[glue-wg] Suggestion for splitting the StorageShare.

[Burke, S (Stephen)]

Laurence Field [mailto:Laurence.Field at cern.ch] said:
> This is what I was trying to express the other day when I 
> said that we need something like the LFC. Where as the LFC maps to
logical 
> names to SURLs, is this notmapping namespaces (directories) to
physical spaces 
> (or is it logical space?).

To some extent that's right - in fact the LFC is to some approximation a
DPM without any storage, just a namespace mapping. However, things are
getting more complicated since it seems that we're introducing a new
concept of authorisation on spaces themselves which is orthogonal to the
namespace. In the unix filesystem world I think this would be like
having a permission to write to a mounted partition which was
independent of the permissions on the files and directories inside it.
That isn't really analogous to the LFC or any other catalogue - in a
sense it's much simpler because the namespace for spaces (sic) is flat,
each space has a name (space token) but there is no structure. (Well,
until we get hierarchical spaces!) 

> I agree that this might not belong in the 
> information system on the other hand this doesn't necessarily mean
that 
> it should not be in the information model

Maybe, but I think we need to be clear about what we're representing. To
me the Path in the SA/Share is a prefix for use when writing a file,
i.e. when you write a file you are supposed to construct a SURL by
appending your choice of file path/name to the published Path. In the
general case the Path would be absent/NULL or equal to / which would
mean you can use any SURL you like. That concept seems to me to be very
different to publishing general properties of a filesystem/namespace,
which could e.g. extend to publishing every directory with its
permissions - I think that is not something which is likely to be useful
in GLUE. (Remember that the old GLUE does have FileSystem and File
objects but we have never used them.)

Stephen