MJ Ray markj@cloaked.freeserve.co.uk writes:
Richard Kettlewell rjk@terraraq.org.uk wrote:
Why? SMTP and NNTP (for instance) have mechanisms for negotiating the use of pipelining; why should a client that doesn't use those mechanisms expect to be able to pipeline safely?
IIRC, SMTP requires an alternating dialogue, but the NNTP spec (like FTP) does not.
The best known implementation of NNTP does indeed require strictly alternating dialogue at certain points. For instance, you can't safely pipeline near MODE READER or AUTHINFO GENERIC.
RFC977 and RFC2980 are silent on the subject both as a general principle and in those two specific cases. Sometimes you have to accept that the spec is really an incomplete description, not a specification.
So, a client should be able to pipeline NNTP or FTP safely with a conformant server, as long as it is happy to handle state change failures earlier in the pipeline when they occur.
I think it's optimistic to expect to use pipelining where it's not explicitly allowed.