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Attachments in SOAP messages

You can send and receive SOAP messages that include binary data (such as PDF files or JPEG images) as attachments. Attachments can be referenced (that is, represented explicitly as message parts in the service interface) or unreferenced (in which arbitrary numbers and types of attachments can be included).

A referenced attachment can be represented in one of the following ways:

• MTOM attachments use the SOAP Message Transmission Optimization Mechanism (http://www.w3.org/TR/soap12-mtom/) specified encoding. MTOM attachments are enabled through a configuration option in the import and export bindings and are the recommended way to encode attachments for new applications.

• As a wsi:swaRef-typed element in the message schema

  Attachments defined using the wsi:swaRef type conform to the Web Services Interoperability Organization (WS-I) Attachments Profile Version 1.0 (http://www.ws-i.org/Profiles/AttachmentsProfile-1.0.html), which defines how message elements are related to MIME parts.

• As a top-level message part, using a binary schema type

  Attachments represented as top-level message parts conform to the SOAP Messages with Attachments (http://www.w3.org/TR/SOAP-attachments ) specification.

  Attachments represented as top-level message parts can also be configured to ensure that the WSDL document and messages produced by the binding conform to the WS-I Attachments Profile Version 1.0 and the WS-I Basic Profile Version 1.1 (http://www.ws-i.org/Profiles/BasicProfile-1.1.html).

An unreferenced attachment is carried in a SOAP message without any representation in the message schema.

In all cases, except MTOM attachments, the WSDL SOAP binding should include a MIME binding for attachments to be used, and the maximum size of the attachments should not exceed 20 MB.

To send or receive SOAP messages with attachments, use one of the web service bindings based on the Java™ API for XML Web Services (JAX-WS).

• How to choose the appropriate attachment style
  When designing a new service interface that includes binary data, consider how that binary data is carried in the SOAP messages that are sent and received by the service.
• MTOM attachments: top-level message parts
  

  You can send and receive web service messages which include SOAP Message Transmission Optimization Mechanism (MTOM) attachments. In a MIME multipart SOAP message, the SOAP body is the first part of the message, and the attachment or attachments are in subsequent parts.

• Referenced attachments: swaRef-typed elements
  

  You can send and receive SOAP messages that include attachments represented in the service interface as swaRef-typed elements.

• Referenced attachments: top-level message parts
  

  You can send and receive SOAP messages that include binary attachments that are declared as parts in your service interface.

• Unreferenced attachments
  

  You can send and receive unreferenced attachments that are not declared in the service interface.

Web service bindings