Java Reference
In-Depth Information
SOAP XML Payload
A SOAP message is enclosed in a SOAP envelope that contains a SOAP header and a
SOAP body. The SOAP body is mandatory, whereas the SOAP header is optional. The
SOAP message is the basic unit of communication between SOAP nodes. A SOAP node
can transmit, receive or relay a SOAP message. The responsibility of the ultimate destin-
ation is to process SOAP messages according to the standard. A SOAP message traverses
between a SOAP sender and a SOAP receiver. The message path may have SOAP in-
termediary nodes in a distributed computing environment. These SOAP intermediaries are
thought of as 'men-in-the-middle, which can cause significant security problems.
The two major message exchange patterns that SOAP supports are 1) request-response
(in-out) and 2) request (in-only). The first pattern is often used where a SOAP request is
processed and a SOAP response is returned to the SOAP sender node. The second pattern
is used when the SOAP sender has no interest in receiving a response (e.g., notification). A
SOAP response may be returned in an asynchronous mode. For example, a server may take
a long time to process a SOAP request. Instead of waiting for this request to be completed,
a SOAP client may receive a callback when the server completes the processing.
Figure 2-1
. SOAP Message Structure
2.1 Examples of SOAP messages
The following shows SOAP messages in three forms: requests, responses and faults.
