In Page 56 of Martin Kalin's Java Web Services Up & Running, the following point is given:
Here are some downsides of the document style:
• In the unwrapped variant, the SOAP message does not carry the name of the service operation, which can complicate the dispatching of messages to the appropriate program code.
The request XML generated for both wrapped and unwrapped variants are same. I'm not able to understand that why unwrapped style does not carry the name of the service operation. The port types are generated differently for wrapped & unwrapped styles. But the request XML carries the same operation name in the WSDL for both the styles. Request you all to clarify why the unwrapped style SOAP message doesn't carry the service operation name.
For unwrapped style, only the parameters are sent to the service. The drawback is we should not have methods with the same set of parameters. For example, if method 1 has two integers, then method 2 should not have two integers. That will create an ambiguity.
Unwrapped style is for backward compatibility with JAX-RPC.
By default, JAX-WS uses wrapped style.