SOAP messages with attachments - Working with types and type mappings
By default, attachments are passed into the Web Services Invocation Framework (WSIF) as DataHandler objects. If the part on the message that is the DataHandler object maps to a <mime:part> tag in the WSDL, then WSIF automatically maps the fully qualified name of the WSDL type to the DataHandler class and sets up that type mapping with the SOAP provider.
In your WSDL, you might have defined a schema for the attachment (for instance as a binary type). WSIF silently ignores this mapping and treats the attachment as a DataHandler object, unless you explicitly issue a mapType() method. WSIF lets the SOAP provider set the MIME content type based on the type of the DataHandler object, instead of the type attribute specified for the <mime:content> tag in the WSDL.
See AlsoPassing SOAP messages with attachments using WSIF
SOAP messages with attachments - Writing the WSDL extensions
SOAP messages with attachments - Passing attachments to WSIF