IPP> Re: IPP PRO HTTP Connection: close

IPP> Re: IPP PRO HTTP Connection: close

IPP> Re: IPP PRO HTTP Connection: close

Carl Kugler kugler at us.ibm.com
Thu Sep 17 12:14:54 EDT 1998


Re: PWG IPP PRO HTTP Connection: close
Carl Kugler (kugler at us.ibm.com)
Wed, 9 Sep 1998 16:53:39 -0400

I agree that the client and server must accept the Connection: close
header.  I'm wondering how to satisfy the requirement that the client
and server MUST include this header for the last operation in a
sequence of operations.  Specifically, how do the client and server
know, a priori, that the current operation is the last operation in a
sequence (and therefore MUST include the Connection: close
header)?

        -Carl

rturner at sharplabs.com on 09/09/98 02:17:29 PM
Subject: Re: PWG IPP PRO HTTP Connection: close

I tend to follow the saying "Be conservative in what you send, and
liberal in whatyou accept..."Whether the text says MUST or not, IMHO
we should be designing clients and servers to handle a "connection:
close" header whenever it is received and still function normally,
albeit with possibly less performance.  Since I am not working on a
client, I cannot speak for what clients are or will actually do, but I
do think the client end should drive the connection status, whevever
possible.

        Randy

Carl Kugler wrote:

Section 4.1, General Headers, says:
> General Header: Connection "close" only.  Both client and server
SHOULD keep a connection for the duration of a sequence of operations.
The client and server MUST include this header for the last operation
in such a sequence.

Consider the (presumably typical) case of an interactive IPP client
with a user interface.  How is the client to know when the current
operation is the last of a sequence of user-initiated actions?
Apparently, the only safe way to satisfy the MUST (an absolute
requirement of the specification) would be to send "close" after each
user-initiated action.  But this would violate the SHOULD, and is
contrary to the recommendations of "HTTP Connection Management",
http://www.ics.uci.edu/pub/ietf/http/draft-ietf-http-connection-00.txt

Quoting:
> "Authoritative knowledge that it is appropriate to close a
connection can only come from the user.  Unfortunately, that source is
not to be trusted.  First, most users don't know what a connection is,
and having them indicate it is okay to close it is meaningless.
Second, a user that does know what a connection is probably inherently
greedy.  Such a user would never surrender the attention that a
connection to a server implies.

But this is talking about the client actually closing the connection,
not sending a header to the server to signal that the connection will
be closed after completion of the response.  Obviously, the header can
only be sent as part of a request.  Also, "HTTP Connection Management"
says clients SHOULD close connections before servers when possible.
How are you implementing this requirement?

        -Carl

http://www.pwg.org/hypermail/ipp/1225.html



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