[AFS3-std] Re: [OpenAFS-devel] convergence of RxOSD, Extended Call Backs, Byte Range Locking, etc.

[Jeffrey Altman]

Jeffrey Hutzelman wrote:
> --On Thursday, July 23, 2009 06:43:35 PM -0400 "Matt W. Benjamin"
> <matt@linuxbox.com> wrote:
>
>> 7. Letting clients and servers negotiate a set of appropriate semantics
>> for operating on a given object, within some given parameters meaningful
>> to the server implementation and storage configuration--this provides a
>> framework for moving around the weak..strong space adaptively, allowing
>> support for a wider range of applications than any fixed semantics could
>> provide
>
> I see no problem with you being able to negotiate different semantics
> for yourself.  However, unless you are somehow privileged, you must
> not be able to negotiate different semantics for _me_.  We can argue
> at some point about exactly what that means, but at a minimum, I think
> it means things like...
>
> - You must not be able to force mandatory locking on me, unless you are
>  privileged in some way (for example, by being allowed to set some access
>  right or other property of the file).
>
> - You must not be able to decide that, when you write a file, a callback
>  to me is broken asynchronously, such that another RPC made on that file
>  by me or by a client with whom I am cooperating begins before I have
>  been notified that you changed the file.
>
> Further, there must be some common set of semantics where are
> guaranteed to be implemented by every fileserver and every client.
>
> Further still, there are some things which are basic properties of the
> protocol and are not open to negotiation.  I believe the one-to-one
> relation between (FID,DV) and bit strings is one of these, as is the
> one-to-one relation between FIDs and files.
>
> -- Jeff
jhutz++

And the usability of the system must not be made so complex that end
users cannot comprehend the behaviors they are experiencing as they move
from andrew.cmu.edu to ir.stanford.edu to fnal.gov.

Jeffrey Altman