Re: [core] Stateless proxy and Request-Tag

[Jim Schaad <[e-mail]>]

If it is a fetch then it has payload

-----Original Message-----
From: 'Christian Amsüss' <[e-mail]> 
Sent: Thursday, October 31, 2019 7:51 AM
To: Jim Schaad <[e-mail]>
Cc: Core WG mailing list <[e-mail]>
Subject: Re: [core] Stateless proxy and Request-Tag

> Isn't this the ETag not Request-Tag?

This is about the server knowing which response to send back out. In the
later phase of a Block1+2 operation, there is neither Block1 nor a payload
sent with the requests that pull out the rest of the response body. The
server, in the proxy-less case, would rely on the endpoint to know which
operation those belong to, and would need a Request-Tag to tell them apart.

A stateless proxy couldn't tell whether those later Block2 come from the
tail of a Block1+2 operation or from a Block2-only one, so it would send a
Request-Tag.

(I originally thought it could tell that it's not definitely not a
Block1+2 follow-up if there is a non-empty payload in the Block2:>0
requests, but reading RFC7959 Section 2.4 again -- is there, at all?
There's no example of a non-zero-but-non-block1-either exchange in the spec;
"the requester may retrieve additional blocks of the resource representation
by sending further requests with the same options as the initial request and
a Block2 Option giving the block number and block size desired" but doesn't
tell about payload. I feel I should know that for certain but am embarassed
I don't).

KR
c

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