The Simple Object Access Protocol provides a model for distributed processing assuming that a SOAP message is originated at a particular SOAP sender and is ultimately received by an ultimate SOAP receiver, and in the path of the message there could be zero or many SOAP intermediaries.
This processing model defines how any SOAP receiver should process the SOAP message and applies to a single message only isolating itself from any other.
A SOAP node is any node that participates in the SOAP message path. It can be the initial SOAP node, in which case it is a SOAP Sender, the ultimate SOAP receiver or a SOAP intermediary. Any SOAP node that receives a SOAP message must perform several processes according to the SOAP specification.
While processing a SOAP message a SOAP node performs one or several SOAP roles, each of them are identified by a URI, also known as the SOAP role name.
The following are three SOAP role names in a SOAP message:
Every SOAP intermediare and the ultimate receiver must act upon this Role
SOAP nodes must not act upon this Role
Only the ultimate receiver must act on this Role