perfsonar development work

["Nina Jeliazkova" <>]

Hi Nicolas,


Nicolas Simar 
<>
 wrote:

> >>>>  Several groups of users have been complaining that there 
> >>>> isn't any discovery of
> >>>> MAs and they'd like to skip the pSUI
> >>>> selection step.
> >>>>       
> > 
> > As a side note: the user can have all MA selected , psUI will find the 
> > correct ones anyway.
> 
> It is quite time consuming. People have been put off from pSUI because 
> of that feature inter-acting with either too slow MAs or no MA. It was 
> taking 4 minutes in some case.
> 

OK. We have yet to find out how time consuming will be the proposed gLS
approach.

> > 
> > The steps are more or less clear:
> > - get domain name of the IP
> 
> That's my main point of interrogation. How can it be done?
> Whois to get the domain or AS name?
> In that case, it is important that the deployer of the LS register the 
> same name as the one used in the reference methodology to map IP 
> addresses to domain name/AS name.

This is what DNS is for :)  It is straightforward to query DNS by Java code
and get IP - host name mapping.

        InetAddress[] addrs = InetAddress.getAllByName ("62.40.125.66");
        for ( int i=0; i<addrs.length; i++ )   {
              System.out.println( "IP Address : " + addrs[i].getHostAddress()
);
              System.out.println( "hostname   : " + addrs[i].getHostName() );
              System.out.println();
           }


and the output in this case will be
IP Address : 62.40.125.66
hostname   : istf2-gw.rt1.bud.hu.geant2.net

From the host name the domain eventually should be  "rt1.bud.hu.geant2.net"


Some time ago (for a different project) I've used DNSJava library
(http://www.dnsjava.org/), which provides finer control, async calls, etc.
Please note DNS queries can be time consuming as well.


For autonomous system number I can indeed think only of whois, but why we
would need AS -IP mapping instead of IP-name mapping ?

Best regards,
Nina

> 
> Cheers,
> Nicolas
> 
> > - send it to gLS
> > - receive URL of LS
> > -query LS for the IP
> > -get MA URL
> > -query MA as usual
>