How can I tell when a WCF operation is being called

Question

I have a WCF operation which is like this,

public bool SubmitDocument(byte[] document)

So the idea is that the caller will serialise a document, and call the operation above. It then gets put into our database.

I am trying to understand the internal workings of WCF, so when someone calls the operation above it seems logical that all of the byte[] data needs to be sent to the server before the actual operation is called.

Is there a way to 'log' when that data starts being uploaded to the server, and also catch an error if that fails part way through? I am having a problem with documents that are about 4mb failing part way through and my WCF service doesn't even register that someone is trying to call that operation.

I have increased the upload size limit like this,

<wsHttpBinding>
    <!-- The upload limit should be 5 Mb, rounding up to 6 Mb just to be sure -->
    <binding name="CarWebserviceBinding" maxReceivedMessageSize="6291456">
      <security mode="None">
      </security>
      <!-- The upload limit should be 5 Mb, rounding up to 6 Mb just to be sure -->
      <readerQuotas maxArrayLength="6291456" />
    </binding>
  </wsHttpBinding>

The problem overall is that a third party calls the WCF operation above (SubmitDocument) and the document never makes it to our end if it is over 4Mb.

BTW, WCF doesn't have web methods. It has operations. This is the industry-standard term. — John Saunders, Mar 16 '11 at 00:27

score 3 · Answer 1 · edited May 23 '17 at 10:33

3

You are exceeding the size of the default buffer size for WCF messages. You probably need to learn about TransferMode Streamed. There is a question about it here WCF HttpTransport: streamed vs buffered TransferMode

edited May 23 '17 at 10:33

Community

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answered Mar 16 '11 at 00:05

Darrel Miller

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I have increased the limit, but I am probably doing it incorrectly. I have updated my question. – peter Mar 16 '11 at 00:08
peter Sorry, I'm not familiar at all with wsHttpBinding. Looks like enabling tracing is probably your best next step. – Darrel Miller Mar 16 '11 at 00:16
do you mean that exceeding the buffer size will cause a 401 error? – John Saunders Mar 16 '11 at 00:26
@John That would be an interesting effect eh! No, when I originally answered the question, the OP had not included details about the 401 message. – Darrel Miller Mar 16 '11 at 01:26

peter · Accepted Answer · 2011-03-18T00:59:43.510

2

I found the answer here,

http://social.msdn.microsoft.com/Forums/en-US/wcf/thread/f6541134-2e08-4eb9-987b-2158fb99b403

So there are various WCF limits which I had already handled correctly like this,

<wsHttpBinding>
  <!-- The upload limit should be 5 Mb, rounding up to 6 Mb just to be sure -->
  <binding name="CarWebserviceBinding" maxReceivedMessageSize="6291456">
    <security mode="None">
    </security>
    <!-- The upload limit should be 5 Mb, rounding up to 6 Mb just to be sure -->
    <readerQuotas maxArrayLength="6291456" />
  </binding>
</wsHttpBinding>

BUT what I HADN'T done was this,

<system.web>
  <httpRuntime maxRequestLength="16384" /> <!-- 16MB -->
</system.web>

IIS has a default limit of around 4MB for any http requests that come in. The above settings overrides that limit.

Another thing to mention is that I added this to my web.config to turn on tracing,

<system.diagnostics>
  <sources>
    <source name="System.ServiceModel" switchValue="Information, ActivityTracing" propagateActivity="true">
      <listeners>
        <add name="traceListener" type="System.Diagnostics.XmlWriterTraceListener" initializeData="c:\logs\Traces.svclog" />
      </listeners>
    </source>
  </sources>
</system.diagnostics>

And in the error log turned up the error,

CommunicationException - Maximum request length exceeded

edited Mar 18 '11 at 00:59

answered Mar 17 '11 at 22:12

peter

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And you're saying that when you added the `maxRequestLength`, you stopped getting 401 errors, and when you take it out again, you get 401 errors again? – John Saunders Mar 17 '11 at 22:20
Yes. Well the 401 thing is hard to comment on because those error logs came from a different company who are using our WCF service. I.e. I cannot see their code, and thus understand why it failed like that. – peter Mar 17 '11 at 22:37
What I can say for sure though is that when a person uploaded a document of size 4086kb to a website (which in term calls our WCF service) it never appears at our end without the setting, and with the setting it appears at our end no worries. – peter Mar 17 '11 at 22:38
I believe you when you say the setting makes it work; but your question says that the problem was a "401", and this setting wouldn't help with that at all. – John Saunders Mar 17 '11 at 22:47
Mate, I have removed the 401 part of the question. It is not really relevant. A separate company told me about the 401 errors, so they could have been something else. It is difficult for me to get accurate information from a third party, I don't see their code, and only get to talk to them occasionally using skype chat. Trace logging at my end told me that the problem was definitely 'Maximum request length exceeded'. – peter Mar 18 '11 at 01:08

How can I tell when a WCF operation is being called

2 Answers2