ietf-nntp MODE STREAM behavior/replacement

[Jeffrey M. Vinocur]

It's becoming clear that the behavior of MODE STREAM, CHECK, and TAKETHIS 
is not well specified by existing practice.  In addition, some minor 
changes could be very useful, and while these changes can probably be made 
without breaking anything, it makes me feel icky.  So here's the question:

Do all existing clients send MODE STREAM before using CHECK and TAKETHIS?


If they do, then we can imagine having MODE STREAM invoke some sort of 
backwards compatibility mode...?


And if that is an option, let's figure out what changes we want to make.  
I definitely like Clive's proposal for additional TAKETHIS responses:

> Can I suggest that we say a server MAY respond with 431 or 438 to a
> TAKETHIS command, with 439 meaning "either of these but I'm not saying
> which". That allows future servers to be more helpful, while existing
> clients will see 43x and just treat it as an error. If this change isn't
> made, make it clear that 439 means that CHECK might return 431 or 438, 
> so retrying might or might not be sensible.

(Regarding the last sentence -- I doubt any implementation retries in 
response to a 439, actually.  Just a hunch.)


-- 
Jeffrey M. Vinocur
jeff at litech.org