perfsonar development work

[Jochen Reinwand <>]

Hi all,

You can find my comments to the various e-mails inline.

On Wednesday 17 January 2007 09:18, Matthias K. Hamm wrote:
> We use SOAP::Lite and XML::DOM. However, we are not happy at all with
> this choice and would like to have them replaced eventually.

AFAIK there is no really usefull SOAP implementation for our needs in Perl. 
But since the SOAP NMWG/perfSONAR is using is very simple, we decided to 
implement something based on the Internet2 NWMG implementation that is using 
directly HTTP transfer modules.

> Perhaps we - all participants who use or provide perfSONAR services with
> PERL - could collaborate in some way to avoid having the same
> developments twice or three times (as now).

That would, of course, be a wise course of action!

I think we have to think about separate "modules" when talking about a Perl 
perfSONAR implementation (btw we called it perlSONAR ;-) ):

- SOAP implementation: Most likely we have to invent something on our own 
here...

- XML implementation: There are a lot of different ways in Perl to handle 
XML. 
But we should try to use only a few modules! We wanted to try doing 
everything with XML::LibXML since libxml is the standard OpenSource XML 
handling library. Therefore it should not be the worst implementation ;-)

- perfSONAR implementation itself: That is what we definitively need to have! 
I haven't really looked at the Java code (yet), but I believe that copying 
the API and keeping it in sync is a lot of work! At the moment our 
implementation is really simple. We more or less use directly the DOM objects 
with some helper function. That's not really an API. But I think that a 
useful API should look like a perfSONAR specific DOM. Instead of getting a 
DOM object containing the whole NMWG message, we should somehow make the 
important parts of the documents directly accessable and enhance/overload 
them with special methods that do typical perfSONAR/NMWG things. This way we 
make simple things easy and complicated things possible ;-)

> What about having a VC

I do not really like VCs, but it might be useful...

> or perhaps even face-to-face meeting ? 

That shouldn't be necessary, but using one of the GEANT meetings might be a 
good idea!

> Yee-Ting Li schrieb:
> > i was interested in porting the java libraries mainly because i felt
> > it was a good place to start; the structure of the objects appears to
> > make a lot of sense. i've looked through your code, and i like the
> > simplicity of the NMWG.pm class, and the way in which it is more
> > perl-like.

That was our goal! Indeed there is not much to do for using SOAP and XML. 
Otherwise they wouldn't be as successful as they are ;-)

> > i was thinking that it may be nice to implement the java api in perl;
> > but utilise wrappers around the api to allow more perl like data
> > structures to be implemented. that way, it would be relatively easy to
> > keep up to date with the current nmwg spec (as the java classes are
> > typically very up to date), whilst at the same time being able update
> > services to use the latest nmwg versions with almost no effort.

I'm not sure whether I understood you correctly, but do you want to use the 
Java classes directly from within Perl? This is indeed very simple! There is 
a CPAN module (http://search.cpan.org/~metzzo/Java-4.7/) that does nearly all 
the work for you! I already thought about that, but we decided that we did 
not want to have Apache, Tomcat, Axis and so on, on all our measurement 
boxes. That would interfere unnecessarily with the measurements and the Java 
implementation also has some more performance issues...

Or do you have something different in mind?

Reimplementing the Java classes in Perl would most likely not be really 
useful. The Java classes are using a lot of third party classes most likely 
not available for Perl. Also Java is to different from Perl I think...

> > i've started a little in this task; the main problems at the moment
> > appear to be the need for a namespace class in perl.

XML::LibXML supports namespaces!

> > does your hades nmwg classes support meta data chaining etc?

I'm not sure about that. Verena is ill today, she would know better.
But I think we use chaining. Perhaps Verena is just directly operating on the 
DOM objects...

greetings,
Jochen

-- 
Jochen Reinwand                                 Tel: +49 9131 852-8689
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