[SAGA-RG] Context attributes

[Andre Merzky]

Hi Steve, Paul, 

the set of context attributes is supposed to allow the user
to point to a specific security token, in a wide set of
environments.  You are right: apart from 'Type', different
grid environments will require different attributes to be
set.  For example, a MyProxy context would probably specify
'Server', 'UserID' and 'UserPass', while a X509 proxy
context would point the 'UserProxy' attribute to the proxie's
location in the file system.  

We hope that the set of attributes cover all currently used
Grid middlewares (we had the OGF security area check the
attributes for completeness).  If not, that needs fixing.

Note that these attributes are what the SAGA _user_ sees on
API level, and what he is supposed to use to specify what
token to use.  In most cases (by far, e.g. 99%), the user
should not need to set the attributes at all (apart from
type possibly), and the SAGA implementation should be able
to pick up the security tokens from default locations etc.

It is a different story altogether on implementation level
though: a context representation within the SAGA
implementation may well keep additional attributes, like
(for the examples above) the MyProxy server version, or the
X509 proxy file checksum.  That might be useful information
for the implementation to keep, and to pass around with the
context - but these attributes do not need exposure on API
level (that is why the context attributes are not
extensible).

I think the latter is what causes confusion for Paul in the
implementation (will send a separate mail on that on the
devel list).

Did I answer your questions?

Cheers, Andre.


Quoting [Steve Fisher] (Feb 05 2009):
> 
> I have had no response - does anybody know why this set of attributes
> has been defined?
> 
> Steve
> 
> 2009/2/3 Steve Fisher <dr.s.m.fisher at gmail.com>:
> > Hi,
> >
> > I have been looking at the spec for details of the Context class. I
> > don't understand why it has specific attributes defined when only
> > "Type" is common to all contexts. Attributes such as "Server",
> > "CertRepository" etc should not be there. The implementation can
> > document which attributes are needed. Have I missed something?
> >
> > Steve
-- 
Nothing is ever easy.