Extract MTOM content

Overview

Message Transmission Optimization Mechanism (MTOM) provides a way to send binary data to web services within standard SOAP messages. MTOM leverages the include mechanism defined by XML Optimized Packaging (XOP) whereby binary data can be sent as a MIME attachment (similar to SOAP with attachments) to a SOAP message. The binary data can then be referenced in the SOAP message using the <xop:Include> element.

The following MTOM message contains a binary image that has been Base64-encoded so that it can be inserted as the contents of the <image> element:

<?xml version="1.0" encoding="UTF-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Body>
    <uploadGraphic xmlns="www.example.org">
      <image>/aWKKapGGyQ=</image>
    </uploadGraphic>
  </soap:Body>
</soap:Envelope>

When the API Gateway receives this request, the Extract MTOM Content filter can be used to extract the Base64-encoded content from the <image> element, replace it with an <xop:Include> element, which contains a reference to a newly created MIME part that contains the binary content. The following request shows the resulting MTOM message:

POST /services/uploadImages HTTP/1.1
Host: API Tester
Content-Type: Multipart/Related;boundary=MIME_boundary;
  type="application/xop+xml";
  start="<mymessage.xml@example.org>";
  start-info="text/xml"
  
--MIME_boundary
Content-Type: application/xop+xml;
  charset=UTF-8;
  type="text/xml"
Content-Transfer-Encoding: 8bit
Content-ID: <mymessage.xml@example.org>

<?xml version="1.0" encoding="UTF-8"?>
    <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
      <soap:Body>
        <uploadGraphic xmlns="www.example.org">
          <image>
            <xop:Include xmlns:xop='http://www.w3.org/2004/08/xop/include' 
            href='cid:http://example.org/myimage.gif' />
          </image>
        </uploadGraphic>
      </soap:Body>
    </soap:Envelope>

--MIME_boundary
Content-Type: image/gif
Content-Transfer-Encoding: binary
Content-ID: <http://example.org/myimage.gif>
  
// binary octets for image

--MIME_boundary
Note   Note the following in the resulting MTOM message:
  • The Base64-encoded contents of the <image> element have been replaced by the <xop:Include> element.
  • The <xop:Include> element points to a MIME part using the href attribute.
  • The value of the href attribute corresponds to the value of the Content-ID HTTP header of the MIME part that contains the binary octets of the actual image file.

Configuration

Complete the following fields for the Extract MTOM Content filter:

Name:
Enter an appropriate name for the filter to display in a policy.

XPath Location:
Use an XPath expression to locate the encoded data elements. For example, in the sample SOAP request message above, you would configure an XPath expression to point to the <image> element. For more information, see Configure XPath expressions in the API Gateway Policy Developer Guide.

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