname on the URL invokes network code and
requires a network connection regardless of where the client is located
No problem occurs, when I use "localhost".
>> I assume this will always work because 'localhost' uses the loopback
port hence no network is needed
HTH, Stan
