[cups-devel] Expect 100-Continue

[David Valleau]

Hello all,

I've come across some issues created by the "Expect: 100-Continue" message
in some ipp requests. It seems that not all printers respond to this field
in the same way.

I looked into how request.c handles the use of this header field and it
seems that it is no longer being used in a useful way.

To my understanding, the use of this field is to verify whether a server is
going to accept a large request before actually sending the body of the
request. And only send the rest of the message once the server has verified
that is going to accept it. This is used in order to save network bandwidth
and avoid wasting time sending a large message if the server is simply
going to ignore it.

However, what I see in the cups code is that this field is bundled with the
actual message body and they are sent all together anyways.

Is there any reason to still use this field anymore or would it be possible
to remove it?

Thanks,
David