[Twisted-Python] Bring multi service up gradually

[Chaz.]

I would know how to do it in C, but I am no twisted expert. The idea
would be to open the socket and hand it off to the service to use. I am
sure there is a way to do it in Twisted (opening a port and using it in
a service).

What you don't want to do is just "test" the port (opening it and
closing it). Once you have it opened, you need to keep it open.

Chaz


David Pratt wrote:
> Chaz. wrote:
>> I don't think there is a way to insure you will get the ports you want.
>> Why bother testing if the port is available before hand? In between the
>> port being tested and the application using it someone can sneak in and
>> take it.
> 
> Hi Chaz. Thank you for your reply. The reason for the test is that I
> don't want the other services to start at all if a connection cannot be
> found to run the main service. I was thinking of writing a simple tester
> using socket module to determine which addresses are alive first. When
> it finds one it stops so in my logic I give this address to my
> ListenTCP/SSL and attempt to start the main service.
> 
> I don't expect the address list to be large. This way no time is lost
> with the client running through a long backoff cycle on an address that
> may not be alive only to have to stop it and try a another until one is
> possibly found.
> 
> I am not aware of something in twisted that evaluates addresses like
> this as part of a startup solution. In any case, if I see that an
> address in the list is available, then I would start my main service
> using it.  When a connection is made to the main address, then I want to
> start the remaining services since they are useless without the main
> service.
> 
> Regards,
> David
>