gtr at ast.cam.ac.uk
Tue Aug 9 01:19:27 PDT 2005
we agree that access to a VOStore must be controlled, yes? Therefore, we have
two possible cases:
1. A store owned by a VOSpace, where the VOSpace agent is the only allowed
user and call the store under its own, agent identity. This is the model
that Reagan is promoting and which is used in SRB. It's also the model in
AstroGrid MySpace to date.
2. A store which accepts access authenticated to more than one identity.
Some of these identities could be used by user agents; some could be
services with delegated identities; some could be VOSpaces. This is the
model promoted by Wil (up to and at Kyoto) and, I think, by others in NVO.
If you implement a store only for use from VOSpace then you naturally use
the first model and do no per-user authorization.
If you allow direct access to stores from DAL, then you have the second model
by default and the stores _have_ to deal with file ownership. However, they
don't _necessarily_ need tables of authorized users.
A minimal multi-user store allows any authenticated user to write data-items
and tracks ownership; it has a metadatum stating ownership for
each data-item. It doesn't check CRUD permissions; it assumes that the owner
has full, implicit permission on all owned items. This is a lot easier than
allowing variable permissions.
I think Matthew is right. The authorization is an implementation issue. The
tricky part is describing the authorization policy in the registration of the
stores: something we haven't looked at so far.
I suggest strongly that the same authentication system be used for both
single-user and multi-user stores even though the authorization is different.
This allows multi-user stores to be linked into VOSpace.
On Tue, 9 Aug 2005, Paul Harrison wrote:
> Matthew Graham wrote:
> > Hi,
> > I would argue that this is an implementation issue: you have to make
> > sure that VOStore can fulfil what it promises.
> > The required functionality for authentication is just that the VOStore
> > can recognise a valid message, e.g. the certificate used to sign the
> > SOAP message has the NVO CA in its certificate chain.
> This simple statement does hide some potentially complex implementation
> issues though...
> - if the signing certificate is a user certificate, then is the VOStore
> expected to have a user database to manage the authorization issues
> (group access for instance)? I thought this was supposed to be delegated
> to the VOSpace level.
> - Often the caller of a VOStore will be another service, requesting
> access on behalf of a user - so VOStore will be dealing with the GSI
> certificate proxy system at the first level
> Paul Harrison
Guy Rixon gtr at ast.cam.ac.uk
Institute of Astronomy Tel: +44-1223-337542
Madingley Road, Cambridge, UK, CB3 0HA Fax: +44-1223-337523
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