如何从WCF SOAP响应中提取二进制附件？

Question

I'm writing a .Net 3.5 solution which is consuming a 3rd party WCF web service. The proxy client for the SOAP service was generated by VisualStudio as a service reference.

A SOAP response from the service includes attachments in the data, as I can see it in fiddler. The attachments have a href field which points to a CID reference. The proxy client that VS 2012 has created when returning the object which includes the attachments doesn't include any binary data, but it does include the href field with the CID reference in it.

As captured using fiddler, this is the SOAP response attachment data including the cid:xxxx ref:

<attachments>
      <cmn:attachment href="cid:52b2d8a50035921e80bf1540" len="309" name="DOC1.rtf" type="application/rtf" xmime:contentType="application/rtf"/>
</attachments>

And in the raw output in fiddler, the attachment data can be seen with the matching cid:xxxx ref:

------=_Part_22_12445037.1389617382038
Content-Type: application/rtf
Content-Location: DOC1.rtf
Content-ID: <52b2d8a50035921e80bf1540>
Content-Transfer-Encoding: binary

{\rtf1\ansi\ansicpg1252\deff0{\fonttbl{\f0\fnil\fcharset0 Calibri;}}
{\*\generator Msftedit 5.41.21.2510;}\viewkind4\uc1\pard\sa200\sl276\slmult1\lang9\f0\fs22 Doc 1\par
\par
Test information inside an attachment for KM retrieval.\par
\par
Here's something else I've written for use in testing.\par
}

Here is a screenshot of the available fields from the returned object:

How do I access that attachment data so I can actually download the file?

Answer 1

Normally with WCF and SOAP, your file binary is encoded as a base64 string somewhere in your response, however I don't see in what you've posted here the kind of long data string I'd be expecting.

If what you're showing here is just the header from the response, you might check the body of the response message,too, since the header has a size limit, but the body the message doesn't - it's therefore the likely place for your binary payload.

Answer 2

Wouldn't it be easier to return a byte[] in one of the entities you are returning, and then work from that on your client to reconstruct the file?

Are you using MTOM? Because WCF does not support SwA (Soap with attachments) out of the box.

Answer 3

Turns out that the issue was due to the way the 3rd party API was returning the response, the MTOM data was not correctly formatted so WCF was ignoring the binary data.

The way I got around this was by using a bespoke class which basically uses an HttpRequest to talk directly to the web service and extract/parse the binary data out of the response.