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How can I handle an HT_UPGRADE 101 Message?

From: Stuart Myles <smyles@wsj.dowjones.com>
Date: Thu, 25 Feb 1999 16:08:28 -0500
Message-ID: <36D5BBCC.3B190C96@wsj.com>
To: "www-lib@w3.org" <www-lib@w3.org>
CC: Stuart Myles <smyles@wsj.dowjones.com>
I am trying to use libwww to access an application server that
requires a somewhat modified version of HTTP/1.1.  As part
of this effort, I need to understand how to handle 101 response
codes, i.e. "Switching Protocols" messages.

In particular, for performance reasons, I need to tell the server
to switch to its "optimized header" mode.  This is meant to work
as follows:

1. I send it a request which also contains a header requesting the
  optimized header mode.
2. The server returns a 101 "Switching Protocols" message (to
acknowledge
  my optimized header mode request).
3. It then returns another response, which is the response to my first
query.
4. My client and the server then proceed to exchange requests and
responses,
  all with the optimized headers.  (In fact, since we are using HTTP 1.1

style
  pipelining of requests, I can send the subsequent requests before the
server
  responds to my first request).

My question is - how can I handle the 101 Switching Protocols message?

At present, I send the request and the 101 message gets treated as an
Error that terminates my request.  Consequently, when the actual
response to
my query comes along, it gets discarded as bad data.

I've figured out that the HTTPInformation function (in HTTP.c) is
determining
that 101 is a "Switching Protocols" message.  And that the "stream_pipe"

function is the one that calls HTTPInformation.  Interestingly, there is

a comment
just before the call to HTTPInformation:

        /*
        **  If it is a 1xx code then find out what to do and return
until we
        **  get the next code. In the case of Upgrade we may not get
back here
        **  at all. If we are uploading an entity then continue doing
that
        */
        if (me->status/100 == 1) {
            if (HTTPInformation(me) == YES) {

"In the case of an Upgrade we may not get back here at all".  I guess
this
means that there is something that I can do to handle this Upgrade
message,
but I am at a loss to know what it is I'm meant to do!  I've tried
looking
for any references to HT_Upgrade or 101 anywhere in the sources or
examples, but I can't find any.

Can anyone give me any clues as to how I could handle this type of
message?  Do I need to create a new Protocol object?

Thanks in advance for any help!

Stuart
--
Stuart Myles -- smyles@wsj.com -- 609-520-7147 -- http://wsj.com
Received on Thursday, 25 February 1999 16:00:46 GMT

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