100-continue status and HttpSoapClientProtocol (Webservice consumer)

  • Thread starter Thread starter spapelier
  • Start date Start date
S

spapelier

Hi,

I'm writting a Webservice consumer in asp.net 2.0 and facing the
following problem :

1. each time a request to a webservice method is made, a Expect:
100-continue header is sent (I'm ok with that)
2. My weblogic server (which host the webservices) handles that
correctly and send back a 100-continue response.
3. Then my asp.net client send the data and every thing goes well.

(I have the log of the traffic if you need)


But, in some cases (heavy load,...) my WLS does NOT send back a
100-continue after it received the Expect: 100-continue header
(sequence 2).
The point is that despite not receiving the 100-continue response, my
asp.net client send the data (sequence 3) and get stuck until the
timeout because the WLS will not handle the posted data...

My question is how to handle the fact that when I do not receive a
100-continue after posting the header i must abort the request or retry
it ?? HttpSoapClientProtocol shouldn't do that for me ?

Thanks for your reply
Stephane
 
When the WLS server fails to send back a CONTINUE, do you know what the delay
is before the client sends the body?

Also, here is one important question: does this behavior happen only on
the first request (the first for that particular client's process lifetime),
or on any request.


The following states that if a client has never received a 100-continue from
a server (in this case, hasn't received it yet in that process lifetime),
it should not wait for 100-continue before sending the body. This rule is
in place for compatability with servers that incorrectly handle the 100-continue
header.

http://www.w3.org/Protocols/rfc2616/rfc2616-sec8.html#sec8.2.3

"Because of the presence of older implementations, the protocol allows ambiguous
situations in which a client may send "Expect: 100- continue" without receiving
either a 417 (Expectation Failed) status or a 100 (Continue) status. Therefore,
when a client sends this header field to an origin server (possibly via a
proxy) from which it has never seen a 100 (Continue) status, the client SHOULD
NOT wait for an indefinite period before sending the request body. "
 
Thanks for your reply.

Here is a small extract from the traffic sniffed during an incident :

16:22:22.222620000 -> Header POST /ONYX WebServices HTTP
/1.1..User-Agent : Mozilla/4.0(compatible; MSIE 6.0; MS Web Services
Client Protocol 2.0.50727.42)..Content-Type: text/xml;
charset=utf-8..SOAPAction: ""..Host:32.50.32.104:7031..Content-Length:
928..Expect:100-continue...

16:22:22.334617000 -> Ack (without 100-continue)

16:22:22.571806000 -> Body <?xml version="1.0"
encoding="utf-8"?><soap:Envelope>.......</soap:Envelope>

16:22:22.684826000 -> Ack


The problem appears after requesting many times the WLS from the
asp.net (for me it seems random...)

ASP.NET -> WLS : header Expect:100-continue
WLS -> ASP.NET : Ack 100-continue
ASP.NET -> WLS : Body call to the webservice method
WLS -> ASP.NET : Ack

WLS Processing time

WLS -> ASP.NET : 200 data response from a webservice method call
ASP.NET -> WLS : Ack
WLS -> ASP.NET : data response from a webservice method call
ASP.NET -> WLS : Ack
WLS -> ASP.NET : data response from a webservice method call
ASP.NET -> WLS : Ack


ASP.NET -> WLS : header Expect:100-continue
WLS -> ASP.NET : Ack (without 100-continue)
ASP.NET -> WLS : Body call to the webservice method
WLS -> ASP.NET : Ack

And then asp.net is waiting for the timeout (I do not get any trace in
my webservice logs neither in the WLS access.log for the last request).

Stephane
 
Thus wrote (e-mail address removed),
Hi,

I'm writting a Webservice consumer in asp.net 2.0 and facing the
following problem :

1. each time a request to a webservice method is made, a Expect:
100-continue header is sent (I'm ok with that)
2. My weblogic server (which host the webservices) handles that
correctly and send back a 100-continue response.
3. Then my asp.net client send the data and every thing goes well.
(I have the log of the traffic if you need)

But, in some cases (heavy load,...) my WLS does NOT send back a
100-continue after it received the Expect: 100-continue header
(sequence 2).
The point is that despite not receiving the 100-continue response, my
asp.net client send the data (sequence 3) and get stuck until the
timeout because the WLS will not handle the posted data...
My question is how to handle the fact that when I do not receive a
100-continue after posting the header i must abort the request or
retry it ?? HttpSoapClientProtocol shouldn't do that for me ?
Click to expand...

As a workaround, you could disable Expectations by setting
ServicePointManager.Expect100Continue = false;

Cheers,
 
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