Re: [Twisted-Python] web client FileBodyProducer - transfer encoding

31 Jan 2017

      Thanks - that's exactly what I was looking for.

*But note* when using FileBodyProducer(StringIO(json.dumps(~blah))) -- I
still see a content-length in the request header as it's received by
twisted.  Am I correct to assume the request is agnostic...meaning it's
shaped the same for twisted as it is for apache.

Headers({'host': ['localhost:8080'], 'connection': ['close'],
'content-length': ['671'], 'user-agent': ['PassengerTest']})

from twisted.web import server, resource
from twisted.internet import reactor

class Simple(resource.Resource):
    isLeaf = True
    def render_POST(self, request):
        print request.requestHeaders
        return request.content.getvalue()

site = server.Site(Simple())
reactor.listenTCP(8080, site)
reactor.run()

On Mon, Jan 30, 2017 at 4:59 PM, Jean-Paul Calderone <
exarkun@twistedmatrix.com> wrote:
...
On Mon, Jan 30, 2017 at 7:44 PM, Glyph Lefkowitz 
wrote:
...
Gotcha.  I guess what I meant was that you shouldn't care about this at
the application level, but you're talking about an operational concern, not
an application-level concern.
Perhaps this should be a tunable on Agent somehow.  Can you file a ticket?
Well... It *is* sort of tuneable, as you implied earlier.
If you pass an IBodyProducer with a non-None length, Agent will send a
Content-Length header - not use chunked Transfer-Encoding.
FileBodyProducer doesn't know how to determine the length of a StringIO, so
you get chunked with this example.  If you write the JSON to a regular file
and FileBodyProducer(open(the file)) you'll get a Content-Length request.
You could also write a new (trivial) IBodyProducer that does know how to
compute the length of a StringIO.
The documentation doesn't exactly spell this out - but the only reason
`length` is part of the interface is to be able to generate the
Content-Length header.
What would the ticket be?  Expanded documentation to make this behavior
into an explicit guarantee of the interface?  A new toggle somewhere to
force Agent.request into one mode or the other (regardless of the
performance consequences)?
And that stuff you said about proxies before was true ... So even if you
can control this in Agent, you're still not *guaranteed* the server will
see what you send.
Jean-Paul
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Re: [Twisted-Python] web client FileBodyProducer - transfer encoding

Kevin Mcintyre