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There are two SOAP message styles:

The Document literal form means that the SOAP request (data on the wire) looks and feels like an XML document. Whilst the RPC literal form is an XML representation of a method call (and sending parameters).

The wisdom is that document literal forms are easier to read (from a programming/parser POV) than an RPC call, so it seems to be the preferred style. Its easier to read programmatically so does not require lots of libraries to implement.