On Mon, 24 Mar 2003, The Purple Streak, Hilarie Orman wrote:
I started trying to read this thread and I find that I need a
summary of how we got here and what we are trying to accomplish. I
can follow the details, but cannot tell why we are discussing what
seems a fairly complicated interaction.
We are discussing this for two reasons (see the first message
on this thread for details):
- we need to decide when an OPES processor can
get rid of the data that was previously marked
with a [copied] flag (the semantics of the flag
does not imply an efficient end-of-life moment for
copies)
- we need to decide how we can let callout
server to get out of the loop without losing any
uncopied data (commitment-based schemes are simple and
fast but lead to deadlocks, other schemes are more complex
and slower)
Both decisions must be documented in the callout protocol specs if
copying-related features are to be supported.
I'm uncomfortable about messages that implied that we are trying to
support a layer 7 switch architecture. If that's at the heart of
this, I'm dismayed. If not, I don't know what's going on.
IIRC, the only suggestion relevant to L7 switching was that no copying
is necessary at all -- we could say that [the initial version of] the
callout protocol supports "move" and does not support "copy"
operations. L7 switch is just an example of an application-level proxy
that may not support "copy" operations. I have argued that "copy"
optimization is too valuable to get rid of.
I have a lot of trouble understanding the value of this if there's
anything other than "this is a copied stream" and "this is not a
copied stream".
This discussion exists because some of us consider copying
optimizations valuable (worth discussing and implementing) but those
optimizations raise questions that protocol needs to address.
Could someone provide a succinct description of the problem?
The first message on this thread describes both problems. The above is
a short summary. However, since I wrote both, it would be great if
somebody else can re-describe the problem for Hilarie in better words.
If there are no volunteers, we can just wait for the protocol draft to
be released this week; hopefully, it will clarify the problems.
Thank you,
Alex.