[OpenAFS-devel] When is an AFS request-response completed?

[Jeffrey Hutzelman]

On Sat, 3 Nov 2001, Andrew J Klosterman wrote:

> On Sat, 3 Nov 2001, Jeffrey Hutzelman wrote:
> > On Fri, 2 Nov 2001, Andrew J Klosterman wrote:
> > > I am observing (epoch, cid) pairs issued as AFS operations with various,
> > > sequential callNumbers without any response packets from the server that
> > > contain any data, only ACKs.  After the ACKs, the client increments the
> > > callNumber and issues an additional operation.
> >
> > Do the RPC's in question have any OUT arguments?  If not, then the server
> > will have no data to send.
> 
> Yes, they certainly do.  The operations I see most often are FetchData,
> in the previously described circumstances.
> 
> And, the second part of your comment intrigues me.  If the FetchData
> operation fails for some reason -- e.g., the requested data does not exist
> -- does the server have respond with the OUT arguments?

No.  If the call fails, the server sends an ABORT packet which includes
the error code.

> This idea indicates to me that I would need to look deeper into the
> semantics of interactions between AFS operations and Rx ACK packets.
> Anyone have any idea on this?  Where to look, experience with it?

The AFS operations are simply Rx RPC's.  The Rx protocol description that
kolya mentioned earlier contains a description of how the RPC system
interacts with the lower layers of Rx, and how RPC procedure numbers,
arguments, and responses are sent within an Rx call channel.

-- Jeffrey T. Hutzelman (N3NHS) <jhutz+@cmu.edu>
   Sr. Research Systems Programmer
   School of Computer Science - Research Computing Facility
   Carnegie Mellon University - Pittsburgh, PA