[SAGA-RG] Suggested errata to the SD spec

[Steve Fisher]

2009/4/15 Andre Merzky <andre at merzky.net>:
> Quoting [Steve Fisher] (Apr 15 2009):
>> >
>> > 1: with URL specified:
>> >
>> >  When you do
>> >
>> >    discoverer d ("glite://cern.ch");
>> >    list = d.discover (...);
>> >
>> >  and you have 5 adaptors (made up list)
>> >
>> >    glite
>> >    mds
>> >    local
>> >    unicore
>> >    condor
>> >
>> >  then you get a valid response from the glite adaptor.  You
>> >  get no errors from the other adaptors, and no time overhead
>> >  to speak off.
>>
>> Thanks for the concrete example. The gLite information system is based
>> on the "BDII" and accepts ldap calls (ldap://...). According to
>> http://globus.org/toolkit/mds/ the mds (in GT4) is WSRF based - so you
>> need to talk SOAP not LDAP. You are sure to get a rude reply if you
>> make an LDAP call to a WS or a SOAP call to an LDAP server. In some
>> cases the adaptor could choose to ignore a URL with the wrong scheme
>> (first part of the URL). gLite does not use gLite as the scheme part
>> of the url but "ldap" and most services use "http" or "https" so there
>> is no easy way for an adapter to recognise the validity of an info
>> system URL.
>>
>> I hope this is clear now.
>
> Yes, a lot clearer, thanks!  At last I think we are getting
> on the same page - thanks for your patience! :-)
>
> So, a given URL can lead to problems if more than one
> adaptor feel able to handle it.

Yes!

> Removing the URL surely would solve the problem.  But, as
> said, the URL is optional anyway.  What is the gain?

OK - I am to keep it in the spec

> Also, the glite adaptor is free to define the schema
> glite://, and translate that internally to ldap://.  We do
> that, for example, with gridftp, which is translated to
> gsiftp.  Also, we do that for ssh:// URLs, which are
> translated into local file URLS (for sshfs mounted file
> systems).

I think that SAGA adapters should not require changes to the
underlying middleware so I don't like this idea.

> I am not saying that you should not remove the URL - just
> want to make sure I understand why the URL is a problem,
> really.

Having had this discussion I now feel that the problem with the SD is
not serious however making proper use of the returned URLs is a
problem for all the other SAGA components. It is however an
implementation problem so I will move it to the developers list.

Nobody commented on the CamelCased attribute names - I would propose
to change all out attribute names in the spec to be CamelCased like
the rest of SAGA and to change the Java and C++ now to match. We want
to get the code released rather soon into gLite.

Steve


> Best, Andre.
>
>
> --
> Nothing is ever easy.
>