of SOAP header to describe any new features being extended upon SOAP. A module needs to realize zero or more features. SOAP requires modules to adhere to prescribed rules. Data encapsulation concepts SOAP message Represents the information being exchanged between 2 SOAP nodes. SOAP envelope It is the enclosing element of an XML message identifying it as a SOAP message. SOAP header block A SOAP header can contain more than one of these blocks, each being a discrete computational block within the header. In general, the SOAP role information is used to target nodes on the path. A header block is said to be targeted at a SOAP node if the SOAP role for the header block is the name of a role in which the SOAP node operates. (ex: A SOAP header block with role attribute as ultimateReceiver is targeted only at the destination node which has this role. A header with a role attribute as next is targeted at each intermediary as well as the destination node.) SOAP header A collection of one or more header blocks targeted at each SOAP receiver. SOAP body Contains the body of the message intended for the SOAP receiver. The interpretation and processing of SOAP body is defined by header blocks. SOAP fault In case a SOAP node fails to process a SOAP message, it adds the fault information to the SOAP fault element. This element is contained within the SOAP body as a child element. Message sender and receiver concepts SOAP sender The node that transmits a SOAP message. SOAP receiver The node receiving a SOAP message. (Could be an intermediary or the destination node). SOAP message path The path consisting of all the nodes that the SOAP message traversed to reach the destination node. Initial SOAP sender This is the node which originated the SOAP message to be transmitted. This is the root of the SOAP message path. SOAP intermediary All the nodes in between the SOAP originator and the intended SOAP destination. It processes the SOAP header blocks targeted at it and acts to forward a SOAP message towards an ultimate SOAP receiver. Ultimate SOAP receiver The destination receiver of the SOAP message. This node is responsible for processing the message body and any header blocks targeted at it. Specification The SOAP specification defines the messaging framework, which consists of: The SOAP processing model, defining the rules for processing