Processing SOAP Messages

Determine the set of roles in which the node is to act.
Identify all header blocks targeted at the node that are mandatory.
If one or more of the header blocks identified in the preceding step are not understood by the node then generate a single SOAP MustUnderstand fault and stop processing.
Process all header blocks targeted at the node and, in the case of the ultimate SOAP recipient, the SOAP body.
In the case of a SOAP intermediary, and where the message is to be forwarded further along the message path, remove all SOAP header blocks targeted at the node, and possibly insert new SOAP header blocks.