ietf-openproxy
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RE: OPES protocol, pre-draft 01

2003-02-26 14:29:12

On Thu, 27 Feb 2003, jfcm wrote:

At 17:24 25/02/03, Alex Rousskov wrote:
        <data-end xid amid [error] reason>
        <message-end xid amid [error] reason>
        <xaction-end xid [error] reason>

Why not also just?
<zap xid [error] reason>

What would be the meaning of the <zap> OPES message? The three old
messages above are based on three persistent "objects" or "states"
that OPES protocol has to maintain (data flow, application message, and
application transaction). See predraft for detailed definitions. What
does <zap> refer to? How is it different from, for example,
<xaction-end>?

I just hit escape. We may have extensions of the protocol in the
future needing to add other commands. I would hate to review all the
code to add <linj-end xid [error] reason> etc. all the way through.

We cannot discuss or accommodate nonexistent extensions because we do
not even have an extension framework yet. What can be extended? How?
Without such a framework, I cannot (yet) say whether new <*-end>
messages may be needed.

"Hitting escape" in a user agent usually means the end of the
application transaction, which is already supported with the
<xaction-end> message. OPES is not about user actions or interfaces
though. It is about modifying application protocol messages.


In general, if OPES protocol deals with some kind of persistency (like
data flow or transaction state), there has to be a way to end that
persistency. In most cases, you want the flexibility of ending one
persistency without ending others that are external to it. For example,
ending an application message must not end transaction processing (in
general) because a transaction may include many semi-independent
application messages. That is why we have the three <*-end> messages
now.

If we discover that there are too many persistent "things" that need to
be terminated, we would have to redesign and/or, perhaps, introduce a
meta-message like the one below:

        <end what xid ... [error] reason>

Alex.