Subject Re: [firebird-support] Possible interaction between Firebird and Skype?
Author Reinier Olislagers
On 30-7-2012 9:37, Svein Erling Tysvær wrote:
>>I've been using a Firebird database with embedded server, accessed
> through a Delphi app, for several years now without
>>Today I experienced a curious problem: I made a Skype call with my son,
> he was busy and said he'd call back in 10 mins. No
>>call came but when he did eventually get through about 2 hours later he
> said that I appeared to have been offline or at least
>>'busy' as far as Skype was concerned. I am 100% sure that from my end
> Skype looked normal, with the green 'online' symbol
>>showing. I am also 100% sure that he had indeed been trying - often -
> to call me. However I had been using my Delphi/Firebird
>>app. and apart from Firefox being open I had no other applications
> running. And Firefox was still running when we eventually
>>made contact ... after I closed my Delphi/Firebird app.
>>Is it conceivable that in some way the Firebird client lib interacts
> with Skype? I find it hard to think of any other reason
>>why I should appear to be offline.
See below why I think it's unlikely Firebird embedded has anything to do
with Skype problems. Of course, I don't know if e.g. your Delphi
application blocks internet connectivity, has such a high CPU load that
connection attempts fail etc (yes, grasping at straws here).

How do you think the Firebird client should interfere with Skype?
OTTOMH, I can think of only:
1. CPU/memory resource exhaustion, starving Skype of resources to take
the call.
2. listening on ports that Skype would listen on

One thing though: you could call your son. If you were running the
application before you had started skype, communication apparently was
still possible (leaving the difference in call direction).
If you started your application after the outbound call, presumably
Skype was already listening on any inbound ports and your application
couldn't take over those ports. It could only do the resource starvation

The Delphi app does use some other
> 3rd party libraries which I must also examine in
>>detail, but I'd be glad of any pointers to possible links to Firebird.
> In this case Google is not my friend because it
>>doesn't reveal any similar reports.
And I think there's a good reason for Google not being your friend here.

Try running a tool like Sysinternals TCPView and then start up your
application. Does it start listening on ports, possibly blocking inbound
connections (if you have listening ports open to the internet at all,
which you didn't mention).

Monitor CPU/memory usage and see what happens.

Try calling the Skype echo service while your application is running.

Try calling somebody again on Skype and let people call you while the
application is running.

From Sven's post:
> This page:
> indicates that unless configured otherwise, Skype randomly chooses a
> port above 1024 for incoming connections. Firebird, by default, uses
> port 3050 (+ possibly some other for events).
That's right, but applies to Firebird server, not Firebird embedded.
Firebird embedded shouldn't open ports.

> I really know nothing about conflicts like these (and I don't use
> Firebird embedded), but if Skype chose port 3050 before you started
> Firebird and then port 80 or 443 was busy with something else, then
> maybe it could be conceivable?
Port 80 or 443 would only apply if the OP has these ports open (e.g. if
OP is running a web server on his machine).
Outbound 80 or 443 can't be "busy".

Firebird embedded shouldn't open ports, so the port story seems unlikely
to me.