Chapter 8. Sending Binary Data Using SOAP with Attachments

SOAP messages generally do not carry binary data. However, the W3C SOAP 1.1 specification allows for using MIME multipart/related messages to send binary data in SOAP messages. This technique is called using SOAP with attachments. SOAP attachments are defined in the W3C’s SOAP Messages with Attachments Note.

The WSDL extensions used to define the MIME multipart/related messages are defined in the namespace http://schemas.xmlsoap.org/wsdl/mime/.

In the discussion that follows, it is assumed that this namespace is prefixed with mime. The entry in the WSDL definitions element to set this up is shown in Example 8.1, “MIME Namespace Specification in a Contract”.

xmlns:mime="http://schemas.xmlsoap.org/wsdl/mime/"

In a default SOAP binding, the first child element of the input, output, and fault elements is a soap:body element describing the body of the SOAP message representing the data. When using SOAP with attachments, the soap:body element is replaced with a mime:multipartRelated element.

The mime:multipartRelated element tells Apache CXF that the message body is a multipart message that potentially contains binary data. The contents of the element define the parts of the message and their contents. mime:multipartRelated elements contain one or more mime:part elements that describe the individual parts of the message.

The first mime:part element must contain the soap:body element that would normally appear in a default SOAP binding. The remaining mime:part elements define the attachments that are being sent in the message.

MIME multipart messages are described using a mime:multipartRelated element that contains a number of mime:part elements. To fully describe a MIME multipart message you must do the following:

Example 8.2, “Contract using SOAP with Attachments” shows a WSDL fragment defining a service that stores X-rays in JPEG format. The image data, xRay, is stored as an xsd:base64binary and is packed into the MIME multipart message’s second part, imageData. The remaining two parts of the input message, patientName and patientNumber, are sent in the first part of the MIME multipart image as part of the SOAP body.

<?xml version="1.0" encoding="UTF-8"?>
<definitions name="XrayStorage"
    targetNamespace="http://mediStor.org/x-rays"
    xmlns="http://schemas.xmlsoap.org/wsdl/"
    xmlns:tns="http://mediStor.org/x-rays"
    xmlns:mime="http://schemas.xmlsoap.org/wsdl/mime/"
    xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
    xmlns:xsd="http://www.w3.org/2001/XMLSchema">

  <message name="storRequest">
    <part name="patientName" type="xsd:string"/>
    <part name="patientNumber" type="xsd:int"/>
    <part name="xRay" type="xsd:base64Binary"/>
  </message>
  <message name="storResponse">
    <part name="success" type="xsd:boolean"/>
  </message>

  <portType name="xRayStorage">
    <operation name="store">
      <input message="tns:storRequest" name="storRequest"/>
      <output message="tns:storResponse" name="storResponse"/>
    </operation>
  </portType>

  <binding name="xRayStorageBinding" type="tns:xRayStorage">
    <soap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http"/>
      <operation name="store">
      <soap:operation soapAction="" style="document"/>
      <input name="storRequest">
        <mime:multipartRelated>
          <mime:part name="bodyPart">
            <soap:body use="literal"/>
          </mime:part>
          <mime:part name="imageData">
            <mime:content part="xRay" type="image/jpeg"/>
          </mime:part>
        </mime:multipartRelated>
      </input>
      <output name="storResponse">
        <soap:body use="literal"/>
      </output>
    </operation>
  </binding>

  <service name="xRayStorageService">
    <port binding="tns:xRayStorageBinding" name="xRayStoragePort">
      <soap:address location="http://localhost:9000"/>
    </port>
  </service>
</definitions>