[AFS3-std] XCB union decoding (was Re: Encoding IPvN addresses)

[Jeffrey Hutzelman]

--On Friday, February 11, 2011 11:12:58 AM -0600 Andrew Deason 
<adeason@sinenomine.net> wrote:

> But in that situation with XCB, if you get an unknown callback type,
> there's not anything you can do with it, so the only thing I can see
> happening is that you drop it. And so, you've dropped a callback break,
> which means losing information or keeping stale data around in the
> cache. I would expect that the fileserver be told that a client doesn't
> understand a certain callback type, and so would have to work around it
> (probably by sending a Cancelled or something).

I think extensible unions are a good fit for XCB, because of the bulk 
delivery mechanism.  But yes, you'd need a way for the client to indicate 
to the fileserver which of the XCB entries it understood, and perhaps to 
return a per-entry error code, in the same way that RXAFS_BulkStatus does.

-- Jeff